Lake Umatilla is a 110-mile (177 km) long reservoir on the Columbia River in the United States, between the U.S. states of Washington and Oregon. It was created in 1971 with the construction of John Day Dam, and stretches upstream to the McNary Dam. It lies in parts of Sherman, Gilliam, Morrow, and Umatilla counties in Oregon, and Klickitat and Benton counties in Washington.
