Marion County, OR. — Marion County has formally called on the U.S. Army Corps of Engineers to strengthen its environmental analysis related to the proposed deep drawdown of Detroit Lake, citing unresolved concerns over turbidity, drinking water safety, and community impacts.
In a letter dated January 6, 2026, the county noted that a turbidity report required by federal law has not yet been completed, despite Congress directing the Army Corps to publish the report by January 4, 2026. County officials argued that the absence of this report prevents meaningful public review of the Draft Supplemental Environmental Impact Statement (SEIS).
Because the turbidity analysis is expected to directly inform the environmental consequences of a deep drawdown—including lessons learned from recent drawdowns at nearby reservoirs—the county urged the Army Corps to extend the public comment period until the required study is released.
“The Army Corps must complete and publish the turbidity report required by federal law,” the January 6 letter stated. It further argued that the Corps’ draft analysis “does not include sufficient evaluation of how turbidity from a deep drawdown at Detroit Lake will harm numerous aspects of the environment.”
The letter follows an earlier communication sent December 16, 2025, in which the Marion County Board of Commissioners raised substantial concerns about the SEIS for the Willamette Valley System. In that letter, commissioners highlighted the risk of severe sediment and turbidity impacts to downstream drinking water systems serving more than 200,000 residents.
County officials also noted a lack of scientific evidence demonstrating that a deep drawdown at Detroit Lake would deliver its intended biological benefits, warning instead of potential harm to ecosystems, drinking water infrastructure, and surrounding communities.
“Our residents depend on clean, reliable drinking water,” said Kevin Cameron. “The Army Corps should complete the required analysis before taking on any risks that could harm our community’s drinking water.”
“We’re simply asking the Corps to follow the law, finish the required work, and give residents a fair chance to review it.”
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