Army Corps of Engineers Halts Green Peter Drawdown Ahead of Schedule

The U.S. Army Corps of Engineers (USACE), Portland District, halted the court-ordered drawdown of Green Peter Reservoir, November 22, after receiving requests from three cities downstream on the South Santiam River.

The cities of Lebanon, Sweet Home and Albany sent letters November 20, 21 and 22, respectively, to USACE and the Oregon Health Authority (OHA), which administers and enforces drinking water quality standards for public water systems. The cities requested the drawdown stop at Green Peter Dam due to risks posed to their water treatment facilities.

While higher turbidity (sediment suspended in water) levels were anticipated, multiple days of heavy rainfall contributed to the increased turbidity.

USACE made the determination to stop the drawdown operation after closely coordinating with the state of Oregon. Outflows were reduced to the minimum permissible rate of 50 cubic feet per second.

The swift decision to halt the drawdown was made possible due to a plan developed with input from the cities and state. The plan outlines the chain of communications and notification and response procedures during drawdown operations.

“When the cities alerted us to the risk their water facilities were facing, we were able to set the plan we developed with them in motion,” said Col. Dale Caswell, the commander of the Portland District. “We developed this plan because we knew the response time was critical and thank the cities and state for responding as quickly as they did so we could make an informed decision.”

The Green Peter drawdown ended thirteen days after reaching the target elevation of 780 feet.

USACE expects  turbidity in the South Santiam River to diminish over several weeks with Green Peter Reservoir refilling to typical winter elevations by mid-January.

USACE is operating Green Peter, Cougar, Fall Creek and Lookout Point dams under the interim injunction measures outlined by the court and in their draft Programmatic Environmental Impact Statement (EIS) proposes continuing with deep reservoir drawdowns to improve downstream fish passage. USACE will continue working closely with the state of Oregon and the downstream cities to ensure these complex and important communications are flowing freely.