 Welcome everyone to the National Academy of Sciences, Water Science and Technology Board, Beezer, I always get it wrong, the earth sciences or resources, I should have written it down. Annual, spring annual meeting, we're doing a joint meeting this year. And my name is Kathy Kling, I am the chair of the Water Sciences Technology Board, along with Isabel Montañez, who is the chair of Beezer. So I don't get the acronym wrong. Are delighted to welcome you. We are tackling the topic of the future of managed aquifers. And there was a really lively and engaging conversation yesterday. I hope many of you were able to join us. Today we do round two of that topic. Next slide please. I'm gonna be giving you just a very brief introductions as we move on to our next slide please. To give, sorry, a little bit of technical slide changing. We'll get it. There we go. So welcome again. We, a very brief introduction for those of you who are not aware of the National Academy's mission. We are the permanent source of expert evidence-based objective advice on science, engineering, and health matters for the nation. In short, we view ourselves and are the scientific advisors to the country. In that capacity, we seek to inform policy with evidence. We seek to spark innovation and progress in science and the wellbeing of society. Always looking to confront challenging issues that are coming on down the pike, particularly things where we can have direct and clear benefits for all of society. Next please. You're gonna flash up here the names of the members of our two boards, the Water Science and Technology Board. As you see, I am the chair. There is bios on all of the members in the documents on online and in the briefing materials. You're welcome to peruse those. Next slide. And as I mentioned, Isabel Montañez is the chair of the Board on Earth Sciences and Resources, aka Beezer. And this is the group of her board members. Again, the bios are available online. Next slide. We very much appreciate the funding and support of our sponsors without our sponsors. We could not have meetings such as this one and these meetings provide a core level of capacity for us to do planning, to lift up the goals and products of the Academy. The Department of Energy, NASA, the National Science Foundation and the US Geological Survey are key funders. And again, we appreciate very much their ongoing support. Next please. Today, we are gonna retake up an issue that we started discussion of yesterday. We are interested in these meetings about exploring topics of relevant events to water sciences, water resources and earth science communities. We always have a focus on how the National Academies can help contribute to problems and the necessary science. In the capacity of our meeting today, managed aquifer recharge is our topic and we'll be focusing our efforts, of course, to do those for more topics. Next please. And just in my discussion with a very brief introduction to the agenda, I'm gonna pass this over to Nelia Dunbar for the next session, which will be technical considerations for Maher, a panel discussion. Nelia is the Director of the New Mexico Bureau of Geology and Mineral Resources. She's gonna introduce her panel and topics. After that, we will turn to a broad discussion on institutional considerations and that will be led by Vincant Lakshmi, who is a member of our board. If you have questions, please put them in the Q&A. And with that, I'll pass it to Nelia. Thanks, Kathy. I'm really looking forward to this next session, which is gonna run for 75 minutes and is going to include four 15-minute talks that are gonna focus on the broad topic of technical considerations for managed aquifer recharge. Following the four talks, we'll have a 15-minute Q&A session. And I will alert each speaker when they have three minutes left of their 15-minute time slot. So to introduce the first speaker, we have Claudia Fount, who is the Program Chief for Groundwater Availability and Use section at the USGS California Water Science Center in San Diego. So Claudia, you can go ahead and start. Hi, thank you. So I'm just gonna try to share my screen. That work? Yep, you're on. Okay. So I'm gonna talk about some of the technical considerations of managed aquifer recharge, oriented towards some of the work that we've been doing in the US Geological Survey in California and the desert Southwest. John has been doing a lot of the work that we have done in the deserts and really has been looking at the role of science and managed aquifer recharge. And together with other scientists, feel that the science comes in and is an important part from looking at well bore scales all the way up to project implementation. There's physical and chemical issues as well as base and scale evaluation things. And I'm gonna go through some of these pieces. In the examples that I'll show, I'm gonna look at some of the things with methods, which is usually governed by the type of aquifer, the topography, the land use, the ambient water quality, and then intended uses of the recovered water. Some of this was brought up in one of the panel discussions yesterday. The location for the managed aquifer recharge is often determined by the method and where available infrastructure is to get water into the aquifer, whether this is natural as like stream channels or man-made spreading funds. The geology has a very important role. The types of deposits that the water goes through, whether they're coarse grained soils and the unsaturated zone are all necessary for like infiltration. If you're infiltrating water from above the ground as opposed to injecting, bedrock aquifers also may necessitate injecting. I'm gonna talk a little bit about flood mar, but not quite, not a lot because Helen, I'm sure we'll be talking quite a bit about flood mar and then some touch on some issues with water quality, with the soils and the aquifer natural, filtering and purifying water and actually absorbing things like arsenic in places, a little bit on barrier wells that keeping seawater intrusion at bay, some of the deposits on aquifer materials, the need to think through if you're using injection, corrosion and crushing of well screens. And particularly with flood mar and in agricultural fields, sometimes referred to as ag mar, the leaching of nitrates or salts becomes an important part of the equation. Physical and chemical issues at various sites are really important. Sometimes the mobilization of arsenic by low ionic strength recharge water occurs and this can sometimes be a positive and a negative. The arsenic can be absorbed by some of the different deposits in the ground and the arsenic absorbed as it infiltrates through the ground. Mineral, weather and cork coatings and dissolution, a change through this addition of water must be considered along with really looking at the redox, the pH and the ionic strength. If you think in a broader scale, California has kind of three major reservoirs. The snowpack is one of our big reservoirs where we count on per storing water, the traditional manmade reservoirs and then the groundwater system. And if you look at the relative scale of the California Department of Water Resources estimated that we have about 15 million acre feet in snowpack, 50 million acre feet. But the groundwater system has a much larger amount in room for storage. And this is becoming more and more important as we look at becoming sustainable in our groundwater management in California. One of the other things that makes California really unique and more extreme than parts of the US is the climate. It's very variable and it's well known for this. This climate change is only expected to exacerbate this with more flooding. So water managers are really eyeing ways to capitalize and are already these extremes by harnessing the available waters and redirecting them into the per shocker. Done a lot of work with the Water Replenishment District of Southern California. Bill Alley talked about this yesterday where the picture in the lower right shows one of the spreading ponds in the upper parts of the basin. We've drilled bunches of wells to really look at the water quality and understand the spreading and timing for this recharge. But conjunctive use of water in California has been done for centuries and is how California meets its water demands. And this adjudicated basin has been spreading and recharging water to allow for the continued pumping of groundwater which has caused seawater intrusion in the past. So there's a whole series of injection wells as well. So the managed aquifer recharge has multiple folds in the LA basin to prevent the seawater intrusion that have been induced from pumping near the coast. So they have these barrier systems to protect the coastal aquifer system. And it's also a huge part of the overall groundwater budget. And the goal is to balance the budget and get less dependent on the aqueduct. In the last few years, they've actually been able to not have to use water coming from Northern California and the aqueduct. So changes in storage in this system which is shown in blue is the water spreading and underflow from adjacent recharge areas is the largest part of the ends on the water budget. The greens on the bottom are the pumping that occurs in this basin. So it balances out and does change with the climate. But the storage change shown by the line shows that it goes up and down. And this was at the end of a relatively recent drought period in California. Some of the other things we've do with basin scale evaluation and we had done it with our product definition district as well is looking in Antelope Valley to look at basin scale predictive modeling. Like what happened if there's actually no managed aquifer recharge versus how all the water levels and drawdowns would change with managed aquifer recharge in this end. This shows Antelope Valley with a much larger cone of depression from the pumping without managed aquifer recharge and how it's reduced by the addition of recharge. The Sustainable Groundwater Management Act has been a large piece of legislation that's been prominent in all of the water availability agencies and ground water sustainability agencies coming up with plans to become sustainable. It's focused around undesirable results part of which are storage losses. But most of these plans incorporate some form of managed aquifer recharge to get at balancing their systems. An example from Borrego Valley where they've started implementing some of their plans is a large amount of water level declines in this very coarse grain valley over 120 feet from the mid 1900s to early 2000s made large areas with cones of depression. These are potential storage areas and volumes that could be filled up with groundwater relatively easily because it's very coarse grain. And if you start to look at the unsaturated zone and find areas where there's less fine grain deposits by the water table and look at those with the water table you can narrow in on spots that are very good for potential recharge in the Borrego area has purchased a lot of land in this area to spread water when they do have it available in this desert basin. The Central Valley aquifer system is the one I'm most familiar with and I'll talk a little bit about it. It's one of the things that makes it challenging is its coarse grained and fine grain. These fine grain layers can cause a problem with managed aquifer recharge in a number of ways. If you start to look at the drillers logs these blues are the finer grained areas the yellows and reds are the coarser grain. There's a lot of coarse fine, coarse fine and some of these fine grain deposits are relatively connected. But if you do look at the southern part of the valley and this is where a lot of the larger managed aquifer recharge areas are in the Central Valley it's much coarser grain. So looking at the geology is very important. One of the things with these fine grain deposits that's happened in the Central Valley and it's well known for is subsidence. So a lot of large amounts of pumping have caused large storage losses and large amounts of subsidence. One of the things that subsidence does is as it rearranges the particles you have a permanent loss of storage. So the Central Valley has this large storage loss where we could refill this volume but there's some estimates of up to 30% permanent loss of storage. So we can't refill that volume of that aquifer and that must be considered when thinking of the volumes of the aquifers that are being used to refill, particularly in the Central Valley. The geology does play a large part in the locations for this, the finer grained areas which have less coarse grain source materials have much more subsidence and are less desirable in most places for managed aquifer recharge. So some ways to think about this is you can refill the storage volume if you look at this large groundwater storage loss. There's been a huge amount of historical managed aquifer for recharging the Central Valley. And if you look at it climatically during wetter periods, more water's gone in and this has been done and continues to be done. One of the newer ways of trying to get getting water in the ground is using flood mar. And I'm sure Helen will talk about this. I am not gonna talk a lot about it. It allows you to take the floodwaters and get those waters into the ground. Some areas are better suited for reducing, for getting water into the ground and some are better suited for reducing subsidence. Part of it depends on your bowl of storage or reducing subsidence or both. One of the things that Bridget talked about yesterday that I like to remind people about is it's one big integrated system, the surface water and the groundwater system. When you put the water either in a natural stream bed or even in a pond on the ground to infiltrate or spread on an agricultural field, you would induce this mound and the water can kind of go into the ground and this is what we want for Manitaka for ReChart to get it into the ground. However, Okay, thank you. In some places, the water table rises up enough in nearby areas that you're then having this water that you've put into the ground go back out in these streams. So we have to consider this lots of storage as well for water going back into the streams. So it's an integrated system and the ends for recharge can go out in nearby stream channels. One of the things we've been doing with the Central Valley model is looking at the geology where the suitable indexes for the soils and the underground aqua system. If we develop a suitable ability index for getting water into the ground, define the available water from the floods that are available and then put those into the simulation to see how flood mar and getting more Manitaka recharge in can abate subsidence and increase storage in the valley. This was a simulation that Simon Jankowski who was a Fulbright student did a couple of years ago at looking at optimal flood scenarios to reduce subsidence and the blue areas show the amount of subsidence that was reduced based on different application rates. So it does have some promise from in addition to increasing storage to reducing subsidence. So it's been done in many ways and for decades and can look at historical loss of storage and assume this volume could be filled but just like extracting all the water in an aquifer system is pretty unrealistic. Trying to fill an entire aquifer system is also unrealistic and the subsidence causing this permanent loss of storage cannot be that area of volume of the aquifer cannot be reused. The amount and rate wells can inject and infiltrate and the spreading ponds as well. And silting is a big issue, especially seen and scraping is needed. And I'm sure others will talk more about this and water quality changes are a big effect that needs to be considered. And this is particularly true in wells with the corrosion or orchestration of the screens and or the filling of the gravel pack. It also affects aquifer systems as well and can have pros and cons like the uptake of either nitrates and cleaning of the waters and arsenic and models can be used to help analyze and understand the flow and the water quality interactions as well as the storage changes. So the location is extremely important and stream capture should be thought about and considered. And I think I'm going to stop there. Some of the other slides are more specific about past pathways and things like that that are featured to this as well. Great. Thanks a lot, Claudia. We won't have time for a quick question. So we'll just move on to our second speaker who's Helen Dahlke and she, Helen is an associate professor in integrated hydrologic sciences at the University of California, Davis. Thank you very much. If you could give me remote control of my slides, please. They're working on it. Here we go. Thank you very much. Thank you for the introduction, Nylia. And I'm honored to be here today. As you can see, I've picked a somewhat controversial title in my presentation, but I think we have to remind ourselves that agriculture shares a lot of responsibility for groundwater overdraft in the United States and worldwide. But I think it can also be a solution to the problem by providing spreading grounds for intentional recharge of groundwater. In this presentation, I'm going to provide a high level overview of a relatively newish form of managed aquifer recharge where we fled farmland. Mainly in the winter with stormwater or flood flows to recharge groundwater aquifers. Let's see if it's advancing. Here we go. Okay. So yesterday, Bridget Scanlon gave an overview on the state of groundwater basins within the United States and the Central Valley alluvial aquifer system in California, which supports one of the largest agriculture economies in the world has been steadily depleted over the last century, reaching about 160 million acre feet of unsustainable groundwater withdrawal over the last century, of which about 68% is occurring in the Tulare Lake Basin. In 2004, as Claudia just mentioned, the California Legislator passed the Sustainable Groundwater Management Act, which requires overdrafted groundwater basins to achieve balance by 2040 and to address undesirable results, including loss in groundwater storage, seawater intrusion, land subsidence, degraded groundwater quality and of course associated impacts on groundwater dependent ecosystems. In California, just as in many other groundwater dependent regions, we ask ourselves, how do we remedy groundwater overdraft of about two to four million acre feet per year in a changing climate? In California, this problem spreads over about 18,000 square miles in the Central Valley and is to 80% created by agricultural pumping. And so the answer is that actually many water managers are turning increasingly to groundwater recharge of the 127 groundwater basins in the Center Valley. 21 have been classified as critically overdrafted, shown in orange in the map on the right. And most of them are located within the San Joaquin Tulare Lake Basin. If you look at groundwater sustainability plans submitted in this region, you will find that most of them actually plan to address the existing overdraft with a variety of supply and demand solutions, but most notably, almost 50% is thought to be addressed by groundwater recharge and only 20% by demand management. Water available for recharge is dependent on California's climate, which really has a high degree of year to year and within year precipitation variability, as you can see here by the coefficient of variation in the upper left graph. And one also needs to know about California that the total annual precipitation we get only comes from a relatively few storm events, particularly these big landfalling atmospheric rivers which can contribute 30 to 60% of the annual precipitation about five to 15 days. So storms are short, intense and can actually cause localized flooding. And so landowners and water districts look increasingly at these high magnitude flows. Here defined as flows above the 90th percentile to support extension of groundwater recharge efforts. And since most surface water is already legally allocated to in-stream flows or beneficial uses, in 2017, we have published a study that actually shows that most of these flows are occurring only for about 10 to 30 days and only every other year. And in the Southern Central Valley, this might only be every seven or eight years. So how do we capture these large amounts of water in the short time we need a large scale approach? California is one of the most complex surface water conveying systems in the world. We have reservoirs that capture water in the winter, release it to rivers and canals. And so through this conveying systems, flood flows can be diverted onto farmland to recharge basins and other working lands. A concept that is known as flood managed aquifer recharge or flood mar widely promoted in California by the Department of Water Resources. It can provide several benefits for ecosystems, including a flat risk reduction, drought preparedness, water quality improvements, and of course climate change adaptation. Recharging flood flows on agricultural land, which we call agriculture managed aquifer recharge, requires buy-in from land owners who farm this land, of course, for food production. Many farmers perceive agmar as an additional financial risk, but many also understand that the recharge could mean staying in business for another decade or two. To address concerns that farmers have, my lab has spent in the last nine years focusing basically on several flood recharge experiments to research several biophysical factors that we need to consider, such as siding of optimal recharge locations, the tolerance of perennial crops to flooding, soil ability to percolate large amounts of water, source water availability, hydrogeology, and of course, conveyance capacity to deliver water. Often however, we see that agmar implementation is not purely a matter of biophysical feasibility, but institutional factors such as costs, incentives, rights and permits often provide a larger obstacle. Another large concern is, which actually directly affects communities relying on groundwater, a strength water source, is the potential of leaching residual nitrate salts and other pollutants into groundwater that is already elevated in nitrate concentrations from decades of fertilizer applications as shown here on the left in red. However, we really think we should look at recharge as an opportunity to improve groundwater quality because targeted and repeated recharge in the source area of public water supply wells could actually help reduce nitrate in drinking water sources by up to 80%. So most recharge programs should be cited in locations where recharge could benefit domestic drinking water supply wells. For low contaminant or clean recharge, site-specific nitrogen management on ag fields will be key, particularly if we use those fields repeatedly for recharge. At many of our Central Valley sites, we have seen similar nitrogen dynamics when flooding farm fields with mountain runoff that is often low in nitrogen concentration. So typically what we see is that in highly conductive soils about 70 to 90% of legacy nitrate stored in the soil is leached within a few hours today's depending on the initial nitrate load. When soils with residual nitrate load are flooded with low nitrogen water, really nitrate leaching is the dominant nitrogen loss pathway and denitrification plays a lesser role. In addition, we find that after flooding, increased soil moisture and toxic conditions often stimulate microbial transformation of organic nitrogen to inorganic ammonium and nitrate, which of course, again, can increase nitrate load in the soil. But we also have other agmar systems in California, particularly along the coast, where the source for water is actually agricultural runoff rich in nitrogen and not low nitrogen mountain runoff. And in these systems, Andy Fisher's group at UCC and the crews has determined that adding a carbon source such as mulch or almond hulls during the recharge provides food for denitrifying bacteria, which then of course maximize denitrification. Based on field research, we have developed several decision support tools and I'm not going to be able to show you all of them, but I wanted to highlight this one here, the Soil Agriculture Groundwater Banking Index, a web tool that uses soil survey data to assess soil suitability for groundwater recharge here expressed as the, or through the SACB rating, ranging from excellent in green to very poor in dark red. And so this ranking uses five different factors, deep percolation, wood zone residence time, topography, chemical limitations and soil surface conditions. And it's based on a Google map platform so you can enter an address and find your location to figure out what suitability your soil has. So far, SACB actually has been a pretty good predictor of site suitability. At some sites that are rated as good or excellent, we were able, for example, to recharge 28 feet with minimal crop loss. Other sites, however, rated as moderately poor or poor showed low infiltration rates of less than one inch. You can see those here in orange. And often this is also for those soils, we also saw a more pronounced impact on yield. So soil suitability is often a good predictor of crop response under continuous flooding. And I wanted to mention that we have now also started to explore flooding agricultural fields planted with perennials such as citrus with secondary treated wastewater to explore whether these act fields could be used for soil aquifer treatment and other more type in places such as Israel where we increasingly have difficulty finding actual land for designated infiltration basins. So instead of a conclusion slide, I'm going to end my talk with this note. Flooding farm fields for groundwater recharge is not going to be a silver bullet that will end groundwater depletion. And we should rather adopt it as one of the many tools to address a growing problem. And to illustrate this, I'm going to use this figure here, which is showing high magnitude flow availability across different water year types. So ranging from critically dry to wet years. And so in California, many water districts as already mentioned have infiltration basins which they have used for decades to recharge surplus water whenever it was available. But often these facilities have a limited capacity and actually run full on the days when we have extra water available. So many districts are now looking towards expanding their recharge capacity to address overdraft by buying land for designated recharge basins. But in the Southern Central Valley, when surplus water is really only available every other year, you have to consider the capital costs of obtaining new land for basins. And that cost needs to be weighed against the use of those facilities. In California, we have land, okay, in California we have land prices that range somewhere between $30,000 to $40,000 per acre. So you quickly really look at a bill of $1 million for a 30 acre basin. And so in those regions, I'm convinced that flood more or flooding form fields provides a really valuable option to capture thousands of acre feet of water during those rare wet years that we only see once in a while. And with that, I'd like to thank you for your attention and leave you with a couple of our references and papers that we've published on this topic. Thanks. Thank you very much, Helen. And I think we'll skip the questions for now and go on to the next talk. And the next speaker is Justin Mattingly. And he's gonna be joining us in person in the room here. So while he's getting set up, I'll introduce him. Justin is with the Water Reuse Program in the Office of Water at the United States EPA. Okay, yeah, just mic stands on for sure. Sorry about that. Thanks everyone, my name is Justin Mattingly with a relatively new program at EPA, the Water Reuse Program really only started about a year and a half or two years ago. But really I'll be talking about managed aquifer recharge and recycled water and talking about the issues that are really endemic to recycled water as in what it takes to go from wastewater to having water that's actually of a sufficient quality for application in aquifer recharge. Next slide, I guess. You have to go two slides ahead. I don't need this first slide. So the first thing is, okay, why pursue water reuse? A lot of this is pretty germane to everyone in the room here, but there are some other things I'll mention real quick. First off, wastewater is generated in proportion to urban water demand. If you have an urban center that has high amount of urban water demand, they therefore have a corresponding amount of wastewater generated. So essentially wastewater, municipal wastewater is generated in places where there is demand for pollutable water. This isn't a case of where your supply and demand, at least spatially, are separate quite a bit. Now, obviously with aquifer recharge, you need to have a suitable groundwater basin. That spatially, that may not 100% align, but again, we're not talking about the need to pump water hundreds of miles away to a place where there's demand. It's a local and climate resilient source of water. Certainly the amount of wastewater available can go down in times of drought as people do invest in more efficient practices, but even then you still are gonna have a certain amount of wastewater available for treatment and reuse. It is less energy intensive than some alternative supplies. Yesterday we mentioned the energy demand in imported water in California, but you also need to look at other alternative supplies. And a big one obviously is desalination. It is a source of interest in places like California, Florida, Texas, but really desalination does have a higher energy demand than water reuse. Even though some reuse applications can have a decent energy energy demand, you need to compare it to other alternative supplies as well, not just sort of traditional surface or groundwater supplies. And then there are the management of the water, such as water quality benefits of wastewater management. For those of you who are here yesterday, you heard Hampton Roads give a talk about how their MAR project is benefiting water quality. That's not just relegated to them. In many cases, this is a bit of a co-benefit. It's not necessarily the primary driver behind a reuse project, but it can be an additional benefit. And this is not just municipal wastewater. This is if you, in capture of stormwater, for example, in places like California, so in California where stormwater can negatively impact beaches, if that stormwater is captured, infiltrated, or just reused inland, that's less runoff, that's less pollution, surface pollution. And again, in California is pursuing reuse quite aggressively. They have a plan to go from about 700,000 acre feet a year in 2015 to 2.5 million acre feet by 2030. This is not just MAR. This is recycled water writ large, but certainly aquifer recharge is a decent, is a good chunk of that amount. Next slide. So wastewater, it's not a clean source of water. There are risks entailed with this. So first I'll talk about microbial risks. And really microbial contamination is the primary acute risk to public health. This is what's gonna get people sick in the short term. Raw municipal wastewater contains high concentrations of pathogens. Really what's most of interest are things like enteric virus, whether it's adenovirus, norovirus, as well as enteric protozoa, Giardia, and Cryptosporidium. And a lot of these are pathogens that are of interest to traditional drinking water sources. They just happen to be present in a much higher concentration in raw wastewater. But fortunately, conventional wastewater treatment, and especially advanced treatment processes can reduce risk and produce water that is protective of public health. And these are both engineered treatment processes as well as natural processes such as soil aquifer treatment. And there is additional research being considered out there on pathogen reduction in subsurface MAR processes. In a lot of cases in terms of regulations and in permitting, that's an area of interest. Typically a lot of the pathogen reduction to meet regulations comes before application to the subsurface. But again, as water moves underground, there is obviously the potential for attenuation and die off of pathogens as well. Next slide. So how is risk determined with these microbial contaminants? And it's a process known as quantitative microbial risk assessment. It's a really complicated process. I could go all day talking about this, but just to give you everyone an idea of what we're actually thinking about here is, it's a series of inputs that go into a model. And what these inputs are, are the concentrations of target pathogens, looking at your source of water, whether it's raw wastewater, secondary effluent stormwater and doing a characterization of the concentrations of those pathogens. Looking at the exposure volume per day and this is a relatively agreed upon value between two and two and a half liters of water per person per day. This is really what people's consumption generally is. And then the different dose response parameters based on those pathogens of interest. And when you take that information and combine it with a risk target and an EPA typically use a risk target of about 10 to the minus four infections per person per year, that you come up with a risk level and then you can come up with, okay, we have a starting concentration of pathogens, how much removal is needed to meet that risk target based on that exposure volume and based on that dose response. And that's how you determine the amount of treatment needed to meet an acceptable risk level. And this is a process that is being actively used at the state level for portable reuse, really for direct portable reuse, but it can be applied into other end uses as well. So next slide. So looking at how we actually quantify pathogen reduction, this is important because there's no date, no one's invented a probe or monitor that can detect pathogens at a low enough level to even matter in terms of public health. There's no monitor available for norovirus, no monitor available specifically for Giardia. So how do you measure reduction? And it's really through what's known as the sort of the log removal framework where each log removal is considered a 90% reduction in overall concentrations. So obviously the more the more logs you have, the cleaner that water is, the fewer pathogens. And the way this works is different unit treatment processes think reverse osmosis, think ozone are assigned different log reduction values based on different operational and monitoring parameters. Usually each process gets no more than six logs. They may be able to be capable of higher, but these values tend to be quite conservative. There is a level of risk built into these values and it's typically capped at about six logs per process. These value assignments can vary state to state. There are certain treatment processes that are well accepted across the board. Others like reverse osmosis, there's a bit more, there's not maybe not 100% consensus quite yet. So a state like Texas and California, they have different ways of assigning pathogen removal for reverse osmosis. But now in terms of what's actually required as of now for portable reuse in groundwater recharge, California has the most detailed water quality criteria as you might imagine. And they require 12 log reduction of virus, 10 of Giardia and 10 of cryptosporidium. So again, looking back at this little chart, I guess flow chart out at the top, I mean, looking at 12 log reduction of virus, that's 99.109 reduction. And it seems like overkill, it seems like a lot, but again, we're dealing with raw wastewater. It's really important to get down to a low level. And this sort of 12.10.10 framework is something that's not used everywhere in the country. I believe Nevada has adopted this. And yesterday, Charles Bach from Hampton Roads, while it's not regulatory in Virginia, they've used this benchmark for the design and operation of their facility as well. So next slide. So looking at chemical risks. Chemicals represent the chronic risks. You're not gonna get sick in a day or two from drinking water that may have an elevated level of chemicals. Long-term, that's when the risks rise. Obviously, there are some chemicals that that can cause acute risks, but in general, chemicals are some of those more chronic risks. And chemicals can come from obviously residential, commercial and industrial sources. These are industrial sources that can come through a municipal pre-treatment program. And there are other pharmaceuticals and personal care products that come from people's homes, all kinds of different things. And obviously, salts can be of a concern as well. That's really regional. Some parts of the country have a greater issue with salts than others. But in terms of treatment, a way to think about chemical control is the different treatment mechanisms. And there's four here that I really mentioned. The first is membrane filtration. This is really size exclusion. Physical removal of chemicals. Reverse osmosis being sort of the classic example of this. There's adsorption technologies. Think of it as like a sponge sort of sucking up chemicals. Oxidation. Ozone is a classic example here, breaking apart chemicals that can then be further broken down by other processes. And then finally, there's a UV photolysis. And what's most important here to think about is a multi-barrier system with multiple mechanisms is what's truly ideal. Not all chemicals are susceptible to the same mechanisms of removal. There are some chemicals that can pass right through a reverse osmosis membrane. But if you have a downstream UV process, you're fine. Essentially, you don't wanna have a treatment system that is overly reliant on a single removal mechanism. So next slide. So performance and chemical surrogates. There are too many chemicals in wastewater to monitor individually, thousands upon thousands. So what a lot of people use is different performance surrogates to evaluate treatment performance. And some of these surrogates can be UV absorbance, conductivity, total organic carbon. And TOC is a very common one, sorry, three minutes, great. That's a very common sort of bulk surrogate for chemicals writ large. And if you, idea being here, if you remove 80, 90% of your TOC, you can be thought of if you're having a corresponding removal to chemicals overall. And finally, there are different bioanalytical tools of interest as well to evaluate mixtures of chemicals. There's been work in California to identify specific chemicals of interest. There are health-based indicators we're looking at, nitrosamines and 1,4-dioxane. And there are performance-based surrogates, one here being sucralose, a very common chemical. It's essentially Splenda. It passes right through biological treatment. And it's really only removed by advanced treatment. But because it's everywhere, because it's really easy to detect, if you can detect removal of sucralose, you can detect removal of a whole suite of other chemicals as well. So instead of monitoring for a several hundred, you can pick a small subset of representative chemicals. So next slide. Now here's the 800-pound gorilla in the room. PFAS can ignore this. PFAS is found in municipal wastewater and it's a concern, obviously, for utilities out there. Concentrations at wastewater treatment plants vary depending on their industrial sources. It's hard to generalize what this might be. Fortunately, PFO and PFAS, they're largely being phased out in favor of some short-chain PFAS. NEPA, we are working on some regulations on PFAS. So next slide. Again, PFAS persists through a lot of conventional treatment processes. But fortunately, there are some advanced processes that do actively remove PFAS. Reverse osmosis, granular activated carbon, two very common mechanisms used in a lot of portable reuse facilities. So these are processes that are being implemented, not just to control PFAS, but for other chemicals as well. So next slide. So how is this actually done in practice? Groundwater augmentation with recycled water. Obviously, spreading grounds. This is the Monteville 4 Bay. We've talked about that throughout the past couple of days. This is really utilizing soil-occurred treatment. And in a lot of cases, tertiary treated wastewater is, in many cases, of sufficient quality, knowing that there is the soil-occurred treatment process that will be available for additional paths in removal. Obviously, very site dependent. Next slide. So injection, this is where you rely more on your engineer treatment. And there's really two basic classes of thought. Reverse osmosis-based treatment. Again, look at this in terms of treatment mechanism. Microfiltration, reverse osmosis, those are both membranes. That's gonna get size exclusion of both pathogens as well as chemicals. Then there's a UV-advanced oxidation process, which is really high-intensity UV light with hydrogen peroxide added. That's both UV-fatalysis as well as oxidation to remove chemicals. On the carbon-based side, you don't have that sort of safety blanket of reverse osmosis. So there's a different suite of processes used. Ozone, your oxidation, biofiltration, that's biological removal of some chemicals. Granular activated carbon, that's your barrier for PFAS. That's essentially your sponge for a lot of chemicals. And obviously then UV-fatalysis. So my last slide is next, actually one more. There's other configurations. That's just sort of a small amount. Now, post-treatment challenges specific to MAR, this is what's most important here is when reverse osmosis is used. Permiate or product water from reverse osmosis is extremely aggressive. It's essentially distilled water. And if you put that underground, it's gonna leach out at anything that's there. Even the actual conveyance pipes from a treatment facility to your injection facility can be ripped apart essentially by RO permeate water. So there is post-treatment stabilization that's necessary. Usually this is done with the addition of lime, quick lime. That's what Orange County uses in California. It's a big balancing act of cost and need here. Obviously you don't wanna put aggressive water in the ground. That's how you get arsenic. That's how you get corrosion. That's not good for anyone. And this is obviously very site-specific depending on water quality and subsurface geochemistry. But this is probably most critical for facilities that use reverse osmosis. And they may not have a choice. Maybe elevated levels in salts, maybe elevated levels in PFAS, but it's almost like having to backtrack a little bit. I mean, my wife lives in Indiana. If you fly to Indiana, you fly to Chicago, you have to backtrack to Indiana. And it's similar with that here with water quality. Sometimes you need to go well beyond and then add back lime and add back other minerals to have a water that's actually compatible with the subsurface. So that's all I have here. The next slide is just basic content information. I'll be here the rest of the day if folks wanna ask more questions. That's it for me. Justin, thanks very much for an interesting talk. And the final presentation in this session is gonna be by David Pine. And David is president of a company called ASR Systems LLC. So David, you're on. Hello, this is David Pine. And I'll be talking to you today about aquifer storage recovery. And let me share my screen here. There we go. So before we get started, wanna make sure that everybody is on the same wavelength. So ASR is the storage of water through a well and a suitable aquifer doing times when water of suitable quality is available and recovery of the stored water from the same well when needed. And we've been doing this now for about 40 years. But for me, it actually started about 1970 as a proposed dissertation topic at the University of Florida, storing water in deep brackish aquifers. That topic was rejected by my committee because it was too practical. So anyway, they assigned me another topic which wasn't of particular interest. So I left them shortly thereafter and went to work. But the idea of storing water deep underground didn't go away. So about eight years later, we were able to assemble state and local funding and build the first ASR project in Florida. And that project was very successful. We basically had, let's see, here we go. Basically, we had a lot of success and won a major national award. And the results or the publicity from that award basically was galvanized the whole ASR market nationwide and subsequently overseas. So now at this point, we have probably at least 600, maybe 700 ASR wells operating in the United States and about 140 ASR well fields in at least 25 states. And it's happening in many other countries as well. So now here's some of the countries that's working in and the lower right hand corner is a picture of that first ASR well and the top is the first ASR well in Australia. So what are the applications of ASR well? There's about 30 of them so far and I'm not gonna talk about all 30 of them but the big ones are seasonal storage, long-term storage and emergency water storage. And if anyone's interested in starting an ASR project, they need to look at these different applications, select those that are most important for them and then move forward from there to develop the ASR program to meet those objectives. So several factors have contributed to ASR global implementation, the growing need obviously driven by climate change and limited opportunities for additional surface recharge and the land availability and cost. But economics has been the main driver for ASR because typically ASR solutions cost less than half of the capital cost and in some cases as little as 10% of the capital cost of alternative sources. So we go to the next slide and you see that there's a broad range of water sources and storage zones utilized for ASR with mostly storing drinking water. Increasingly in recent years, we're seeing more interest in storing highly treated reclaimed water. We're storing rainwater at a couple of sites and groundwater from overlying, underlying or nearby aquifers. We're storing in fresh brackish and saline aquifers, confined, semi-confined and non-confined aquifers and a whole range of geologic settings. And we're also storing water in multiple aquifers on top of the other. So operating ranges up to about 900 meters, storage intervals are up to about 122 meters thick as thin as six meters. We're storing in aquifers ranging very fresh up to seawater. Storage volumes up to about 330 million cubic meters or 270,000 acre feet. Bubble radius is usually quite small. Typically about 300 meters or less. And the largest ASR well is about 8 million gallons a day or 30 mega liters per day. And the well-field capacity is up to about 600 mega liters per day. So what are the primary challenges for the National Academy of Sciences and the scientists out there? Well, the big one is geochemistry. We need to achieve a better understanding than we have right now regarding subsurface, physical, microbial and geochemical reactions. We think we understand them, but on the other hand, we know that there's some things going on down there between the physical, the geochemical and microbial reactions that we don't yet fully understand. Second thing is the hydraulics. We've always assumed that you run a pump test and you get aquifer hydraulic characteristics that you can model. We're increasingly getting the impression that it's not the same during recharge as it is during recovery. So we call this the balloon effect. It's easier to let the air out of a balloon than it is to inflate it. We'll come back to that in a minute. And the big one for this meeting is the effective integration of demonstrated ASR experience with published peer-reviewed science. We have a lot of experience over 40 years of it, but most of it is in engineering and hydrogeologic reports. Most of it is not published in peer-reviewed science documents. So anyway, as a result, we have the experience with the buffer zone formation to manage arsenic and we have some information available, a lot of it on the natural subsurface treatment processes. So what are the operations to achieve success? Well, the first one is a phase development. Start small, learn from your early results and then adjust to as you expand the system. What we do at every site now is to initially develop a buffer zone around the well, separating the stored water from the surrounding groundwater. And we do that at every site before we start pumping any water out. The target storage volume is the next thing, which is to develop the buffer zone plus the volume that you want to be able to recover. We use interim recharge between the time that the well is constructed and the typically about a year later when the well is equipped and use that time to build up that storage bubble. Then we conduct cycle testing and then we move into operations with the associated clogging and backflushing to remove clogging redevelopment of the wells. So here's the target storage volume. Basically, you have his own right close to the well that is very changes in flow from a turbulent to laminar. Then you have your stored water volume extending out typically a few hundred feet and then your buffer zone that separates your stored water from the surrounding groundwater. And the target storage volume is the sum of the stored water volume and the buffer zone volume. And it is expressed in terms of million gallons per MGD of recovery capacity, or in other words, in days. This is a project at Boynton Beach, Florida where we learned a lot and this is what we learned. We ran 13 cycles starting at 28% recovery efficiency and eventually got to 100% recovery efficiency. And this was in a brackish aquifer chloride concentrations of about 1,920 milligrams per liter. And it turned out that it occurred to me at the end of that time after a few years of cycle testing that we could have done something better because I added up all of the volume of water on every cycle that had been stored but not recovered and it came to 200 million gallons. And it occurred that maybe you didn't need to do it at multiple cycles. You could do it in one initial buffer zone and then start out close to 100% recovery efficiency. And that's what we've been doing ever since. So a model was done for the South Florida Water Management District simulating this and sure enough, it showed that it would take many years to get to your target storage volume without a buffer zone, but with a buffer zone, it happened very quickly. So the target storage volume is something we do at every ASR site. But what we've noticed is that if the TSV is less than 70 days, we have elevated arsenic concentrations at sites where arsenic is present. But if the TSV is greater than 70 days, we have acceptable arsenic concentrations. So we've been working with that ever since. And so here's a relationship from Bradenton, Florida between arsenic and chloride. And you can see that there's an R squared value of about 0.75. And that's a pretty high correlation for a complex natural system. So we started considering the use of chloride or TDS as an operational surrogate for arsenic. There's another slide from Tampa, Florida. Tampa didn't build a buffer zone, they just put in a billion gallons into their eight ASR wells every year and then recovered a billion gallons. And at the end of that time, we plotted up the data. And after 13 years, we found out that the wells that had a net positive amount of water in storage had acceptable arsenic concentrations. And those that had recovered more water than they had put in had higher arsenic concentrations. Once again, the R squared value was 0.75. And this is another example from Bradenton, Florida where after five cycles, we handed over responsibility to the city and with an advice to them that they not over recover the water and just stopped pumping when they reached a certain volume out. Well, they decided they wanted to see what would happen if they pumped out their buffer zone. And you can see what happened on that purple line there. Arsenic spiked up to about 70 micrograms per liter. The state regulatory agency moved in, shut down the project. It cost the city about a million dollars and lost them about five years of time before they could get their ASR program back on track. And one more from Tampa. As I mentioned, they put in a billion and took out a billion every year. And you can see the steady improvement and eventually after cycle 13, they got down to acceptable arsenic concentrations. So then we talk briefly a little while ago about the balloon effect. And this is not a picturesque slide, but it tells you an effort that is underway right now to look at detailed data from operations at a number of sites and compare the transmissivity, the storitivity and the leakage during recharge periods and during recovery periods. And the effort that is going on right now between the United States, Australia and South Africa is to get other data sets like this. This one's from New Browntels, Texas and compare the results and see if there is a difference, which as I suspect there will be between the aquifer hydraulic characteristics during recharge and recovery. And if so, that could affect future modeling for ASR programs. Okay, very quickly, we've learned a lot over the years of the improvement in water quality during aquifer storage underground. Going through these very quickly, we know that disinfection byproducts attenuate very quickly underground. We know that bacteria and virus attenuate very rapidly and are typically gone within a few days. We know that nitrogen and phosphorus also eliminated over a period of weeks to months. Bacteria are eliminated, typically at a few days per log cycle. And then hydrogen sulfide is gone very quickly. So the question here is, what would be wrong with having a compliance zone around an ASR well for a couple of hundred feet or so that provides for natural treatment of this water in many cases, instead of having to build expensive treatment facilities above ground to achieve the same goals? If you have drinking water available for recharge, that's great. That's how ASR got started. But if you don't have drinking water already available, this might be a better solution. So future directions for ASR, we're looking for regulatory frameworks that match ASR science and technology. We're looking for reclaimed water storage. We're seeing more and more of that in the United States. We're looking for biotechnology and geochemistry advances that achieve subsurface treatment objectives. We're seeing that ASR programs are getting larger to meet regional and national needs. I expect that we're gonna see ASR wells that are used not only for storage, but also for treatment and for conveyance. We're already seeing more focus on strategic water reserves, particularly in areas where they need to store their water underground to protect them from drones and missiles. We're gonna see a lot more marginal cost pricing, taking advantage of low cost water for storage during off peak months. Industries will probably more likely get involved with thermal energy storage. And I think we're gonna see combinations of ASR with bank filtration, desalination, surface reservoirs and reclaimed water sources. So these two are not competitive. These are in each pair. They're very supplemental to each other. I think we'll see more vertical stacking of storage zones. That's already going on. And then maybe well pairs and arrays to achieve both storage and treatment. We need well field protection areas for ASR. And finally, we need, I think, need to move in the direction of applying a long established technology, which is horizontal directional drilling for ASR wells. So in conclusion, this has been a very quick treatment of ASR. If you're interested, there's a well-written book here. Christmas is coming up and you can buy it from the National Groundwater Association or you can contact me directly at this email address. Thank you, David. So we have six minutes left in the session for some questions. And I think first I'll open it up to people who are in the room here. If anyone has a question, just go ahead and raise your hand, your virtual hand. And then while I'm waiting for people to think about a question, I have a question for Claudia. Claudia, I was really interested in your slide where you showed the base in architecture with coarser-grained and finer-grained layers and how they're, so I have two questions related to that. First is, is that stratigraphy such that you could target the coarser-grained layers or is it just too, are the individual stratigraphic layers just too thin to do that? And second, I was interested in the time scale on which you get that collapse. So does it take 10 minutes or 10 years or 100 years? So just your thoughts on that. Okay, on the first one, I think in certain areas, there's areas you can definitely target and look at the logs. And with, I didn't talk about it, but they mentioned it quite a bit yesterday at Airborne Electromagnetic. They're doing a lot of flying of that. I had a slide of all, I started throwing out slides because I had too many, but they're flying and have flown most of the central valley in particular already, but they're flying pretty much all of the basins in the state. And that geophysical information really indicates where the coarsen fine-grained layers are in a lot more detail than just what we used to have with just drillers logs and geophysical logs at Wells. So that can be used to help target locations where there are much more likelihood of being interconnected coarser areas. So, yes, there's ways to target and ways to really look at trying to get into the upper part of the system where you get into the recharge area so that you can get the water down into the deeper parts of the system. In terms of the second part of your question, which I'm trying to remember. Here, I can run. It had to do with the time scales upon which collapse happens. Okay, so it's not like earthquakes. It's not like, boom, the ground goes down. There are places during droughts where there's been like two feet of subsidence in a summer, in a growing season. So it can be relatively rapid, but there is some elastic rebound and almost kind of breathing of the aquifer that goes up and down in here. It's very kind of smooth and broad compared to earthquakes though. So like things like high speed rail and rail lines and things can be built and engineered around in general a lot more than structures associated with like faulting that are abrupt drops. So it works with both the geologies. So the extents of the fine grain layers. And really it's these thin fine grain inner bed layers that are doing this collapsing, not the big clay layers like the cork and clay or something. And so it's smoothed out and kind of blurry because of that. And it's also related to the water level declines and the pumping. So you have kind of a combination of the geology and the stresses together to get where you're gonna have the subsidence. Great, thanks Claudia. John Arthur has his hand up. So I'm gonna give him a chance and then we've got one question in the Q and A that if we have time, I'll also ask. Well, I think it was just partly answered. Thank you, Claudia. And thank you all to all speakers for the excellent presentations. David, you mentioned a balloon effect. And I was going to ask this question of both you and Claudia because Claudia mentioned this storage zone loss which I had not heard a whole lot about. And I'm one kind of guessing that might be local hydrogeologic conditions and a soliciclastic aquifer as opposed to carbonate. But you mentioned, David, the balloon effect. Is that tied to storage zone loss to some extent or could you speak a little more about that, please? The balloon effect is at this point, it's just a concept but it's based upon some real hard information of what happens when we inject and actually we've observed a two sites ground level rise. And as soon as the pump turns off ground level drops. So I got to believe that, yes, it's probably related to some of the things you're talking about particularly in California. But it may be a bit more than that. And that's why we're doing this exercise. Thank you. Okay, I think we have one minute until the next session starts. So I think we'll have to hold off on the other questions. And I would like to again, thank all the speakers for really interesting and stimulated talks and I'm looking forward to following up with some of you. And I think we are now ready to start our next session. Hi, good afternoon, everybody. Welcome to the last open session of this Water Science and Technology Board meeting. We have five speakers this afternoon. They are in order, Maliva, Owen, McDowell, Myers and Logan. Each one of them will have 15 minutes and I will make sure that the give a time of a minute or two before the 15 minutes expires. Without any delay, first speaker is Robert Maliva from WSP. Okay, is somebody gonna put up the slides? Okay, my talk today is on regulations and policies impacting MAR economics and implementation. This is gonna be very much from an applied perspective. Next slide, please. You know, I think pretty much all this attending this sort of conference workshop appreciates the benefits and value of Manishak for recharge. It certainly makes great sense to store excess water on the ground for later use, rather than having it be lost to beneficial use. I think it's also recognized that with increased climatic variation, the need for MAR is gonna increase. And I would argue that MAR for the most part now is a mature technology, that there is ample knowledge exists on the factors critical for system success, performance and mitigation, risk. Although as David noted, there's always more to be learned. So the question is, what is slowing implementation of Manishak for recharge? And certainly in some parts of the United States. And I would argue that in parts, it's related to the regulation of Manishak for recharge, particularly involving systems used in wells. The regulations really haven't kept pace with the science and regulatory associated cost can render projects economically unviable. Next slide, please. Just some basics, Manishak for recharge like any other project, a basic economic requirement is that the benefits should exceed the costs. I usually quantified using some net present value type approach, specifically the value of the additional water available during times of need should exceed the cost to construct and operate the system. Project rewards in terms of net benefits really exceed any risks. And again, risk is a key factor with Manishak for recharge and health risks in general as well as environmental risks are a function of the contact, both the frequency type and amount of the dose, the concentration of the hazard in each contact and the dose response function. Now Manishak for recharge reductions can be reduced in three main manners. First of all, we can prevent contact, minimize exposure. We can reduce the dose by treating of the water. Again, getting the concentrations of hazards as low as possible. And thirdly, there's treatment of the recovered water prior to consumption. Next slide, please. So how does the regulations impact project economics? It can impact the well construction requirements. Again, with wells as UIC specific requirements. And anybody involving the trying to permit any sort of MAMAR system, there's a whole myriad of local issues that come into play that can impact the economics of systems. There's general land development requirements, there's construction codes, et cetera. The big issues of water quality standards and thus pretreatment requirements and then a subsequent monitoring and reporting requirements. You know, the basic UIC requirement is the federal non-endangement requirement, which basically is you can't endanger or cause a violation of a primary drinking water standard in an underground source of drinking water, which is defined as a non-exempt aquifer that contains less than 10,000 milligrams per liter of TDS. And a key point to note that there's variations in how this is interpreted across the country, particularly the compliance point for non-endangement. Next slide, please. So I'm based in Florida. So I'm going to just focus a little bit on some of the issues that arise in our state. Again, for projects involving underground injection, the injected water must meet primary and secondary drinking water standards. Although relief can be obtained for secondary standards for water quality criteria exemption. The point of compliance is that the well head and any project that involves reclaimed water has an additional layer of requirements under the reuse rules. And particularly if the TDS of the receiving aquifer is less than 3000 milligrams per liter, full treatment and disinfection requirements are applicable, which basically assume indirect potable reuse would occur. You know, you need to go to full advanced treatment or something equivalent to that. The TDS is higher, there are lesser requirements, basically disinfection, high level disinfection. And if you're in 1000 or 3000, you can get some relief from principal treatment and disinfection. If you can demonstrate that the ground water will never be used for public water supply. And any project involving non-potable managed act for recharge, the main challenge is meeting both the total coliform and disinfection byproduct standards, as well as with the arsenic leaching issue. Whereas if the stored water exceeds the 10 micrograms per liter MCL, it's considered a regulatory violation. Next slide, please. A number of people have mentioned natural contamination attenuation. I think it's certainly been fairly well established. It was a fairly large literature showing that the concentrations of microorganisms and many chemicals, including some of the trace organics are naturally reducing the ground water environment by a variety of physical, chemical and biological processes. Most pathogens are enteric, they do not survive long in a ground water environment. And we have field studies, including some very nice Florida specific studies and sort of international laboratory studies all demonstrate that most of the pathogens, but certainly not all have 90% log 10 removal times on the order of days or weeks at the worst. Trace organic compounds, many of them are attenuated, but there are some refractory ones that stick around. And disinfection byproducts, for how long, that things in particular are also attenuated in the chemically reducing ground water environments. Leaching of arsenic caused by the introduction of DO can be a regulatory violation. And it really has been a great damper on the implementation of ASR in Florida, but it appears to be an ephemeral issue. There's a finite amount of leachable arsenic in them within the aquifer and their, you know, what's released has to be re-sequestered fairly quickly. Next slide, please. I'm gonna talk a little bit about a reclaimed water ASR project that I've been working on for a long time. And you know, the story I give is that, you know, when I started working on it, my kids were in preschool and now they're in graduate school. So it's been a while. We've collected an enormous amount of data from this system. Again, it stores reclaimed water in a sand and gravel aquifer. The water is disinfected by chloramination. We have over 1,000 stored zone monitor well samples for analyses for THMs. Going into the, you know, our injected water THM average is about 80, 61 micrograms per liter. And remarkably, over 99% of the storage zone monitor samples, the THMs were below detection limits. Again, the THMs are almost completely attenuated by the time they reach the first storage zone monitor well, which indicates how effective natural contamination attenuation can be. Next slide, please. So as arsenic leaching, it was kind of a bit of a surprise in this formation in this system that it did occur, but you know, it's something we had to deal with. But the main thing is that over, you know, the initial cycle test and subsequent operational cycles, it just pretty much is gone by now. This slide isn't complete. You know, the latest analyses from all the wells, all seven wells, the produced water, the concentrations below 10. On the left is the produced water. On the right is the storage zone monitor well samples. You can see early on there have been some exceedances, but since the 19, 2016 onwards, everything has met the MCL, it's below 10. So again, it's a problem that just went away over time. You know, it's an ephemeral issue. Next slide, please. So what are some of the implications of the Manage Act for Recharge Water Quality Requirements? Again, from practical experience, you know, the requirements to meet drinking water standards has rendered some Manage Act for Recharge Projects in Florida economically unviable. You know, we also apply the precautionary principle better safe than sorry, you know, which appears to be a prudent course of action but it can result in the loss of much needed water resources benefits. And I think it's increasingly being recognized that natural contamination, attenuation, should be recognized as a cost-effective alternative to more expensive engineered treatment. And one option that, you know, that can be exploited to, again, reduce or effectively eliminate risk is exposure controls. And this was used on a dusting water uses ASR system. The aquifer, storage zone aquifer, as it contains basically fresh water. On the existing reuse rules, we'd have to go to, again, full treatment and disinfection, RO, et cetera, which would have made the project economically unviable. But there was a local ordinance in the Destiny City Code which stated that shallow wells which draw water from the standing gravel aquifer, the storage zone aquifer, shall be used for irrigation purposes only. We were able to say that, well, nobody's gonna be able to drink this water so it makes absolutely no sense to have to treat it under the assumption that indirect potable reuse would occur. Next slide, please. So what are some of the options for facilitating a managed aquifer MAR implementation? Certainly is to recognize and try to capture the benefits of natural contamination, attenuation processes. The compliance point should be at the boundary of a zone of discharge or attenuation zone rather than at the wellhead. And this is already allowed in some states, but not in others. Institutional controls should be taken advantage of to try to expose, prevent exposure to recharge water. Systems can be constructed in areas that are not used for potable supply and just a legal mechanism so you can preclude the installation of future potable water supplies in some areas. Under federal and in Florida state UIC rules, aquifer exemptions are allowed, which can be used to provide a treatment zone. But a key problem is they're allowed under rules, but policy is that they're not allowed to be issued. And as David noted, more research is certainly needed to document natural contamination, attenuation. I think it's more to assuage policymakers and the public and finally I think recharge water quality standards should be based on a full risk assessment that considers actual exposure scenarios and produce groundwater treatment as opposed to using potable water MCLs that are based on consumption of two liters of water every day for a lifetime. You know, if we want to use this for an ASR system storage zone that has a TDS of 5,000, well, nobody's going to drink 2,000 liters of water of that 5,000 TDS water every day for a lifetime. Again, it's sort of an, I think, an obsolete requirement. Next slide, please. So one of the challenges and way forward is certainly recognize that any effort to formally change rules is a very long and arduous journey. But what we also find is that, again, from the regulatory perspective, there's inertia, there's an unwillingness to really change things. And also, there's really opacity on the policy making level. Again, you have rules that are written that are legally binding and there's policies that sort of influence what regulatory agencies can do. For example, in Florida, why or who made the decision to aquifer exemptions which are specifically allowed under state and federal rules are not to be issued in Florida. It was done once in early 1990s and this could be a valuable tool to allow for, again, attenuation zones and facilitate managed act for recharge in some instances. And again, that other issue, why or zone of discharge is allowed in some states in US EPA regions, but not in others. So I think the way forward is that, I mean, I'm a scientist, I don't really like dealing with the policy levels, politicians and very much, but basically all groups involved managed act for recharge need to be more active in promoting regulatory and policy changes that will facilitate implementation of managed act for recharge while ensuring that public health and the environment are protected. Again, there's three ways to reduce risk. You can control exposure. You can provide very high levels of expensive pretreatment and also you can provide treatment of the recovered water. So I think all of those options need to be considered. And on that, I'd be happy to answer any questions. I think we have time for one quick question. If anyone has a question. Any questions to the end? Okay, let's just save the questions till the end. Thank you so much. Thank you, Robert, for starting. So the second talk is given by Dave Owen from the University of California Hastings School of Law. Dave, take it away. Okay, I'm gonna share my screen. Let's see if I can just get out, here we go. Okay, so I am, because I'm a lawyer in contrast to the last speaker, I like talking about the politics of law. So that's where we're gonna focus here. And I'm gonna give you an overview and it's going to be at a fairly 30,000 foot level just because there's a lot of complexity and also a lot of state specific law here and we can't get into all the details obviously. But I think it's helpful to start out by thinking about what people usually think about when they think about groundwater law. And usually groundwater law is in this country is a set of laws that protect groundwater quality. Many of them federal environmental statutes and some of it is fairly well developed. And then we also have a lot of law, perhaps not as much as we need, but still a lot that involves groundwater extraction. So laws like California Sustainable Groundwater Management Act which you've already heard about today. And then if we wanted to broaden this out, we could also say that laws that deal with things like municipal or public finance are important here. Land use law is important here. Surface water law is important here, but there's no specific body of law that evolved directly focused on groundwater recharge except in a few Western states that have really tried to develop it. And so one theme of this talk at the outset is going to be that we're dealing with an activity that is at the intersection of a lot of areas of law and none of which were designed with this particular activity in mind. Another framing point is that I think it is helpful as we think about recharge to think about it on a continuum from very lightly and more diffusely managed recharge processes to the kinds of highly and intentionally managed shock for recharge that we've been primarily talking about in this conference. And I'm going to start out by talking about the second type of recharge and the laws that apply there but I'm also going to spend a bunch of time talking about the first kind of the more lightly and more diffusely managed recharge. And also I think make a case why I think the law of that is very important for us to be thinking about. So let's start with highly managed aquifer recharge. And if you have managed aquifer recharge project, you typically have a couple of main legal issues to confront and they arise around obtaining the water, inserting it into the ground, storing and protecting that water and withdrawing the last two issues are closely related to accounting. In addition to these, I didn't put them on the slide but you also have finance issues. You have to think about how the project is going to be funded and you have administrative law, public governance issues and thinking about who is going to manage the project and what sorts of rules will apply to that entity if it is a public entity. If it's a private entity or if it's a public entity probably also have some contracting issues as well. So I'll go through each of these in turn. So first off, one key question with obtaining water is whether you can obtain surface water rights. In most states in order to divert water and put it into the ground, you need a water right to that water. And a couple of issues can come up here. One is just that in many states there are not many surface water rights to be had. So as Helen Docky talked about already in California, the only thing really left to be appropriated in the surface water environment is extreme flood floods. There's not much else available. And so a first question is, is surface water even available for appropriation? A second question that comes up is whether groundwater storage itself is classified as a beneficial use of surface water. So particularly in Western states, a water right can only extend to beneficial use of water and beneficial uses are often defined in a categorical way. And different states have different approaches to doing this with respect to groundwater storage. So Idaho provides one example in Idaho groundwater storage under state legislation is categorically treated as a beneficial use. Obviously that makes it easier to put together a managed for recharge project. A different approach comes from California. In California, storage of water either above ground or below ground is not itself a beneficial use unless it is stored for the purpose of some other specific beneficial use. And so this creates challenges because if you think about some of the different purposes we've heard for managed aquifer recharge, some of them it is unclear whether they would count as beneficial uses. And if your goal with the recharge project is just to store water because you know it's going to be useful somehow, but you don't know exactly what use you're going to make for it. That's probably not legal under California law. That's probably not a beneficial use of water. And I should also say these are two examples of states that have actually answered the question at least to some degree. There are many states, particularly in the East where there's just a lot less groundwater recharge law. There are other states that don't really have a clear answer to this question. And so the third question is if the groundwater storage itself is not a beneficial use for them a state where the project is going to occur, then the key question is, well, has the proponent of the project identified another beneficial end use to which that water is going to be put? We've also heard a lot about projects involving stormwater. And so a key question with stormwater is do you have a right or the legal authorization to actually manage that stormwater? In some Western states in particular it's questionable whether you do because the water that you are putting in storage otherwise would flow to surface waterways and someone else may have a more senior right to that water. Again, there are a couple of different ways of dealing with this issue. So California here, you can see by statute has said that municipalities that capture stormwater pursuant to a stormwater management plan have the right to manage and use that water for augmenting storage. Again, this facilitates managed aquifer recharge. Somewhat different law comes from the state of Washington. So in this case, somewhat recent case, the Washington Supreme Court said that it was okay to inject or not inject, but to infiltrate stormwater and use it to augment streamflows because that was management and not use. Well, the implication is that if it was used a water right permit would have been needed and that permit would have been subordinate to more senior water users. And again, that's a potential problem because a lot of the different uses of managed aquifer recharge water that we've been talking about would probably qualify as use under Washington state law or under the law of another state. So the next set of issues, which we've just heard about a little bit, so I'll go through these quickly, involve injecting water. And here, the primary source of law is the Safe Drinking Water Act, which is a federal statute. Here's some of the key language from the statute because there's a lot of text on this slide. I will highlight a few key points. The first is that the Safe Drinking Water Act is what we lawyers call a cooperative federalism statute. That means that it's a federal law, but it envisions state and in some cases local level implementation. And so that means that the regulations are done on a state by state basis and they're different. They're not always the same. There are some general rules about how the regulations should work here. And the key point, and again, this is what we just heard a little bit about, is that there is this non endangerment mandate and the need for permeate processes. And it's not a zero discharge of pollutants requirement. There's some flexibility, but there's also some room for interpretation. And the underlying goal here, of course, is not to facilitate getting water into the ground. It's to protect aquifers and to protect resources from injection that is thought to be a potential source of danger. So your next step in managing a project is to store water. And a couple of key legal points here. The first is that states that have developed law on this subject typically treat stored surface water as legal surface water. And that means that it is in theory, subject to separate accounting mechanisms and separate water rights systems than the native groundwater that may also be or almost certainly also is in that same aquifer. That sounds straightforward and simple enough. The catch is that you may also have groundwater users with groundwater rights in that same aquifer with pumps and their pumps are not going to differentiate the source of the water they're using. And so the upshot is that in order to have a project that works in an area where you have both native groundwater and native groundwater rights and stored surface water, you have to have accounting rules and you have to have enforcement mechanisms. And that may be relatively simple in an aquifer that is small and where you have essentially one manager that controls the water rights within the aquifer and the water in the aquifer more generally. But if you're thinking about a big aquifer, think about the Central Alley Aquifer in California, this is potentially a huge challenge. And then the same issue basically comes up when it's time to withdraw water because you have to make sure that the people withdrawing water are actually withdrawing water in accordance with the rights that they hold. And this can be, again, it's a simpler issue if you have one manager with consolidated control over an aquifer, but if you either have multiple users within the aquifer or in some cases we have aquifer storage and recovery project or managed aquifer recharge projects, I should say, they're designed as banks for multiple users. Again, you're gonna need both accounting mechanisms and contractual mechanisms to allocate water among those different users and make sure people aren't withdrawing water to which they aren't entitled. So stepping back, a couple of themes here. One is that in most of the country, managed aquifer recharge law is relatively new. And in fact, in a lot of states it really isn't a thing yet at all other than the Safe Drinking Water Act. And it is also often quite complicated. And that complexity obviously is a challenge that can be managed that we can try to work with and resolve. But I think it's important also to keep in mind that the complexity arises in part because we're taking water out of surface waterways which is inherently a complicated legally thing to do. And we're putting it underground. Groundwater management is also inherently legally complicated. And we're also often doing it through complex institutional arrangements. So the upshot is this is always going to be tricky. This is always going to raise some challenges. All right, so that's highly managed aquifer recharge. On the other side of the spectrum we have much less managed aquifer recharge problems or projects or in some cases just practices. And let me just say at the outset why I think it's important to think about these. And there's a couple of reasons. One is that in many areas there isn't all that much surface water that's going to be available for recharging. And that's because surface water in the areas that have the greatest demand for these projects, surface water is often already somewhat overtapped and there's real value in flooding landscapes. There's ecological benefit in doing that. And so getting rid of all the flood flows and putting the ground might not be a good idea. The other reason is just that most of the recharge that occurs out there across our landscapes is not occurring through managed aquifer recharge projects. It is occurring in a much more diffuse way across a lot of the landscape. And some of the points I'm going to make in the discussion that follows here are discussed in more detail in a recent article that this just came out last year. So if you're interested in more detail I'd refer you to that. So the themes here are going to be really limited legal coverage and a lot of it incidental. A lot of it just sort of an accidental consequence of rules devoted to other purposes. And there are good reasons for that. I mean, we're talking now with diffuse recharge about things that are not readily visible but people don't really understand that take place on a very diffuse basis. And they're complicated. And then most importantly that often arise from practices that we otherwise might think of as bad, like burning down forests to the ground or installing leaky water supply infrastructure. So I'm going to give a couple of examples of how this law works and where some of the gaps and problems are. First deals with development. So I think probably everybody on this call or this conference knows that when we develop urban landscapes we alter recharge practices or patterns in a variety of ways. And you might wonder how a lot deals with that. Well, the traditional way that common law dealt with that issue was to say you can basically do whatever you want. And even if it injures your neighbor that's your neighbor's problem, not yours. So there was a common law doctrine called the common enemy rule which basically said any excess runoff that you created by changing water flow patterns on your land was your neighbor's problem, not yours. We've changed, yes. Two minutes. Two minutes. All right, I will fly through the rest. We've changed that a little bit with Clean Water Act MS4 permitting which now does facilitate recharge in many cases but this only applies to very limited sectors of the American landscape. Flood Planes, from Helen's talk we've heard a lot about how flood plains can be very important recharge zones. But the reality of US law for many years has been that we try to keep water out of flood plains and we don't oblige the people who keep those recharge zones dry to compensate anybody else where the impacts to surface flows or to ecological systems that are created by that lost recharge for us. And I'm gonna put all the text here at once sorry for fleshing through. Again, a very similar story. Forestry law in the United States particularly the National Forest was born to some degree out of concerns about water flows but if you look at federal forest law either statutes, regulations, cases there's very little focus on recharge and groundwater in fact hardly any at all. State forestry law is similar. And this is true in spite of the fact that this is where most of the water particularly in the West starts where most of the precipitation falls. I'm sorry if you are hearing my dog yelping in the background she's a little poorly behaved this morning. And then finally with agriculture. Again, there's not a whole lot of law that applies here that actually directly deals with recharge. We don't think about it when we zone land for agricultural use. We don't really think about it when we award water rights to agricultural users. The one exception is that there's a legal doctrine called the rule of recapture which allows an agricultural landowner to recapture recharged water from that owner's surface water irrigation. But that is basically it as far as systematically thought out law that applies groundwater recharge to agriculture. So two last points. One is I think there's value in more robust legal systems for dealing with these issues but not everywhere. There are a lot of places where you just don't have enough recharge taking place. You don't have enough scarcity or you just don't have enough money to deal with a legal system that tries to address these problems. But I think there are plenty of places where more thought to the law that applies to groundwater recharge across the landscape would make sense. I'll give just three examples here. The first two, the Southwest where we have huge pressure for water. And we also sometimes have huge pulses of flow coming out of mountains and that could be effectively recharged. The other place where this has already become a significant issue and much more recently is Cape Town which as you probably all know very nearly ran out of water a couple of years ago and has responded to this among other things by trying to actively manage vegetation throughout the watershed in hopes of increasing recharge levels and having more secure water supply for the city. I'll stop there and I'll look forward to your questions. Thank you, Dave. Thank you very much. The next speaker is Sharon McDowell from University of Arizona. Sharon, take it away. Hey, thank you. And I think I'm empowered to advance my slides. Am I? Okay, now it says- Yes. Okay, now it should work. I'll try it one more time. It says, okay, here we go. All right, thank you. Thank you for the opportunity to present to you today and I'm gonna talk some about the regulatory framework for managed aquifer recharge. A lot of what we've heard yesterday and today has become additive and so we have the benefit of being able to refer to each other. But I wanted to start out with just providing some broad context build on a little bit of what Bill Alley talked about yesterday and talk about how Mar is really recognized globally as a water management solution. And there are efforts to bring some of these case studies and the rationale for doing them to the forefront through some special issues of journals and volumes and so forth. And I just wanna talk about what they show is the purposes of managed aquifer recharge and some of these global compilations. And then I want to talk some about Arizona's regulatory framework for water storage and recovery. And throughout this, I will show photos and if I show publications, I do provide the links to them when readily available and so I'm fine with your distributing these slides in whatever way you wish. Anyway, timely topic managed aquifer recharge as a water management solution. Wanted to just remind everybody if they're or inform everybody that a World Water Days focus was on groundwater. The UN makes really the whole year about the focus of World Water Day. And recently the World Water Development Report came out talking about groundwater making the invisible visible. And there are many references to managed aquifer recharge in that volume. And Bill mentioned the managed aquifer recharge. He may have mentioned both of these Bilali yesterday but in 2020, I think it was this compilation called managed aquifer recharge for water resilience was put out, Peter Dillon was the lead guest editor for this issue of water. I was one of the other guest editors. And this was based on papers and presentations from the International Symposium on managed aquifer recharge from three years ago. And then actually from six years ago, that's right. It took us a while to get the papers out. And then the UNESCO book that he mentioned. And so I want to just mention that the first one includes 23 papers. And actually I think I have the wrong date there. But it talks about the goals and improving water security, improving water quality, improving the environment assessing opportunities because some of these are pilot. And obviously some projects have more than one purpose. But I highlight here one of the statements in the editorial paper that managed aquifer recharge can be economic, it can be benign and resilient and socially acceptable, but frequently has not been implemented for reasons listed here, lack of awareness and adequate knowledge. And then incomplete policies for integrated water management. This UNESCO volume Bill showed yesterday that map showing where the case studies occurred. And in fact on World Water Day 2021, my water center held a webinar where we highlighted the case studies from North America which were either from the US or one from Mexico. Interestingly, there were no case studies in that volume from South America. And we had a case study, Ken Cichols from Central Arizona Project and I on the Arizona Water Banking Authority, the role of institutions in supporting managed aquifer recharge. And if I recall correctly, our case study was the only one focused really on an institution, not some of the more physical aspects of the storage and recovery. Again, pointing to the interest in and importance of institutional mechanisms. Recently, a former grad student now a postdoc with me and I wrote a review paper that's kind of a review of the reviews and we looked at 37 projects and more than 75% of the efforts had been created to improve water security. And so the point is, is that while we may have many, many reasons for doing these projects as water scarcity or water imbalance concerns are becoming more paramount due to climate change and so forth, the need to share experiences and lessons learned from these projects is very important. And that includes sharing some of the negative aspects or negative lessons learned. As David Pine mentioned in his remarks and I was asked about at an international conference where I spoke in March and they said, well, is there anywhere where you have the failures written about and we tend to not write so much about that? And then just one more instance or example of the interest in the policy and management aspects is more 11, the international symposium on managed doctor for recharge, which is a triennial conference. It was just held in Long Beach, California until at different locations all over the world every three years. I was asked if I would help organize a workshop that explicitly focused on meeting water management objectives, the role of mark governance and policy because very often the workshops and even the sessions can be dominated by some of the technical aspects, yet there is great interest in many questions about the more institutional legal aspects. And so I show you the simple workshop agenda where we talked in terms of frameworks, Arizona, Israel and Australia, and then implementation of MAR, we talked about Orange County, Israel and New Zealand. And so it is really beneficial to talk about these experiences and Adam very modestly suggested that the boards could help with more dialogue on these and Adam did a wonderful job of chairing that conference. So let me now switch to speaking some about the Arizona regulatory framework. And Dave's presentation gave a great overview and Arizona is one of the states that has had a regulatory statutory framework for we call it water storage and recovery or water storage savings and replenishment. We don't use the term managed aquifer recharge in Arizona, but it is what we do. And this is a slide from the chief legal counsel, Ken Stalinski at the Arizona Department of Water Resources that he presented at the workshop. And he talked about the history of the legislation and the purpose. And so our statutes go back to 1986 where Underground Storage and Recovery Act was introduced into our statutes, introduced into our groundwater code and Arizona is quite famous for its 1980 Groundwater Management Act. And the major substantive addition to that since 1980 has been about storage and recovery. And then there was adding the concept of indirect storage or in-lue storage. And then the two were all put together in 1994 in this underground water storage savings and replenishment program. And as came out through some of the examples in case studies yesterday, we do have different types of storage facilities. So there are underground storage facilities and those have to be constructed and they require facility maintenance. They may be in the form of basins or wells. And we also have something that we call a managed underground storage facility. And I have to admit on the record, I hate that term because those projects aren't really managed the way the constructed basins are. And I show you some photos on the left of some of the constructed basins all in the Tucson region, but not all in the same part of Tucson. Pre-pandemic, I typically would take my graduate class out for a field trip to some of Tucson water's sites. And so those require wet-dry cycles and raking and things like that. What we tend to call a managed project is where we're using the riverbed and Leslie Myers who's gonna follow me may talk some more about that. And then we have what we call groundwater savings facilities. That was a term that was given to this in lieu or indirect recharge where we're leaving water in the ground by delivering surface water instead of or in lieu of the groundwater. And so here's a photo I took of one of the fields, I believe it was Cantaloupe's growing in central Arizona that was depending upon surface water in lieu of groundwater. And I do wanna mention that the Water Center has put out a publication that summarizes some of the examples and the rules and regulations relating to storage and recovery. And so what we have through our framework really is a framework for project operations, storage, protections and water recovery. And this program provides predictability to the applicant for those who wish to install a managed aquifer recharge project. So there aren't different permits for those different aspects, the facilities, the storage and the water recovery. There's required reporting, there's accounting, there's the opportunity for pilot scale projects. Interestingly, in a state where surface water and groundwater connections are not recognized by law, this program allows or introduces some connectivity to the management of those two water sources and effluent, which is actually a third water source or in Arizona law. And then the more regulatory framework has been used over the years to meet multiple water policy objectives, including providing water during periods of Colorado River shortage. And here we are experiencing that now, not yet using that bank water yet through the Arizona Water Banking Authority. But there are other objectives as well. You heard yesterday about how Tucson has developed the drought resilient water delivery system out of the desert, that was their plan B. But because this framework for storage and recovery was in place, they could pivot from original plan A, which was direct delivery after treatment to this highly drought resilient and hydrologically connected system of storage and recovery. You heard yesterday from Peter Mock about the Healer River Indian community, how they have chosen as a sovereign nation to come under the regulations of the state of Arizona, because they're able to accrue credits and those credits have a marketability that has helped the state in many ways and has helped them, the tribal nations monetarily. And then we've used the framework to deal with replenishment for areas where they're still pumping groundwater. This is a topic beyond the scope of what I can talk about today. This accounting for storage that's left after the end of the year, enables the accrual of long-term storage credits. And that is one of the most marketable aspects of water in the state of Arizona, in the central part of the state of Arizona that's heavily populated. A grad student and I published a paper about that a few years ago, it was part of her PhD dissertation if anybody is interested in that. But there are outstanding issues. Sharon, just two minutes please. Yes, I have two more slides, so I'm good. So some outstanding issues have to do with the fact that this is a base and wide approach. And the way it's implemented can lead to a disconnect between the location of pumping and the location of storage. And that can result in local depletion of aquifers. And this is something that's been recognized, but sometimes once you have the laws in place and the rules and regulations and people are used to that, it's hard to change that. And that's something we are working on in the state of Arizona. The central Arizona groundwater replenishment district matters, which I said are beyond the scope of what I could talk about. But I did wanna talk about recovery a moment and Dave gave me the perfect introduction to that in his remarks. And I talked about two straws in a basin where in lieu recharge occurs. And I've shown you here a cross section from Arizona Department of Water Resources modeling of the Penal Active Management Area. And that's the area between Phoenix and Tucson that's largely agricultural. And they've been depleting groundwater depending on non-renewable groundwater in the same areas where there's been this in the recharge going on. And now with the shortage conditions of the Colorado River, the irrigation districts no longer have the amounts of surface water available to them. So they're going back on the pump and they can by virtue of our state groundwater rights and their quantification. At the same time, there's been all this water stored there, those two deep bluish areas are the two areas of agricultural use. That's where water's been stored indirectly and there are recoverable credits. So there's kind of at least multiple straws and there are concerns about are those credits recoverable and so forth. So the issues of recovery are in fact very significant. So with that, I wanna thank you the photo if anybody wanna look afterwards if you can find the frog that was taken at the Mar-5 Heela River site. And I thank you very much. Thank you Sharon. Thank you very much for that presentation. We move on to Leslie Myers from the US Bureau of Reclamation, the Phoenix Area Office. Leslie, take it away. Good morning, everyone. Hope you're, I see you're seeing my presentation. I'm not sure if you're seeing me. But that's okay. No, you're not visible. Well, perfect. That's okay, thank you. There we go. Well, thank you very much. I appreciate this time this morning. So you have heard a lot about managed offer for a recharge and a lot about Arizona. Today, I'm gonna tell you a little bit of a story about how we've used it in Arizona and specifically how the Bureau of Reclamation has made use of a recharge and recovery. I think it's a really interesting story. And so, but we'll go through it pretty quickly and I'll be available for questions. So next slide, please. The Bureau of Reclamation's mission is to manage, develop and protect water and related resources in an environmental and economically sound manner in the interest of the American public. Reclamation is the largest wholesaler of water in the country. It's the second largest producer of hydroelectric power. I've been with Reclamation for 33 years and our role has always been to develop water and get it from its source to where people can use it. So in general, we don't hold water rights. We're not necessarily a water user, we're a water provider. Next slide, please. And the Bureau of Reclamation exists in the 17 Western States. It was established in 1902 by Teddy Roosevelt to reclaim the arid west for irrigation. Unlike other federal agencies, we are political, geopolitical boundaries are based on watersheds and river basins. Our office in the state of Arizona is in the Lower Colorado River Basin where on behalf of the secretary, the Bureau of Reclamation acts as the water master for the Lower Colorado River. We also own and operate several projects within the state, I'm sorry, we own but don't operate several projects within the state of Arizona. Next slide, please. So within the Colorado River Basin and we're gonna focus on Colorado River today, there are 30 recognized tribes, tribal nations within Arizona, there are 22 recognized tribal nations. So it's a huge part of what we do in our day-to-day business is working with the tribes. Each reservation when it was established comes with reserved water rights. Today of those 22 recognized tribes in Arizona, four reservations have decreed rights from the Supreme Court, seven have legislated settlements, three of those are partial settlements or three additional tribes have partial settlements. There are ongoing negotiations with six tribes. So tribal settlements are a big issue and in Central Arizona. Next slide, please. So I wanna step back for one second and talk about the Colorado River and how it pertains to tribal water rights. We talked about the Colorado River in the Lower Basin has a whole series of priorities. This is gonna be a theme in this story. The first priority are present perfected rights and those four decreed rights that we talked about for the tribes that have rights and are adjacent to the Colorado River. There's a whole series of priorities through 1968 when the Central Arizona Project was authorized. And then after 1968, priorities were fourth priority generally that contracted for on the Colorado River. Then we have priorities for unused water in a year and for surplus. Next slide, please. So the Central Arizona Project is the project that that diverts and delivers water from the Colorado River. Arizona has an allocation of two point and apportionment of 2.8 million acre feet. A little more than half of that is diverted each year and delivered into Phoenix and down through Pinal County and to the Tucson area. It's a 335 mile long canal. It's a beautiful piece of infrastructure if I say so myself. And what it does was it gave us the opportunity now to deliver water to Central Arizona and made water available. Those Indian water rights settlements. Next slide, please. So we talked about priorities on the river within the Central Arizona Project. We have our own set of priorities. The highest priority on this slide is at the bottom. So there is a little bit of Colorado River priority three water available through the Central Arizona Project that was acquired after the fact. And then the highest priority within the Central Arizona Project belongs to those two blocks there that say M&I which are generally the cities and industrial water and the original Indian allocations. There were nine original contracts for water allocated to tribes outside of settlement. These are just the contracts. Then we have a priority for non-Indian agriculture and then we move into what we call excesses which is the ag pool and other excesses. So next slide, please. In 2004, the Arizona Water Settlement Act was passed which results the Indian water rights for several tribes but it also did something else that was very important. It reallocated 197,500 acre feet so about 200,000 acre feet of water to the secretary for secretarial uses and made that water then available for settlements. It also set aside an amount, a subset of that which was about a third of that water supply to be firmed and we'll talk a little bit about what firming is. Next slide. So firming means that the United States will make water available when it's not otherwise available and that is because of reductions or shortages on the Colorado River that are then taken by the Central Arizona Project. So of that 200,000 acre feet, 60,648 acre feet were to be firmed and that firming is for 100 years. So that means in any year when a tribe that has a water supply that's designated as firm is shorted or reduced, the United States needs to provide that water. So this provides us with a whole series of conundrums that we'll talk about. One of them is, where do we get the water from? How do we get it to the tribe? If water is shorted in the Central Arizona Project, where are we, what other options are we going to have? So of the 197, I'll talk about this just for a second. Of the about 200,000 acre feet that was reallocated in 2004, 100,000 acre feet of it was allocated to the Healer River Indian Community in the Arizona Water Settlement Act. And 28,200 acre feet of water was allocated to the Tona Automation. Of that water, of the Healer River Indian Community's water, 15,00 acre feet of water a year was firmed and that was firmed by the state of Arizona. Sharon mentioned the Arizona Water Banking Authority. So they are responsible for affirming just a portion of Healer River Indian Community's supply. 28,200 acre feet was allocated to the Tona Automation, all 28,200 acre feet of water is firmed by the United States. The balance of that water, which was about 17,500, 17,448 acre feet is going to be divided into the future. Some of it's already been allocated. Some of it will be allocated in future Indian Water Act settlements. Next slide, please. So I'm gonna talk specifically about the United States obligation. The Tona Automation, actually their total contracted amount through their settlement is 66,000 acre feet. That's from two different priorities that we just talked about, 3,780 acre feet of water is Indian priority water, which is the highest priority in the Central Arizona Project. 28,200 acre feet came from reallocated non-Indian agriculture, NIA priority water, which is a lower priority. And so because that water was a lower priority, their settlement requires us to firm that water to MNI priority. And that means that as long as MNI water is available, we have to firm their water in a year. So next slide, please. So this, I just wanted to show you again this same graphic to give you an idea. We're looking at the yellow priority there. And Sharon mentioned that here we are in 2022 in our first year of a declared shortage on the Colorado River, and with significant reductions to that ag settlement pool, the NIA pool, right, the non-Indian agricultural pool. So we are in fact firming this year for the first time about three quarters of the amount, well, maybe about a little more than half, sorry, of the amount of water in their contract. And the Arizona Water Bank is firming for the Healer River Indian community. Next slide. So here's our conundrum, and here's really the crux of our story. How do we acquire water and store it and make it available for the next 100 years? In 1994, the Arizona Legislature passed a bill that allowed for water to be recharged. And Sharon talked a little bit about our different methods. We have underground storage facilities. We have groundwater savings facilities. We have all kinds of different options in our queue. This is the answer for our conundrum. We acquire water while water is available and we store it underground and we manage it that way. Next slide, please. So one thing that the Arizona Water Settlement Act did, and well, actually the Tahona Automation Settlement did, was we were provided that same volume of water, 28,200 acre feet of water in effluent in the Tucson area. Tim Tomier talked about that yesterday. All of our partners have been on before me and told their stories. So we've worked extensively with the partners in Tucson about how to, and can I ask you to just advance, this is just gonna show a whole series of studies that have been done over the years, many, many studies looking at the best way to store and recover and manage credits for our Tucson effluent, so that we can then have water to provide for the tribe when we need it. Next slide, please. Leslie, one minute. Oh, okay, thank you. So we have partnered then with, in the Santa Cruz River Manus Recharge, the Lower Santa Cruz River Recharge, we've partnered with the Gila River Indian Community in their Mar-5. We've partnered with Roosevelt Water Conservation District. Next slide, I'll just talk really quickly. One of the issues has been, and Tim talked about this yesterday, that we would store 28,200 acre feet of credits of water in a year. Sorry, we would recharge it, but for a number of reasons, we would only end up with about a quarter of that in recharge credits. Next slide. So I know somebody asked about this yesterday, very important, a big issue for us then, was in 2009, there was legislation that allowed us to accrue 95% credits for our managed recharge instead of just 50%. So next slide. So the moral of this story is, we have used extensively used recharge options throughout the state of Arizona. We've looked to other places to acquire this portfolio. And actually what we've done is we've developed a whole series of very unique and ingenious methods for recovery and delivery. And a lot of them include, sometimes the transfer of credits, sometimes we'll transfer credits to one entity which will deliver water to another entity for us. It's a very complex system, but it works very well for us. We're in our first year of implementation and so far, so good. So last slide. There's my contact information. I'll be around for questions, but please if anyone has any questions in general about how this whole network works, I'd be happy to speak with them anytime. Thank you. Thank you Leslie. The final speaker for this session is Will Logan. Will's right here, so thank you. Great. Well, I appreciate this very much. I do wanna emphasize this is my personal opinion, not those of my, the people who pay my salary. Thank you very much. And some of it is based, some but not all is based on a white paper that I did in 2020 on the MAR and the CORE simply because I thought it was an important topic and someone was willing to let me do it. So with that, I do wanna just mention that if you look at your own National Academy's reports, the CORE of Engineers, especially in the Everglades Restorations at the heart of it. And that includes some studies that I did back 20 years ago and many that Stephanie Johnson has done, of course. And then I also directed the earlier, the 2007 report on prospects for managed underground storage. And that, of course, has good people like, well, the late great Ed Bauer, but also the not so late great Don, thank you. Thank you. Boy, how soon they forget. Anyway, so interestingly, for the benefit of folks like Bill Alley who continues to underline how we made that terrible statement about water reuse is the last worst option. This report actually concluded that MAR, as of 15 years ago, was generally successful in doing what they said it would do. And of course, there's lots of research to be done, but that it should be considered a good tool in the water managers portfolio. One slide, people have hit on all these, but climate's a huge deal to the CORE of Engineers. It's also a big deal to everyone else. And the language of climate adaptation is the language of water management. And so if you look at all these ways that the water management can integrate with climate adaptation, you see that MAR really is in the center of many of these and certainly consistent with most of them. So you say, this is a great thing. So surely the CORE of Engineers who manages this absolute ton of water in the United States, it must be all over the CORE of Engineers. And if you look at our typical propaganda slide here, you have a hard time finding it. And there's a little bit in the environmental stewardship part of things, but really groundwater hardly, I don't know, where is it? So it's hiding, but so the question would be, well, if we're not doing a lot of research, if we're not doing a lot of it, is that because we're not allowed to? So essentially the first half of this talk is about, well, what are we allowed to do? As you recall as a government agency, unlike in your private life where if it's not against the law, you can do it. An agency can only do what we're told to do, what we're allowed to do, what we're funded to do. And so the question is, well, what do we have? What do we have in our pocket to do that? And the Everglades restoration was huge for Managed Aquifer Recharge because it was the first really large scale authorization for MAR, any number of the original projects that were approved were active storage and recovery or seepage management oriented. So that was a major, a major, major step forward. In 2007, some projects that Andy O'Reilly and talked about in the Mississippi, Mississippi River alluvium, the alluvial aquifer. It was, this was approved, this engagement with groundwater was approved on a regional basis. So in addition to what Andy and in collaboration with June Morekki of the Corps is working on there, there are a number of other projects being considered and being worked on in that general region. And then the first general authorization. So this is a nationwide, non-specific authorization that actually talked about MAR was in the Water Resources Development Act of 2016. So that was, I'll just skip this and give you some of the details on the next slide, which is this, there are three sections. Two of which, one came from the house, the other came from the Senate, they mashed them together. So they're kind of similar, but a little bit different. And 1116 authorizes us to carry out, to study and carry out water supply conservation measures in the States, which were having the drought in 2016, basically a lot of the same ones as now, but not exactly. And it specifically mentions groundwater replenishment and aquifer storage and recovery as if they're two different things, but that's okay. And as usual, since we are not in the water supply business ourselves as a Corps, we store water, the non-federal interest our partner has to pay for everything that we can figure out that they owe associated with the study and the project. So section 1118, very similar for the reasons I mentioned, but it actually mentions increasing the quantity of supplies, that's a little different from conserving water, but same general thing. And again, it mentions recharge, it mentions ASR and it mentions you guys have to pay for it. So 1117, I don't have in a lot of my other presentations, but it's because of the interest here in water reuse, there's definitely, I'm sorry, that's the next one, but to prioritize manuals for seasonal operations, and that was something helping our partners manage for seasonal operations was not really in the cards. And again, for these states that were in drought, we were allowed to spend a lot of time with our water control manuals to manage our reservoirs in a way that's a little more helpful for managed aquifer recharge. And you saw that with Adam Hutchinson's his talk yesterday with Orange County, that's a perfect example of where we're working with Orange County on Prado Dam to try to manage water safely because flood control is what we do, but also make it so that that water doesn't get released and just blow past Orange County's water recharge basins unless we have to. So this next slide is hot off the press really, a new nationwide permit that was released in December, it's now had 60 days to stew and I believe it's good. And this is the reuse. This is the only thing we regulate, of course, at the core really is the sediment being dumped into waters of the United States. And so it does simplify life since so many reuse facilities are associated with managed aquifer recharge. And this was mentioned in a bunch of the comments on earlier versions of this. And so it just does, it provides a nationwide permit if you're not really going to be causing a lot of damage then it helps to make these projects go a little more smoothly. So we can use, we being the core and our partners, the core itself, we have federal interest in flood risk management. So if you wanna use MAR to take the top off the hydrograph, it's not fantastic for that, but it can help. If you wanna use it for aquatic ecosystem restoration for salmon migration, for whatever species like cool water rather than the hot summer water, for example, we can do that, we can spend your federal tax dollars on that. And a lot of the other things though, a lot of the drought resilience, these multi-purpose projects, thinking of Phoenix, Arizona, Perez Rios, places like that, we need a partner's involvement in their money to make those happen. Saltwater intrusion, of course, on the coast. So just to say, there are things going on at the core with MAR, I was very generous when I put little numbers on a map here, some of these are very active. Of course, you see the Everglades in Florida, you see all the California sites where we're doing something or another, you see in the Mississippi Valley, some of the projects related to what Adam, I'm sorry, Andy O'Reilly talked about yesterday with the USDA, but a lot of these other ones are kind of well worth thinking about it or we thought about it and discarded it, but someone's got it in their head there. So it's, but it's all kind of scattered around, right? If you're looking for a MAR program at the core, you will not find it. So I'm gonna blame the Congressional Research Service here and it's tradition. So you sort of just looking at that first bullet there, USAIS authorities don't restrict folks from doing groundwater recharge programs, but historically, we haven't done it. Historically, we've done a lot of surface water and very little groundwater. And I think the same could be said for the viewer of reclamation, I guess I'll let them speak for themselves. But so why is that? Well, you see the laundry list of issues, but we haven't. And it's not because we can't at this point, it's that we haven't. There's a momentum factor. And so that leads to a culture factor. And this is why I am saying that these are my thoughts and not my bosses. Because any institution, this talk was supposed to sessions about institutional issues. We are an institution, we have issues. And so there's some momentum factor here. Really, MAR fits in well with a lot of the other things we do. We have this whole planning, step one, step two, step three, I think through step six, the planning process fits in fine. It fits in with all kinds of things that we do. It's not like you'd have to do something totally different here. But our engineers, hydrologists, who are they? They're surface water engineers. They're surface water hydrologists. The hydrologic engineering center used to have one hydrogeologist. He retired, right now we have zero. So I mean, there's, I don't know, 60, 70 people there. No hydrogeologists. So the hydrogeologists are there at the core, but what are they doing? They're specializing in sepid gender dams and levees, piping, those kinds of things. Or they're cleaning up all the messes that DOD made throughout the 20th century. So they're doing different things. They're mostly not thinking about this either. And then one of the issues is just, yes, we have a planning process, but we also have a whole pile of policies and guidance that tell us how these things are gonna be done. So if you're gonna do a surface water project, you just go to Army regulation one, two, three, and it will tell you what you need to do to keep your job. And whereas a lot of these things, the economics and the policy and the politics of groundwater recharge, they're just different. People feel unprotected, let's say, if they wanted to do something like that. So a lot of new ground to be done. So with that, let me, this is my final slide. And I do wanna say there's the what we can do and there's the what we are doing. And so the first part of this is the what we can do. And the Everglades Restoration Authority and our authority to do ecosystem restoration in general, those were game changers. Those were big because it provides a federal interest for MAR, means we can spend your federal tax dollars on those kinds of projects. The regional authority and the word of 2016 authorities that actually mentioned MAR, they've given MAR some credibility, they've given it a little bit of publicity, let's say, and then this new nationwide permit that I showed on water reclamation and reuse facilities may help. Sorry, I've got my own little thing there. So that's all good. So that's what's allowing what we can do, what we could do. And then the second half, MAR turns out to work out really well with most of what we're doing and including our kind of cutting edge things, our shared vision planning or stakeholder collaboration process. The forecast informed reservoir operations that Adam Hutchinson mentioned on managing our reservoirs in a more scientific way, more with better rainfall forecast information. It works together with that. And then water reuse, it all ties together. There's no real problem, but it just, it's tradition. So, and then the last point is that for those of you who are with the water utilities, the irrigation districts, tribes, if you want to make some of these things happen, you need to talk to your district, to the district hydrologist, district engineer, district planners. And because a lot of it's still, you've got to pay for it. We're able to collaborate with you, but you've got to pay for it, you've got to want it. And so tell us what you need, tell us what you want. Thank you very much. Thank you, Will. And thank you so much to all the speakers in this session. It was a very nice bow tie to the wrapping paper of this conference. It's interesting because we went all the way from identifying what is happening in the aquifers and the changing climate to manage aquifer reach our definitions to case studies, to technical considerations, to institutional considerations. So now without any delay, I'm opening it up to questions from the board members to start off this Q&A session. Okay, so I'll start with the first question to the people in this institutional considerations panel. Now that we have managed aquifer recharge as one of the real important aspects to combat, not just floods or restore ecosystem services or help in periods of drought, do you really think there has to be some kind of national level framework to do it? And if so, which organization will be responsible for doing it? I mean, basically trying to synergize all your presentations together. I'll just say briefly, I think you need a national framework for federal agencies to be able to do it for the reasons that we just heard. So that would be true for the Bureau of Reclamation, for the Army Corps of Engineers and potentially if there are other federal agencies that are going to get involved, it's helpful for them to have federal regulation. But beyond that, I think having, there's some things that are going to be consistent about the science and law everywhere and some things are gonna be different. And there's a lot of tradition of state water management. So no, I think there's probably more than one path forward and national legislation could be helpful but probably is not necessary. Yeah, and if I could just add, I think some issues came up, Robert Malaga brought up some issues about where federal rules and regulations can be obstacles. And so I think looking at that would be good. But I think the federal government should not be an obstacle but should facilitate when they can. And I'll give one example. There was a big question several years ago about whether the storage that was being done in Arizona of Colorado Riverwater was considered a beneficial use of Colorado Riverwater and whether that interstate banking could be used in a way to support whether that water banking could support interstate banking. And so, and Leslie, I'm sure you remember this, the Department of Interior adopted some of record of decision. I think it went to that level, Leslie, you can correct me saying that, yes, this water stored by California in Arizona can serve California and all that. And so there are instances where the federal government has stepped up and accommodated, facilitated and we certainly want that where it's needed. Thank you, Sharon. So let's go ahead. Sorry, this is Leslie. I was just going to affirm what Sharon said that it was as the Bureau of Reclamation acts as the water master, we need to verify reasonable and beneficial use each year of Colorado Riverwater and that was a big issue with whether or not stored credits were a beneficial storage was a beneficial use and we worked through a long process and came to that point. So there's a lot and I think the issue with the federal having from the federal perspective having federal oversight is how to do that in a meaningful way and but to still support the statewide programs in a way that they've been developed and is necessary. So I think it wouldn't be important but it'll be a long process. Thank you so much. Let's move on to the next question. David said like you had your hand up. Yeah, so it's a question more for Sharon and Leslie about the water quality aspects of managed aquifer recharge in Arizona. How does it intersect with salt management issues? It seems like historically there's been concerns about the buildup of salt in the basin and ways of flushing it out. And as you more efficiently use water and decrease the amount of runoff, it seems like in the longterm it leads to less sustainable salt management practices. So what is the kind of administrative way or the policy way of making sure that managed aquifer recharge doesn't exacerbate water quality issues like total dissolved solids? Leslie, you wanna take that first? My quick answer is we haven't really been addressing that, David, and that is an issue. The salt load is clearly an issue and the reason I was gonna defer to Leslie is that there were some reclamation studies on that. And so Leslie, I don't know if you wanna add to that but that is an issue, David. We have done some studies and we have done with our Trace-Rios project and several other basin studies and even some of the reports that I showed you earlier talked about recharging inflation rates based on certain qualities of water. So it is, in Tucson generally we've been storing effluent in other areas we're storing Colorado river water. So there's been a lot of work done. I'm not sure that we have a resolution. I would say that in the managed areas it's much less regulated in the constructed areas it really falls to the managers of those constructed recharge projects to manage. Yeah, and Dave, if I could and I know we have other questions but you have to look at kind of the intended use of the water as well. And in Tucson's case, Tucson water's case they're using the deep alluvial aquifers and they're mixing that Central Arizona project water that Colorado river water with the ambient groundwater that has much lower TDS. So although TDS is increasing it's still within manageable range and that Colorado river water was not meant to be drinkable water at the delivery point of the CAP water. So it's up to the utilities then to deal with issues like increasing TDS. And I could say more about that but I won't for lack of time but there is a gradual increase in the salt loads. Yeah, I think we should be careful about calling it a sustainable practice if we're not also paying attention to this long-term creeping issue of salamization. I think that's also true in the lower Tulare basin as well. Thank you. So the next question, Andy. Yes, hi. I guess this question is directed at Will Logan with the Corps of Engineers but I guess the group in general regarding paying for operation from our facility. For example, what we're doing in Mississippi it's just a pilot project and it's a long way toward if, when or ever it would be expanded to a larger scale but in a region where you don't have the existing institutional infrastructure it's not just constructed but to operate this system long-term. How does that, who would do that? Could that be the core or how to get paid for considering this case? It would be primarily the ag community benefiting from it. Any thoughts on that? Okay, can I add, Will, can I add a question from the chats? How do you envisage how US Army Corps Engineers mission can be weaved into other municipal partners? Can you provide an example of how this will work? So the first question about who pays for what the answer is generally for, I hear you talking about a lot of infrastructure needing to be built. I think all else being equal, the assumption is that the partner would pay for that but the actual answer is whatever Congress says, whoever, whatever Congress tells us to do that's what we do. So I think some of the projects that are north of you in Arkansas and Bayou Mecho and there's another one I'm forgetting. I think the core is paying for some of those things. Don't quote me on that, but it's because that's what Congress told us to do, right? I think you had your hand up too, please. Robert, can you hear me? Oh yeah, I'm sorry. Yeah, it's important to recognize that most managed aquifer recharge projects are initiated on a local scale and are financed on a local scale, both construction and operation. And that's why they're very sensitive to economics. It's just, it's not like there's an unlimited pot of federal government money to pay for this. I mean, it has to be justified on a cost benefit basis and that's why, key part of my point I want to make in my presentation is that just the regulatory aspects to it is, I can think of a number of projects that are not going forward just because of the economics associated with regulatory pretreatment requirements. One project, they want to just recharge surface water into an aquifer. If you had a zone of discharge, you could deal with the coliform bacteria, but if you have to construct a water treatment plant for that water, it's not economically viable and the water resources benefits are lost. Thank you, Robert. Next, Kathy Klink. Great, thank you. So I want to raise another economics issue and I don't have to comment or question. I'm going to try to frame it as a question. So we just heard, this was a great group of speakers. We heard a lot about the legal issues. We heard a lot about the sort of regulatory barriers which impact the economics. What I'm curious about is, as I said a different economic aspect, it sounds like, if I understand what I've heard, learned in the last two days that large scale managed aquifer recovery is going to happen. If we're going to do it, we're going to have to engage a lot of private agricultural land users. If I'm correct, and that I think depends regionally on what we're talking about, maybe that was just the examples we learned from California, almond and so on. But if that's the case, then we have to have incentives for private landowners to want to engage. And the fundamental economic problem there is that if you're a landowner and it costs you something to hold the water on your field, on your acreage, that water then refills the aquifer but you don't get the benefits because those benefits are shared with everybody in the aquifer. Is this something that's been thought about, addressed, am I wrong? Are there solutions? I just would welcome any edification. And yeah, Helen, I see your, this was actually, thank you. Yeah, I wanted to be careful because yesterday I'm new to myself and cause a big feedback loop here. But so right now, this has actually left a little bit again to the local scale to figure out. So what individual water districts have done sort of come up with a net metering approach, for example. So whoever does recharge and puts water in their report, how much they did and they get credit for it, either monetary or in volumes that they can then pump out again against that number in the summer. But there are really different approaches and it is one of the number one questions we get from growers is like, okay, what are the incentives? What can you put on the table to make me do this? And for the really desperate ones, the motivation and incentive is to have water in 10 years. So yeah. Thank you, Helen. So the next question is from John Arthur. John? Still here. Many thanks to all of the speakers in both sessions and this question might extend to the earlier session as well. Dave, oh, and I particularly think of you when I think about this question and sort of echoing the regulatory irregularities that Bob Maliva and others voiced. Is it practical to think about a model code that could be developed for MAR that would be used as a guide? Maybe there's an East and a West version but does that make sense at all or are the local laws so unique and the local situation so unique that that would not be practical? I would say, I think it does make sense. I think you might be looking at at least two because I think the issues for ag MAR and perhaps forestry MAR and then urban stormwater MAR or urban water reuse MAR are different enough that one code probably doesn't do it. But I mean, the great thing about a model code is it's just a starting point. You can adapt it to the particular needs of your area and you can account for the differences that way. So I do think there would be value in that idea. Robert, did you have anything to... Sorry, go ahead. Go ahead, Shannon. Well, I'll see if Justin wants to say something first or Bob and then I'll come in later on because I do have something to say about it. Yeah, I would add that I would think that a US EPA guidance document on that that again, considers the current state of the art of the science could be quite helpful and that it could provide guide the states in the right direction towards maybe getting the regulations up to date with the current science. I don't think a change in the rules are necessary, but if you can give the states cover, because I know in Florida, on some cases I've worked on it was a matter where the state agency DEP is saying, well, we can't do this because EPA doesn't allow it. So if we could get some good guidance documents by the US EPA that could guide the states, I could see some real value in that. And in terms of water reuse, we've EPA's done similar things in the past. In 2017, there was essentially an addendum to our 2012 water reuse guidelines looking specifically at portable reuse. And by portable reuse, it includes surface water augmentation, even direct pulver reuse to a certain extent, but it did include indirect pulver reuse through groundwater augmentation. These aren't national rules or even, they weren't even called guidelines. This was a really a compendium of a lot of the existing state of science, existing literature. This is from 2017. A lot has obviously changed since then. And I mentioned it yesterday, but what we are currently doing is really collecting catalog and a better understanding the state level regulations for water reuse, including reuse for aquifer recharge. And there's obviously a lot of site-specific considerations as far as what happens underground, but in terms of water quality of treated wastewater, there's been a lot of this is being led by states, states like California, Texas, Colorado, Florida, but we're actively looking at what the different states are doing and not just identifying what they're doing, but identifying a lot of those scientific basis and the technical basis of that. And our Office of Research and Development is doing a fair amount of research as well. And, you know, stormwater came up and stormwater is different than wastewater, not just in an institutional and regulatory side of things, but certainly in a water quality side of things as well. It is also considering how these different things are managed, you know, wastewater is managed in many ways centrally. You have the benefit of sort of centralized treatment that can be used where stormwater, it's both a disadvantage, but also a potential advantage that a lot of that can be managed in a decentralized way. And a lot of this is happening through things like green infrastructure, urban, some urban stormwater management. And there's been some concerns voiced by let's say the National Groundwater Association on groundwater impacts from that. And it's something that we're, the EPA is certainly taking into consideration. And you're speaking for myself personally, so then I'm working on is with our Office of Waste Water Management to try to bridge the gap from stormwater management in terms of service water quality, bridging that into potential water supply as well. It's a process, it's not something that EPA has traditionally done in the past looking beyond water quality and into water quantity, but it's an area that I'm interested in and just sort of taking the next logical step in terms of stormwater management, not just from a quality perspective, but thinking it as a potential resource as well. If I could just add really quickly, first of all, I wanna put in a plug. We have the director of the Water Reuse Office for EPA giving a brown bag at my water center next Tuesday at noon, Arizona time. If anybody's interested, let me know. I'll give you the info. But I wanted to mention, I think you'd have to have a bit of a dialogue of what these guidance documents would focus on because there are the different sources of water and I think there would be some concern about too much regulation coming in where there hasn't been, even if it's only guidance. So I would just say, need some dialogue on what kind of guidance you're talking about. Thank you, Sharon. And the last question goes to Dave Begner. Dave. Thank you. And I wanna thank all the speakers today. You did a great job, fascinating discussion. I wanna make one short comment and then a quick question to Sharon and Leslie and anybody else who wants to chime in. Will Logan, your assumption may be that Congress knows what it's doing when we provide guidance. I think that's a bad assumption. So that's my comment. The question though is, as we've heard today and yesterday, there is a lot of emerging legal direction on the use of managed aquifers. There's a lot of technology that's evolving and there's a lot of knowledge that's being developed. My question is we deal with a lot and especially in what Sharon and Leslie just spoke to about the managed aquifers being used in Arizona to kind of meet some legal requirements under water settlements and to try to get through some of our shortages that are on the horizon or if we're already feeling them. How are we developing capacity with those folks who may not be as knowledgeable about managing these resources, the legal side of it, et cetera. And I'm thinking specifically, Sharon of our tribal colleagues who don't necessarily have the technical expertise on board or will for some of the shareholders who you wanna have step up and pay for this stuff, how do we bring them along? Are the agencies and groups helping to develop knowledge in terms of bringing people the knowledge piece to make sure we can implement these programs successfully? So Dave, very, very briefly, I know we're short on time, but as you know and most many know, the issues of capacity for certain segments of the water management communities, whether it be tribes or small communities, cities and towns, many are facing capacity, human capital, capacity constraints. It's interesting, I'll just share that at that international symposium a month ago, I, besides the workshop, I hosted a organized a panel, Mara in Action, and two of the four speakers represented tribal communities. One from the Yakima Nation and David Deong who was mentioned yesterday from Healer River Indian community. The representative of the Yakima Nation afterwards asked me, am I aware of a network of tribal folks working on Manitaka for Recharge? And I said, well, ask David, he'd know, but I don't think so. And if there's something I can do to help organize a round table or whatever, I'd be happy to. So I think this whole point of dialogue and how to bring people together, we're also busy doing our work. And so if these boards can help contribute to how to kind of improve that dialogue and capacity building at the same time, that would be great because we need more of people just knowing who's out there to ask questions of. They don't even know that. So, and I agree with you and I know we're short on time, but I just wanna mention a couple of things. This is Leslie, thanks, Dave, for asking this question. So the Tahuna Automation actually has a really, really knowledgeable crew that works on storage and recovery because we've looked at this, not just for firming, but for lots of other aspects of reliability and they've developed their own water management plan that includes storage, development of long-term storage credits and ultimate recovery. So has Keelan River Indian Community. There is a, so there's a small subset of folks that are very, very knowledgeable about this. Reclamation does sponsor a group called the Tribal Leaders Water Policy Council through the Intertribal Council of Arizona. That is tribal leaders in general, but there are a group of folks that speak to these technical aspects, including EPA regulations and local regulations and things. So we try, but we probably haven't even scratched the surface of the knowledge base that's really needed for tribes to be able to adopt these principles and move forward. But we at Reclamation are always ready to help in any way we can. Okay, Bill, you have the last word. Wonderful. Yeah, I wanna say a couple of things. First of all, read Dave Owen's paper that he cited there. It's the most readable 50-page paper you will ever read. And I did it beginning to end. Second, the two talks that Sharon refers to at the Maher Conference in Long Beach a few weeks ago were two of the best talks at the conference and they were fascinating. The Yakima and the Pima River, is it? Healer River, Healer River. Healer River, excuse me, just fascinating. And it opened the question, managed aquifer recharge is often a way to solve stakeholder conflicts by producing a little extra water at the right time of the right type. And this was true with the Everglades. I mean, the Everglades restoration would not have happened without a 1996 letter to the governor that was signed on by 40 some entities from the sugar people and the government to the, I hate everything. And it basically everyone signed it. It was a unanimous letter that said we need Everglades restoration. A lot of that happened because for better or for worse, they promised a lot of water from aquifer storage and recovery. They said, here's how we'll make everyone happy. A little tough, but that's the bottom line is I think there'd be a lot of interest from a lot of folks in how we get water to tribes that we owe them, but haven't gotten them yet. Thank you. Thank you, Will. And thank you so much for both the panels, the technical considerations panel and the institutional considerations panel. And over the last two days, we've had some excellent presentations on managed aquifer recharge or MAR. And I can say it was marvelous. Thank you.