Judge to rule by month's end on Detroit Lake drawdown that Salem says threatens its drinking water
A federal judge says he will decide by the end of October whether the U.S. Army Corps of Engineers can begin draining Detroit Lake to historic lows this fall, a plan that Salem and Marion County leaders say could muddy the North Santiam River that supplies the capital city's drinking water.
U.S. District Judge Mustafa T. Kasubhai heard arguments Tuesday, Oct. 6, in Eugene. Marion County, the City of Salem, the City of Stayton and the Santiam Water Control District want a preliminary injunction to stop the drawdown while their larger lawsuit plays out. Kasubhai also told the Corps to notify the court if it plans to start a drawdown before Nov. 15, Courthouse News Service reported.
"The biggest question for me is about likelihood of harm," Kasubhai said during the hearing, according to Courthouse News.
What the Corps wants to do
The plan, finalized by the Corps earlier this year, calls for lowering Detroit Reservoir to an elevation of 1,395 feet in late fall and early winter, well below its minimum conservation pool of 1,450 feet. The drawdown would start in mid-November, lower the lake gradually over two weeks and hold it there for two more, according to Courthouse News. OPB reported that the reservoir would refill each spring and go even lower in later years.
The goal is to help young spring Chinook salmon and steelhead, both protected under the Endangered Species Act, get past Detroit Dam. Juvenile fish usually stay within 25 to 50 feet of the surface, so when the reservoir is full they struggle to reach the low outlets that offer safe passage and can be killed in the dam's turbines instead.
Lawyers for the Corps argued that the Endangered Species Act requires the agency to act and that the sediment would not overwhelm local water filters, OPB reported. They said that if the plan ultimately cannot go forward, the Santiam River's yearling Chinook and steelhead would probably go extinct. The Native Fish Society and the Northwest Environmental Defense Center joined the case on the Corps' side. "This is a critical, critical element for saving Chinook and steelhead populations," said their attorney, Lauren Rule.
Why Salem is worried
Salem's drinking water comes solely from the North Santiam, Courthouse News noted. The city treats it on Geren Island, 27 miles downstream of Detroit Dam, using slow sand filtration, a method that only keeps running when the incoming water is very clear. City officials have warned that heavy sediment could force the plant to stop drawing river water, possibly for several weeks. The city says its system serves about 220,000 people, and OPB put the number of Marion County residents whose drinking water is at stake at 230,000.
In court, Salem asked the judge to block the drawdown outright. Failing that, it wants the Corps required to halt the drawdown whenever river turbidity reaches 10 nephelometric turbidity units (NTU) and to wait until it drops back below that level before resuming. By the city's description, water at 10 NTU or less generally looks clear.
The local plaintiffs pointed to nearby Green Peter Lake, where a court-ordered deep drawdown in 2023 killed thousands of salmon and sharply increased turbidity downstream, according to Marion County. They also argued that a strong El Niño winter could leave Detroit Lake slow to refill. "If Detroit Reservoir does not refill its minimum conservation pool as of Feb. 1 there could certainly be irreparable harm with respect to fulfilling water supply obligations," said Samantha Sondag, an attorney for the Santiam Water Control District.
"We made our case today, and we made it clearly: the Army Corps is moving forward with a catastrophic plan without safeguards for the people who depend on this water," Marion County Commission Chair Colm Willis said in a statement after the hearing.
How Salem has prepared
Salem declared an emergency in July 2025 to speed up backup projects. According to a February update to the City Council, crews drilled four new wells at Geren Island (early production was lower than hoped), added a pump station to draw more than 8 million gallons a day from Keizer's well-fed system, and filled the South Salem aquifer storage system to about 900 million gallons. The city expects those sources to cover average winter demand of about 25 million gallons a day, but cautions there is little redundancy if one piece fails.
What it means at home
The city has not asked residents to stockpile water. Separately, Oregon's Department of Emergency Management already advises every household to be "2 Weeks Ready." For water, that means about one gallon per person per day, or 14 gallons each. A refillable container like the Scepter Flow Control 5-gallon water jug, or a bathtub storage liner such as the waterBOB to fill if an outage is announced, are simple ways to get there.
Updates on the drawdown and the city's water supply are posted on the City of Salem's drinking water page. Willamette News will report Judge Kasubhai's ruling when it is issued.
Related gear: Reliance Aqua-Tainer 7-Gallon Water Container · Midland ER310 Emergency Crank Weather Radio
Sources: Battle over drinking water, fish protections and Detroit Lake reaches federal court, OPB (Oct. 6, 2026) · Oregon communities fight plan to drain reservoir, Courthouse News Service (Oct. 6, 2026) · Marion County Makes Its Case in Federal Court to Stop Detroit Lake Drawdown, Marion County (Oct. 6, 2026) · Update on the Pending Deep Drawdown of Detroit Reservoir, City of Salem staff report to City Council (Feb. 23, 2026) · City of Salem Prepares to Protect Water Supply During Detroit Reservoir Drawdowns, City of Salem (Feb. 25, 2026) · Be 2 Weeks Ready, Oregon Department of Emergency Management
Photo credits: Cover: Detroit Dam and Detroit Lake, by Gary Halvorson, Oregon State Archives, CC BY 4.0, via Wikimedia Commons. Inside: Low water in Detroit Lake, 2001, by Robert Ashworth, CC BY 2.0, via Wikimedia Commons.
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