45°35′44″N 121°11′22″W / 45.59556°N 121.18944°W The Wascopam Mission or Dalles Mission was a branch of the Methodist Mission opened at Celilo Falls in 1838. Among the tribes proselytized were members of the Cayuse, Klickitat, Nez Perce, Shasta, Tenino, Walla Wallas, and Wasco-Wishram.[1][2] In 1847 the mission was closed and later became the site of Fort Dalles.