 This dam generates about 457 gigawatts of power a year, most of which goes to the pumps in California's Colorado River Aqueduct. But for Arizonans, it has a more well-known job. It creates Lake Havasu, a 19,000-acre reservoir that's a recreation site fostering one of the state's fastest-growing cities. It's also a major reservoir where Arizona and California, which border either side, access their shares of the Colorado River.