Boundary Dam, Washington

The Boundary Dam is operated by Seattle City Light, the electrical utility for that city, and provides up to 40% of the power for Seattle, nearly 250 miles away. The powerhouse was built inside the cliff, and generates more than 1,000 Megawatts. This dam is on the Pend Oreille River in western Washington, just a few miles south of the international border with Canada. The river it floods forms a long lake through the river valley, 17 miles upstream to the next dam, at Box Canyon. Downstream, the swollen Pend Oreille River crosses the boundary line northward, and arcs through Canada for 12 miles. The river passes through the Seven Mile Dam in Canada, and then another at Waneta, just before joining the main channel of the Columbia, and crosses the boundary for the last time, back into the USA, where it meets its next empoundment, the Grand Coulee Dam, 100 miles downstream.