Judge allows Detroit Lake drawdown despite drinking water concerns for 220,000 Oregonians

A federal judge has refused to block the U.S. Army Corps of Engineers from lowering Detroit Lake this autumn, despite concerns that the operation could affect drinking water for about 220,000 people in the Salem area, dailytidings.com reported.

Marion County filed a lawsuit seeking to halt the drawdown until a turbidity report required by federal law was completed and public comment was allowed. The judge denied the preliminary injunction request, stating plaintiffs did not provide enough evidence that turbidity would cause irreparable harm during the operation.

The judge left open the possibility of renewed injunction requests if new, site-specific evidence emerges during the 2026 drawdown or before the planned 2027 operation. Marion County announced plans to appeal the decision to the Ninth Circuit Court of Appeals and may seek an emergency injunction during the appeal process.

The Army Corps of Engineers said lowering the reservoir will improve downstream passage for ESA-listed juvenile Chinook salmon, which are at risk when passing through the dam's turbines. Salem’s Geren Island water plant relies on low-turbidity water, and high sediment levels could shorten the lifespan of its slow-sand filters, a concern cited by local officials.