The Hanford Reach is a free-flowing section of the Columbia River

Columbia River

The Columbia River is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, Canada, flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and the state...

, about 45 miles (72.4 km) long, in eastern Washington state, named after a large northward bend in the river's otherwise southbound course. It is the only section of the Columbia in the U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 that is not tidal and not part of a reservoir, excluding a short reach between the U.S.-Canada border and the upper end of Franklin Delano Roosevelt Lake, the reservoir of Grand Coulee Dam

Grand Coulee Dam

Grand Coulee Dam is a gravity dam on the Columbia River in the U.S. state of Washington built to produce hydroelectric power and provide irrigation. It was constructed between 1933 and 1942, originally with two power plants. A third power station was completed in 1974 to increase its energy...

. Much of the Hanford Reach flows through the Hanford Site

Hanford Site

The Hanford Site is a mostly decommissioned nuclear production complex on the Columbia River in the U.S. state of Washington, operated by the United States federal government. The site has been known by many names, including Hanford Works, Hanford Engineer Works or HEW, Hanford Nuclear Reservation...

, a nuclear production facility that started during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. It is also the site of the Hanford Reach National Monument

Hanford Reach National Monument

The Hanford Reach National Monument is a national monument in the U.S. State of Washington. It was created in 2000, mostly from the former security buffer surrounding the Hanford Nuclear Reservation...

, created from the original protection area around the Hanford Site. Upstream of the Hanford Reach is Priest Rapids Dam

Priest Rapids Dam

Priest Rapids Dam is a hydroelectric, concrete gravity dam; located on the Columbia River, between the Yakima Firing Range and the Hanford Nuclear Reservation, and bridges Yakima County and Grant County, in the U.S. state of Washington. The dam is 24 miles south of the town of Vantage, and 47 miles...

 and downstream is the McNary Dam

McNary Dam

McNary Dam is a 1.4-mile long concrete gravity run-of-the-river dam which spans the Columbia River. It joins Umatilla County, Oregon with Benton County, Washington, 292 miles upriver from the mouth of the Columbia at Astoria, Oregon. It is operated by the U.S. Army Corps of Engineers' McNary...

, which also impounds the last stretch of the Snake River

Snake River

The Snake is a major river of the greater Pacific Northwest in the United States. At long, it is the largest tributary of the Columbia River, the largest North American river that empties into the Pacific Ocean...

, the largest tributary of the Columbia.