Judge allows Detroit Lake drawdown this fall as Salem and Marion County appeal (Nov. 8)
Quick Read
U.S. District Judge Mustafa T. Kasubhai on Nov. 4 denied requests from Marion County, the City of Salem, the City of Stayton and the Santiam Water Control District to block this fall's Detroit Reservoir drawdown.
The judge did not rule on the merits of the lawsuits, finding only that the local governments had not clearly shown the drawdown is likely to cause irreparable harm to drinking water or refill.
The Army Corps of Engineers says it will lower the reservoir to 1,425 feet starting in late November, a level reached in 2015 and 2019, and step down in later years toward 1,395 feet.
Marion County and Salem say they are appealing to the Ninth Circuit, and the Corps plans virtual public information sessions on Nov. 18.
SALEM, Ore. - The U.S. Army Corps of Engineers can go ahead with lowering Detroit Lake this fall to help young salmon get past Detroit Dam, after a federal judge ruled Nov. 4 that Salem, Marion County and other local water users had not shown the drawdown is likely to cause irreparable harm to the North Santiam River drinking water supply.
U.S. District Judge Mustafa T. Kasubhai denied the motions for a preliminary injunction in a 20-page opinion and order. He left the door open for the local governments to ask again during this year's drawdown or before next year's, if new facts and data specific to Detroit support it. Marion County and the City of Salem both said they would appeal.
Willamette News covered the Oct. 6 hearing in Eugene and said we would report the ruling when it was issued. This is that follow-up.
What the judge decided, and what he did not
The case combines lawsuits filed by Marion County and the City of Salem against the Corps and Army officials. The City of Stayton and the Santiam Water Control District joined on the plaintiffs' side. The Northwest Environmental Defense Center and the Native Fish Society joined on the Corps' side.
Kasubhai did not decide whether the Corps broke the law, and the lawsuits continue. Under the U.S. Supreme Court's Winter standard for preliminary injunctions, he assumed without deciding that the plaintiffs could win on the merits, that the balance of hardships favored them and that an injunction would serve the public interest. He denied the motions on one ground: the plaintiffs had not made a "clear showing" that irreparable harm is likely without a court order.
The judge wrote that losing drinking water would "undoubtedly" be irreparable harm for hundreds of thousands of residents, hospitals, schools and businesses. "The problem for Plaintiffs' motions, however, is that Plaintiffs fail to show that the proposed drawdown is likely to cause that harm," he wrote.
He also rejected Salem's argument at the hearing that the size of the possible harm should lower the bar for showing how likely it is. "While that idea has an inherent and appealing logic to it, it is not the law," Kasubhai wrote, noting that the Supreme Court rejected that kind of sliding scale in Winter.
Why Green Peter was not enough
The local governments relied on two kinds of evidence: tests showing what sustained muddy water, or turbidity, would do to slow sand filters like the ones at Salem's Geren Island plant, and what happened at Green Peter Reservoir in 2023. That drawdown sharply increased turbidity on the South Santiam River, disrupted water treatment plants in Lebanon and Sweet Home and killed thousands of kokanee, according to the order.
Kasubhai wrote that the plaintiffs failed to "connect the dots" with scientific evidence showing Detroit would produce similar turbidity, or any specific level of turbidity for any specific length of time. He pointed to three differences in the record: the Detroit drawdown would expose much less sediment, would go to a level the reservoir has reached twice before and would happen later in the year. Each of those factors suggests less turbidity than Green Peter, he wrote, but the record does not show what level to expect at Detroit or for how long. "In other words, there is no site-specific analysis or data that shows turbidity will reach damaging levels for any particular length of time," he wrote.
On whether the lake will refill, Marion County and the Santiam Water Control District pointed to a predicted very strong El Niño, which tends to bring a drier fall and winter. The judge wrote that "more likely than usual" does not show how likely it is at all. Marion County's motion said rain fails to refill Detroit enough "one in four years," but cited no evidence for it, the judge wrote. He said he was unsure a Corps graph the county pointed to at the hearing shows that, and that even a 25% chance would not amount to likelihood.
The judge also cited the Corps' Deep Drawdown Emergency Response Communications Plan as an added reason to deny the motions. Under the plan, a city with drinking water concerns contacts the Oregon Health Authority, which considers whether to ask for a halt, and the Corps will not halt the drawdown "unless requested by the Oregon Governor's Office or unless a drinking water emergency has been determined." The order notes the plan sets no timeframe for how long a pause would take, but said the plaintiffs did not show why the plan is inadequate.
"But 'possibility' is not 'likelihood,'" Kasubhai wrote, adding that the court shares the plaintiffs' concerns about high turbidity and inadequate refill.
What the Corps plans this fall
In a Nov. 5 release, the Corps' Portland District said it plans to start the drawdown in late November and lower Detroit Reservoir to an elevation of 1,425 feet. Reaching that level may take up to two weeks, and the Corps will then hold it for two weeks unless a storm requires refilling sooner. Historically, the Corps lowered the reservoir to 1,450 feet each fall to make room for flood storage.
This year is the first step of a multi-year "step down." The 2024 Biological Opinion from NOAA Fisheries calls for an eventual fall elevation of 1,395 feet, and the Corps plans to go lower each autumn until it reaches that level, using turbidity data from each year to decide how far, according to the Corps and the court order. Earlier coverage of the case, including Willamette News' Oct. 7 story, described this fall's plan as going to 1,395 feet. The court order and the Corps' Nov. 5 release say this year's target is 1,425 feet, with 1,395 feet reached over several years.
The Corps says Detroit reached 1,425 feet in 2015 for low flow augmentation and in 2019 for spillway gate maintenance, with no adverse turbidity reported downstream. "Drinking water is not expected to be impacted," the release says. Marion County describes it differently, saying in its Nov. 4 release that the new policy would drain the lake below its minimum conservation pool "to its lowest historic level in the first year" and deeper in later years.
The Corps also said the drawdown has not started. The lake's current lower than average level is due to seasonal drought and is still within a normal range, according to the release.
The purpose is fish passage. Juvenile salmon are surface-oriented and are unlikely to find the dam's regulating outlets unless the reservoir is drawn down within 20 to 25 feet of the outlet opening, according to a 2021 ruling quoted in Kasubhai's order. The Corps says the drawdown is meant to help young salmon and steelhead in the Santiam basin, including Upper Willamette River Chinook protected under the Endangered Species Act.
Salem and Marion County appeal
"We are extremely disappointed in today's decision, but this fight is far from over," Marion County Commission Chair Colm Willis said in the county's release, written by communications officer Jon Heynen. "The Army Corps is endangering our drinking water, our farmers, our fish, and our canyon communities. We are immediately appealing to the Ninth Circuit and asking for an emergency injunction during the appeal."
The county said the underlying lawsuit continues and that it also wants to stop an even deeper drawdown planned for fall 2027. Its release puts the number of people whose clean water supply is threatened at over 220,000 in one passage and over 230,000 in another. The county also emphasized that the Corps has not finished a turbidity report Congress required after Green Peter. The court order says that report was due Jan. 4, 2026, that the Corps has not submitted it and has no estimated completion date, and that the Corps says completion depends on funding.
Willis told OPB on Nov. 5 that downstream water systems are not prepared for extreme turbidity. "It's just not true to say that we didn't prove that similar damage was likely to happen in this case," he told OPB.
The City of Salem said in a Nov. 5 statement, distributed through the city's FlashAlert news account, that the drawdown will go forward as planned after the injunction was denied. "We have reviewed the Court's order and will be appealing the decision," Public Works Director Brian Martin said. "We remain concerned about the impact of drawdowns on our drinking water supply and our ability to meet long-term community needs for clean and safe drinking water."
Salem filed its lawsuit July 8 and in August asked the court to block this year's drawdown or to halt it if sediment kept the city from filtering water at the Geren Island Water Treatment Facility, according to the city. The city says it supplies about 220,000 residents plus hospitals, schools, businesses and firefighting needs, with a service area that includes Turner, two water districts and parts of unincorporated Marion and Polk counties. The court order adds that Salem is the sole emergency drinking water source for Stayton and Keizer. Salem declared an emergency in July 2025 to speed up backup water projects. Updates are posted at cityofsalem.net/drawdown.
The federal court docket in the case, as indexed by the docket-tracking site Docket Nexus, lists notices of appeal of the preliminary injunction ruling filed Nov. 5 and Nov. 6, appeals court case numbers issued on those dates, and a motion to expedite filed Nov. 6. Willamette News could not view those filings or confirm which party filed each, and did not find a public Ninth Circuit ruling on any emergency request as of Sunday morning.
Fish groups welcome the ruling
The two conservation groups that sided with the Corps praised the decision, Courthouse News Service reported. "Upper Willamette spring Chinook are at high risk of extinction, and young salmon have waited nearly twenty years for a safer way past Detroit Dam," said Jennifer Fairbrother, legislative and policy director of the Native Fish Society. "We take the concerns about drinking water seriously, and so did the court."
Jonah Sanford, executive director of the Northwest Environmental Defense Center, told Courthouse News the group was pleased and that "there is every reason to believe that this year's drawdown will not significantly impact municipal water supplies and other downstream interests."
What comes next
The Corps says it will hold virtual public information sessions on Nov. 18 to explain when the drawdown will start, how long it will last and how the Corps will work with state agencies and drinking water providers if problems arise. As of its Nov. 5 release, the Corps said specific meeting times would be published within the week. Willamette News did not find posted times as of Sunday morning.
Real-time reservoir levels are posted on the Corps' water management pages, and the City of Salem posts drawdown updates at cityofsalem.net/drawdown. The city has not asked residents to stockpile water.
Willamette News Local Desk. Edited by Channing Webb.
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