Alder Dam is a concrete arch dam

Dam

A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

 on the Nisqually River

Nisqually River

The Nisqually River is a river in west central Washington in the United States, approximately long. It drains part of the Cascade Range southwest of Tacoma, including the southern slope of Mount Rainier, and empties into the southern end of Puget Sound....

 in the U.S. state of Washington. When construction was completed in 1945, Alder Dam was among the tallest dams in the United States, although this title has already been surpassed. The dam generates 50,000 kilowatts of power, most of which is sent 25 miles (40.2 km) away to the city of Tacoma.

Water from Alder Lake is drawn through two penstocks into two generators at the base of the dam, each of which produces 25,000 kilowatts for a total nameplate capacity of 50,000 kilowatts.

Alder Lake

Alder Lake

Alder Lake is a long reservoir on the Nisqually River in the U.S. state of Washington, which was created following the construction of Alder Dam in 1945. At the very eastern end of the lake is the town of Elbe, Washington....

 is the lake that is formed behind the dam, stretching about 7 miles (11.3 km) upstream. With 28 miles (45.1 km) of shoreline, the lake is a popular recreation spot close to Mount Rainier National Park

Mount Rainier National Park

Mount Rainier National Park is a United States National Park located in southeast Pierce County and northeast Lewis County in Washington state. It was one of the US's earliest National Parks, having been established on March 2, 1899 as the fifth national park in the United States. The park contains...

.