 And welcome you to this public session of the Owens-Lake Scientific Advisory Panel. I'm going to read some prepared remarks. I'm Dave Allen, the chair of the panel. The panel's work is being conducted under the auspices of the National Academy of Sciences in response to a request from the Great Basin Unified Air Pension Control District in the LA Department of Water and Power. The panel has been asked to evaluate the effectiveness of alternative dust control measures for their degree of reducing particulate matter emissions from the Owens-Lake bed and reducing the use of water and control conditions. I would like to emphasize the panel is focused on conducting science and engineering evaluation. The panel will have no direct involvement in designing or implementing dust mitigation plans. The panel's statement of task and other relevant materials are available on the outside of this room. Today, the panel will hear a series of presentations. I'll note that we're on a pretty tight schedule, so I'm going to hold everyone to their allotted time. We'll hear a series of presentations that are relevant to its task. I'd like to emphasize to everyone that this is an information gathering session. That is, the panel is in the process of collecting information that we'll consider in the course of making its scientific conclusions and recommendations. Therefore, I asked everyone here today to be extremely mindful of the fact that the panel has not completed its deliberations. Comments made by individuals, including members of the panel, should not be interpreted as positions of the panel or the National Academy of Science. In addition, some questions asked by panel members during these information gathering sessions are intended to probe a topic and may or may not be indicative of their personal views. Once the panel's draft report is written, it must go through a rigorous peer review process before a draft is considered a National Academy of Sciences report. Therefore, observers who draw conclusions about the panel's work based on today's discussion will be doing so prematurely. I want to note that this entire session is on the record and is being recorded. Each presenter will be asked to provide remarks and then panel members will have the opportunity for follow-up discussion. However, because of time limitations, the panel presenter should not be expected to entertain questions from members of the public. Near the end of today's session, at five o'clock, members of the public will have the opportunity to provide comments. If you're interested in making comments, we ask that you sign up at the information table again just outside this room by 4 p.m. today. For those joining the meeting online, if you would like to make a comment, please sign up by 4 using the chat feature online and send a message under the heading Ask Questions Here. Each speaker should plan on taking no more than a few minutes. Also, anyone who wishes to submit written comments or other materials that are relevant to our charge should contact Ray Wassell. Ray, would you raise your hand? The responsible staff officer for this study. Before we begin the presentations, I'll ask the panel members to introduce themselves to the audience and indicate their affiliations and relevant area of expertise. I'll begin. I'm Dave Allen. I'm the chair of the panel. I'm from the University of Texas at Hoffman, and I have a broad array of air quality management experience. I'm PT Busswas, Washington University in St. Louis. My expertise is in aerosol science and technology and focus here on particle control technology. I'm Ted Russell from Georgia Tech, and I actually started particulate matter modeling in California about 40 years ago and been doing it ever since. I'm New Shredded Johnny. I'm director of a lot of policy programs. I stand with the University. My expertise in hydrology and water resource management and water energy management. Greg Okin, department of geography, professor and chair, mostly study destination processes and Aeolian processes in the presence of vegetation. Good morning. I'm Stephanie Johnson with the National Academy's staff in the water science and technology course. Ray Wausel, I'm the responsible staff officer. I'm Cliff Duke. I'm director of the Academy's ward on vital studies and physicality. I'm Ben Kedrone from U.S.S.I.D. and Mike Spadee, the administration of the U.S.S.I.D. Scott Van Pelt with the USDA wind erosion water conservation and research laboratory. My area of expertise is the emission processes industry. And can we have the people on the phone introduce themselves please? The panel members. Yeah, this is Scott Tyler with the University of Nevada, Reno, the Department of Geological Sciences and Engineering. My focus is on near-surface hydrology, transport of energy, water, solutes across the land-atmosphere interface. And I have worked down at Owens Lake about 20 years ago working on understanding the evaporation rates and water balances on the lake bed itself. I'm Ruya Barini from environmental sciences at UC Riverside. My research is focused on understanding the sources, their precursors, and transformation pathways in the atmosphere. Okay, great. Thank you all for those introductions. We're going to proceed immediately to the agenda. I know we're already five minutes behind by my watch. So what we're going to do is hear from three speakers in the interest of time. We're going to have the three speakers make their presentations and then we'll follow that by questions for all three speakers at the end of that. And so we're going to be targeting getting to the questions by 1120. So the speakers will still have the time that they were initially allotted. Our first speaker is the air pollution control officer from the Great Basin Unified District, Philip Cadu. Thank you, Dave. Good morning, everybody. Members of the academy, scientific advisory panel, Great Basin staff, DWP staff, piece of members from the state of California, members from our sovereign nations, also the public. Good morning. So I've got a lot to cover. You can probably, well, I'm really fast-squeezed by a year. But it's a good overview and I'll give you a good history, a brief history of the timeline, the regulatory timeline and the dust control implementation timeline. Again, my name is Philip Cadu. I'm the Great Basin Unified Air Pulsion Control Officer. I'm the executive officer, the director of the general manager of the agency. I oversee all functions and operations of that agency. Great Basin is a regional government agency. We're comprised of three counties. We're a unified air district. And our mission is very simple. It is to protect the public's health from the harmful effects of air pollution. And in that mission, we also have the responsibility to protect the environment as well. Great Basin is a unique air district. There's not a lot of unified air districts in the state of California. And our legal authority comes under the Federal Clean Air Act. It also comes under state law. The air district story is quite fascinating because we're, the Clean Air Act is a sub-cooperative federalism structure. So the federal government said, we're going to regulate air quality. We're going to set these standards, but we don't have the resources to enforce them. The state's going to do that. And the state did the same thing. And they delegated that authority to the counties. Well, in rural California, the counties didn't have the resources either. That's why we unified. If we were the size of a state, we'd actually be the ninth smallest state in the country. This just to give you a geographic overview of what the Great Basin is. So Great Basin is a watershed where there are no outlets from the tributaries to the ocean. And the Great Basin Air District, which is just a California air basin, sits on the eastern side of California. And we have two unique sources of pollution that make our air district unique. One source, Mono Lake, and another source, Owens Lake. What makes each unique is Owens Lake is actually the country's largest source of PM-10 pollution in the country, and it's controlled. And Mono Lake is now currently the largest active source of air pollution in the country, seven years around. One thing unique about the tributaries and lake systems in the Great Basin is that they don't drain to the sea, so they're strictly rely on those tributary inputs and evaporation to maintain lake level. This is a picture of Owens Lake taken in 1891, looking towards the Sierra Nevada, along the shoreline of Keeler. So 110 square mile lake with about 50 feet deep, are usually 90 if you measure the thickness of the mud. Just to put that into perspective, if you had a kitchen table and put a penny on it, the kitchen table surface area is the surface area of Owens Lake, and the thickness of the penny is the depth of it. So it puts it into scale a little bit. Owens Lake was a lake that was navigable. There were steam ships that pulled sewer ore from Sierra Gordo over to ports on the other side and down to San Pedro. Some claim that the lines at Owens Lake were the lines that built Los Angeles. And something changed. This was in 1913. What had changed was the city of Los Angeles built the Los Angeles aqueduct. And that Los Angeles aqueduct's purpose was to supply the growing city of Los Angeles with water. As a consequence, the water that arrived in LA in 1913, that rise today of millions of water with the most cleanest and reliable drinking water for the city of Los Angeles, ended up resulting in the desiccation of Owens Lake. The desiccation of Owens Lake is why we're here today. Here you can see some of the surfaces and surface conditions at different times of the year. Some of the heaved crust surfaces that you can get. And then also in the bottom right, you can see a picture of Owens Lake prior to any dust controls where there's about a 10 square mile area of PN10 emissions. Quite a large source area. It's one of the warmest areas there was before control. And it's what we call the North Sand Sheet. Just kind of put that into perspective. You're looking at about 65 miles of searing about a crest there and just the northern portion of Owens Lake. This is what a PN10 event looks like at Owens Lake. We're going to get to this specific area in about slide 17. But the put this into perspective is the largest source of pollution in the country. You know, what were and how large were those PN10 events? Well, there's different ways you can measure it. You measure it on a 24-hour level over the clean air loss, 150 micrograms per cubic meter. You can measure the severity of it based on the frequency. You can measure the severity of it based on the order of magnitude. So we would have 45 exceedances of the federal level per year. That's the frequency. We'd have concentrations of up to 20,000 micrograms per cubic meter per day. And to put that into perspective, especially for members of the public that don't deal with micrograms and cubic meters and those types of units, if you're exceeding the law, which is the law, 150 micrograms per cubic meter, and you're doing that 100 times over, the equivalency of that is you're pulled over by a high-risk patrol on a 65-mile-an-hour zone and you ask you how fast you were going. You have to tell them you're doing about 6,500 miles an hour. So if you're trying to get out of the ticket by telling them you're late to dinner for your grandma's pie, it's probably not going to be too sympathetic. It's an endangerment to public health and some endangerment to society, too, yourself. So that kind of puts the problem into perspective. The regulatory timeline really begins with the Air District Formation 74. And then something that happened in 1983, and that was the legislative action of the State of California that implemented the Health and Safety Code 4206. And what this did for the first time was it decided that the City of Los Angeles was actually responsible for the M10 emissions data once late because the water diversions, it was determined to be an anthropogenic cost, meaning that it was man-made and they were going to be the responsible party. We'll use this in the next couple of slides because it's pretty important to understand because normally our pollution control laws work differently. They work based on ownership and property ownership. And one other special thing about the laws is that this pollution source predated the Clean Air Act. So today, if somebody wanted to build a coal fire power plant in downtown Los Angeles, they'd have to go to the South Coast to get a permit. And they couldn't be able to build that facility until they could have already meet the requirements to prevent emissions that would impact public health. Owens Lake had already been doing that. They've been doing it for 100 years. And so we had to develop controls that can bring that source under the federal state regulations. And so my staff, Grace, Dr. Grace Holdern, and Logan will be talking about that later today. So it's an important thing to understand. There aren't a lot of special circumstances at Owens Lake. One of them being in the Federal Clean Air Mandate doesn't need to be met anywhere at Owens Lake except the 3,600 rotation line. The PMTAN standard of 150 micrograms was promulgated in 87. And then the Owens Valley planning area was designated non-attainment. What this meant was that the Great Basin Unified Air pollution control district had to develop a plan to control the source of emissions. And so our first plan was written in 1987. This is the serious non-attainment designation boundary for Owens Lake. It goes from south of Tinnemaham just to Hawee. And I think it's the central Hawee, but it may be south end of Hawee. Just gives you a little bit of perspective. The geography were bound by three mountain ranges. On the west we have the Sierra Nevada. On the east we have the Inyo Mountains and the Coastal Mountains. And the prevailing meteorological patterns are north and south winds depending on the time of year. It's like somebody breathing very deeply through a straw. That's how the winds move through the Owens Valley. And this is just normal. This is the environment. Play the interesting piece to the puzzle because DVP responsible for the controls has to get the permission of the landowners to implement the controls. So as you can see the state of California has, so that's about 95% of the ownership of the lake bed. DVP has some, the Bureau of Land Management has a little bit. There's some private in holdings on the south end. Water, Crystal Geyser and the duck club. So primarily it's state property. And in the early days deciding how the controls are going to be put into place, what controls are going to be used. It was important to understand what the landowner was going to accept, what DVP can implement. And the things that the scientific advisor panel is going to be considering in alternative dust control technologies. In 1998 this was Great Basin's estimate of the areas that needed control. It's actually 46 and a half square miles. And I think this was put together with cardboard and Xerox and like a light bulb or something. It was pretty cool. All right, the good stuff. So we get into a regulatory timeline. You keep track of time, Anna. All right, we've got a good step here. The blocks of dust control implementation are really important. Maybe understanding all of those specific intricacies of them are not so much. But what's really key here, and I'll try to highlight some of the brief components of each block, is the 1998 SIP. Nat actually provided a state implementation plan for the first time that had been approved by the Environmental Protection Agency, that had been approved by the state of California. That said, yes, this plan is going to work. There are areas for dust control. And that was 16.5 square miles. In that plan there were provisions to build out dust control to about 30. In the 2003 plan there was a provision for over time developing supplemental control measures or deciding what areas needed additional controls. There's really specific procedures in our implementation plan on how that's done. We collected four years of data and the dust control area group. We had a settlement agreement at DWP, subsequent SIP that incorporated all of these provisions and the dust control was built out to 43 miles. After the 2008 SIP, following the same provisions for supplemental control determinations in 2011, the district ordered additional controls. 2011 and 2012 added 3.16 miles. 2013 added zero. We didn't find any additional areas. We had a modified, stipulated order of abatement that required two additional square miles of control in the North End of the lake. We had a keeler due settlement where the district received $10 million in funds to do a keeler due dust control project. And then in 2014 we had a stipulated judgment. The stipulated judgment and the 2016 SIP is what we'll talk about most of today because that is where we are and how we look into the future and how we regulate Owens Lake as a best source. There's also another, it's rule 433 and that's a component of our 2016 SIP and that's the federally important mechanism of the state implementation plan. This brought Owens Lake 48.6 square miles for control. However, 1.2 square miles are deferred for controls at this time if it's a census resource area. The map obviously doesn't add up. DWP as they have built controls are actually a little larger in some areas than smooth boundaries. So we actually have 47.8 square miles of dust control. So this is what it looked like. 1998, 16.5 square miles, the most emissive areas on the lake, North Sanchi, South Sanchi. The 29.8 in 2003 and Jaime Valenzuela is going to give our presentation actually talking about DWP's faces of these projects later this morning. The 2005 supplemental control determination settlement agreement in 2008 SIP. That was 43 square miles of 2011 stipulated order of abatement as this two square miles of gravel the north end of the lake and that's where the photo of the PM10 event was from, was pretty much that area. Steps, the additional supplemental control determinations modified stipulated order of abatement, KW installment and the SIP, SIP management and this is where we are 47.8. There's the center of the lake. There are no controls required for that area. DWP actually does not need to ever control those areas as part of stipulated judgment. It's the brine pool. That's what's left of all those lakes. There's still water there. Around the edges of the lake a lot of that area is naturally controlled with vegetation and seeps and springs. The question everybody always asks are we done or all the dust controller is controlled and it's a really difficult question to answer. It's not that I don't want to answer, it's just a difficult question. What you're looking at here is all of the dust observations. We've had staff for a quarter century looking at the dust plumes at Owens Lake and they go out these observation points and delineate these areas and this is what they've seen over that quarter century. You can see we've captured most of the areas and the focus here was really on the lake. We have some additional off-lake areas like the Keeler dunes and the Lancia dunes, some other sources over by Flat Rock or we have some depositions. One thing to put into context here is that Owens Lake was a source of emissions for a century and those emissions have depositions, secondary depositions along the shoreline and those depositions zones are still there and still there are emissions associated with those. This is what it looks like. It is a piece of artwork. It is the eighth wonder of the world. It's the dust control at Owens Lake. It's an engineering marvel and one of the most successful air pollution control stories I think in the history of this country. It is the largest source of air pollution control and pound for pound one of the cheapest control measures that's ever been implemented for fugitive dust emissions. These are these controls and we'll get into much later. Are we done? Are all areas controlled? This is just looking at potential emissions and the reason why I'm using potential emissions versus annual emissions which is how it goes where agencies normally look at emissions is because the annual emissions change. The lake is very dynamic. They're not the same. They will change if it's a one-year year. They'll change if it's a drier year. They'll change if there's precept at different times of the year on crust surfaces with warm temperatures that are maybe hotter earlier in the year than previous years. So it's very, very dynamic. What this does is it looks at all of the areas that have ever been emissive at Owens Lake in 2011 was when this analysis was done. So when we talk about times of emissions, potentially could have seen 240,000 tons of PM10 annually from Owens Lake. The most we've ever measured is about 76 tons, 76,000 tons per year. So this is where we are today about 2,600 tons a year of potential emissions and so some years we see it, some of that and some years we don't. We haven't seen a lot of new areas open up since 2016. We've seen some areas open up that haven't been emissive for a few years and we've seen some areas actually open up more significantly than we've seen in a long time but they're not real large. So what do future dust control source areas look like? And this is a map from our 2006 settlement discussions with DWP's identifying areas that require controls that might need controls and definitely won't need controls. The take-home here is you can look at some of the areas like Wahoo, and this is a low priority, we're not going to need emission controls there, you see cottonwood, cotton's low, there's some other areas in north and the lake and then you look at a similar map that we made for radiation in 2011 and those areas have actually changed. Wahoo's now maybe, you get some areas by the Delta now maybe, the lake does change, our knowledge already changes. One of the great things about the regulatory software that we have is that there are provisions for additional controls. There are provisions for 4.8 miles of contingency areas that would bring our dust control areas of 83.4. That's one of the provisions of the stipulated judgment. Some of the other provisions of the stipulated judgment have yet to be completed. One of them is the formation of the scientific advisory panel but other than that, other than the additional contingency areas in the scientific advisory panel, most of those provisions have been fulfilled. Even the force manager has been exercised, stipulated penalties have been exercised, so we've been operating under these documents and they've been working very successfully. The incorporation of everything accumulated over time over the last quarter century for regulatory documents in our knowledgeable lake have been incorporated into these and we'll talk about these in much further detail later on today. This is what our lake looks like. It is a mosaic of dust control, natural lake surface, Ryan's surface, these are areas with vegetation, these are areas with water. You see different distribution systems with water. You can see areas covered with earth or crushed rock or what we call gravel and this is just a little mining, a new wedge lifted towards the canyon. That is all I have for this morning. Okay, great. Thank you very much. As we discussed at the beginning of this, we're going to hear from the remaining two speakers and then go to questions. So I have the next speaker as Mr. Valenzuela, the manager of the Owens Lake Dust Mitigation Group. We're unresponsible for planning and implementing the dust control orders that come from the Great Basin and also maintaining compliance with those. You'll hear from some of the operations and maintenance managers as well later today what it takes. So I jump right into it. Phil spoke great, said a lot about regulation and I'm going to speak a little bit about actual implementation and what we've done just give you a little more sense of what it takes. So for those of you who don't know where Owens Lake is, it is about approximately 220 miles from the city of Los Angeles up to 14 Highway 395 as well. My staff and I make that drive probably four times a month and as Phil mentioned, here's a zoom in. There's the eastern Sierra to the west in the Inyo Mountains on the east and it creates a wind tunnel. So if you have an emissive source, then you're going to have a dust problem. The question is why, obviously as Phil mentioned, the DWP built the Los Angeles aqueduct that brewed water away from the river, Owens River and away from Owens Lake, the final destination for the river and towards the city of Los Angeles created a dust problem. If you get wind gusts of 70 to 100 miles an hour sustained, you get turbulent flow at the surface of the ground. That will start to degrade the crust on the surface of the ground and that crust is typically anonymous. It's pretty hard. It almost feels like concrete when you walk on it, but as that crust starts to get sandblasted away, it exposes the finer PM10 particles from beneath and we have a big problem. Let's talk a little bit about regulation. I'm going to just hit some general points here. In 1913, the Los Angeles aqueduct was completed. In 1987, the EPA established national ambient air quality status for PM10 and they established a 24 hour average of 150 micrograms per cubic meter. Owens Lake was classified as a serious area of non-attainment. 1998, Great Basin adopts its first state implementation plan, which is enforceable under the Health and Safety Code 42316. In 2000, DWP starts its dust mitigation projects on Owens Lake. If we fail to comply with the deadlines or with the actual performance criteria, we face fines of up to $10,000 a day. Huge incentive to get the work done in a timely fashion. In 2011, after 10 years, 11 years of dust mitigation orders, DWP saw no end in sight and started contesting the orders. In 2013, a settlement agreement was reached, which established a limit of 53.4 square miles and that's defined by the historic shoreline of 3,600 foot elevation. 2018, 10 projects have been built, 48.6 square miles of dust mitigation have been completed. What kind of dust controls are we talking about and what does it take? So, shallow flooding is exactly what it means. You have standing water on the surface of the ground. You have to maintain 75% wetness on that ground and that 25% can be shaped any way you want it. And as you can see in the picture to the right, there's some islands for the birds there. Kind of looks like the Dubai Island, so we don't know creative. A variation of shallow flood is sprinkler shallow flood. We started using sprinklers and as you can see here, the soil from a compliance standpoint, this probably would not pass because only the standing water would get achieved performance compliance. The moist soil would not. Talking in decreasing order or descending order from water demand. Then we have managed vegetation, which is another federally approved dust control vacuum that's available control measures. And what does it take to grow vegetation on a lake that received deposits for thousands of years from the entire valley downstream, I mean upstream. And the soils are very saline. It's almost impossible to grow anything unless you have, you leach all of the soils, all of the salt out ahead of time. That requires a massive amount of drainage infrastructure, irrigation infrastructure to and testing salinity testing to make sure that the soils are susceptible to actually grow any type of vegetation. We're currently allowed to grow 41 types of native types of vegetation on the lake. Very one of the most challenging types of dust control, because there's so many variables and factors, soil characteristics play a huge role. The performance criteria is generally 37% coverage on an area, on average, plus some spatial distribution criteria that's kind of challenging at times as well. We have brine. Brine is a subset of shallow flood. It's not a new type of vacuum. Brine is just super saline, highly saturated water with salt. It doesn't want to evaporate because it's so heavy. And it forms a crust at times and at times it forms a liquid that doesn't evaporate. So we are measuring our performance criteria either for the wet portions. It's looked at like shallow flood for the crescent portions, the thickness of the crust is measured. If we fail to comply with brine, we go back to shallow flood. We can be ordered to go back to shallow flood. That's why it's a subset of shallow flood. Dust control. It's pretty basic. It's an ancient method of mitigating dust by simply creating roughness on the surface and to reduce wind speed at the surface to avoid the saltation that I mentioned earlier in the sandblasting of the surface. The more aerodynamic roughness you have, the more effective it is. It's a subset of shallow flood because if it fails the performance criteria, you have to reflood the area. You have to flatten it and reflood it. But apples to apples, cost-wise, tillage is probably the most cost-effective dust control method on the lake. We have gravel. Gravel is a very effective type of dust control. We have to install 100% coverage of the gravel, two inches in thickness over a geofabric. And if we don't use a geofabric, we have to put four inches of gravel thickness. The color of the gravel is approved to look as natural as possible. So how is our compliance? Generally speaking, I know we're going to get into more details later, but how is our compliance measured? Well, the performance measure. So for managed vegetation, there's a variety of ways to measure compliance. There's sand flux, satellite imagery, and then there's ground truthing of that satellite imagery. The image to your left is a measurement of managed vegetation. Using the satellite imagery and the ground truthing, you're able to determine what percent coverage is in this area. We have greater than 20th grade. The red is bad. For shallow flood, we use light detection and ranging, the shortwave infrared. If the reflected, then it is hitting a dry area. If it hits water, then it is absorbed and they're able to analyze this data and determine how much standing water is actually on the surface. Tillage, very basic. It's based on dimensions to determine the aerodynamic roughness of it. We have the furrow spacing and furrow depth. We have to maintain specific ratios of performance. We also have cloud sizes and that cloudiness is kind of represented in this picture here. Usually happens in more clay soils as opposed to sandier soils. Gravels, we use aerial photography, site inspection. You have to have 100% coverage. We want to speak a little bit about some of our efforts to refine our current methods. We, the Department of Water and Power and our staff, our consultants, have to achieve 75% with for shallow flood. But literature review and data testing, excuse me, laboratory testing and data analysis have demonstrated to us internally here that you don't have to have 75% with to achieve 99% control efficiency of the, we believe it might be less. So we've kind of started to test this by having different performance and different curvatures to try to refine this curve with the ultimate goal of using water more efficiently for shallow flood. The challenges of constructing on Owens Lake, there are several challenges. Climate change is one of them. 2017, we had almost a record snowpack here. And if you're the terminus lake of a watershed, guess where the water's coming? If you can't send it all down the aqueduct. And if you're having shorter winters, meaning all of your snow is in a, in a shorter amount of time and you don't have the capacity to convey it down to LA, then you're going to have a runoff problem. And we have to mitigate for that by massive amounts of spreading and really strategic maneuvering of filling our reservoirs here in downtown. So that's the problem. If the lake floods, we're obviously going to destroy a lot of our infrastructure out there that is corp mandated and legally required to stay in compliance. We have salt saturated soils all over the place. Very difficult sometimes zero varying capacity. So it's slow going. They're very corrosive soils. So you have to use materials that are stainless steel, high-density polyethylene, non-corrosive materials. So construction materials are very customized and very expensive. And then you have your wind gusts. The reason we have a dust problem, if you don't strap down your electrical shelters, it happens to it. If you don't strap down your connex with steel connex and materials in it, it's going to roll over a few times. But again, we can't just do anything we want out there. You have to balance your different interests out there. As we started putting water on the lake, the birds started showing up. There's a variety of environmental resources. There's habitat. There's public trust, valley. There's archaeological resources, paleontological resources, tribal cultural resources that we have to avoid impacts to or mitigate impacts to a picture of the arrowhead. There's no enclover. Just a variety of birds show up. Protecting public access and local resources. We're very closely with the state, the land owner. And whenever they believe that the public trust has been impacted, we work with them to develop features to enhance public recreation. This is an enhancement project that we did at the T-30 dust control area. We hired architectural designers, landscape architects. We have bird viewing areas. And since we started seeing that more and more people were being invited to the lake, we actually had to have put down some guidelines, basic rules to follow and trash cans. Kathy Bancroft is here today. We work closely with her to make sure that we protect cultural resources. How do you balance habitat? Well, our biologists, a whole team of biologists up in Bishop, have determined that there are groupings of birds that use resources in a very similar fashion and have them into six guilds. And the resources are defined in water, the type of salinity, the depth, types of dry areas, and how much vegetation. So they've developed a habitat suitability model, which not only measures current habitat value at the lake, but it can also predict future habitat value based on proposed changes. Have we achieved a date? As Phil mentioned, and his slide pretty much represented it as he went through each regulatory order, we've done 10 capital projects completed since 2000, installed 40.6 square miles of dust control. There's 4.8 square miles of contingency. We've controlled emissions to approximately 90.6 percent reduction. And we've seen a reduction of 75,000 tons per year reduction on average. This is a representation. I know it's very difficult to see all of all 10 phases starting from phase one north, south, phase two south, three, four, five, seven, eight. We skipped the number. Then we went to phase seven A, because phase seven couldn't be built completely. Parts of the lease were delayed or not are denied. This was completed in seven A and then phase nine, 10 at the very end. What it looks like now compared to 1998, the rainfall is blacked out because the satellite overpass did not capture it. So it just looks black right now. That's not much water in there. But the rainfall looks more like this even today, just standing saturated brine water. Probably speaking, we have about 32 square miles of shallow flood, 5.8 square miles of managed vegetation, about 5.4 square miles of gravel, 4.4 square miles of tillage. And we have some sand fence. Not much more than this is going to be allowed, because this is a limited type of agreement. We have some less than backup or alternative types of backup that have been implemented at the lake because of in order to protect cultural resources or habitat. Total cost to date is estimated at $2.1 billion. 55% of that being capital. O&M is about 18%. 21% is the cost of replacement water. Every drop of water that is used on the lake for water conservation, excuse me, for dust mitigation, is not since LA. And to supplement that, we have to buy that water from the Metropolitan Water District. That water comes from either Colorado River or the Northern Delta. And then we have our regulatory fees that are built in some of the infrastructure. It's not visible. You go out there, you're not going to see all this pipe. All of this is buried. It's enough infrastructure for an entire city. If you guys have ever been to the city of Long Beach, 30 square miles, well, we have 48.6 square miles of infrastructure. The possible next steps for us, obviously a lot of the infrastructure is becoming very old, so we have to replace and enhance aging infrastructure using new technologies, better ways of doing it. The early phases were quick and dirty, get it done, wet the areas. Let's go on to the next. We have to obviously maintain compliance with our national ambient air quality standards. And we're also looking at converting existing water intense dust control methods into water efficient dust control methods. While balancing this, achieving dust performance standards, maintaining habitats, conserving water, and mitigating impacts of public trust, environmental, and cultural resources. And we're also looking to test new water efficient dust mitigation methods, which is primarily the reason why we're all here today. Looking at alternative dust control methods. That's all I have. Okay, great. Thank you. So our third and final speaker this session before we turn to questions will be Dr. Holder, a senior scientist with the Great Basin District. All right, good morning. My name is Grace Holder. I was the Great Basin Unified Air Pollution Control District. I started working with the district back in 1990. So I'm probably the one with the most tenure that's probably in the room anyway, for working on Owens Lake. When I first started working on Owens Lake, obviously there was no dust control implementation. And so we are really kind of in a research and testing mode. I'm going to be talking about some of the research and work that's been done on dust control development over time. To divide this into sort of three basic groups, the first section is going to be talking about early dust control development on Owens Lake. And then I'll be talking about the development of the backup measures that you've been introduced to already. And then some of the other dust control measure testing that's been done on the work since dust control, the overall dust control project started in 2000. So if we look at the initial work that was done on the lake, it started almost 40 years ago in 1980 with the development of or the formation of the Owens Lake Dry Lake Task Force. That was a group of agencies and interested parties that were, that consisted of the State Lands Commission, Great Basin Unified Air Pollution Control District, Los Angeles Department of Water, Power, and the China Lake Naval Weapons Center, which is located down in Ridgecrest, because they were impacted by the severity of the dust storms that used to move from Owens Lake down to the south to Ridgecrest, which is about 60 miles away from Owens Lake. It affected a lot of their testing that they were doing. So they were an initial party to some of the work that was done on the lake bed. There was two main phases of projects that were done in the 80s as part of the Owens Lake Dry Lake Task Force. And the first phase was really a series of very small little projects. It's called the West Tech Studies, because it was run by a company called West Tech 1981-1983. So over a two-year period consisted a whole variety of different little things, sand fences of different spaces and different construction. Also, small little vegetation projects, just trying to see if you could even grow anything on Owens Lake, leach pits, laying different configurations of things on the surface. It was a kind of a wide variety of different little projects that were done. It also included some of the first chemical stabilizer testing on the lake. The second phase was conducted after that. Now it was a little bit larger scale, sort of built on the first phase of the work that was done. It mostly consisted of sand fences. Originally it was supposed to include six linear miles of sand fences, actually only finally had about three miles of sand fence that were actually built and tested. And there was also some chemical stabilizing materials that were applied in a couple different areas on the lake to see how they would work. Another project that weren't tested that had been proposed in the early phases of dust control development were things like flash piles, trash, tires, repairing corridors, folders, all kinds of different things. So I'm not really going to go into any of those. I'll just talk about more of the actual testing that's been done. And then at the bottom on bullet number three there, I'm going to talk a little bit about some of the early projects that were done by the district. This was outside of the task force projects that were done. These were conducted by Great Basement back in the 80s and through the mid 90s. So this is a map on the right that shows the locations of the phase one and phase two work by the Owens Lake task force. So the West Tech project is shown by the magenta dot down there in the south end of the lake. That was the location of the phase one project. And then the phase two are shown in green. And then you have two pictures over there on the left that shows sort of the some of the sand fences that were built. So the primary fence that was built off of Keeler was called the Keeler Sand Fence and that's shown up in the north there with the arrow. That was a one mile long sand fence that was built on the north sand sheet, started in the middle of the north sand sheet extending from the shoreline, one mile out into the lake bed. It actually filled up very quickly. And so it was actually three, two tires. So after the first two years filled up, they added another layer and then another way. So it was actually about a 12 foot doom by the time the project ended. We had a similar one mile long sand fence in the middle of the lake. That's one of those two green dots sort of in the mid lake part. And then also that's where the chemical surfactant test was conducted. And then there was an existing dune field on the lake bed on the south end of the lake called the dirty sock students that are now removed. So they're no longer there, but we had some sand fences that rings the dunes trying to kind of figure out where the dunes were moving to and how much the sand motion was in each of those areas. So you have eight short segments of sand fence that ring the dirty sock students. So the dunes themselves are the sort of the smiley face feature in the middle of the photo. Then you have the sand fences that ring around the outside. One of the first projects that was done by the district outside of the task force was the sprinkler project. And this was done on the northern part of the lake at the north end of the north sand sheet. The water for the project was provided by a well that was drilled in 1989, 1990. There was two production wells that were drilled up near the river Delta called the Riverside provided wells. So there was a several mile long pipeline that was brought that brought water down to the northern of the north end of the north sand sheet. And it consisted of 150 acres of wetted area was wetted by sprinklers at various spacings and various amounts trying to actually wet the surface in advance of predicted wind events. So it really wasn't what we call shallow flooding that was just the idea of to try to moisten the soil before the wind event was predicted and see if that was stabilized the surface. Now on the other side of that you can see in the photo here was a similar size control plot. And this was actually one of the first projects that this was the largest project by far but it led to the sort of the development of what we see as shallow flooding now today. I'll talk a little bit about that in a few slides. This is some other projects that were done by the district. So there was some tillage projects sort of in the middle of the lake and the heavy clay soils that brought the clay claws up to the surface. So the tilling is not what like what we have out there today with the roughness that's you know five feet high. This was more of a uniform clawed field that was about 10 acres in size and a couple different places on the lake bed. We also have the gravel projects that was done in a couple different locations very testing various sizes of gravel and different screen sizes and things like that. That was the initial development of the gravel blanket measure. Before I get into the next series of slides talking about vacuum and you've already been introduced to vacuum a little bit I just want to sort of discuss a little bit so you have a better understanding of what it is. So vacuum is what is required by the Clean Air Act for serious non-attainment areas and almost like it's considered a serious non-attainment area. And the definition of vacuum is as you can read up at the top is the maximum degree of emission reduction considering technical and economic feasibility and environmental impacts of the control. For Owens Lake, vacuum measures are designed to be 99 percent control efficient so it's supposed to reduce the particulate emissions by 99 percent due to the severity of the amount of dust that produced from the lake bed. It has very strict performance criteria that allows us to make sure that it meets compliance at all times. If we've already been introduced there's the three main vacuum measures. There's shallow flooding. There's basically three different ways to cover the surface. So there's covering with water, that shallow flooding, covering with vegetation, the backup managed vegetation, and the covering with gravel. So those are the three main measures. There's modifications that are allowed for shallow flooding. So as Jaime talked about there's the tillage with backup and backup. We call it TWB square and then there's the brine with backup and backup also called just brine vacuum. For the vacuum development, as I mentioned before with the initial sprinkler project that was done in the early 1990s, the most effective part of that test was actually the outflow at end of the sprinkler pipeline. So when we weren't sprinkling the surface, the water was still in the pipeline. We hadn't put it somewhere so we just dumped it out on the end of the lake, the end of the pipeline, and it was the most effective dust control. So that sort of led us to the initial development of the shallow flooding dust control measures. The first formal test of that was called the North Flood Irrigation Project or the North FIP and that was done in 1994 and 1995. It had a sister project on clay type soil called the South FIP or the South Flood Irrigation Project that was done in 95 and 96. And then in the late 90s, right before they started doing dust control implementation on the lake bed, there was a project to sort of refine the shallow flooding method and that was called the SERF. Also, we like the acronyms at that point in time. So that's defined as the shallow, unconfined, recirculated flooding project. So that's the SERF project. There's also been quite a few different managed vegetation projects over time starting real small scale. The first one was called the Flooding and Salt Tolerance Study and that was actually just done in our yard in Keeler. We have office complex in Keeler and it was done with salt grass that was harvested from different locations around the natural meadow system that ranks the shoreline areas of Owens Lake and because it's all done in little pots, we call it the Potson. We also have little vegetation plots that were done on the North FIP as well as other areas on the North Sand Sheet called the Meadow Enhancement Study and then we had the 20 acres and three rows on the north end of the lake. Then after that we started getting a little bit big so we had the agrarian farm which was done off of Keeler and that was a 40 acre project. We also have the divot, another acronym, drift irrigated vegetation implementation test. That was done and that that was actually I think four or five different plots or about 10 acres in size each so it was about 50 square or 50 acres in size and then we had the vegetation on sand or the boss project that was done also on the North Sand Sheet but that was something that was supposed to be sort of a model of how you would transition from shallow flooding to vegetation so it's kind of a combination type project. This is a picture of the North FIP as you can see it attracted a lot of birds. That was pretty exciting for us as well as a lot of other interested parties on Owens Lake especially the Audubon Society and it led to ultimately the destination of Owens Lake as a national important bird area. It was heavily instrumented. There were some early PM-10 monitors as well as some other monitoring devices on that bottom photo. So this is just a map that shows the test area so it was 300 acres in size for the wet area 300 acres in size for the control area. It was located up at the North Sand Sheet kind of near where the sprinkler project was located. This is the sister project the South FIP so it was done sort of in the middle of the lake in the heavy clay soil. They had only two little plots that were much smaller in size than the North FIP because the water source was limited for the project. So the water came from an artesian well it was it did not have a pump station there's there's no electrical at least at that point there was no electrical lines out there and we didn't have a diesel pump for anything so the artesian well that was drilled as part of our hydrology studies that we're doing up the time only provided about 250 gallons a minute which really limited the amount of water that was available and how much area that could be wetted. This is some pictures of the surf so this is a shallow unconfined recirculated flood test. It was also done on the North Sand Sheet similar to the location of the North FIP it was confined by two main features on the northern end and the southern side so we had the keeler stand fence with the shown on that upper photo is that long linear line that's one mile in length and there was an also an old wooden pipeline that produced the dune on the other side as well so I don't confine the the water flow laterally from side to side as you went from the shoreline outlets up in the upper part of the project and then it was about a mile long down to the southern end of the project and it was done differently so instead of just releasing water on the surface and just sort of seeing where it would go we tried to control a little bit more so it adds the distinct lateral lines and bobblers similar to what the initial shallow flooding project looks like out on the lake bed. Talking a little bit about some of the vegetation work there's a picture of some of the fog grass that was grown out as part of the plot study and we also had these small little plots called the meto enhancement study just trying to grow salt grass out on the lake bed. It was various different types of irrigation as well as not a leeching and things like that. The tree road project is one of the more varied projects we had on the lake in terms of vegetation so it not only tried to grow salt grass which was the main species that we were interested in before but also tree roads have been used quite a bit for dust control or for wind erosion in the past so we tried to grow trees on the lake. They don't grow very well because of the closeness of the highly saline groundwater. We did actually put in a drainage system but still the trees would get to a certain point and then they would start to die once the roots got down into that shallow groundwater system. It was irrigated using sprinklers as well as drip lines and we also started testing the ability to grow shrubs out on the lake. One of the larger vegetation projects that we did on the north end of the lake anyway was called the farm, the grain farm. So there's an air photo of it up on the upper left. It was a 40 acre project using flooding as the irrigation method. It was all based on flooding and these panels that were built on contour and then they were planted. So you can see some of the salt grass meadows that were grown out. This was in a heavy clay soil so the idea was that it would have actually better drainage because the clays on our old lake are heavily cracked so the cracks have to provide water drainage for the soils. And it was also some of the first time we got to use heavy equipment on the lake and we actually sort of did our initial pillage tests and ripping of the soils. Here's some pictures of the divots that were done also in clay soils looking at different ways to grow grass with drip irrigation as well as sprinklers. Other pictures of the boss, the vegetation on sand so as the picture on the lower left shows you the idea of this project initially was to try to grow vegetation areas that were originally shallow flood. So the area was flooded with sprinklers and then leached out and then planted with grass. Initially it was irrigated with drip lines and then the drip lines started having issues with roots and things growing into them so we retrofitted it with a gated pipe that would release the water and deferrals. So that's sort of the discussion of some of the backup development and some of the other work that's been done since the main dust control project on the lake started getting developed. Includes the projects that are listed here so we've got things like salt plants or salt pans. Ultraman that sort of has went to the development of the brine backup method. Sand fences have been tested multiple times as well as all the way back to the early 80s all the way up into early 2000s. And then mowed row, tillage, surface or factants or chemical dust across them and then various kinds of roughness elements on the surface. This is an air photo here on the left side that shows a seven acre area kind of where the divot was located in the middle of the lake trying to develop a salt cloud or dust pan type dust control measure. So the idea here is completely different than what we use now for the brine backup and the idea here was to try to control the control the crystallization of salt as they would be concentrated through the process and then ultimately end up with a stable halide or sodium chloride surface at the end. Down here on the box on the bottom right kind of shows you some of the salt chemistry. The salts are dominated by sodium carbonase and bicarbonase and sodium sulfate salt and they go through quite dynamic changes based on temperature and moisture conditions and they can be quite difficult to control and some of the as they go through that phase change back and forth between hydrated and dehydrated it can actually tear the surface and create a real powdery surface that is a dust problem. So the idea was to try to develop ultimately the end leading up to halide which is a sodium chloride salt which is the most stable on the LLS. So the idea was to go through a series of evaporator ponds that would concentrate the salts in the water and then ultimately try to crystallize the salts out of different phases as they led through the crystallizer panels. We also had a moat row that was tested on the lake and this was led from the 2006 Settlement Agreement so it was implemented in 2008 to 2010. So the idea was to create these stimulus lines of series of berms and ditches with usually the berms would have fences on the top which is called a moat and row system and you can see the air flow of what it looked like in one of the tests so you have the main moat row features there kind of lined up in view there as well as some fences that kind of help divide the test area up into the two sides. The tillage so the tillage has changed quite a bit over the years so back in the 90s that was done more of it as a uniform field of clothed surface now it's done more of the surface roughness feature as well as the clobbing on the surface. The model for the current way that they do tillage was based on temporary tillage that was done in 2010 so you can see this is an oblique air photo that shows several square miles of temporary tillage that was done in 2010 and part of the phase seven areas. There's some also photos of some of the models of the tillage features that are implemented now and some of the T12 areas over on the right side or the left side of the slide as well as some areas off of Peeler. Chemical suppressants have been tested multiple times going back to the early 80s so in 2013 DVP ran a chemical suppressant test that was much more complicated and had several different chemicals that were tested on the lake and multiple replications so that's why there's all these little test cells in the area that's shown on the photo. It was I think pretty successful in the beginning but it was an area that was impacted by surface runoff from off the lake that kind of put an end to the test and it hasn't really been picked back up yet at this point. Getting into roughness elements the district has a project that's off the lake bed it's called the Keeler Dune project so if you look at the photo over on the left side the area that's shown in brown color there that's the Keeler Dune project area it's up above the shoreline so you can see the shadow flooding area that's on the lake bed down in the bottom part of the photo then you have the Keeler Dune project so the idea of the Keeler Dune project is we're trying to re-establish the vegetative dune system and in order to do that we have straw bales have been placed on the surface in sort of a natural vegetation type pattern so it's more random it's not in the regular array you can see in the air photo on the top and then associated with that we've got native shrubs have been planted so the idea as the straw bales provide the initial control mechanism on the surface to control the sands it allows the the plants to establish and then ultimately the straw bales deteriorate and the plants take over we've also tested engineered roughness elements out on the lake bed so the air photo over on the left side there shows a test area that was done in what's called a cell that's called T26 so that's 100 meters by 100 meter square area has about a thousand of these gray tulled gray buckets or the tubs that were out there held down to the surface by adding soil on the inside so there's something that could be picked up pretty quickly if need be that was a test that was run in 2014 and then 2016 so in two different locations and then and then we also have done some wind tunnel testing of porous elements porous elements are more efficient at controlling sand motion and movement on the surface and those solid elements that really eliminates a lot of the scouring issues that we have around the edges of the bales or edges of the elements and then down here on the photo that's up the bottom this is a test that was done at Mono Lake and these are testing the porous elements set of wind tunnel size elements these are a meter high in size meter cubes so some of the modifications that have been done to back them over the years so there's only been one change to gravel so we have the free backings across the top so the change in gravel was just the change in the thickness that's allowed so originally the development of vacuum required a four-inch thick layer of gravel and it didn't have any kind of geotextile fabric underneath when dvp started actually implementing gravel on the lake deck they put the geotextile fabric underneath because there was concerns of gravel sinking into the soils below so recognizing that the in 2013 the thickness of gravel was changed to allow just a two inch thick layer of gravel provided there was that geotextile fabric underneath so the changes that have been made to vegetation over time is primarily the vegetation cover so originally it was 50 percent cover of vegetation originally just soil grass over the surface on every acre that it was implemented now it's recognized that you probably don't need 50 percent cover instead it was modeled after what the the first dust control project the city implemented on the lake for vegetation was in 2006 and that was 37 percent cover on average over the whole area but it had different spatial distributions so we applied that and allowed that as a modification to the vacuum in 2011 and then there's been various species that have been added over time so instead of just having salt grass it's the only species that was allowed now there's 42 different species of native plants that are allowed to manage vegetation control measures and then shallow flooding has had the most change so the first changes there were to allow ramping of the water use on the within the shallow flood areas both in the early part of the dust season as well as the late part of the dust season so the dust season starts in October and goes to the end of June so originally it was October 1st through June 30th now it's October 16th through June 30th and the ramping allowed reduction in the amount of water during the highest evaporation times of the year in the fall as well as in the spring this is Scott Tyler we just lost our our video feed of the monitors we've lost it in the room as well and we're working on fixing that thank you for letting us know okay sorry we're about to get back to the presentation to hopefully you're seeing all this activity on the screen um for those of you who are out we're not seeing anything yet okay let's let's wait for the application to come up and then and then we'll see this is Tamara NAS and DC I don't think that the screen is being shared so we're still loading the application oh okay okay uh I'll let you know since we have power points showing on the screen and we do now but okay so you shouldn't see it just yet I think we're back up here in the room but I'm not sure the yeah I think we'll need to proceed and uh those of you on the line please bear with us uh and we'll probably need to get this rectified at the at the questioning period so and I'm almost done anyway yeah right thank you so we talked a little bit about the shoulder ramping that was allowed as part of the 2006 settlement agreement other changes have been what's called dynamic water management which is the ability for the dust control season to be shortened even further beyond the ramping in certain areas and then there's also the brine back on which we talked about as well as the TWP squared which are other modifications to shallow flooding so this is the dynamic water management so as I said before the the main dust season now is October 16th the June 30th so that's eight and a half months in time there's three other modified dust seasons that are allowed in certain areas on the lake that allow the dust season to be shortened even further so the first one is October 16th the same start date but then it can end on April 30th so it's only six and a half months long the second one is even shorter it's only five months long and it starts to summer first and goes through April 30th and then the last one is only three and a half months long and that was uh starts on January 16th and ends on April 30th and the reasoning behind those are we looked at the historic sand floods information that was done through monitoring over a long period of time on different sources on the lake and a lot of those areas where we had applied the dust season for the whole length of time weren't actually emissive for that whole period of time so we tried to narrow down the length of time where controls actually actually had to be implemented on the surface so as of now there's 13 square miles of area that are allowed for dynamic water management that's about 37 percent of all the shallow flood areas and they're shown in different colors on the on the map here in the the sort of the yellowish color the red and the blue indicating the different lengths of dust season right we talked a little bit about before so it's a measure where some of the water that's being applied on the surface can be replaced by either a thick evaporite salt crust or a thick what we call capillary salt crust it still needs to meet the overall cover requirement based on the shallow flood wetness cover curve so if it's a 99 control area it needs 75 percent cover but that 75 percent cover can be a mix of these three different surfaces so it can be a mix of the water it doesn't have to be brining like that can be any kind of water because the water provides the control not necessarily salt content then the evaporite surface as well as the capillary groin and then we've talked about the TWB square so it's just a modification of shallow flooding that allows the area to be tilled it has to meet certain roughness criteria for the ridge height ridge spacing as well as the cloud cover that produces a surface armoring effect at the end of my presentation okay so let me invite all the speakers up let me just make a brief note in time and I thank all the speakers for staying within there a lot of time for presentations as we went through this what I'm going to do is still allow 15 minutes of the panel question time because I think probably a lot of questions arose will then eat into our lunch time and so the two remaining speakers before lunch will still continue to your scheduled lengths of presentation and with that I'm going to open up the questions I'm going to take the liberty of asking the first question as the chair but I'd ask panel members put up their 10 cards if you could keep track I saw Scott then Ted then Greg so as I thought about the backup and the control effectiveness assigned to the bathroom this is directed at anyone who wants to answer this typically it's given as a single control effective 99% effective 95% effective but especially for those control measures that are not shallow flat flooding how exactly do we evaluate that is it only at the wind conditions that are likely to lead to an exceedance of the national ambient air quality standard is it 70 miles an hour is it overall wind conditions over a typical year how do you evaluate a vacuum and its control effectiveness so the 99% control requirement is the effectiveness for the entire project in the area and that was the standard for vacuum the effectiveness you can only you'd have to know the potential of emissions which a lot of times you can't do in natural situations until certain events yeah maybe if you could hold on to the mic there sure test yes great so the emission potential from a certain area can vary over time from times in a year and the emission potential more or less the you would have to determine what you needed to reduce those emissions to a certain point to prevent violations at shoreline there's also contributions and it's complicated so yeah potential yeah I'm trying to understand the complications right so so you have the potential emissions which presumably would be associated with a certain pattern of wind conditions over the over the course of a typical model year or typical year so the control efficient setting to establish that would have to be overall times overall possibilities of those emissions okay so so you have the potential emissions which are established based on that pattern of an entire year of wind conditions and then then then to be a vacuum it needs to achieve a certain percentage from those potential emissions correct and not just annual though okay all right all right I think I understand so let's go through the questions starting with Scott yeah this one's primarily directed towards felt you talk about this shoreline of 3600 C above mean sea level with the recent severe drought that you guys had here probably the effects in the groundwater hydrology are yet to be felt on the lake surface plus you don't know what the feature holds as far as rainfall in the area how how long do you think that 3600 foot shoreline is going to remain and the reason why is because that's the shoreline that's written into the law the lake level has always changed and you know grace to talk a lot about the hydrology if you have specifics on those but the regulatory shoreline is established because that's what the lake level was at the time the water was diverted so that's the lake level then that needs to be controlled because that's where it started to change as the factory was exporting water so tell us not the current level of the brine no the current level of brine pool is 3555 how long do you expect that to be maintained well there's a lot of things that can influence that groundwater pumping underlines like could change that instantaneously the lake itself still doesn't know a lot of the lake doesn't know that the lake is gone so there's artesian pressure up to the old lake level a lot of those seeps and springs change over time there's some that respond quickly to changes in precipitation and some that seem delayed that's very complicated just i'm in a large geographic area you got anything to add to that grace uh it is a pretty complicated system um switch the ton of foot elevation i think is you know it's sort of a essentially concession on the district's parts that allows them to only meet the standard at the shoreline and above they start shoreline and above they don't need to meet the sometimes standards on the lake bed itself so i think it's something that's been made in place how about the brine pool that's actually changing so the brine backup measure is actually sort of modeled off of the the brine pool itself so there may be less water in the brine pond over time but i think it'll remain stable because it's going to be consisting of you know a real set of decorative salt crust it's actually got salt mining that's done in the silent part of the brine pond um and uh because of the evaporation rates too it's probably not going to change that much it's probably the lower evaporation rates off of the the standing water in the brine okay let's move on to ted's question i'm going to cut off the questions with those that have their ten cards up at this point so two related questions probably primarily for dr holer but others as well is one how predictable are the events the exceedances or near exceedances at this point and you know you talked about i think sprinkling sort of is uh which i have a dynamic a bit um control you might do before an event so i'm just curious on those two is how predictable are the events the wind events themselves are very predictable i would also put the related amounts of uh p m 10 p m 10 yeah that's less predictable the areas that were the most frequent and the most predictable in terms of the sources on the lake bed were the first ones that were controlled so like the north sand sheet area and then some of the areas on the southern end of the lake those were controlled first because they were the most predictable most frequent and easiest to identify the other areas and one of the reasons that you've got the sort of the piecemeal approach for implementation of the dust control areas is that some of the areas are much less frequent they may own certain weather conditions and they're um they're so they're less predictable i think at this point in time though you've got essentially most of the important dust control areas control so we're seeing a little bit of the periphery areas below but we haven't actually seen much in the way of exceedances from those areas at the shoreline and in terms of controls that you might put dynamically in place i think there is a potential role for that and that's one of the things that we're maybe interested in looking at with the panel is looking at um you know using some kind of alternative dust control measure that can be done temporarily in certain areas that might open up outside of the current project so they wouldn't have to be ordered wouldn't necessarily have to have a bad one measure implemented on them and you seem to have done that at one point uh with sprinkling right before was that not that was the first initial uh idea was to use sprinkling to moisten the surface in advance of wind events it didn't work very well or we implemented it because it was a real sandy soil to dry out too quickly there might be potential for looking at in other areas okay great um one um i have several questions so i want to be traditional here um one thing that i guess this is for dr holder um one thing that was there was how much annual maintenance that these things require so one of the our our charge sure every liability um and uh it would be nice to have an idea of when you have to till how often you retail when you have to yeah i think that's more of a question for how i go ahead and do my best but jennifer long here uh manager owns like operations going to do a presentation then that's the next one all right um in the interest so okay then it's on the topic of durability in the lives already then um might have been concerned about all the things the temporary results right we're expected to have massive snow for years and years with no snow at all right um and so one of the questions is um which and it seems like the biggest problem is that actually a major protocol could actually work out a huge amount of work right so uh which are the most critical measures to that time yeah give this one a shot um because we've been through this twice now in 2017 we had the emergency snowmelt runoff and then again this year um the infrastructure bonus they can all be impacted differently the uh extreme flooding actually provides test control because the lake's wet and that would actually take a long time to dry down and we saw that in 1969 the piping can float and break that could be a problem the firms can be breached that'd be a problem for shelf flooding a lot of the vegetation would probably die a lot of gravel especially on the inner area or the lower elevation parts of the lake would be inundated and submerged and would vanish and be required to put back out there so each back and differently some of the banners could maybe never be re-established because it's a freshwater influx um and definitely all of the tillage areas would be obliterated and smooth and then last question again it's not a question about variability talks about certain clay surfaces certain sandy surfaces right so can you give us an idea which of these backings work best and which uh kinds of um I'll just give a shot at that response here um what we see is a tillage works best in clay soils you get a lot of clottingness it is also effective in sandier soils but you don't get the clottingness and clottingness is a performance criteria um with managed vegetation we see sandier soils with high percolation rates um some of the clays have sand in them uh those soils that are porous enough to reclaim the soil leech all the soils out through our drainage subsurface drainage systems if an area gets hit with water to try to reclaim and and it just stands on the surface you're not going to leech those uh the salts out would never be able to grow any managed vegetation there um um some areas historically have had more saltier water uh they've been a historic brine sump so to try to make that area a brine area over time is probably our best shot uh to try to establish brine in a fresh area in a fresh water area nearly impossible so the the lake kind of tells us what it wants putting gravel in an area with extremely soft saturated soil is very difficult contractors usually have to go in a swirling direction and they create the path for themselves to be able to put equipment on there um the the closer you get to the brine pool the softer the soils are the more say lean the soils are so you want to keep your vegetation away from the brine pool you want to keep your freshwater ponds away from the brine pool and fresh water ponds are important because uh the birds like fresh water it's a limit is a huge factor for maintaining habitat across the lake and if you want to add any theories I don't think you covered it really well thank you um you're sure uh actually interestingly enough David and Scott and we're covering most of my questions but I in one of the main questions they had was on how these different that can look to respond to a rain event or a storm event but you actually you mentioned in 1959 for the water to put a lake to go back to being a dust bowl and having an issue and the reason I'm asking the city that's been using them to add to that is um we do often have the extreme wet seasoners and they're not every 50 years but actually they happen more than every 50 years so I'm wondering how they can potentially use uh that it has been adding a lot more cost to prevent them so how can you use them as an adaptive measure and it is actually not I can use a sale of two things during 2017 we maximize the pond levels on our shallow flood areas uh in order to mitigate any excess runoff into the brine pool we that was the only real way we could use that water the rest of the water was being spread in the valley we hadn't we had an excess let's see to use that water creatively for dust mitigation maximizing our brine oh some of the tillage areas were taken out of service we turned them back to shallow flood uh we deferred the use of dynamic water management which is the ramping down periods that's the only way to maximize our pond levels um but really it doesn't uh create a situation where um we can use it for long term use uh I don't see where we could we could do that I don't know if you want to add it so just to the brine pool question in 1969 and to dry down I don't think it was until the 80s that we started seeing the really big storms but you know every year is different so you know there was a long drop in the 70s there were some large elving events in the early 80s so and the tree rings in the first ones tell us what we've seen in the last 500 years there's nothing like the last 4 000 so it's hard to say but if the brine pool is elevated like we were expecting 200 000 acre from 2017 um we'd probably be looking at a very similar lake today if that had happened yeah one other question I have for you was uh in your position so you've had the slide 22 then you have the on like anal tons of potential pms and and you can see significant drop and I'm hoping that we can get the numbers for 2015-17-18 but right now it's the it's the fascinated and I can probably see that the the it's still high that's potentially you cannot see the impact of water here in here but I don't know whether it's the zoom in with smaller numbers is there a way to see like as you go through with your hydraulic because I'm really curious during the current current drought 2012-15 how these numbers are fluctuating for happy at all yeah they definitely have and there's it's not a single variable and it's not so simple because a lot of times are um water years or the more emissive years and it's because of the precipitation and how that changes the surface of the soil versus the drier years where it actually becomes crusty and less emissive so in longer droughts um so there's not that real simple relationship all the time