History Beneath the Waters

History Beneath the Waters. . , A bit of history lies under the water behind Oahe Dam. Before the dam was built many islands and sandbars were commonly found along the Missouri River. When the Corps of Discovery traveled along this river on the way to the Pacific Ocean they landed on one of the now water-covered islands on October 8, 1804 and visited an Arikara village. This water-covered island (near the mouth of the Grand River close to Mobridge, South Dakota) was later dubbed Ashley Island, most likely after General William Ashley. Ashley accidentally ran his boat aground in front of the island in 1823 and the Arikaras, who had come to mistrust Euro-Americans attacked. Seventeen of Ashley's men were killed. , Today much of what Lewis and Clark observed in this area in 1804, including Ashley Island, is under water. Many features included on their maps were swallowed once the dam construction began in 1948. Today, Lake Oahe is the 4th largest man-made reservoir in the United States offering a myriad of recreational opportunities. , Background picture caption. , Sunset on the Missouri River near Mobridge, South Dakota. , Inset picture captions., Captain William Clark and Captain William Clark's map of the area showing Ashley Island.