In the United States, volume of irrigation water is usually expressed in acre-feet. One acre-foot is a volume of water sufficient to cover 1 acre of land to a depth of 1 ft (640 acres = 1 mi2, 1 mi = 5280 ft). The principal lake in the California Water Project is Lake Oroville, whose water storage capacity is listed as 3.54 x 106 acre-feet. Express the volume of Lake Oroville in (a) cubic feet, (b) cubic meters, and (c) US gallons.