Stanford [00:00:13]:
When it comes to sediment projects, it might seem like today's guest has a type. I recently described Chris Nygaard as the Corps BSPs, our big sediment pulse specialist. I met Chris when the corps decided to revisit their Mount St. Helens sediment management plan and put him in charge of the sediment modeling. And more recently, he led a team that developed the sediment models of a hypothetical dam removal alternative for the Snake river environmental impact assessment. For both those projects, he had to analyze and model real or potential sediment pulses on the scale of hundreds of millions of tons. But Chris has worked on every scale of sedimentation river process while he is back with the core. He recently spent a few years as a project engineer with Bonneville Powers River Restoration Mission, where he got to see more in progress are post construction river restoration projects in a couple of years than most people see in a career. And you can't see that many projects without developing some thoughts on best practices. So I wanted to talk to him about both those scales, giant sediment pulse modeling and small to medium scale in the ground restoration river engineering. So on this episode, we talk sediment slugs and restoration lessons learned with Portland district's sediment transport specialist, Chris Nygaard. Chris Nygaard, welcome to the podcast.

Chris [00:01:30]:
Thank you, Stanford.

Stanford [00:01:31]:
Would you say that dam removal analysis is more or less challenging than other sediment analyses?

Chris [00:01:37]:
I would say that it's on par with other sediment analyses, and in some respects it's easier. You know, we have a lot of academic work and actual prototype removals that we can lean upon. But, you know, you can lean on the model and you can do some sensitivity around your parameters, but you're data driven. And if you can talk about processes and you can relate that to what the model is or is not doing, you get the answer and you can color it with your experience. To that end, it's similar.

Stanford [00:02:05]:
But wouldn't you say that maybe that's why it's harder, is because other processes have been happening for a while, but in dam removal, maybe you're trying to model something that's never happened.

Chris [00:02:15]:
I would say that implies that you trust your model pretty explicitly, right? Tim Randall pushed this on us in the snake, and I think it was a really good thought and something that's in the dam removal sediment manual conceptual model. If you can't get it in your head what you think is going to happen and have that intuitive concept at least to start bouncing your numerical answer off of, you're kind of starting from the wrong place. You should be with your modeling, informing your intuition. At some point, you should be able to logic your way through. I believe these results, and you need to be able to explain your analytics.

Stanford [00:02:51]:
So you mentioned the snake.

Chris [00:02:52]:
Yes.

Stanford [00:02:53]:
And that is in fact why I'm asking you about dam removal models.

Chris [00:02:57]:
I assumed so, yes. Yes.

Stanford [00:02:58]:
I actually remember the first time you mentioned this to me. We were in Paranopolis, Brazil.

Chris [00:03:02]:
True.

Stanford [00:03:03]:
And you had just spent the day hiking with my young children.

Chris [00:03:06]:
Yes. Greatest day.

Stanford [00:03:08]:
We swam in waterfalls and we went out to dinner. And then you dropped this bomb on me that you've been asked to model Snake river dam removals.

Chris [00:03:16]:
That's true.

Stanford [00:03:17]:
How on earth did you get involved in that?

Chris [00:03:19]:
The agencies that are in charge of the Columbia river system operations. So that would be Bureau of Reclamation, the Corps of Engineers, and as an adjunct, Bonneville Power for people listening that aren't familiar with the Pacific Northwest. We live in a land of litigation, and it's a lot of litigation around listed cell monets. And so a lot of our operations and a lot of our. You can nearly say all of our operations and what we do is colored underneath the CSA lens.

Stanford [00:03:43]:
Environmental species.

Chris [00:03:44]:
Environmental Species act. Yes. The acting agencies behind Columbia system operations, which is the main stem dams and dams at a select group of dams on the snake. We got basically a court injunction, a court order that said your existing ESA compliance is stale.

Stanford [00:04:03]:
A funny adjective.

Chris [00:04:04]:
A funny adjective. Courts are funny. It was incumbent upon the agencies to redo their ESA coverage, which is a massive undertaking. And honestly, the route was not direct. It was circuitous. I came in as the technical lead for the core for the project, which turned into the h and h lead, which eventually turned into the river mechanics lead by a series of promotions and retirement. Part of the story of how you get to be you is luck and doggedness on what you want to pursue.

Stanford [00:04:33]:
I would love to chase that question, how you get to be you. But this was part of a bigger environmental impact study of these four dams on the Snake river. And one of the alternatives that the injunction asked you to analyze is what if the dams weren't there? What if they were taken out and what would the sediment impacts be?

Chris [00:04:52]:
That's correct. The EIS was actually for a larger group of dams that included the. For Snake river dams. The development of the Snake river for, you know, hydro regulation and navigation was some of the last dams that were really. The last ones were in the seventies.

Stanford [00:05:08]:
Right.

Chris [00:05:08]:
And, you know, they went in under environmental contention. We were into that era where they weren't necessarily welcomed by all constituents and.

Stanford [00:05:18]:
All stakeholders, which wasn't true, say of the Missouri dams in the fifties and sixties. Correct?

Chris [00:05:23]:
Correct. Those dams have lived a life of contention, and it's always been on the table that they weren't welcome to some stakeholders. And so the idea of removing the dams has been investigated multiple over the years. There was a big study in the nineties that looked at it, and this is the latest. EIs was the latest opportunity to put it in an alternative set for continued operations of the federal system, of which they are a part.

Stanford [00:05:50]:
And so you mentioned that Tim Randall, who was with the Bureau of Reclamation, he was one of the reviewers on our study, and he pushed us to include a conceptual model that would lead into the numerical model. And so what would you say is your conceptual model of what the sediment would do if these dams were taken out?

Chris [00:06:07]:
We actually got that comment from Tim pretty late in the process. We did, yes. And we scrambled a little bit to say, yeah, we really do need a conceptual model. But it really colored a lot of my thinking when we got around to it, because we'd been working that way anyway. Yes, you have to have some intuition about what's going on to even set up your models correctly and to parameterize them correctly to pick hydrologic sequences that are correct, to give modeling stents that are correct. To that end, we already had it. Part of it's driven by the removal process. And in the particular case of the snake, the work that was done in the nineties, which was pretty extensive work, I mean, a lot of documentation and a lot of reports and investigation written around optimization of removal, it was decided that we were going to use that removal methodology. These are four dams in sequence. They backwater each other so you can get continuous navigation through a series of locks. They have ladders on all of the project so that fish can move upstream. And the process of removal was in one water year, you would remove the upper two dams, and in the successive next water year, you would reach the lower two dams. And how that was going to be done, including drawdown sequence and hold sequences, and what pieces of the dams would be removed and what would be left, was already programmed for us. We had a lot to start with, or I guess the question was constrained pretty much already. So we knew the timing, we knew how, we even knew when in the year. And what we know about dam removal is you have a pretty abrupt release of sediments as soon as you don't have the dam holding them back anymore. And so the conceptual model was that a large portion of the sediments would pretty abruptly move downstream and move into the main stem columbia projects. And then the main stem Columbia projects would capture some of the material, though the finest grain portion of it would likely move through some of those run of river projects and potentially make us all way, all the way down to the estuary.

Stanford [00:08:18]:
So just to get the map in our head, the Snake river has these four dams that we're evaluating, and it flows into the Columbia, which has its own reservoirs.

Chris [00:08:26]:
It flows into a reservoir behind McNary Dam.

Stanford [00:08:29]:
Right. The closest reservoir on the Columbia, which is what the snake flows into, actually backwaters up the snake. And so the sediment's not going far. That's one of the things you're looking at.

Chris [00:08:42]:
Yeah, that is absolutely what we wanted to do.

Stanford [00:08:44]:
And so let's actually ask that question because I find that whenever people start talking about dam removal, they know that sediment's this like 800 pound grill in the room and someone in the room will say, we need a sediment model. And let's say that like on system like this, a damn revolt this big and with this many stakeholders, I think you do need a segment model. But I think that what ends happening is people are like, we need a model because that will tell us whatever answer we want. But you actually have to, like, craft a model to answer a certain set of questions. And so what were the questions that you were trying to answer with this model?

Chris [00:09:16]:
So it's absolutely true. And I think the reality is that sediment, the political environment and the operational environment in the Pacific Northwest is really driven by our ESA listing in salmon. But there's a lot of water uses, navigation to water use. There's water quality issues for drinking water and municipal uses. There's a bunch of different uses, but a lot of that is going to be where you, in our environment at least, you need to know who needs to know the answer. It's the biologists and the interest in fish that, that need the answers. And so I would say when you scope your study, know who the stakeholders are and know who they're really deciding. Stakeholders, who has the biggest stake, or at least who's going to ask the questions you need to be responsive to. But we, you know, we looked at a full range of things. We were, we were really trying to understand one, first and foremost, the biological aspects which had to do with water quality concerns for suspended sediments and what the implications of that are for dissolved oxygen and water quality. We were interested in changing habitats. And, you know, fish is a big one, but there's avian species around that are also of interest in these reservoirs.

Stanford [00:10:35]:
That could be affected by fine sediments.

Chris [00:10:37]:
Yeah. Yes, absolutely. So there's habitats that are valuable, that people interested in migrating waterfowl are very interested in what changes could happen to those habitats.

Stanford [00:10:49]:
Interesting.

Chris [00:10:50]:
Beyond that, which is a very strong stakeholder in our region, we need to speak to the impacts to the ports and to navigation. We need to speak to that. There's irrigators that have water supply intakes that are in these pools. Are they going to be impacted by mass deposition? So really it was a wide range of who could be impacted. So it was just trying to get your head around the whole story.

Stanford [00:11:14]:
So the question I led with is dam removal harder or easier than other studies? I've actually gotten different answers to that.

Chris [00:11:20]:
Oh, really?

Stanford [00:11:21]:
Yeah. Yen Tao sui, who's done a lot of this work, he said to me once he pad was easier because the signal to noise ratio is positive. You got a really nice signal. It drowns out the noise. But I've always thought that the fact that you're trying to model something that has never happened, that has no precedent, makes it harder. But you did something different in this study. This is the first dam removal study that I saw that was actually calibrated to an erosion event. You want to tell us about that?

Chris [00:11:46]:
You work in different data environments with different projects and the Snake river, because there's been such interest and there's other sediment issues going on in the region. Walla Walla district has an active dredging program occurring at the upstream end of the highest reservoir on the snake. The upstream of the four. The communities of Luce and Clarkston, they've got an active dredging program. It's head of reservoir, it's the confluence of two. But, you know, lubial streams have deposition and they need to maintain depth. So between all of the interests, there's a lot of data. It's a data rich environment, which is joy when you're, when you're doing sediment work. Data's king. The data really drove how we could set up our model, how we could parameterize it, and how much confidence, really, we really had in it. Because we had an active dredging program and because there's been this interest in trying to decrease costs associated with dredging and also potential dam removal and habitat issues. There's actually a drawdown of the upper reservoir that was performed in the nineties. It was one of these planned actions and data was collected pre drawdown, post drawdown. So they drew down the reservoir. What was it, 30ft?

Stanford [00:13:02]:
Yeah, something like that.

Chris [00:13:03]:
30, 40ft. So it made the upper portion at this confluence between the snake and the clear water run of river and mobilized a lot of that head of reservoir sediment. And it's the bulk of the sediment that's deposited in the system, you know, over. I think the numbers are over. Half of the total sediment in the four reservoirs is deposited in the upstream reservoir, which should make good sense. It's been there since the seventies collecting sediment, at least all the coarse material. And so the drawdown actually mobilized the.

Stanford [00:13:32]:
Sediment so it eroded the delta like.

Chris [00:13:34]:
A dam removal would do, exactly as a dam removal would do. And so we had this data and we had everything we wanted. We had flow, we had stages in the reservoirs. We had good before and after bathymetric data. We had great bed material sediment sampling. We had everything you could want. So we had an opportunity to do a drawdown in erosion calibration.

Stanford [00:13:56]:
I think that's really interesting because I do think that as we think about more dam removals, especially some of the big ones, the questions around modeling and uncertainty in modeling the idea of actually doing an intentional drawdown as a calibration event, I think that could really inform other big dam removal models.

Chris [00:14:13]:
Yeah, no, I totally agree. It's one of the big lessons learned I've got inside of sediment modeling generally, is that erosion and deposition are two really different processes. Which one's harder? Well, what's hard is trying to put both into a single parameterization there you have to split the difference. If you can build just an erosion model and you've got data to calibrate it, you're good. Same thing with deposition. It's when you're trying to merge it all together, you have the. I have found you have the most problems.

Stanford [00:14:43]:
Well, that's a good segue because you told me recently that your thoughts on numerical models and morphological models have changed over the years. How have they changed?

Chris [00:14:52]:
So I've been in the game a bit and I came in kind of at the end of the hek two era, right. So I've been here when GIS was really coming on in geospatial data, when you can actually geospatially reference a model and when you could start visualizing and you started having lidar coming online and you started having denser bathymetric data sets or repeat bathymetric data sets that you could geospatially reference the physical landscape, our models got way better. And part of me thinks it was just in really complicated modeling scenarios. In the heck two framework where reach length was disconnected, it was nearly an abstract. You'd drawn it off of some plan somewhere. I don't know if it was modeling error or if it's just the limitations of the model. I'm inclined to think it wasn't. I think the geospatial aspect of it has just made us better modelers, we building higher quality models. So what I've run into kind of repeatedly in really complicated models is that our hydraulics are really good. And at some point, and I say this because it's happened a few times, we've outstripped some of our other inputs. At some point, you need to start looking a lot harder at hydrology, and you need to start looking a lot harder at your calibration data. To the point where we're finding errors in calibration data and hydrology, it's not an error necessarily. The hydraulic, it has gotten good enough that you can take this holistic view of the hydraulic model and start poking at the things that go into it. And I'm finding more air there than I'm finding in the model proper.

Stanford [00:16:34]:
So let me see if I can reproduce this. So we have this, we have this lifecycle of water in our numerical models, from hydrology to hydraulics to sediment transport or water quality. Plus those things are fed with data input. And what I'm hearing you say is that as the Lidar data gets better, we have a piece, the hydraulic model, which is actually more precise than the other models feeding it or receiving from it or even the data feeding it, that it becomes a tool with which we interrogate the fidelity of those other data and models.

Chris [00:17:07]:
Yes, that's exactly what I'm getting at. And the USGS does mind bogglingly good work. And we are fortunate as a nation to have them providing the data. But I'll give an example. So we have a really complicated hydraulic scenario in Portland district, where the Willamette meets the Columbia in Portland. And we've got a few gauges around. So there's a gauge on the Columbia. There's also a long term gauge that sits in Portland, downtown Portland, in our building and calibration of our models in this zone, we've gotten to the point where we really feel confident about our geometry of our model. We were having a really hard time catching calibration, and we felt like something was wrong in those two gauges, but it wasn't really wrong. It just forced us into calibration values that didn't feel right. And so we actually compelled the USGS to go out and survey their gauges, and they found a 0.25 foot, you know, two tenths of a foot bust in the data. And that was driven because we didn't feel comfortable with our calibration factors. When it all gets tighten, you're getting to that kind of fidelity.

Stanford [00:18:11]:
What I hear you saying is that we're in this symbiotic analysis relationship where the data has some uncertainty and some truth, and the model has uncertainty, but has the ability to reinforce the data collection itself.

Chris [00:18:26]:
Yeah, absolutely. The model is a simplified representation, but it's a static physics representation, it's a static numerical representation. And when things start, especially in time, start running counter to it or you can't explain it. I have found, as often as not investigating the data that fed in is as important as investigating what's going on in your model.

Stanford [00:18:46]:
And so then the model, and this is one of the biggest differences that I find between people who've been modeling as long as you and newer modelers, is the model is an invitation to investigate the world.

Chris [00:18:57]:
Yes, absolutely.

Stanford [00:18:58]:
Rather than a tool to tell a manager an answer.

Chris [00:19:03]:
Absolutely correct. Yeah. And that's me as an engineer, is I have a lot of trust in my intuition and, you know, the models are, the analyses are going to help me learn. I always love it when I run a model and it blows up my intuition.

Stanford [00:19:19]:
Yeah, right.

Chris [00:19:19]:
Because you, you know, you spend your nights up thinking about what just happened.

Stanford [00:19:22]:
That's right.

Chris [00:19:23]:
And your understanding changes. You need to get your head around that. But I'm, I'm definitely. I need to understand it and explain it before I believe it kind of guy.

Stanford [00:19:34]:
So let's move from kind of this one big flagship study to just another big flagship study, which is, this is the Chris Nygaard brand. We met about ten, over ten years ago on the core's most dramatic sediment problem and maybe our nation's most dramatic sediment problem, Mount St Helens. So can you just give us, especially for those listening who maybe weren't born then, can you just give us a little background on the eruption and how that affects the rivers and why the core of all agencies is involved?

Chris [00:20:04]:
Yeah, absolutely. And I'll just disclose this upfront that that was a really big part of my career of several years ago at this point. Right. So a lot of time is passed, but, you know, the facts of the case haven't. You know, we've got a chain of volcanoes in the Cascades. Mount St Helens is one of the more active. It is the most active one. And in 1980, there was a landslide. Effectively, they'd been a growing bulge. They knew there was activity. There was a lot of seismic activity around the mountain and they cleared the area. It was to the point where they moved people out of what their expected blast zone was. And so in May of 1980, massive landslide happened. It removed the overburden on top of a high pressure zone. And you had this mass eruption. Basically the mountain turned upside down and it wiped clean the landscape that was.

Stanford [00:20:55]:
Sitting on the mountain, took the side of the mountain and flipped it upside down.

Chris [00:20:59]:
Indeed it did. It shook it all up.

Stanford [00:21:02]:
Yeah. Okay, so we have a mountain that's been turned upside down.

Chris [00:21:05]:
Yes.

Stanford [00:21:05]:
What does that do to the rivers and communities downstream?

Chris [00:21:08]:
We get a lot of rain up on the mountain, so we have a big orographic effect that goes on.

Stanford [00:21:12]:
One of the things we all know about the northwest is you get rain.

Chris [00:21:15]:
Yeah. You know, the overall quantities, you know, Portland aren't really that impressive, but you move up on the mountains where they, they catch the marine layer coming in and it's really impressive. Right. So Mount St. Helens is one of those. So now you've got this flipped over andesitic mountain. And so it's a lot of ash, a lot of pumice, a lot of sand, a lot of. So what I'm trying to tell you is a lot of non cohesives and light specific gravity. Non cohesives that have no rivers, that have no valleys. Like how the water is going to get off. All this water that's coming in is going to get off. This landscape is undefined at this point.

Stanford [00:21:50]:
It's almost like this is an experiment. Like the only other place you'll see this is in a lab or maybe a Ydezenhe an actual, like, legit kid sandbox.

Chris [00:21:56]:
Right.

Stanford [00:21:56]:
You actually have a brand new giant surface of sediment and it's raining a lot.

Chris [00:22:02]:
Yes. And the initial years, you read those old reports and they're harrowing. They're fascinating. You know, you'd have all these big hummocks that would. These lakes would form and brand new deposit, unconsolidated material holding it back. And they were out there draining them and blasting them and having periodic breakouts.

Stanford [00:22:20]:
Oh, I haven't heard about this.

Chris [00:22:22]:
The original few years were crazy.

Stanford [00:22:24]:
Lakes would form in the middle of the deposits and they were afraid that they were going to, like, burst.

Chris [00:22:28]:
Yes.

Stanford [00:22:29]:
And so they went out and actually, like, drained them.

Chris [00:22:31]:
Yeah. Oh, yeah. There were a couple years of just constant battling and they had repeated blowouts and, you know, it was, it was mayhem. Wow. You know, in this process, you have all this water moving on the sediment without rivers and valleys and terraces and vegetation and anything that kind of helps keep your landscape together. And it just moved an ungodly amount of sediment. All that sediment, sediment mobilizing, started moving downstream. And so what's downstream? What's downstream is a bunch of population that's right down near the confluence with the Columbia. You've got four communities. You've got more than that before. Communities down on the Cowlitz, which is the receiving waters of the toutle, which the mountain is on the North Fork toutle, the bigger option. And then the cowlitz flows into Columbia. So there were communities down on the Cowlitz that were experiencing rapid aggregation of fans in their river and creating flood risks for those communities.

Stanford [00:23:29]:
And some of these are protected by.

Chris [00:23:30]:
Core levees, and they had levees. And part of the authorization that moved through was to improve those levees. And it's one of the major hallmarks of the authorization that came through was to provide flood protection for those communities. And the choices that were made at the time were to manage the sediment closer to the mountain.

Stanford [00:23:52]:
So it doesn't take Chris Nygaard, the sediment specialist at the Portland district, to put together what happens if you put hundreds of millions of tons of sediment in a channel with levees that you're going to deposit and the level of protection behind the levees is going to decrease. What is an SRS, and how does that play into the story?

Chris [00:24:11]:
The core looked at a bunch of different alternatives, and the alternative that moved forward that got implemented was to build a effectively large dam, the sediment retention structure. So the SRS, the SRS, it is a large dam. It is over 100ft high. We think it's about 110ft over the historic falwag. And it had a pool that was a couple miles long when it was originally built, 100ft deep. And the intention was never to have a still water pool. The intention was to strip sediment out of the load that's moving downstream and capture it and send out clearer water so that you don't overwhelm the downstream reaches with sediment and manage the deposition. And this was built, I think it became finalized in 89. Construction started in the mid eighties. About 86 became a fully active structure in 89, the Stillwater pool. So 110 foot high dam was full of sediment. Full of sediment to the extent that at least sediment was spilling over the spillway. First time the spillway became active was in 96.

Stanford [00:25:13]:
Oh, wow.

Chris [00:25:14]:
So 96 was a very hallmark year in the Pacific Northwest. It was roughly a hundred year event on the Columbia, one of those hydrologic, big hydrologic events. And you can only imagine, you know, that the mountain had only been 16 years since it had been flipped upside down. A lot of available sediment. There'd been virtually no vegetation recovery. Incisional processes were still extraordinarily active. Kicked out a huge amount of sediment and had filled the reservoir to the point where water spilled over the spillway. It was a couple years later before sediment had filled the reservoir to the point where it was sediment level to the spillway crust. It's always been a fascinating thing, and it's nice thing about talking to sediment people is that I battle over this comment all the time, but everyone here will get it. It's not full of sediment. It is just full to the spillway crest. The valley needs to a grade.

Stanford [00:26:05]:
That's right.

Chris [00:26:05]:
So, and furthermore, the sediment that was trapped behind the srs while you're still trying to move water through an outlet works, was trapping sediment. That's not a problem downstream. You know, medium sands and coarser really are your problem downstream. So if you're past, if you're trapping silts at all, right, that would have passed.

Stanford [00:26:22]:
That's a waste because that won't end up depositing.

Chris [00:26:25]:
But to create an outlet works that has the capacity to hold water surfaces down so you can selectively trap is outsized outlet work. So they just accepted that they were going to trap a lot of unnecessary material. And really that's the challenge going forward is how do you selectively trap the problematic material without trapping more than you need?

Stanford [00:26:45]:
So basically we built a dam. Yes, we built a dam in the eighties.

Chris [00:26:49]:
Yes.

Stanford [00:26:50]:
This is unlike any other dam in our portfolio because this was entirely meant to trap sediment. And within the 16 to 20 years, sediment had filled up to the spillway and the trap efficiency had decreased. We're sending more sediment downstream, which is when you get involved. And I want to get to. When you get involved, but I want to kind of burrow in on something you said. So sediment has filled to the top of the spillway.

Chris [00:27:15]:
Yep.

Stanford [00:27:15]:
If you draw the picture of the dam and draw a line, sediment goes all the way back. It's flat. But you said that that's not full of sediment, right. What do you mean by that?

Chris [00:27:24]:
It's not even halfway full. So full of sediment is when you hit that quasi equilibrium condition where, you know, for a reasonable amount of time, sediment in and sediment out is, becomes equal. You need a gradient on the valley upstream of the reservoir. You can imagine it. You know, we're all familiar with, like, geologic nick points that create floodplains upstream of them. We created a geologic nick point with a dam. At some point there's gonna be enough deposition that in is gonna equal out over a long reasonable range of time. And until that happens, we're not full. It is a net depositional, it's a net sink. And we think we'll be in net sink for century or longer by the time we get to this true kind of quasi equilibrium condition. We haven't done the analyses to predict exactly what that slope is going to look like. We're leaning on work that was done in the southwest that estimated it was going to be original valley slope divided by two has to do with a lot with the debris dams in the southwest. But even then, we're less than halfway full at this point.

Stanford [00:28:28]:
So this is something I think that Tony Thomas taught me on this system, is that when you think about how much sediment can a reservoir hold, it's not a question of just kind of draw the line from the spillway back, because a lot of the sediment is actually going to get stored up in the valley and in other systems, if their community's up there, they're going to be exposed to increasing flood risk, even though they're above kind of that flat water pool.

Chris [00:28:56]:
Yes, and Tony Thomas is correct.

Stanford [00:28:59]:
We were seeing. Okay, so speaking of Tony Thomas and kind of some of the legends, everyone who was anyone in sediment in the eighties worked on Mount St. Helen. You're kind of like second generation Mount St. Helen. My understanding is that in the nineties, after that big event, the trap efficiency of the reservoir decreased, and that's when your phase of the project came on.

Chris [00:29:20]:
There's kind of a precipitating event for that. We had this really interesting storm come through and believe it was November of zero six. And I'm hoping I remember this correctly, it was early in the season. Part of the sediment story on volcanoes is that snow actually provides a lot of protection and cover for. For sediment supply. So when we get into these high intensity events that happen early in the year, when you don't have a snowpack, you have potential for a lot of exposed sediment to become mobilized. And this happened, and it happened all over the region. It wasn't just Mount St. Helens. The upper collets on Mount Rainier had a big blowout.

Stanford [00:29:57]:
This is also one of the climate change issues. The snowpack is so important for sediment yield. This is how climate change might affect some of the sediment stuff.

Chris [00:30:05]:
Right. And what makes Mount St. Helens unique is it's one of the few growing glaciers in the world because it was eliminated at one point. Right. And, you know, so this event happens in zero six, and it's a regional event. It was the first really big sediment release, you know, big discontinuity between flow and sediment, which is really the story of Mount St. Helens.

Stanford [00:30:27]:
So the flow that's coming out of the SRS to the downstream communities, there's a mismatch now between that flow and the sediment. The sediment's higher for the flow.

Chris [00:30:35]:
Yeah, for this particular bend. So the flow itself, as far as frequency flows, not stand out. The sediment yield was extraordinarily.

Stanford [00:30:44]:
And so there's a mark that there's a trap efficiency problem with the SRS.

Chris [00:30:47]:
Right. Well, we're to the point where trap efficiency, so it's a nonlinear decrease in trap efficiency as the valley starts to aggrade. What we experience are these episodic events where we have this high sediment yield off the mountain that say you're trapping on average 35% in the SRS. Well, that discontinuity and flow load can overwhelm sediment supply and deposit on the downstream end. And those really are our problems. That's what's going on right now. It's event driven. This was one of them. It deposited a lot of material down in the cowlitz where we have the. Our authority, the levees and the communities we're protecting. Clearly the community noticed it and it became an issue. So that was really the start of this next round of study. I became involved in 2009, and that's when we really dug into the long term plan to try to figure out what we were going to do. Like the next hard look, we've done our original authority and our original planning. The original planning said, hey, this is a really novel event. We're going to kickstart this with the SRS, but sometime in the future you're going to need to do something more. But we don't know what it's going to be because we don't know how this is going to play out. That's what we got today.

Stanford [00:32:02]:
The 1980s scientists said, hey, future scientists, you have a job. And it came due about 1998.

Chris [00:32:11]:
Yeah, it did. It did. Yeah. 2006 was the precipitating event for it, and that really started our planning around through our authority at that time, still our authority through 2035. So 50 year planning horizon on the original structure.

Stanford [00:32:26]:
Okay, so several years ago, you and Paul Scafani, who's with the Portland district, and Colin Thorne, who was at the University of Nottingham, but it's kind of a big player in the northwest as well. You published a paper in geomorphology on the big work you did. And my understanding is, the big question you were asking is, what is the total future sediment prognosis? Let me ask you two questions. One is how much sediment can the SRS hold? What's the capacity and what is the sediment prognosis within one or 200 million cubic yards?

Chris [00:33:03]:
Yeah, Colin came in and suggested we write this paper. And it was really at the end of that study that kicked off in 2009, and we really completed around 2012. And that was the long term sediment management plan for Mount St. Helens. And, you know, it was the standard core planning project where we looked at a bunch of alternatives, including some, you know, really wild stuff like terracing the mountain. It opened up all the options.

Stanford [00:33:27]:
There were like 16 options. Yeah, 16 alternatives or something like that.

Chris [00:33:30]:
There were, you know, it came down that the option that got chosen was to take a hard look at the srs and see what we could do to increase the amount of material that it could hold. And what we discovered was that in the early days, when they were looking at this and they didn't know a lot about the future, they were radically conservative with how they investigated everything. They were conservative on sediment yield, they were conservative on hydrology, they were conservative on assumptions around future mud flows. And when we took a sharper pencil and harder look at all these things, our probable maximum flood went down. So the spillway capacity was. Was overly large. We used better numerics on mud flows. The USGS did a bunch of great work on that. And it was assumed that the mud flow was going to reach the dam. And they showed that it doesn't. It actually dies up in the sediment plane. And so what it came down to was that we had additional capacity on the spillway. And so the plan that moved forward was to do some incremental raises of the spillway crest. And why that's important is the earlier discussion that we're really targeting a very specific gradation range. We looked at. How could you feasibly just target that? And what we determined was, you know, relatively small crest raises, creating that higher nick point. You could catch that range.

Stanford [00:34:50]:
So let me, let me make sure that this is clear. So you don't want to catch all the sediment.

Chris [00:34:55]:
Right.

Stanford [00:34:56]:
In fact, there's some sediment. If you catch it, you're essentially wasting space.

Chris [00:35:00]:
Correct.

Stanford [00:35:00]:
And so you want to design incrementally the structure. So only collects the problematic sediment, kind of optimizes the space you have, which is not unlimited.

Chris [00:35:11]:
Yeah, that's what we tried to tease out. All right, so we did a seven foot crest raise in 2012. What we were targeting was just trying to increase the overall trapping efficiency of the SRS. And we actually increased it from somewhere in the mid thirties. And these are rough numbers. We spent a lot of time to up towards the mid forties. But that incremental change in trapping efficiency, which we estimated that's going to decay as you get increased deposition in the SRS. But it was going to take a decade or maybe longer to decay. So long as you didn't get some anomalous event come through and deposit a lot of sediment. But that was enough to change our d 50 passing the srs and target that medium sand and coarser material that we were after.

Stanford [00:35:52]:
So you were only capturing 10% more material, but it was the right 10%. Yeah, that's good.

Chris [00:35:58]:
Exactly. And so the plan was that we had, I think it was 21ft that we could raise the srs before we couldn't pass the PMF. And we started having structural issues on the, you know, start loading up a dam higher at some point. So.

Stanford [00:36:12]:
And the PMF is the probable maximum flood.

Chris [00:36:14]:
Correct.

Stanford [00:36:15]:
All of our structures have to pass this like theoretical maximum flood that could happen.

Chris [00:36:21]:
Correct. So what's going on now is that we are in the design process for the second race.

Stanford [00:36:28]:
One of the things that you and I have talked about, okay, you've done these two big sediment models. The sediment model you did for the Mount St. Helens project was really, there's the first big sediment model in ras. Like that's the vintage of it. And the Snake river is honestly one of the biggest, most complex dam removal models I've ever seen. And so you've had some experience with some of these big, high uncertainty, big data models, one of the things you've talked about is the way you see, see that changing in the future. You want to talk a little bit about that?

Chris [00:36:57]:
Yeah, for sure. Okay. The stochastic world, we're just going to start with that.

Stanford [00:37:01]:
Okay. All right. Can you define that word?

Chris [00:37:04]:
Yeah. Parameterization of our uncertainty.

Stanford [00:37:08]:
I'm not sure that definition helped it.

Chris [00:37:10]:
Okay, so basically one answer isn't enough. There's a lot of uncertainty in the world and especially in sediment, there's a lot of uncertainty. Mount St. Helens in particular has got, you know, even when things are going good, that we've got four orders of magnitude and the sediment load flow relationship and individual events can get outside of that. So, you know, when you're working in this rigid type of physics environment of a model you know, fitting a single load curve in to a single hydrologic assumption doesn't really tell you the whole story.

Stanford [00:37:48]:
Right.

Chris [00:37:48]:
It tells you a piece of the story. And my experience in the past is we didn't have the numerical. We didn't have the computer resources. You're at the kind of at the fringe of stability. They take a long time to run. They produce a tremendous amount of data. So the storage requirements are huge. And it really led you to simplify your inputs to a single deterministic scenario or maybe one or two or three. So you could at least stay dry, medium and wet.

Stanford [00:38:18]:
Right. Which is the progression you went through in the mid two thousands. Mount St. Helens had like one conservative future. Hydrology. Correct.

Chris [00:38:26]:
That was built on load, you know.

Stanford [00:38:28]:
Right.

Chris [00:38:28]:
We deconstructed it from hydrology and took it into observe load and tried to do median load conditions under multiple parameters. So at least you had one, that.

Stanford [00:38:37]:
Which is essentially one conservative future.

Chris [00:38:40]:
Yeah, one conservative.

Stanford [00:38:41]:
And then the snake river model took a step forward and you did kind of, you know, expected wet dry into the future is building a little stochasticity into it. But your vision for the future is a little bit more complex.

Chris [00:38:53]:
Yeah, absolutely. Because what I've found is that when we are the sediment experts and we're supposed to be creating the most accurate picture we can, but the accurate picture really is that the future is uncertain. There's inerrant uncertainty in, you know, in hydrology alone. Not to mention, you know, sediment load. If you're in an environment where. Where it really disconnects from the hydrology. And you can create expectations, political and otherwise, around that deterministic world that you built. Now, as we all know, communicating risk is really hard. Communicating curves is really hard. But backtracking when the future doesn't look like that deterministic, when, you know, when today doesn't look like that deterministic future that you laid out a decade ago is also really difficult.

Stanford [00:39:42]:
And I think this is one of the places where you have some wisdom because there's not a lot of folks who are around who are still interacting with the community about a sediment model they built ten years ago. And so you're looking back on this conservative sediment model you built ten years ago. And it doesn't necessarily match the present. And you're kind of wishing that we had been in a technology situation where you could have been more explicit about the range of possible futures.

Chris [00:40:06]:
Right. And I was talking to Paul Sclafani before this. And Paul was mentioned. He and I really were the. The two core people that were actively involved. In working many, many overtime hours on Mount St. Helens. And he reminded me, it's worth saying it. That we are the people that are going to speak for the sediment. We are the people that are going to try to tell as direct and truthful a story as we can about the sediment. And if we don't champion that, no one else is really positioned to do that. And so we need to. I'm not certain that many, many solutions that create a curve is the solution for us. But I do know that when the future ends up not looking like your model. Your seat at the table gets shoved a little further back.

Stanford [00:40:52]:
And by a curve, you mean we shouldn't have a sediment result. We should have a range of potential futures?

Chris [00:40:58]:
I think so. And granted, I haven't seen it exactly play out, but, yeah, I think it would do a better job on setting expectations. And when the future lands in your curve, as opposed to not matching your deterministic result, you've got a better position to work from.

Stanford [00:41:13]:
So people could have listened to our conversation so far. And think, Chris Nygaard only gets involved in the biggest, most controversial projects in the world. That's his brand. If it's not hundreds of millions of tons of sediment, he's not interested. But that's just not true. You've interacted with more small, medium and large restoration projects. In northwest rivers than almost anyone I know. And that's because you took what I'm just going to call. A little sabbatical from the corps of engineers. You worked for bonfil power for a few years as one of their project engineers. And got more reps on field and office review of in the ground restoration studies of anyone I know. And you and I haven't spent a lot of time since you came back from your sabbatical. So one of the things I just really wanted to know is when you've seen all of those restoration studies. Surely you've built some intuition. So here's what I wanna do. I wanna talk in reverse order about the good, the bad and the ugly of the restoration projects you've seen. But first, why don't you just give us a little background about what your job was at Bonneville Power. Maybe how many projects you interacted with. And why it is you interacted with that many.

Chris [00:42:20]:
Yeah. Okay, so I'll even take it a step further back. Why did I leave the corps and go to Bonneville?

Stanford [00:42:27]:
So, after those two big studies, I think people can use their imaginations.

Chris [00:42:32]:
So, you know, I was at the tail end of the. The eIs, for that included the Snake river dam, was one of the alternatives, was just completing, or we'd done the heavy lifting. Right. And eis has had a long life after that. And this opportunity came to go to Bonneville. I'd been down these. These big projects that live in theoretical land for quite a while, and at some point, you know, you've been around and people depend on you to give answers. And I just didn't feel connected to the reality. I felt like I was too far into numerical and theory, and Bonneville is unique. Bonneville runs this massive. It's a mitigation project for marketing the hydropower. Their fish and wildlife program is on the order of a quarter billion, 250 million a year. And it's spread into a bunch of aspects. There's hatchery aspects and some land acquisition work and a few major business lines. But one of the big ones is habitat restoration.

Stanford [00:43:29]:
Let's make sure everyone caught that. We're talking about an organization that is putting tens to hundreds of millions of dollars into habitat restoration a year.

Chris [00:43:39]:
Yep. And they're the biggest player. But, you know, the states, state of Washington, state of Oregon, other agencies are also putting a bunch of money. The amount of restoration work that's occurring in the Pacific Northwest is really massive, and a lot of it is led by. I mean, there's a group of consortiums that the players include. Tribes are a huge component of this. There's a lot of nonprofits that are out working. So there's a lot of players, and there's a lot of engineering firms in our region that specialize in this. This is all they do. So Bonneville's program for habitat restoration is in the tune of about $150 million a year. And it's been going on at that level for many years at this point.

Stanford [00:44:21]:
So there's a lot of projects in the ground.

Chris [00:44:23]:
There is a lot of projects on the ground, you know, on an annual basis, major projects where you're significantly altering the morphology of the reach is in the dozens.

Stanford [00:44:35]:
Okay?

Chris [00:44:36]:
And it's throughout the entire anatomist range in the Columbia. It's a pretty big zone that they cover, which is fascinating in its own right, because the Willamette Valley doesn't look like the upper snake, does not look like the Metau. And so the opportunity to go and actually interact with that business line, all the players, and actually see implementation and lots of implementation, and watch successes and watch failures and have a seat. There was too much to pass up.

Stanford [00:45:04]:
So tell us a little bit about what your daily life was like and maybe how many projects you got your hands on.

Chris [00:45:10]:
So I was fortunate. I had two engineering counterparts over at BPA that are known entities in the region, one of which is Doug Knapp, who was an X core employee who I knew well. They recognize right off the bat that to be effective in that environment, you need to see everything in the field. A lot, I would estimate conservatively. I laid eyes on 100 implemented projects in that first six months, including big failures and some really cutting edge stuff like stage zero work, the whole gamut, and really tiny little things, too. And then the day to day, the engineering unit kind of served as internal consultants. And so anything that was engineering oriented, you're at the disposal of all the people that are working to make the program happen. We were a cog in the wheel of ESA compliance, the ESA programmatic the BPA operates under. To do these restoration projects is actually really, really broad. And it's broad partly because they've committed to have an engineer review. So that was the role.

Stanford [00:46:10]:
So you and two other engineers were reviewing all of the projects that are coming through this system?

Chris [00:46:15]:
Correct.

Stanford [00:46:16]:
Okay, so in six months, you saw three times as many restoration projects as I have in my life.

Chris [00:46:22]:
Yeah. My estimate, I think I reviewed somewhere. It was shy of 170 or 80 projects. Probably 20 or 30 of significance.

Stanford [00:46:32]:
Yeah.

Chris [00:46:33]:
And then probably laid eyes on, you know, by the time it was all said and done, a few hundred.

Stanford [00:46:38]:
Few hundred. So this is why I want to have this conversation, is because I just. I really think that intuition comes from reps. Right? Just reps. And we just. Our lives as river scientists are not long enough to generally get that many reps. So the good, the bad and the ugly. Yeah, let's start with the ugly. What were the most common failure modes of river restoration projects that you saw?

Chris [00:47:02]:
I think one thing you really need to recognize in restoration, and the engineers need to hear this, is that it is multidisciplinary. There are very few. I've met a couple, but there's very few single entities that can take a complicated project that, frankly, it's geology, it's geomorphology, it's hydrology, it's riparian wetland, it's wetland, it's aquatics, it's macroinvert, it's everything, and be able to do a competent job across them all. The most frustrating failures was when there was a lot of opportunity, but potentially a narrow vision.

Stanford [00:47:39]:
So just really applying one of the disciplines, and you were kind of leaving value on the table. If you had brought other disciplines to play.

Chris [00:47:47]:
Yeah. Yes. When there was potential left on the table. Now, the reality in restoration is that you can do really different things if you own the land versus if you're writing an easement against the land. And the vast majority of restoration is happening on easements. And so it absolutely is a dance. And I have a lot of respect for the practitioners because their social skills on being able to go out and work with landowners and with watershed councils and everybody else to do projects, you know, it's a soft skill. There's usually not a lot of people on these projects. So they're largely the biologists. A lot of times they're the dreamers, the geomorphologists. They have a lot on their plate. You know, to that end, when we talk about what, you know, potential being left on the table, you know, the current thoughts around restoration, kind of the hallmark stuff really is restoring the floodplain. It's moving away from basically rewetting the floodplain so that the seed source that sits there is working in the hydrologic regime. It should. And what that really means is in a lot of cases, raising the river. And the practicality of raising the river is really dictated by land ownership and then what's upstream and downstream of it. So you hate to point it at failures because they all live inside of the reality of the situation. But a lot of potential is necessarily left as kind of the crosswalk between what you can really do.

Stanford [00:49:10]:
Let's transition to an adjective that's not as severe. What kind of analysis do you think maybe is getting overdone or underdone for these sorts of studies?

Chris [00:49:21]:
The firms that are working in this environment compete against each other and there's a limited pot of money and there's a very strong desire. You know, it's a really passionate community that chooses restoration as a vocation. People are really trying to do as much work for as little money as they can, and you see some heroic stuff. But what that means is that, you know, you need to do the engineering, you need to do the applied science just enough to have reasonable confidence in what's going on and really know more. I'm not certain that I ever. I take that back. I saw one project that actually had a sediment transport model as part of it. As far as sediment goes, most projects end with like an incipient motion type of analysis. And, you know, keep in mind you're talking about the signal and the noise when you are filling a channel and cutting a new one over there. It's a big signal.

Stanford [00:50:12]:
That's right.

Chris [00:50:12]:
You know, so you can pretty easily demonstrate big changes. That environment just moves fast. It tends to not work in high risk zones. That tends to preferentially work in least lower human risk and infrastructure risk zones. Into that end. It does appropriately.

Stanford [00:50:34]:
Less rigor. Well, yeah, there's less risk than that. Scales.

Chris [00:50:38]:
Right. And depends a lot on skilled practitioners applying intuition and honestly, everyone in the chain, funders, reviewers having knowledge and faith as well.

Stanford [00:50:50]:
Yeah. Okay. So then the good, what are some components that some of the best or most successful projects had in common? In particular, morphologically, like, what are some of the things that you, you saw it and it made you feel like, oh, this is going to go well.

Chris [00:51:05]:
I ended up with favorite watersheds. Now this is weird.

Stanford [00:51:09]:
Favorite watersheds.

Chris [00:51:10]:
Yeah. What I really, one of the things I really.

Stanford [00:51:13]:
You're not, I understand you're not a huge sports fan, but you cheer for watersheds.

Chris [00:51:16]:
Yeah, I cheer for watersheds. And one of the things I really learned and the way I described it as some rivers are really responsive, what that mean to me was that the processes in the river that actually create geomorphic change, meaning you have enough water, you have enough sediment mobility, you have enough in our region, enough large wood, because it is a major component of the morphological regime, it has enough of all of that that you get rapid results and you can go in and do a project and if you get a decent water year, you can go back the next year and you actually have a significant change. Now those are so. They're my favorite.

Stanford [00:51:56]:
Yeah, right, right.

Chris [00:51:57]:
They're responsive. Like you can push them and they push back and they respond. And that's, you know, some watersheds are just, the really, really challenging ones have really, you know, short growing seasons. They are very delicate. The soils are delicate, the hydrology is delicate. And I guess that's the intuition I was chasing when I went there. And it's a lot of what I gained. You know, you see enough of that, you can look at a watershed and say, oh, that's, that's a fun one.

Stanford [00:52:23]:
It's funny. We were just playing with your dogs on the way in here. And it strikes me as you're describing some water, what some watersheds are dogs and some are cats.

Chris [00:52:30]:
Right.

Stanford [00:52:31]:
Like some will respond to you and others will just kind of decoy.

Chris [00:52:34]:
Yeah, absolutely. And I guess you need to recognize that. So what it gets into is my favorite types of projects, aside from my favorite types of rivers that are just easy fun and talk back to you is one of the big things you hear talked about in the restoration community right now is process based design. And I think that's a term. It's a phrase that is still really being defined. You have one, one definition is that you're removing the anthropogenic aspects of the river. So think about like removing a levee or removing roadway or removing a culvert and allowing process to happen. You know, as a sediment guy and an morphologist, I look at it more along the lines of the macro processes of the river that you're giving it the space and the tools it needs to manifest its processes. And so, you know, you can look at process based as opposed to like a form based restoration technique. I'm going to build the river in the form I want and it will yield the gains I'm looking for. Or you can say I'm going to give the tools it needs and I'm going to let the river manifest its processes and create that complex, you know, that complex habitat that this complex species with a very complex lifecycle utilizes. And so my favorite projects were the ones that were deeply invested in process based that worked, that had that, you know, that mindset and worked to, you know, get the lands available, thought about it, and all of the drivers on process accurately or reasonably accurately foresaw the potential of the restoration reach. And the reality is it happened on so many scales. You know, some of the smallest projects are, people are familiar with beaver analogs or some of the small, low tech process based wood structures. It's all hand placed wood. You don't bring machinery and you build little, you know, this is all pretty small headwater type of stuff. But if you have really good vision and you're working in the right river, you can do amazing things with hand placing wood.

Stanford [00:54:49]:
Wow.

Chris [00:54:52]:
You know, two mile long highway setback. I'm carving a new river, but I'm carving anastomosing channel. I'm planting and creating, you know, big jams and putting a bunch of wood can happen at that scale, too. Yeah, but my favorite projects were process space, but, you know, I'm a sediment guy, so.

Stanford [00:55:07]:
Yeah, so one of those. So the distinction you're making is between kind of a form based model where you are kind of drawing the river on a map and what it's going to look like now and process, which seems a little fuzzier to me, but you're talking about empowering the river with the resources it needs. One of those sounds a lot scarier than the other.

Chris [00:55:30]:
Yeah, well, yeah, and it absolutely can be. But I mean, you can apply it at scales too. Processes can be, can be large scale or small scale. But my favorite was when people were thinking in those terms and designing projects around those terms, even if it's a single appropriately placed log jam that interacts with its floodplain and some relic floodplain channel. And yeah, you've got a process in mind when you did it.

Stanford [00:56:02]:
So I want to end with a question been asking on several of these because one of the objectives of these podcasts is kind of welcome new practitioners into the field.

Chris [00:56:15]:
Sure.

Stanford [00:56:16]:
And so I want you to imagine that you're starting over, that you're early twenties and you just kind of got your first job in sediment transport morphology and you don't know anything. But you now in your current state, have the chance to tell that 20 year old a couple of things that you've learned that will serve them well for the whole career. What are a couple of things that you would tell your past self that you've learned that you think would set that person up for success?

Chris [00:56:52]:
Well, the first thing that comes to mind is no job is too small to care about to be good. I think to be good at Rivers, you need a really, really wide skill set and you need to talk about a lot of disciplines. And you don't just start being the expert in something, you do it incrementally. And so I would say be ultimately curious about everything and anything you're given as an opportunity to grow your skillset and grow your knowledge and build as big a one as you can, because you'll work your whole career and you'll never see the end of what rivers can be. So there's one, I think number two is probably the other part of, is technologies are going to change over time and you need to be adaptive to that. You need to be open to that. And I do look back at where modeling's come and the reality is that the fundamental equations really haven't changed. It's how we, I mean, and I'm not certain, 20 years ago I would have said, you know, there's not going to be massive advances in the equations. The massive advances came in, you know, in the way of computing power.

Stanford [00:58:08]:
That's right.

Chris [00:58:09]:
And you needed to be open, you know, you need to be open to that to change however it comes, and embrace it as it comes.

Stanford [00:58:18]:
I will. Chris Nygaard, thanks for, thanks for being on the podcast.

Chris [00:58:21]:
Thanks, Stanford. Super fun having the chat.

Stanford [00:58:26]:
While it was great to hear about the experiences and insight that Chris got from his Bonneville power years. It sure is good to have him back with the core, and I appreciate Chris, who has been careful to minimize his online profile. To make an exception for this conversation. Take the time to talk with us. This would be a great week to check out the podcast website. Or the HSC sediment YouTube channel. Which are both linked in the upper description. We're posting video shorts from these episodes there. And this week we're running some pretty remarkable footage. Of the sediment deposits downstream of St. Helens. With Chris's description of those processes. We also have a link to a Google forum at the top of that website. Where you can leave recommendations for podcast guests. Or let us know what your favorite classic sediment papers or river process papers are. We're working on a classic paper series. And want to know what you think those top papers are. Next episode we're going to unpack the abbreviation in the title of this podcast. RSM. We're talking to doctor Katie Boucher. Who led the corps regional sediment management program for several years. We're going to talk about the regional sediment management principles. That the Corps of Engineers is leading into. And I think RSM is just a good sediment management paradigm. Which is applicable to most sediment and river mechanics projects. And Katie is also directly responsible for this podcast. Because she got behind our vision for this about 18 months. And was at the helm of the RSM R and D program. When they decided to fund this series. These are informal conversations and the views expressed do not necessarily reflect the positions of the US Army Corps of engineers, their partners, or the offices or centers of the guest or host. Mike Loretto mixed the episode. And wrote the music for the season. Thanks for listening.