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A timeline of the Howard A. Hanson Dam
1850s - Settllers begin moving into the Green River Valley, setting up farms on the fertile flood plain. Begin working around the Green River’s capacity for flooding each winter.
1906 - An especially bad flood kills two men on horseback in the Green River Valley.
1926 - The Associated Improvement Club of South King County is formed, with one of its top projects being flood control in the Green River Valley. Turns to the federal government to seek help.
1936 - U.S. Army Corps of Engineers begins studying the problem.
1941 - Army corps recommends building a flood-control dam several miles upstream from Auburn. The concept isn’t popular due to concerns over disruptions to fish runs. Studies are shelved with the onset of World War II.
1946 - Army corps resumes study of the flood problem.
1949 - Army corps recommends construction of a flood-control dam at the Eagle Gorge, a narrow part of the Green River in the foothills of the Cascades.
1950 - Congress adopts the Eagle Gorge Dam as a federal project. Planning continues for the sructure.
1957 - State legislator and Seattle attorney, Howard A. Hanson, a longtime advocate for the dam, passes away.
1958 - Congress approves naming the structure - formerly known as the Eagle Gorge Dam - to the Howard Hanson Dam.
1959 - Groundbreaking for the Howard Hanson Dam begins with a dynamite explosion.
1961 - Nearly completed dam stops its first flood on Christmas Day.
1962 - Dam construction is completed; formal dedication takes place.
1960s onward - Unhampered by the winter flooding, developmment grows in the Green River Valley, fueling the local economy and transitioning the valley from an agrarian interest to a hotbed of industry. Boeing builds large complex in the valley in the 1960s.
1968 - Issues with continuing seepage from the earthenware abutment spurs the Army corps to install drainage tunnel to carry off excess water. Seepage continues.
2002 - Eagle Gorge Reservoir becomes a municipal water source for the City of Tacoma. Army Corps installs a grout curtain onto the abutment to reduce seepage.
2009 - Severe storm in January causes the reservoir to reach a record height. Army corps discovers depressions in the abutment following the storm and subsequent release of water from the reservoir.
Summmer 2009 - Army Corps begins temporary fix of a grout curtain to reduce continued seepage from the damaged abutment.
November 2009 - Corps completes installation of grout curtain, which lessens likelihood of flooding . Cautions that flooding still more possible, until a permanent, multi-billion-dollar fix is implemented in the future.