Howard A. Hanson Dam

Howard A. Hanson Dam
Howard A. Hanson Dam (rear)
Location	King County, Washington, USA
Construction began	1959
Opening date	1961
Operator(s)	U.S. Army Corps of Engineers
Dam and spillways
Impounds	Green River
Height	235 ft (72 m)
Length	675 ft (206 m)
Width (crest)	23 ft (7 m)
Width (base)	960 ft (292 m)
Spillway type	Service, controlled
Spillway capacity	107,000 cubic feet per second (3,000 m3/s)
Reservoir
Creates	Howard A. Hanson Reservoir/Pool
Total capacity	106,000 acre⋅ft (131,000,000 m3)
Catchment area	220 square miles (570 km2)

Howard A. Hanson Dam is an earthen embankment dam on the Green River, 21 miles (34 km) east of Auburn, Washington. The dam was completed in 1961 and its primary purpose is flood control along with water supply for Tacoma, Washington.

After the dam's reservoir reached record levels in January 2009, the U.S. Army Corps of Engineers discovered seepage in the right abutment of the dam, leading to efforts to mitigate a potential flood.^[1] Improved drainage works were completed in October 2011 and although studies are still underway, the dam was declared safe to maintain its maximum reservoir level.