 A stream assessment is a critical first step as you begin to explore options for a stream smart road crossing. The assessment steps include what to gather in the office before going into the field, a field overview of the stream, a longitudinal profile, a cross-section analysis, and a pebble count and key pieces assessment. In this video, we will walk you through each step in the process. Before heading out to collect information, we really want to sort of put this structure and this crossing in context of watershed issues, of land use issues, of maintenance issues at the site itself, and of resource issues that we care about. If we're in a forested landscape, we'd want to know a little bit about the land use history, or in this case in a development, we'd want to know how built out the watershed is. And not quantitatively, but just sort of qualitatively, what are we dealing with here? What watershed issues maybe are we dealing with? What land use issues are we dealing with? We'd want to look at nearby sites, or are there a whole range of other structures upstream and downstream from the site? We'd want to talk to the owner and find a little information about the culvert itself or the crossing itself, and what have been some maintenance issues. Another issue is to sort of begin to think about objectives, and especially with resource issues, what species are we interested in passing at the culvert? What's the range of aquatic organisms that are in this reach, and in this watershed? If we have access to GIS, we'd want to delineate an upstream boundary for the watershed, delineate the upstream watershed, calculate an area. So let's say at this site, we're 1.1 square miles. We then want to go back and look at regional hydraulic geometry curves that relate drainage area to bankful widths, and get a rough idea of potentially what size structure we're looking at here. And we can do that in the office. We don't need to be in the field to do that. So if we're at 1.1 square miles, if we looked at our regional hydraulic geometry curve that the USGS has published, and others have, we might say we need a span of X, maybe in this case 9 or 10 feet. We have the initial information that Jed talked about that we gathered in the office. So before we got here, we have an estimation that this stream is about 9 or 10 feet wide. So the first thing we want to do is confirm that estimate is reasonable in this site. So if we look upstream, we're in that vicinity. So setting up, one of the first things we're going to do is a longitudinal profile. That bankful gives us an indication that we want to survey the stream about 20 to 30 times that bankful, or in this case about 200 to 300 feet upstream, and also downstream. Another thing we want to do is looking at the stream upstream and downstream. If we first of all look downstream, we have what looks to be a step pool style of channel, a lot of big substrate versus I turn around and look upstream, and I have a very sinuous channel. If you come on over and look at the stream bed, once we get past the road, I don't see that big structure. We don't have that rock and that step pool. So one of the first challenges that we're going to have when the upstream downstream channel are very different is the location of the road a coincidence to that, or is it a causative agent? In particular, how far upstream do I have to go before I'm looking for indications that I'm outside of the influence of the road? I'm also going to be looking and getting approximate measures of what that actual bankful is out in the field. I'm also going to be looking for something that may be my reference reach. I'm outside of the influence of the road. I'm getting to an area of the stream that looks like it's relatively natural. I have a riffle in the straight section of the stream, and that's eventually where I'm going to set up and do my cross section. So I need to do that kind of observation upstream. I also have it doing downstream, because at this point in time, I don't know for sure where my reference reach is going to be. The other thing I would do during this process is actually do a plan view sketch of the stream. So looking down from above, get that approximate sinuosity, then as I move up and downstream on that diagram, I can record key things that are happening. So as part of that overview, I want to now look at the culvert itself. What are some of the issues regarding it, both the present structure and thoughts with regard to what a replacement structure would be, and some specific constraints. This is a concrete box. It's flat on the bottom and smooth concrete all the way across. And as you look in that, there's some leaves in there, some organic material this fall has come into the pipe, but there is no substrate. We have no sand, gravel, stones of any kind. So what's happening here? That's an indication of during high water events, any material that comes into the culvert is flushing right through. So problems in low water conditions like we have here, there's no form to that channel, no complexity. So we don't have a low flow channel that if I'm a fish that can make it up through into here, I have approximately an inch of water to swim through. So if I'm an adult fish with a three inch body depth, I'm going to have some problems here. As Steve said, we're going to look upstream about 20 to 30 bankful widths. So approximately in this case about 200 to 300 feet upstream, we're going to run a longitudinal profile that distance down to the culvert and then down the other side the same distance. The profile is a really important component tying back into setting the elevation of our structure. We'll learn things about scour depths, how much is the stream able to scour its bed and to down cut into its bed. So we'll use that to set the elevation. We also want to match the slope of the stream, the overall slope of the stream. So those two S's setting the elevation and matching the slope, we gain that information from our longitudinal profile. So to begin the profile, we're going to stretch a tape down the centerline of our stream, just longitudinally, walking down stream, trying to keep it as center of the stream as possible. So in order to collect our information on our stream here, we're going to use some fairly basic survey equipment, a tripod, a rod that's measured in this case intensive feet. And then we're going to use in this case a transit and auto level. In some cases we might use a laser level depending on the field conditions. When we survey, we want to minimize the amount of times we have to actually move our instrument. So we do turning points as we go down the stream, moving our survey instrument down stream. So just think a little bit about where you want to set that. So you maximize the amount of observations you get and minimize the amount of times you have to move it. So before we begin our actual stream survey and collect features in the stream, we actually want a monument to put a benchmark in, a permanent location that we can get back to in a year or two when we start construction. So in this case we put a little magnetic nail in the base of this maple tree. And the first touch shot that Steve's going to take is just this elevation of this monument. So I'll place the rod on the nail here. Okay, so Steve now has recorded the elevation of that monument. He'll record the location of this. We would take a GPS point on that tree and right down we flag it and make sure that we can get back to it. So in our profile, we're going to record the elevations of various bed features, bank features, and then if we have cross sections, the locations of cross sections. So here I'm at this top of this riffle. And I'm going to call out to Steve the station, which is our distance going down the stream. Steve, it's 32.3. And now Steve's going to shoot the elevation of this top of this riffle. Now come down to the bottom of the riffle and grab this elevation at the bottom of the riffle here. And once again, I'm going to call out a station to Steve. Steve, 43.1. We're also going to grab locations of other features like tops of banks. If there's any kind of bankful indicators, would any other materials that influence channel stability? So Steve will grab a top of bank here. And this is at 37 feet. And we would want to record the side of the bank too, either river right or river left, as you're looking down stream. So in this case, Steve, river right, top of bank, at station 37. So as we continue our longitudinal profile, it's really important to pick up features that influence bed elevations. In this case, we've got a piece of large woody debris in the channel. We're going to pause here, take a shot upstream of the bed elevation. Steve will shoot that. We're then going to get the top of our wood. We're going to shoot that. And then we continue down below it and find our maximum scour depth down below it. Steve would then shoot that. The stream has been able to scour out that with the assistance of this wood. And this is a good thing. When we think about the species we're interested in, this wood has helped form a pool here and some complexity to the bed. But once again, the wood has influenced the bed elevation also. So we want to make sure we pick that up as we do our longitudinal profile. So these are really very important shots on our profile. We actually want to capture the elevation on our profile of the elevation, the inward elevation of the inlet of our culvert. So Steve, this is at 96.10. We'll shoot that bed elevation. And then we're going to come up here and shoot the top of our culvert. And Steve, this is at 100.7. And we'll take another shot actually on top of the culvert, recording that feature. Same station. And that gives us an idea of the control here upstream and then the opening, the actual dimensions here. Now we're going to make sure we capture our road surface too on our longitudinal profile so we know the depth of the fill. So we'll take a right edge of the road here. Steve will grab that shot. We'll walk over to the center line. We'll grab a shot in the center of the road. And then we'll come over to the right edge of road here. Grab a shot here. And we'll continue down and grab a top of the culvert and then continue our longitudinal profile down through this step pool environment. All right, we're now downstream of the road and we're going to continue our profile. We're going to take shots at the outlet here, invert the bottom of the culvert. We would have shot that. We're really interested too on many culverts through this perch height. So we would actually shoot that difference between the stream bed and our structure, bottom of our structure. We'll continue our profile downstream now and in this step pool environment, we really want to make sure we capture in enough detail the top of a step. There's a little leaf in that matter here. I'll get rid of the top of this step here, which is just basically that a pool and then a step. We take a shot here and then we're going to come down to the bottom of a step and record that elevation at the bottom of this step. And now we're interested in that pool, finding the pool, the maximum depth of our pool. So we're just going to probe around in here, looking at our rod and our water elevation. And that right there is our maximum pool depth. So once again, we'll record a station. Steve will shoot that elevation. We've got a top of a step, the bottom of a step, our pool depth. And now we walk down to the outlet of the pool. We want to find this elevation now, which is the top of the next step. And that elevation is really controlling the upstream water depth and our scour depth upstream. So we're now going to shoot this shot, grab the station and then continue down through the next series of steps. We'll grab, that would be our top of step. We might grab a shot here. And then continue with our bottom of step and replicate that through next to our maximum pool depth. And we would continue this down that 20 to 30 times bankful depth, a bankful width downstream too. Picking up other features, grade control features, tops of banks, if we thought that was important, any wood that was in the stream. Once again, the complexity and diversity of features downstream of the culvert. That information is useful for a variety of reasons. One way we might use that information, once again, we not only have elevations, but we have lengths. And this template that we've surveyed, very stable reach here, in some cases, we actually may want to use that information for design purposes up through our structure. We may want to continue this gradient upstream, build a series of steps up through our structure, up through our crossing. And having this great information, what nature built for us is a template for what we might want to use to design up through the structure itself. We're setting up to do our cross section now and then selecting our site after reviewing all the different parts of the stream, we have a riffle feature that is going to mimic our, be our reference channel that we mimic the stream through the road. And if you go back to the original S's, we're going to be spanning the streams. That's some of the information that we're going to get when we actually gather information on our cross section. So here we select a spot. It is a riffle feature. Outside of the influence of the road, we happen to be upstream in selecting this. We want to set up our cross section basically perpendicular to the stream. And eventually, as we do the cross section through here, we're going to get quite a bit of detail. So I'm up here to the edge of the flood plain. I'm going to go up the bank a bit so we can get some of this feature. Just pinning the tape down here because eventually we want to stretch it fairly tight so we have a nice station. So as we shoot our elevations based on the station off of this tape now. So we selected our cross section. We set up our instrument, set up the tape for stations. So now we're going to start beginning to actually take measurements. So beginning your station zero, we're up a little bit of get the contour of the bank of the flood plain. And catching now the toe down here, five feet. So as we look across this flood plain, it's pretty uniform so we don't necessarily have to take shots every foot or two so we can jump a little bit on our detail in here, 14. So now as we get in the vicinity of the channel, we want to get quite a bit more detail. We're on the left hand bank. I want to record at 50.5. Left top of bank. Then the immediately down, I want to catch, I'm at left edge of water, 51.5. In this case, I happen to have a piece of wood that's a foot in, so I want to capture that. Here's a little bit deeper spot, 54.5. This is getting to a higher elevation. I want to make sure to capture that, 56.5. And again, a little bit deeper. In this case, a little bit deeper is about an inch, 59. So as we're hitting here, our cross section, we want to tie that back to the elevation of the profile. So we're at station 39 on the profile. Gently record that. So as we capture the elevations of our cross section, we can tie that to the elevation of the profile which tie back to our benchmark. So all these elevations a year or two years from now are all tied together based on the original benchmark that we put in place. Now I'm getting that right edge. 61 feet. Here I want to note in the comments, I'm getting some fine deposition. So that's an indication that water does get up here. We're up into the flood plain as you crest over into the flood plain. The stream out here loses velocity so its sediment load is dropping out. So this kind of fine material is an indication that you're out into the flood plain at this point. Okay, now similar to the left side, I'd like to carry this cross section across the flood plain and start capturing the upslope on the other side. So thinking back to the four Ss, one of the primary ones is span the stream. That is the bank full condition of the stream. If I look at this deposition as an indicator of my bank full, I have 64 feet on this side. What do we have on that side, Jed? Steve, it's about 49. And doing the math in my head, we have about 15 feet is the bank full width of this particular stream at our reference cross section. So we have 15 feet. Our culvert in this case was about 12 feet. So spanning the stream, it's a little bit narrow. We're not gonna proceed to collecting information on the substrate in the stream bed. In this case, we're in this pool riffle environment. And at a riffle, we're gonna do what's called a Wolman pebble count. We're gonna collect a hundred different pebbles and look at the dimensions of them. The pebble count and characterizing the bed substrate is really important when we begin to think about constructing a culvert, a crossing downstream. This bed material we wanna make sure is retained within the structure. So we want a distribution, an idea of the distribution and the size of the material in our reference reach. So on our riffle now, Steve, we're gonna do our hundred count across the active bed and we're gonna do this random pebble count using our gravilometer. I'll be calling out to you. Okay, Steve, 16. So we're measuring the intermediate axis on a rock. So as I pick one out, what we wanna measure is the intermediate axis of that pebble or of that rock. It's not the long axis. In this case, it's not the short axis. It's this intermediate axis. And that's essentially what would pass through a sieve. So if I take our gravilometer with this particle, I can basically size it for different holes here. And Steve, that would pass through 64. So we'll record 64 millimeters. So then onto our next count. I'm gonna step forward, not look, place my finger in the stream and pick up the first pebble I touch with my finger. Steve, in that case, 5.7. Gonna move forward another step, reach down, not looking, pick up the first pebble, 32. So we're gonna continue taking a hundred count, a hundred pebbles across this active bed, zigzagging back and forth across the riffle. I'll be continually reaching down. Not looking, randomly picking up a rock, looking at that intermediate axis, passing it through the gravilometer, 32, Steve. And then recording another measurement, zigzagging across through the riffle. All right, so upstream, we actually conducted a pebble count of the intermediate axis of the smaller material. Downstream, we're really interested in these key pieces. What are these large features that are stable and the dimensions of those? So I'm actually gonna record all three axes. And then we'll actually get whatever's visible here, too. That information is then used to look at sizing materials. If we had to build a similar size step pool environment up through our structure, we could use some of these key piece dimensions. So we would record 10 of the features that we feel are actually stable in this step pool environment. 10 pieces, we would record all three dimensions. So now let's think of all the information that we've gathered back to our four Ss. We have spanning the stream, setting the elevation, slope of the channel, and substrate. The existing culvert, we have about 12 feet wide. If you think back to our cross-section, spanning the stream, we had bankful indications there that our stream up at our cross-section reference reach was about 15 feet. So 12 versus 15 feet is truly spanning the channel. Setting the elevation of the stream up setting the elevations, we gather that information from the longitudinal profile. We're gonna use that to set our elevation in what's buried through the road here. Also, the slope of the channel, if we would pick up this culvert, remove it and set a new stream bed through here, we'd refer to that longitudinal profile. And then finally, substrate. You'll notice this is a box culvert. We have a very flat, smooth concrete bottom. If we do an open bottom, we'll have access to the stream bed material that's underneath here. If we do some kind of closed structure, we'd have to decide using that pebble count and key piece analysis, what kind of a material we'd use to create that channel. Now we're gonna take all this information back to the office and put it into the spreadsheets, plot it out and start interpreting it. And we're going to come up with a preliminary design that is gonna look to allow fish passage and also with other stream processes have it so this road is actually invisible to the stream. Support for the production of this video comes from Poland Spring, the Sewol Foundation and the USDA Natural Resources Conservation Service. StreamSmart is a collaboration of the following partners. Thank you to the following organizations and individuals who helped make this video possible.