Lower Granite Lake is a reservoir created by Lower Granite Dam. The dam is a concrete gravity run-of-the-river dam in the northwest United States. On the lower Snake River in southeastern Washington, it bridges Whitman and Garfield counties. Opened 49 years ago in 1975, the dam is located 22 miles (35 km) south of Colfax and 35 miles (56 km) north of Pomeroy.