Lake Aldwell was a reservoir located about 4.9 miles (7.9 km) from the mouth of the Elwha River on the Olympic Peninsula in the U.S. state of Washington.

The Elwha Dam blocked at least 70 miles (110 km) of fish habitat for Pacific Salmon and steelhead within Olympic National Park.

Lake Aldwell was home to a population of kokanee sockeye salmon from Indian Creek and Lake Sutherland which, unable to access the Pacific Ocean, used the reservoir as their habitat during their adult lives.

Immediately after the draining of Lake Aldwell, revegetation crews began planting native vegetation to stabilize the slopes from erosion and speed up ecological restoration.

It is expected that the fish populations that reside above the lake will return to their original anadromous lifestyle shortly thereafter.