The 890-square-mile Idaho National Engineering Laboratory (USDOE) site is located in southeastern Idaho, near Idaho Falls. The Atomic Energy Commission set up the National Reactor Testing Station on the grounds in 1949 to build, test and operate various nuclear reactors, fuel processing plants and support facilities. Prior to that, parts of the site were used by the Department of Defense (DoD). The Idaho National Engineering Laboratory (INL) consists of a number of major facilities that contribute contaminants to and draw water from the Snake River Plain Aquifer. Site activities also included the discharge of liquid wastes to several unlined ponds and an earthen ditch. These activities contaminated soil, sludge and groundwater with hazardous chemicals, heavy metals and radioactive constituents. EPA has divided the site into several cleanup areas, or operable units (OUs), to better address site cleanup. Remedy construction has been completed at several OUs. Remedial design and construction are underway at the remaining OUs.