Potholes State Park, State park with reservoir in Grant County, United States

Potholes State Park is a 773-acre (313 ha) public recreation area on the southern shore of Potholes Reservoir in Grant County, Washington. It has 6,000 feet (1,800 m) of shoreline and lies 13 miles (21 km) south of Moses Lake and 13 miles (21 km) northwest of Othello. The park was created after the O'Sullivan Dam was completed in 1949.

The reservoir was created in 1949 when the O'Sullivan Dam was built to store water for irrigation and hydroelectric power. The park was established afterward to provide public access and recreational opportunities around this water resource.

The park's name comes from the potholes, small depressions in the surrounding basalt that fill with water and give the reservoir its name. Anglers fish the reservoir from the 6,000 feet of shoreline, and the park's boat launches put them on the water.

The park lies on the southern shore of Potholes Reservoir, 13 miles south of Moses Lake and 13 miles northwest of Othello in Grant County. Its 6,000 feet of shoreline give access to the water for boating, swimming and fishing, with camping and hiking facilities on land. A Discover Pass is required for parking.

Water levels in the reservoir fluctuate significantly between spring and fall, revealing different landscapes depending on the season. These changes affect which wildlife species are present and visible throughout the year.