It is defined by the volume of one acre of surface area to a depth of one Foot. Since the area of one acre is defined as 66 by 660 feet chain by a furlong then the volume of an acre-foot is exactly 43,560 cubic feet. Alternatively, this is approximately 325,851.4 U.S. gallons or 1,233.5 kL (or m³).
As a rule of thumb in U.S. water management, one acre-foot is taken to be the planned water usage of a suburban family household, annually. In the desert SouthWest, where water conservation is followed, a typical family uses only about 0.25 acre-feet of water per year.
The acre-foot (or more specifically the time rate unit of acre-foot per year) has been used historically in the U.S. in many water-management agreements, for example the Colorado River Compact, which divides 15 million acre-feet per year (586 m³/s) among seven western U.S. states.
- ↑ The state of Montana assumes 1.0 acre-foot per year for a family of five. See Water Rights Bureau, state of Montana (April 132004). Form No. 627 R8/03 Notice of Water Right (PDF). Retrieved on 2008-01-30.
- ↑ Santa Fe, New Mexico rate averages 0.25 acre-feet per year per household.See Planning Division, Planning & Land Use Department, City of Santa Fe, New Mexico (February 2001). Water Use in Santa Fe: A survey of residential and commercial water use in the Santa Fe urban area (PDF). Retrieved on 2008-01-30.
Adapted from the Wikipedia article "acre feet" http://en.wikipedia.org/w/index.php?title=Acre-foot&oldid=210404705 released under the GFDL