How culverts create problems for migratory fish in Oregon and Washington

Culverts are all around us and you may not even know it. Culverts are pipes and tunnels, often under roadways and railroads, that allow water to pass through them. While water easily passes through them, the same can’t be said for some migratory fish like salmon. Ben Goldfarb is an environmental journalist who reported on the efforts being made to fix culverts for Hakai Magazine. He joins us to share more on the impacts the infrastructure can have and what it takes to replace them.

This transcript was created by a computer and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. If you piece together all of the conversations we’ve had on this show about the impact that dams have had on salmon, it could easily add up to 30 or 40 or 50 hours of radio. But I’m pretty sure that we have never talked about culverts: those often-hidden pipes beneath roads and bridges and railroad tracks, despite the fact that they, too, can impede the progress of salmon and other fish. Well, culverts are finally getting some serious federal attention. About a year and a half ago, the U.S. Department of Transportation announced it was going to make $1 billion in funding available to remove, replace or restore culverts, with an eye toward protecting critical fish populations. And a lot of that money is going to be spent in the Pacific Northwest. The freelance environmental journalist Ben Goldfarb wrote about this recently for Hakai Magazine, and he joins us now. Welcome to the show.

Ben Goldfarb: Thanks a lot for having me.

Miller: I gave the short version just now. But what are examples of culverts?

Goldfarb: Culverts are any piece of infrastructure that funnels water under a road or a railroad or another piece of infrastructure. Often you see them as these corrugated metal pipes, sometimes they’re concrete box-shaped culverts. They’re basically any water conveyance structure that’s funneling a creek or a wetland or a river underneath a road or a railroad - not a bridge though.

Miller: What are the various ways that culverts can cause problems for fish?

Goldfarb: Typically, lots of culverts have been built too small. They’re too narrow to convey the entire stream or river. And so they concentrate the flow, like pinching a garden hose, and they create this torrent that basically blasts away any fish that’s trying to swim upriver.

Then what happens over time, is the force of all of that concentrated water scours out a deep pool that disconnects the downstream side of the culvert from the upstream side, so fish would have to jump to get into the pipe. And those two effects – the force of the water, and then the disconnection of the pipe from the downstream end – prevent incoming salmon from migrating up to their spawning grounds.

Miller: Oh, you can think of it almost like a small waterfall that creates its own pool beneath where the water exits the pipe?

Goldfarb: Exactly. Yeah, exactly.

Miller: How many culverts are there in the U.S., and can you even answer that question?

Goldfarb: Yeah, it really is unknowable, certainly there are millions. I’ve seen estimates of around 2 million, but that’s a completely ballpark figure. Lots of transportation departments don’t really keep track of these things. Lots of them were built many, many decades ago, some have been covered up by parking lots and subdivisions and other infrastructure. So there are huge numbers of culverts out there. And, as you say, of course, we talk a lot about dams as this barrier to fish passage and dams are these giant incredibly visible structures, and culverts are comparatively invisible, of course, they’re much smaller. But it’s kind of a ‘death by a thousand cuts’ situation or death by a million cuts.

Miller:  Who owns these culverts? Who’s responsible for managing them?

Goldfarb: Well, it really depends on who the road manager is. Obviously, lots of roads are managed by counties, lots are managed by states, many are managed by the federal government, by the Department of Transportation. So, management of the culverts really falls to the road manager.

In some cases, it’s private landowners who manage the culverts under roads. And that creates another big challenge too, is that there are so many different stakeholders out there. So you can have a situation where a fish-bearing stream is being blocked by a number of different landowners, and land managers and road managers. And that makes it hard to deal with.

Miller: What are some of the ways that culverts can be fixed?

Goldfarb: The biggest one is just replacing them. Historically, certainly transportation departments and fish biologists tried to retrofit them by putting in little baffles and other structures that slow the water down and make it a little bit easier for fish to move up. But really, the best thing we can do is just get rid of those old culverts. A lot of them aren’t just too small, they’re also maintenance issues. They get plugged up by logs and rocks and debris and silt. In many, many cases we’re better off just pulling out those old culverts and putting in bigger, wider ones that allow streams to flow uninhibited and let those fish move upriver.

Miller: What about cases [where], as you mentioned earlier, the force of the water over time has, in a sense, disconnected the culvert from the rest of the water flow. If the water has created, in effect, a pool beneath the pipe, what can engineers do?

Goldfarb:  In some cases, that definitely calls for some stream restoration, where you’re actually adding material to the streambed to build that streambed back up and reconnect the downstream side of the road with the upstream side, so that fish are moving seamlessly. But you’re definitely right that just taking a culvert out and saying, ‘OK we did our job,’ doesn’t always cut it. And in some cases, you really have to rebuild that stream bed to create a seamless water course again.

Miller: So let’s turn to this $1 billion in federal funding for culvert work that was tied to the bipartisan infrastructure bill from a couple of years ago. Can you put this in perspective? Has there been anything like this in terms of a federal infusion of cash before?

Goldfarb: No, this is certainly the largest pot of money that’s ever been allocated to culvert restoration and replacement, and that’s really exciting on one hand. On the other hand, it’s sort of a drop in the bucket, in some cases. We know, again, that there are many, many, many thousands of fish-blocking culverts out there – not just on the Pacific Coast, but all over the country, something like a quarter million in the Great Lake states alone.

So, certainly this funding is welcome. It’s helping a lot of Northwestern counties and transportation departments deal with some culverts. But we know that we need a lot more. Fixing culverts in the state of Washington alone is costing the state many billions of dollars. So there’s more funding being allocated to the issue of culverts, and a recognition that these structures are really serious problems for fish passage, but we certainly have a long way to go.

Miller: The Washington example is really striking. I’m glad you brought it up. The Seattle Times had an article just a few weeks ago, pointing out that the price tag for the state’s Department of Transportation to fix culverts to ease salmon passage, that that could be close to $8 billion. And then, according to the paper’s analysis, for every barrier that Washington DOT [Department of Transportation] fixes, there are maybe 11 other barriers that are partially or fully blocking fish migration – and that’s just one state. So, it gives some sense for the scale right now. But let’s turn back to this $1 billion, since it is a real chunk of money. What is going to be done with that money, on the Cowlitz Reservation?

Goldfarb: That’s a really good example of an important project that this infrastructure funding is helping with. The situation there is that there’s actually a culvert under a railroad that’s cutting off a stream called Hardy Creek, a tributary of the Columbia River. And it’s preventing chum salmon, steelhead, chinook, really that whole suite of anadromous fish. And that’s one of those classic perched culverts we were talking about before, the waterfall-like culverts where there’s just this sheet of water that fish really have a hard time swimming against.

So there, they’re going to tear that culvert out beneath the railroad and put in a larger kind of open-span bridge essentially, that lets the stream be a stream. I think that’s the ultimate goal of these projects, to let water flow naturally, and where water can flow naturally, fish can also migrate naturally. I think that’s an exciting project because it demonstrates the power of Native tribes to deal with this issue.

You mentioned all of the money that’s being spent on culvert remediation in Washington. Well, that whole culvert replacement program was really compelled by a lawsuit brought by a coalition of Native tribes a couple of decades ago. So these culverts are really environmental justice issues in a sense. They’re blocking the movement of fish that, in many cases, are integral and fundamental to Native subsistence and culture.

Miller: What did you hear from leaders or fish managers at the Cowlitz Tribe about the work that’s being done now? And what did they tell you?

Goldfarb: Well, I think they told me this was incredibly exciting and unexpected in a way. I talked to Pete Barber, who is one of their habitat restoration experts, and he had identified this particular culvert as a problem 20 years ago, doing fish surveys, and assumed that it was never going to be dealt with. And then suddenly this pot of federal money arrived, and Pete and the railroad put in an application and were able to get this project funded.

So, I think that there are, again, lots and lots of culverts out there that are causing similar issues that this pot of funding is addressing. But again, it’s the tip of the iceberg in some ways.

Miller: What kinds of projects in Oregon are going to be funded through this federal money?

Goldfarb: There are a bunch of them along coastal rivers, and I think that one of the exciting things in places like Tillamook County is that this salmon recovery money can really address a rural infrastructure need, in some cases. All of these derelict old culverts out there, and a lot of them are big transportation issues.

If you have an undersized and battered corrugated pipe under a road and it gets plugged up with logs and debris and silt, well, the road washes out, and suddenly you have this major impact to rural transportation. That’s one of the exciting things about culvert replacement, I think, that it’s one of those issues that really aligns the interests of not only fish biologists and environmentalists, but also Native tribes and dairy farmers and loggers and other people who are using those rural roads. It’s really a non-partisan, non-controversial issue in a hyperpolarized world.

Miller: That gets to one of the points you make near the end of your article, that culvert replacement or renovation could actually be seen as tied to climate resiliency. What’s the connection?

Goldfarb: We know that as the climate changes, weather is becoming more unpredictable and more intense, our infrastructure is vulnerable. In the Northwest, we see these enormous downpours that plug up culverts in some cases. On the Eastern seaboard, in places like Virginia, which is doing culvert replacement, sea level is rising, and roads are increasingly being washed out. Having larger culverts there that can carry more water can prevent some of that coastal flooding.

So, we know that climate change is rendering our infrastructure more vulnerable, and culverts are a serious Achilles heel in that infrastructure, so replacing them and putting in bigger, better ones is a climate adaptation strategy as well as a fish conservation strategy.

Miller: Ben, thanks very much.

Goldfarb: Thanks for having me.

Miller: Ben Goldfarb wrote about the efforts to remove or replace culverts to protect critical fish populations. He wrote about this for Hakai Magazine. He is the author of the book “Crossings: How Road Ecology is Shaping the Future of Our Planet.”

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