Two weeks. That is how long the U.S. Army Corps of Engineers now plans to keep Detroit Lake at a low elevation near the end of 2026, cutting down the time Salem expected to lean on backup water supplies. The shorter low-water window reduces, but does not eliminate, the risk that sediment churned up by the drawdown will overwhelm the Geren Island water treatment plant. The operation is still expected to drop the reservoir about 55 feet from its typical fall level to help threatened salmon and steelhead move downstream.
Corps confirms a shorter low-water window
The timing update came in a recent staff briefing and was confirmed by the Corps on March 3, which said the reservoir would sit at the targeted low elevation for a two-week period to allow fish to pass. As reported by Salem Reporter, Greg Taylor, the Corps' supervisory fisheries biologist, said the drawdown would amount to roughly a 55-foot reduction in lake level. The change shortens how long Salem will have to depend on emergency supplies if turbidity spikes downstream.
Why federal biologists ordered the drawdown
Federal fisheries managers issued a biological opinion in December 2024 requiring a deeper fall drawdown at Detroit Reservoir to improve juvenile salmon and steelhead passage, and the Corps is preparing a supplemental environmental impact statement to study the consequences. As outlined by the U.S. Army Corps, the SEIS will evaluate the deeper drawdown along with other actions required by the BiOp.
How Salem is bolstering its supplies
Salem uses roughly 25 million gallons of water per day and has been fast-tracking resiliency projects, including new groundwater wells, accelerated maintenance of slow sand filters, an aquifer storage system in south Salem and a second emergency connection to Keizer. The City of Salem says tests show Keizer’s system can deliver more than 8 million gallons per day. At a Feb. 23 council briefing, Public Works Director Brian Martin told Salem Reporter that wells at Geren Island currently produce about 1.5 million gallons per day and he hopes to boost that toward 2.5 million.
Filters, costs and the worst-case
Engineers warn that prolonged high turbidity can quickly clog Salem’s slow sand filters and force them offline, potentially requiring expensive re-sanding or replacement. Reporting by OPB notes that modeling and tests suggest filters could be overwhelmed in weeks and that refurbishing them could run into the millions per filter.
What happens next
The Corps says it will use the SEIS process, consultation with NOAA Fisheries and weather-driven inflows to set an exact schedule, and does not expect the deep drawdown until fall 2026 at the earliest. As the Portland District has explained, public comment and continued coordination with local utilities will shape mitigation steps ahead of any action.
