Banks Lake

Eastern Washington state, USA. Banks Lake is doubly artificial; it's held in the Grand Coulee by dams at either end, and filled by Columbia River water pumped up using hydropower from Grand Coulee Dam! So it's filled by an artificial river as well. It's the master holding pond for the Columbia Basin irrigation project, as all the irrigated lands lie downhill from here. It can also be used as a "peaking pond"--the pumps can be run in reverse as generators for when the electrical load peaks. In effect electricity can be stored by pumping water up into the lake.