sentences:  The Nine Mile Dam, constructed in 1905 on the Walla Walla River below the confluence with the Touchet River, impeded anadromous fish migration into the Touchet, but a wild steelhead population (listed as threatened under the Endangered Species Act) continues to return to the river.The Touchet River lay in the traditional range of the Palus American Indian tribe, marking their southern border with the range of the Walla Walla tribe.These peoples were of the Sahaptin-speaking group which traditionally inhabited the Columbia Plateau region of the northwestern United States.