Banks Lake is a 27 mile long reservoir in central Washington in the United States.

Part of the Columbia Basin Project, Banks Lake occupies the northern portion of Grand Coulee, a formerly dry coulee near the Columbia River, formed by the Missoula Floods during the Pleistocene epoch. Grand Coulee Dam, built by the United States Bureau of Reclamation on the Columbia River created Franklin D. Roosevelt Lake, the reservoir on the river behind the dam. The surface of Lake Roosevelt is several hundred feet above the original Columbia River, making it easier to pump water 280 feet up and out of the river's canyon into nearby Grand Coulee. A low earth-fill dam called Dry Falls Dam, keeps the water in Grand Coulee, thus creating the reservoir named Banks Lake.

At the north end of Banks Lake the city of Grand Coulee and the town of Electric City are located. The town of Coulee City is at the south end of the lake. From the south end, the water stored in Banks Lake is distributed over a large region for irrigation purposes.