Tucson's Clearwell Reservoir, with a capacity of 60 million gallons, is Arizona's largest potable concrete reservoir. It delivers two-thirds of the city's daily water supply. Surrounded by a nature preserve and trail systems, the reservoir went to great lengths to lessen the impact on the surrounding nature. Builders safely relocated several large saguaro cacti and installed a specialized animal fence around the construction site to keep animals out of harm's way.