It’s all for the salmon: Dalton Lake’s New Bridge

Dalton Lake bridge restoration st. helens oregon columbia county northwest

Every year, tens of millions of juvenile salmon rush down the Columbia River. It’s a race for survival, and the race depends on two factors: How fast they can get to the ocean, and how much food they can find on the way.

A significant issue for these salmon is that there isn’t enough food to be had. Young salmon find little to eat in the deep open waters of the Columbia. They instead must locate shallow wetlands bordering the river, where they hunt for insects, crustaceans, and tadpoles. Unfortunately, such wetlands have become tough to find ever since we dredged, diked, or filled 80% of tidal wetlands in the lower Columbia. And that’s where Dalton Lake comes in.

An aerial map of the region shows the problems our salmon face. There’s hardly a natural riverside marsh in the five miles between Sauvie Island and Deer Island. And both of those islands have seen their habitat degraded and wetlands filled as well. Development and agriculture now dominate the shorelines, so where can young salmon go?

It’s been a long time since Dalton Lake has been much of an option either. The lake used to be a “tidal backflow”, daily swapping water with the Columbia River. Thus, it provided excellent habitat for juvenile salmon swimming downstream. But the process of dredging and dams reduced the degree to which water levels varied, and thus flow between the river and wetlands decreased. In 1996, ODOT built an artificial berm and 109.5-foot concrete culvert that destroyed much of Harrie Creek, reduced tidal flows to the lake, and cut off fish access entirely.

The Bonneville Power Administration, responsible for mitigating their own substantial impact on the salmon runs, recently realized that Dalton Lake could help sustain those juveniles on their way downstream. So, BPA sponsored a project by the Columbia River Estuary Study Taskforce (CREST) to improve the salmon habitat in the wetlands.

“CREST, located in Astoria, OR, is a community organization specializing in environmental planning and habitat restoration for fish and wildlife.  CREST offers expertise in habitat restoration project design, funding, management, implementation and monitoring with the goal of improving and enhancing the natural resources that are essential to the vitality and resilience of the neighboring communities along the Columbia River Estuary.”

According to project manager Tracy Hruska of CREST, the heavy equipment work to restore the feeding grounds became possible last summer. CREST’s team temporarily isolated the area via nets and cofferdams to reduce the impact on aquatic life, with Tracy there to rescue fish and frogs that made their way into the construction site. In August and September, they removed the culvert, breached the berm and widened the creek. Over it all they installed a new bridge to facilitate continued pedestrian access to the east side of the lake.

After this earth-moving, CREST planted thousands of native plants to support the restoration. Wetland species like wapato were fixed into the water, riparian trees and bushes bolstered the banks, and upland denizens, including common camas and Pacific madrone, were rooted into the mounds of excavated dirt.

That work is complete, and if you visit Dalton Lake you’ll see it’s beautiful. Harrie Creek is now about 250-300 feet long, and its more natural route is a substantial improvement over the previous artificial berm. The impressive 65’ boxcar bridge is tastefully incorporated and fun for kids to go over. Any aquatic insects, amphipods, copepods, tadpoles, salamander larvae, and small fish that populate the creek will become potential salmon food, as will insects and isopods that wash into it from the lake or nearby shores.

A related effort completed at the same time was the removal of ~0.2 acres of reed canary grass that was impinging on Dalton Lake. CREST took out the root mass and carved out a deeper footprint for that end of the wetland, favoring native plant growth.

Now, we’ve spoken on how the creek has become juvenile salmon habitat, but what about the far more substantial lake? When you walk the new restoration zone, an interesting complication you’ll notice is the beaver dam forming a boundary between the lake and the creek.

I asked Tracy about this and he provided insight into the dynamic. I want to quote his response at length:

The beaver dams were included in the design as existing features we wanted to protect. Before beaver were virtually extirpated from the Pacific Northwest by the beaver trade, beaver dams existed on essentially every stream and river in the region, except those too big to dam or too small to produce good beaver habitat. Beaver are a natural part of the system, and salmon lived and thrived in a world of abundant beaver dams. The dams generally benefit the wetland ecology of Dalton Lake [i.e., – by ensuring the water is deep enough to suppress the growth of invasive reed canarygrass] and so we did not want to remove them or scare off the beaver.

While the beaver dams do affect fish passage into Dalton Lake itself during most flows, there are times of the year when it is passable. Fish can still move in and out of the lake during the freshet, and the site will continue to evolve over time, as it should. The outlet channel will provide habitat for juvenile salmon all the time.

Tracy Hruska, Project Manager for CREST

What comes next? CREST will continue to monitor the work for five years, conducting additional native plantings where needed. Patrick Birkle of the Friends of Dalton Lake Nature Preserve states that their next plan is to improve and extend the trails, including “a boardwalk on the south end and an entrance from Belton Road, create portions of trail for handicapped access, blinds for bird watching etc.” FDLNP also holds regular work parties where volunteers can remove invasive plants from the lake shore and plant natives in their place.

I’m excited about the potential this effort has to provide a slight boost to salmon survival rates as they strive to reach the ocean. God willing, there will be more such projects up and down our portion of the Columbia, restoring wetland access a little at a time to create sufficient “rest stops” where the salmon can replenish their reserves on the way. They need all the help they can get.

(Many thanks to Tracy Hruska and Patrick Birkle for being patient with my substantial questions about the project. Everything that’s correct in this post was a result of the information they provided. Thanks also to Matt D’Agrosa, Luke Green, and Patrick Birkle for their pictures of the site.)

Dalton Lake Nature Preserve at a glance

What: walking, biking, wildlife viewing, birdwatching

Trip Reports: Nostalgia at Dalton Lake
Updates at Dalton Lake

Where: In St. Helens, turn east off Highway 30 onto Deer Island Road, then left onto Oregon Street. The trailhead is next to the Columbia Humane Society parking lot at 2084 Oregon St, St Helens (45.873484, -122.812915). Look for the paved trail parallel to the railroad tracks, do not turn into the mobile home lot.

There is also a parking spot or two at the opposite end of the trail on 4th Street in Columbia City.

Dalton Lake Nature Park directions map St. Helens Oregon columbia county
Map of the Dalton Lake Nature Preserve, with paved path in thick red and smaller trails in narrower red. (Google Maps directions to the Humane Society parking lot can be found at this link)

Hiking: About 1.5 miles of trail with a main asphalt bike path, a gravel road halfway around the lake, and a narrow dirt trail in the forest.

Camping: None

Notable Wildlife: Beaver, nutria, muskrat, otter, herons, waterfowl, woodpeckers, warblers, garter snakes, salamanders, treefrogs

Property status: Oregon Department of Transportation

Website: Friends of Dalton Lake Nature Preserve

Published by mattyd112


2 thoughts on “It’s all for the salmon: Dalton Lake’s New Bridge

  1. As always I love your articles.

    I question whether Harrie Creek or Dalton Lake have ever provided Salmon with a feeding ground.  This is just based on my personal experience with the lake.  As a kid, we used to go down and hunt fish that would get trapped behind the Beaver dams.  I spent my whole childhood on the banks of Harrie Creek and never once in my life did I ever see any fish except for Carp which we would shoot with bow and arrow.

    The creek itself is not natural but looks like it was initially dug by the Samill in the early 1900’s in order to draw water for the mill from the lake which is fed by streams coming off of the hillside.  I say this based off of the ariel photos I got from the Corp of Engineers from 1929 and 1939 where you can plainly see the trench from the lake to where the mill was. (see attachment).

    Historically in my time the lake would practically dry up in the summer and in the spring was just a mosquito breeding ground.  The county routinely flew crop dusters over the lake and sprayed the mosquitos.  Now that they have deepened the creek I fear the lake will dry up completely in the summer changing the ecology of the current ecosystem.  But what do I know. 

    I do hope they are correct and this will help the young salmon.

    Keep up the great work.

    Best Regards


    Mark W Stevens Volunteer Columbia County Oregon Historical Society and Museum President 7th Fighter Command WWII Historian 20th Air Force Association WWII 1505 3rd St Columbia City, OR 97018 Mobile: (503) 397-2291 or (206) 853-1197

    Liked by 1 person

    1. That’s great insight Mark. I drew a line at 1996 which was probably not warranted because as you note, the situation changed at multiple points in the decades before then. This all would be much better answered by someone from CREST or one of the other groups that study the Columbia, I’m just an amateur when it comes to fish and rivers. But I have some guesses.

      I think back before our time when the Columbia’s flow varied a lot more, it definitely would have been juvenile salmon habitat. It’s just too close to the Columbia with too little elevation difference to not have regular interchange back and forth whether or not the creek was there, especially during the spring when much of Sauvie Island, Deer Island, and parts of the Scappoose Bottoms used to flood over as well. Remember the salmon don’t need to live in the lake, they just need access as they move downstream, even if the access only lasts a few days. It would be interesting to know what that land between the lake and the river looked like back in the 1800s – whether or not Harrie Creek was there, the water would have created some sort of path as it overflowed in heavy rain, then that path would be carved out more when the Columbia itself rose from flooding or tides.

      Once the dredging and dams reduced the variation in flow during the 1890s-1940s, the situation would have changed, and the amount of interchange probably would have reduced. An interesting factor though is that by 1900, beaver were almost gone from Oregon. They’ve been steadily recovering since then, but it seems likely there was a period in the early 1900s or longer where beaver might not have been around to dam the lake, and thus access would have been easier even after floods were managed. I’d be interested to know when beaver returned to Dalton.

      At some point, beaver dams returned AND the Columbia wouldn’t have been varying as much. This would have reduced lake access. But as Tracy points out above, juvenile salmon still would have been able to access the outflow creek in this period as well as the lake itself during especially high waters, at least until 1996. They might not have spent much time there (such that you didn’t see them), and it might have usually been during high spring flows, but it would have at least been available.

      I grew up in St. Helens in the 1980s and 1990s and tried to fish the lake a couple times, though I’m pretty sure we didn’t catch anything. My father and I even waded across trying to do what we could and I dropped head high at one point. I wish I could better remember what the layout was like back then before the water control pipe went in, but I wasn’t quite observant enough as a kid.

      In terms of your question about the lake drying up, I got the impression that the beaver dam wasn’t touched. If that’s true then the outlet height shouldn’t have changed at all and the lake won’t drain any easier than before. Even though the berm past the dam was taken out, the land directly below the dam is still the same height. Also, the fact that they took out all that reed canarygrass and deepened the lake in that area means it has at least a little more water to store. But if the lake did briefly dry out occasionally, I don’t actually know whether that would be a good thing or a bad thing. At least for the amphibians, it might be a good thing because the main casualties would be the non-native bullfrogs that eat everything else – the native frogs and salamanders would be likely to have metamorphized already. But I don’t know enough about the rest of the ecology to predict other effects.

      Liked by 1 person

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