On August 25, 1939, the U.S. Army Corps of Engineers awarded Guy F. Atkinson Co. of South San Francisco, Calif., the contract to build Mud Mountain Dam, a flood-control dam on the White River southeast of Enumclaw, Wash. At 425 feet above bedrock and 3 million cubic yards, it was the world's highest embankment dam until completion of Idaho's Anderson Ranch Dam in 1950. The lower part of the dam was in a vertical-walled gorge 300 feet deep, and Atkinson was faced with significant problems just accessing the site, let alone placing fill at a rate sufficient to meet the project's schedule. Access to the canyon floor was initially gained by roads built down to 175 feet above the riverbed to an inclined tramway at the downstream diversion tunnel portal and a stiff-leg derrick at the upstream portal, and by cable-ways over the fill area. Workers hiked in and out on trails, stairways and ladders.
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