O'Sullivan Dam (National ID # WA00268), one of the largest earthfill dams in the United States (200 ft/61 m high; 19,000 ft/5,791 m long; completed 1949), is on Crab Creek in the U.S. stateofWashington, about 45 km south of Ephrata and 25 km south of Moses Lake.
The 27,800-acre (113 km2) Potholes Reservoir formed by this dam collects return flows from all irrigation in the upper portion of the project for reuse in the southern portion. A system of wasteways has been built on both the West and East Low Canals to provide operational safety for the canals and a means of delivering water into Potholes Reservoir to supplement the natural and return flows.[1]
The dam was built as part of the Columbia Basin Project.
46°58′57″N 119°17′28″W / 46.98250°N 119.29111°W / 46.98250; -119.29111
