Lake Oahe Lake Oahe Lake Oahe (oh-WAH'-hee) is a large reservoir behind Oahe Dam on the Missouri River; it begins in central South Dakota and continues north into North Dakota in the United States. The lake has an area of and a maximum depth of . By volume, it is the fourth-largest reservoir in the US. Lake Oahe has a length of approximately and has a shoreline of . 51 recreation areas are located along Lake Oahe, and 1.5 million people visit the reservoir every year. The lake is named for the 1874 Oahe Indian Mission. Lake Oahe begins just north of
Wells Dam Wells Dam Wells Dam is a hydroelectric dam located on the Columbia River, downstream from the confluence of the Okanogan River, Methow River, and the Columbia River in Washington state. The dam, associated structures, and machinery make up the Wells Hydroelectric Project. It is owned and operated by Douglas County Public Utility District. It has produced electricity since August 22, 1967. Its operating license from the US Federal Energy Regulatory Commission is next up for renewal in 2052. In addition to the two public utility districts, the project provides electricity to Puget Sound Energy, Portland General Electric, PacifiCorp, Avista Corporation,