by Jacob Espinoza

The U.S. Army Corps of Engineers plans to drop Detroit Lake far below its normal winter water level starting as soon as Nov. 1. The drawdown would eventually be deeper than the dam has ever gone, to help endangered salmon and steelhead pass downstream, which the Corps says a federal biological opinion requires it to do.

Marion County says the plan could muddy the drinking water for more than 230,000 people, kill many of the lake's fish, and gut the canyon's economy. They say the Corps hasn't proven the benefit to fish is worth the risk.

On Monday, Aug. 10, the county asked a federal judge to hit pause.

I sat down with County Commissioner Kevin Cameron earlier today and walked through what's actually happening and why the county is fighting it. Here's what he said you need to know.

Detroit Lake sits at 1,450 feet elevation in a normal winter. That lower winter level, compared to spring or summer, is deliberate and useful because it leaves room to catch storm runoff and prevent flooding downstream.

This fall, the Corps wants to draw the reservoir down another 25 feet, then hold it there for about two weeks before letting it refill. In future years it would go deeper still, as low as 1,395 feet. "It's never been that low in the history of the dam," Cameron said. The county's court filing says this would repeat annually, getting more aggressive over a timeframe that could stretch 30 years.

The goal is fish passage. The idea is that lowering the reservoir opens up an outlet that lets salmon move past the dam in the fall.

(Sourcing: the drawdown depths and timeline are from Marion County's Aug. 10 court motion; Cameron's comments are from an interview with WHS earlier today. The Corps' explanations below are drawn from its own July press release and its public statements to other outlets, including Salem Reporter, KLCC, and the Statesman Journal.)

Before getting into the county's case, it's worth laying out the Corps' side, because this isn't a situation where the agency is acting on a whim.

The Corps says the drawdown is required, not optional from its point of view. A December 2024 biological opinion from NOAA Fisheries, the federal agency responsible for endangered species in the water, found that the Corps needs to do deeper drawdowns to help threatened spring Chinook salmon and winter steelhead survive their trip past Detroit Dam. As the Corps' program manager Kathryn Tackley put it, spring Chinook are surface-oriented, so lowering the reservoir closer to the dam's outlets improves their ability to get out of the reservoir and downstream. The Corps frames these drawdowns as the "new normal" until it can build permanent fish-passage structures that would make them unnecessary.

In finalizing the plan, the Corps' Portland District public affairs chief, Alan Davis, called it a "data-driven decision" that "effectively modernizes dam operations and fulfills USACE's environmental responsibilities." The Corps describes the Detroit drawdown in its own materials as "actively managed to protect downstream water quality and ensure a reliable summer refill.”

Which is exactly the point the county disputes.

Salem, Stayton, and the smaller towns below the dam don't pull their drinking water from wells. They pull it from the North Santiam River, which flows straight out of Detroit Lake. So whatever the Corps does to the lake ends up in the pipes downstream. That's the whole reason a fish-passage decision has turned into a drinking-water fight.

There are two problems, and they compound each other.

The first is mud. When you drop a reservoir this fast and this far, you disturb decades of fine sediment sitting on the lake bottom. That creates turbidity (dirty water) that flows downstream.

We've already watched this happen once. In 2023, a court-ordered deep drawdown at nearby Green Peter Lake sent a wall of sediment down the South Santiam. Cameron described what the Corps' own people told the county about it: "there's 60, 70 years of silt built up in that reservoir bed that gets head cut by the water and moved through the system." Sweet Home's water treatment plant, in his words, had "the wheels coming off." The cities of Sweet Home and Lebanon have since sued the Corps together over that drawdown, seeking a combined $37 million for damage to their water treatment systems, which they say the Corps caused by failing to control sediment.

Here's why Salem should pay closer attention than most: the city's water system uses slow sand filtration, which is especially vulnerable to turbidity. Cameron put it plainly: "Once that turbidity hits those filters, it's too late. They can't pull back because the mud's already coming down." The court filing quotes a Corps manager admitting Salem and Stayton's sand systems are "way more sensitive to turbidity" than the systems that got hammered at Green Peter, and that once one starts failing it's "too late" to reverse without expensive, monthslong damage.

If you've lived in Salem a while, you already know what a water crisis here feels like. The 2018 toxic algae bloom had the city warning residents not to drink the tap water, and, as Cameron recalled, "You couldn't find bottled water on anybody's shelf, right? People were going outside our community to get water supply." That's the scenario the county is worried about repeating — except a turbidity event during a drawdown could force a full shutoff.

Small towns are even more exposed. Stayton, just under 4,000 people, runs a low-cost system that the county says simply cannot handle high turbidity, with no funds or time to upgrade before fall. A shutoff there also hits the North Santiam School District (which relies on Stayton's water and says it couldn't operate or serve meals safely without it) and Santiam Hospital.

The Corps has heard these fears and says its plan is built to avoid exactly this. Its supervisory fisheries biologist, Greg Taylor, argues the drawdown is deliberately incremental for that reason. Starting with a 25-foot drop rather than going straight to the deepest level should generate, in his words, "a little bit of turbidity, but not enough to impact the drinking water systems," and reaching the deepest levels could take several years of watching what happens along the way. He's also noted the Corps has taken Detroit down to 1,425 feet before for maintenance "without any real significant impact to turbidity," which he says is why the agency is confident about this first phase.

The Corps also draws a hard line between Detroit and Green Peter. Taylor has said the 2023 Green Peter drawdown was locked in by a strict court order that left no flexibility on timing, while at Detroit the Corps says it can slow down or even halt the drawdown if problems show up. Corps officials have told people during public forums that Green Peter exposed more than four times as much sediment as Detroit's drawdown is expected to.

Deep drawdowns only work if the rain shows up to refill the lake. If it doesn't, Detroit stays dangerously low.

Cameron laid out the mechanics: after the drawdown, the lake is at its lowest point right when Salem needs the river running high enough to pull its water. According to the city's own comments to the Corps, Salem's drinking-water intake needs 750 cubic feet per second to operate. For a sense of how tight that already is, on Aug. 9 the North Santiam and Little North Santiam were together providing just 413 cubic feet per second, well below the intake threshold, before any drawdown. "If we have a dry December, dry January, they may not have enough water to even send down to meet the minimum flows," Cameron said. The Corps' own analysis says the combination of a deep drawdown and low rain that could cause shortages happens about one year in four.

And the forecast this year points the wrong way. The county's motion cites NOAA's Climate Prediction Center giving an 81% chance of a very strong El Niño this fall. That's potentially among the strongest on record since 1950, and El Niño winters in Oregon tend to run warmer and drier. That's an elevated risk of a dry refill season, not a certainty, but it's exactly the condition the county is worried about walking into.

The county also points to history: in 2015, when Detroit couldn't refill normally, "tourism heavily declined, docks had to move out, and during the annual free fishing weekend in June, there wasn't even enough water to allow for fishing."

The county isn't arguing that salmon don't matter. Its argument is that the Corps hasn't shown this actually works, and may be jeopardizing the very fish it's trying to save.

Two things stand out from the interview and the filing. First, the county argues existing measures already handle most fall fish passage. It points to a Corps biologist's statement, quoted in the motion, that when the reservoir hits a certain level, the Corps shuts the turbines at night and opens an outlet, and "like 90% of the fish pass at night." The county's read is that the deep drawdown is therefore aimed at only the remaining 10% of fall fish, at a large cost to the water supply. The Corps sees it differently: it says the deeper drawdown is what makes the lower outlets accessible to juvenile fish in the first place and is required by the biological opinion, not a marginal add-on. Which interpretation is right is part of what the lawsuit is asking the court to sort out.

Second, the drawdown itself kills fish. At Green Peter, the 2023 drawdown flushed out and killed thousands of kokanee salmon and badly muddied the water. That much isn't disputed. Detroit has one of the best remaining kokanee fisheries in the state, and Cameron says the Corps has acknowledged there's no way to stop the kokanee from being swept downstream. 

The county goes further, arguing in its filing that state data since 2023 shows the wild, endangered salmon the drawdown was meant to help have declined as a share of fish returning to the South Santiam, its point being that the strategy hasn't demonstrably worked. The Corps' position, backed by NOAA Fisheries, is that these drawdowns are the best available tool for getting juvenile fish safely past the dams until permanent passage structures exist, and that short-term losses like the kokanee are the cost of a longer-term recovery for the threatened species the law requires it to protect.

Cameron's bottom line: "It'd be one thing if we had the science to back up that this was actually helping fish and not harming drinking systems. The data is showing the opposite."

There's also a wrinkle about who decided this. Cameron says that on a call with federal fisheries staff, he asked who made the drawdown call, and was told it traced to a small number of NMFS staff in Oregon and Washington who wrote it into a 2024 report, reversing the Corps' earlier position that it wouldn't pursue this option. Notably, this drawdown is not itself under a court order the way Green Peter was; the county argues the Corps isn't required to do it.

The county sued in May. This week's motion is a request for a preliminary injunction, a court order pausing the drawdown while the case is heard, because the Corps has kept moving toward a November start without a court date set.

The county frames it as a narrow ask. The 2024 federal biological opinion made 55 recommendations, and the county says it wants 54 of them to proceed. It's only trying to pause the one calling for annual deep drawdowns. Legally, the motion argues the Corps broke multiple federal laws, the clearest being a turbidity study that Congress required it to finish by Jan. 4, 2026. As of the August filing, that report is more than seven months overdue, and, according to the county suit, the public never got to weigh in on it before the comment period closed.

Cameron also stressed the coalition. The cities of Stayton, Sublimity, Mill City, Idanha, and Detroit, plus the Woodburn and Silverton areas, have sent letters or signed onto coalition letters. And the county's full federal delegation, U.S. Sens. Ron Wyden and Jeff Merkley, and U.S. Reps. Janelle Bynum and Andrea Salinas, wrote to the Corps asking it to delay until downstream water systems are ready.

"It's a regional issue," Cameron said. "This isn't just a Marion County issue."

The City of Salem has filed its own lawsuit against the Corps. But it hasn't joined this injunction. When I asked whether it planned to, the city said, "We have no announcement at this time."

The county has asked for an expedited hearing, ideally by early October, ahead of the Nov. 1 drawdown window. Now it waits on the judge. Other jurisdictions may join the injunction or the underlying lawsuit.

Cameron isn't taking the outcome for granted. When I asked how likely the county is to win the pause, he said, “I think that our case is strong but it depends on the judge.”

The Corps, for its part, generally hasn't commented publicly on the lawsuit, which Cameron attributes partly to litigation caution. We'll update as the case moves.

The full 46-page motion is posted by the county here. The introduction is a readable summary if you want to go deeper.