How much land is irrigated with the help of the dam?

Water supplied by Grand Coulee Dam irrigates more than 600,000 acres of rich farmland in the Columbia Basin annually.

Water from Lake Roosevelt (behind the dam) is lifted 280 feet up a hillside to flow into the Banks Lake reservoir, where it starts a journey that eventually covers an area more than twice the size of the state of Delaware. Each of the six conventional pumps in Grand Coulee’s Pump- Generator Plant is powered by a 65,000-horsepower motor and will pump 1,600 cubic feet of water per second, or 781,128 gallons per minute.

In addition, six pump-generators, each having a 67,500-horsepower rating, can pump 1,948 cubic feet of water per second. One of these 12 units can fill the water needs of a city the size of Chicago.