Acre Feet

Acre-feet are a common way to measure water volume in the United States, especially for large water resources such as reservoirs, aqueducts, canals, sewer flow capacity, irrigation water, and river flows.

An acre-foot is a unit of volume. It is the amount of water needed to cover one acre (43,560 square feet) with one foot of water. One acre-foot is equal to 325,851 gallons of water, or enough to cover a football field with a foot of water.

The formula for acre-feet is:

acre-feet = surface area (acres) x average depth (feet)

For example, if you have a pond that is 1 acre in size and has an average depth of 2 feet, then the volume of water in the pond is 2 acre-feet.

Here are some other ways to think about how much water is in an acre-foot:

• An acre-foot is enough water to meet the annual indoor and outdoor needs of two average households in California.

• An acre-foot is enough water to flood a football field 1 foot deep.

• An acre-foot is equal to approximately an eight-lane swimming pool, 82 ft (25 m) long, 52 ft (16 m) wide and 9.8 ft (3 m) deep.