Detroit Lake to be dropped to extreme low water level in controversial plan to save salmon

The U.S. Army Corps of Engineers is planning to drop Detroit Lake to the lowest water level in its history next fall, in a plan aimed at saving endangered salmon that could also impact fishing, reservoir access and drinking water in the Santiam Canyon and Salem.

The reservoir east of Salem would be drawn down to 1,395 feet above sea level, about 55 feet below its normal low-water pool and 30 feet lower than it has ever been taken, to allow baby salmon to migrate through the reservoir and reach the ocean. Then, it would be refilled before the summer tourism season.

Detroit Lake would become the fifth reservoir in the Upper Willamette Basin to undergo what’s known as a “drawdown” — turning a reservoir into a river for a temporary period each year. It’s part of a wider strategy to keep dams in place for flood control while reopening habitat blocked for decades to endangered salmon and steelhead teetering on the brink of extinction.

But drawdowns have brought significant problems in other locations, and could impact the area from Detroit to Salem in the following ways:

• Muddy water flowing from the reservoir, down the North Santiam River and into the drinking water systems of cities that pull from the river, including Salem.

• A decline or loss of the popular kokanee fishery at Detroit Lake, in addition to reduced numbers of rainbow trout, which could harm tourism.

• Several months of lost reservoir access in late fall or winter.

• Detroit Lake would return to its regular summer water level under normal conditions, but would be increasingly susceptible to drought.

News of drawdown brings concern in Detroit

Dean O’Donnell, a longtime business owner and now city councilor in Detroit, said news of the drawdown was a concern for a city still rebuilding from the 2020 Labor Day wildfires that burned much of the town.

“It’s just one more hurdle to overcome — one that we really don’t need up here,” he said. “I’d say everybody is frustrated that fish always come first and this is just another example of that.

“But what other choice do we have? I guess we’ll just have to make it work.”

Erik Petersen, Willamette Valley operations project manager for the U.S. Army Corps of Engineers, said he wants to work “early and often” with city officials, wildlife officials and anglers to reduce impacts as much as possible.

“We want to be as transparent as possible,” he said. “I do understand why people would feel like it’s just adding insult to injury.”

There is a slight chance the Detroit Lake drawdown could be delayed by recently signed federal legislation regarding hydropower, Petersen said. But currently, the Corps are preparing to implement the drawdown this fall.

Why is a reservoir drawdown planned for Detroit Lake?

The drawdown at Detroit was mandated by what’s known as a biological opinion published on Dec. 26. Authored by the National Marine Fisheries Service, the document outlines actions the federal government, in this case the Corps, must take to stay in compliance with the federal Endangered Species Act.

Basically, it means improving conditions for wild spring chinook and winter steelhead, two species protected since the 1990s that have seen their numbers drop so low biologists say they could go extinct as soon as 2040.

The biological opinion requires the Corps to improve habitat, river flows and hatchery operations. But the hardest part is fish passage — allowing salmon and steelhead to spawn in habitat above the dams and their offspring to migrate back down to the ocean.

Because Willamette Basin dams are too tall for traditional fish ladders, and building fish collection devices is time-consuming and expensive, “deep drawdowns” have emerged as the best option. Local tribes and environmental groups have advocated for drawdowns as the best shot at saving the iconic fish.

“The (biological opinion) shows that dams are driving salmon to extinction in the Willamette Valley,” said Kathleen George, tribal councilwoman for the Confederated Tribes of the Grand Ronde. “It does not have to be this way. The region deserves a future with vibrant salmon runs, where dams control floods when needed but the rivers flow more freely. We commend NOAA Fisheries for requiring the Corps to make sensible improvements in the way the dams are operated to help protect salmon.”

When will Detroit Lake be drawn down and for how long?

The drawdown would begin with Detroit Lake dropping to its normal low water mark in the fall of 1,450 feet. Then, the Corps would continue dropping it, past the lowest water levels ever recorded (1,425 feet) and all the way to 1,395 feet.

Petersen said he’s planning the drawdown to be a “bounce back,” in that once it reached 1,395 feet, it would fill back up to 1,450 feet and begin its normal rise in the spring toward “full pool” of 1,558.5 feet for summer.

Drawdowns have brought major problems to other Willamette Valley towns

Deep drawdowns are currently taking place at Cougar, Fall Creek, Lookout Point and Green Peter reservoirs in the Upper Willamette Basin. Detroit would be the fifth.

They’ve brought major problems at some locations.

At Green Peter, muddy water flushed downstream by exposed reservoir beds has wreaked havoc on city drinking water systems in Sweet Home and Lebanon the last two years. The two cities sued the Corps for $38 million for damages to their water systems. This past year, after a water filter in Sweet Home failed, the drawdown of Green Peter was ended early.

“It’s created serious public mistrust in government,” Lebanon City Manager Ron Whitlatch told the Statesman Journal earlier this year about the drawdowns. “Our water meets regulations, but does have taste issues, coloration issues, and that really raises alarms for residents when our water has always been pristine. It’s been a big disruption and I’d love to see it stop for good.”

The drawdowns also led to a mass die-off of kokanee salmon. Over a million of the stocked fish were flushed out of Green Peter during its first drawdown and later likely died. The drawdown has all but ended what was once among the state’s most popular fisheries — harming tourism in nearby Sweet Home.

Will muddy water be a problem for the Santiam Canyon and Salem?

The amount of sediment pumped out by the Detroit Lake drawdown, into the North Santiam River, isn’t expected to be as dramatic as other locations.

“We know there’s going to be some turbidity, we’re just not expecting it to be as bad as other locations,” said Greg Taylor, a fish biologist and spokesman for the Corps. “It’s been different for each dam so we just don’t know.”

This year, the Corps have developed an emergency response system for all the cities below drawdowns. If the cities are having issues with the high turbidity, they could communicate it to the Corps and state of Oregon, which makes a decision about whether to stop the drawdown, as it ultimately did at Green Peter.

Is Salem prepared for muddy water?

Cody Marrs, the Water Treatment Plant supervisor for the City of Salem, said the city does have a pre-treatment system in place capable of handling muddy water before it enters the sand filters.

“We can definitely handle higher turbidity for a short duration, it’s just the length that might get questionable,” he said. “But we have a lot of resources that we can draw on.”

Marrs noted the city has had success filtering cyanotoxins out of the North Santiam River water and delivering it safely to Salem residents from its Geren Island treatment facility.

How would rebuilding salmon runs actually work?

The point of the drawdowns is to allow salmon and steelhead to colonize superior habitat in the upper North Santiam River to help rebuild its population.

The hope is that it works something like this:

When the fish return from the ocean, they are collected at Minto Fish Facility. Then they’re put into special trucks, driven above Big Cliff and Detroit dams, and released into the upper North Santiam.

After spawning upstream, juvenile salmon begin the process of migrating back to the ocean. In the past, they’d get stuck in Detroit Lake and often wouldn’t make it through dam openings to reach the ocean.

That’s where the drawdown comes into play. By dropping the reservoir level, it increases the probability the baby salmon will move with the current and migrate through a large opening in the dam — the regulating outlet — that is safer than passing through the dam’s turbines.

“Data collected during past operations indicates that the surface elevation needs to be within 50 feet or less from the outlet for better passage downstream,” Taylor said.

The fish would swim through Detroit Dam and into Big Cliff Reservoir, which is shallow enough that fish can navigate out through its spillway gates, Taylor said.

At that point, the baby salmon could continue to the ocean, feed and return years later and repeat the cycle. The same process would be taking place at other tributaries of the Upper Willamette, with the hope of forming a growing population that helps numbers rebound.

Last year, less than 5,000 wild spring chinook returned to the Upper Willamette Basin and an average of just 3,082 winter steelhead have been recorded the last five years (although their 2024 numbers were a much-improved 9,000) fish. Both are a tiny fraction of their historic numbers.

For supporters, the upside is clear: the return of salmon, a culturally critical fish to tribes and an iconic fish for anglers, to the Willamette Valley, all while dams stay in place to protect cities from floods.

“The Grand Ronde people have lived with salmon since time immemorial,” George said. “Native salmon — icons of the Pacific Northwest — are a part of our identity, culture and heritage.

“It’s time to take action for salmon.”

What about having enough water for Salem?

The City of Salem needs a minimum of 750 cubic feet per second in the North Santiam River to have enough water for the city.

The Corps said it was confident it would be sending out enough water — a minimum of 1,000 cfs. However, if a significant drought developed, that could lead to a shortage of water that would require the Corps to drop the reservoir even lower than planned to ensure Salem had the water it needed.

That, in turn, could lead to higher turbidity and a greater struggle to refill Detroit Lake by the summer.

“It’s unlikely given typical conditions, but there have been some extremely dry Januarys, so it’s something we’re really working to plan for,” Taylor said.

Will the drawdown impact Detroit Lake’s summer water level?

The Corps said they’re optimistic about being able to reach the “full” reservoir level at Detroit Lake by summer tourism season “unless severe drought conditions are experienced.”

Because the drawdown would take place in late fall or early winter, it would have the entire rainy season to catch up after the drawdown.

However, there have been dry winters and springs recently, and the lake has struggled to reach full pool multiple times. The drawdown could certainly make that process harder.

Drawdown likely have a negative impact on popular kokanee fishery at Detroit Lake

While the drawdowns are meant to help one type of salmon (spring chinook), it’s been the opposite for a different species.

The drawdown at Green Peter led to a mass die-off of kokanee salmon. Over a million of the mini sockeye salmon, which are stocked in some reservoirs and have become very popular for anglers, were flushed downstream and died immediately or later. The die-off has essentially eliminated Green Peter as a place to fish for the good-tasting, fun-to-catch fish.

Taylor said it’s possible the same thing could happen at Detroit Lake.

“We do expect a significant number of kokanee to be passed out of the reservoir,” Taylor said. “The whole goal of the drawdown is to pass juvenile chinook out of the reservoir and kokanee behave a lot like chinook in terms of migrating out under those circumstances.”

A loss of kokanee fishing would have a big impact on Detroit’s tourism economy, said Brad Halleck, treasurer of the group Kokanee Power of Oregon and an avid Detroit Lake angler.

The group hosts a kokanee fishing derby every spring, bringing in anglers who buy groceries, gas and food.

“That’s a huge blow,” Halleck said. “It’ll destroy the economy of Detroit. Our group has spent a ton of money working to make that lake what it is today (in terms of kokanee fishing), and now they’re going to drain it? I do not understand it.”

Petersen said that of all the impacts from the Detroit drawdown, he was most worried about the loss of kokanee fishing.

“Kokanee are a really important resource at Detroit, so we want to talk with the (Oregon Department of Fish and Wildlife) to see what we could do to salvage or mitigate some of the impacts,” Petersen said. “We want to think through what could be done differently here compared to Green Peter so the public gets a better benefit of these fish.”

What about rainbow trout at Detroit Lake?

The other main species at Detroit Lake is rainbow trout. Some of them could also likely get flushed out, Taylor said, which is likely to impact the amount of “holdover” trout. However, lots of rainbow trout would be stocked at Detroit Lake after the drawdown, which should still keep fishing in place.

Lack of winter reservoir access at Detroit Lake

Once the drawdown takes place, it will eventually draft the water level well below the low-water boat ramp at Mongold Day Use Area at Detroit Lake for an extended period — possibly months. That will make the reservoir inaccessible to boats during the lowest parts of the drawdown, short of hauling a smaller boat down to the lake.

“It’s a great lake to fish in the winter,” Hallock said. “So we’re also losing access to the lake.”

Have the drawdowns improved salmon numbers so far?

The big question, which can’t really be answered at this point, is whether the drawdowns will work in the long-run.

Wild salmon advocates have pointed to Fall Creek, where the truck-and-drawdown method has helped establish a wild salmon population that ranges from 100 to 800 fish each year in the relatively small stream. Once larger streams get established, the hope is their population can take off as well.

However, at Green Peter and Lookout Point, fish biologists say the results haven’t been there yet.

The number of juvenile fish that migrated through those dams in the first year was described as “disappointing,” and the same is true at Cougar Dam, Taylor said. He did stress it will take years to see whether the process is working.

Jennifer Fairbrother, with the Native Fish Society, questioned the accuracy of the Corps numbers earlier this year and said there were lots of salmon spawning upstream of the dams “and reproducing successfully,” she said.

The Corps are required to conduct studies of fish passage at the reservoirs to see whether the method is working.

The rise of relic hunting at Detroit Lake

When the water level gets extremely low at Detroit Lake as it has in the past, relics from the buried town of “Old Detroit,” which was covered in the reservoir’s floodwaters, start to emerge.

That includes the famous “ghost wagon” and could include other relicts. There are, however, two problems with that. One, the mud is extremely dangerous and anyone wondering out into the freshly undercovered reservoir bottom can be swallowed like quicksand. And two, relics of “Old Detroit” are protected by federal law — something that’s been a problem when Detroit Lake drops to low water at other times.

“We’ve had a lot of looting over the years in Detroit Reservoir. People come in and take pieces of Old Detroit,” U.S. Forest Service archaeologist Cara Kelly told the Statesman Journal in 2020. “They think it’s OK. But under federal law it’s illegal to dig, damage, excavate or remove anything from an archeological site like this one (the ghost wagon).”

Is there any way the drawdown doesn’t happen at Detroit Lake?

Drawdowns have become so controversial that some have wondered whether it’s possible for the Corps to ignore the biological opinion and not implement the drawdowns at Detroit or anywhere else.

While the arrival of a new administration could change things, in the past, the Corps were sued by environmental groups after failing to implement parts of an earlier biological opinion. In 2021, a federal judge ruled the Corps were in violation of the federal ESA and ordered them to conduct the drawdowns at Green Peter and Lookout Point.

So for now, the Corps say they’re preparing to stay in compliance with the biological opinion and prepare for the Detroit drawdown.

Zach Urness has been an outdoors reporter in Oregon for 16 years and is host of the Explore Oregon Podcast. He can be reached at zurness@StatesmanJournal.com or (503) 399-6801. Find him on X at @ZachsORoutdoors.

This article originally appeared on Salem Statesman Journal: Detroit Lake to be dropped to extreme low level in plan to save salmon