The Potholes Reservoir is part of the Columbia Basin Irrigation Project. It is formed by the O'Sullivan Dam and located in central Washington, in the United States. The reservoir is fed by water from Moses Lake, part of the Crab Creek basin. The area features several lakes (typically 30-70 yards wide and 10–30 feet deep). These lakes, known as "potholes" were created through both natural and man made processes. The potholes were initially carved out during the Pleistocene by flood waters originating from Glacial Lake Missoula. Subsequent damming of the area by the Columbia Basin Project raised the water table high enough to allow these topographical depressions to become lakes.

Recreation

On the shore of the reservoir is Potholes State Park, a 640 acre member of the Washington State Park System. It has 6000 ft of shoreline on the reservoir.

Fishing

There are many types of fish inside of the reservoir, including: