Army Corps begins to fill reservoir at Howard Hanson Dam

Water managers for the U.S. Army Corps of Engineers have begun slowly filling the reservoir at Howard Hanson Dam at the headwaters of the Green River.

As is typical operations, the Seattle District of the Corps slowly begins in early March allowing water levels to rise within Howard Hanson Dam's reservoir for the annual spring fill of the reservoir, according to a March 2 Corps media release.

During the roughly three-month refill period, the Corps will conduct testing and in-depth investigations of the dam's current effectiveness. The current plan targets a maximum pool elevation of 1,167 feet, unless engineers, geologists, and other scientific experts on the ground see anything troubling, in which case the reservoir level can be reduced as appropriate.

Additionally, throughout the reservoir fill, the Corps will constantly monitor the operations of the facility including special observations and tests to measure the effects of the pool on the right abutment.

The Corps continues to work to repair the dam after a January 2009 storm damaged the right abutment next to the dam that limited the capacity of the dam's reservoir. The Corps expects to complete repairs by the end of 2012.

Water stored during the spring refill of the reservoir will be used to provide water supply to the City of Tacoma and its water supply partners, including the city of Kent.

At least three-fifths of the reservoir's supply will be used to augment downstream flows to help endangered species of fish, including Chinook and steelhead. Project managers believe that the regulated downstream flows will aid spawning and other life-cycle events for the fish.

The Corps operates the Howard Hanson Dam project, which provides flood damage reduction to the Green River valley, low-flow augmentation to the Green River for environmental benefits, and water supply to the City of Tacoma and its water supply partners.

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