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Lower Mississippi-Gulf Water Science Center -- Louisiana

Water Use Glossary

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Pierre Sargent


Aquaculture Withdrawal

Aquaculture withdrawal refers to the withdrawal of water for fish, crawfish, and alligator farming.

How large is a million gallons per day?

One million gallons would form a cube that is 51.1 feet on each side. A million gallons per day (Mgal/d) as a rate of flow of water is equal to 133,680.56 cubic feet per day, or 1.5472 cubic feet per second, or 3.0689 acre-feet per day. A flow of one million gallons per day for one year equals 1,120 acre-feet (356 million gallons).

Industrial Withdrawal

Industrial withdrawal refers to water withdrawn for industrial purposes such as process and production, boiler feed, air conditioning, cooling, sanitation, washing, and steam generation. The five major industrial groups defined by the Standard Industrial Classification (SIC) codes (U.S. Bureau of the Census, 1986) are:

  • SIC 20 – Food and kindred products; the manufacture or processing of foods and beverages for human consumption, and related products such as ice, vegetable and animal fats and oils, and prepared feeds for animals and fowls
  • SIC 26 – Paper and allied products; the manufacture of pulps from wood and fibers; the manufacture of paper and paperboard
  • SIC 28 – Chemicals and allied products; the production of chemicals and chemical products such as drugs, cosmetics, and soaps
  • SIC 29 – Petroleum refining and related industries; petroleum refining and the manufacture of paving materials, roofing materials, lubricating oils and greases
  • SIC 33 – Primary metals industries; smelting and refining ferrous and nonferrous metals from ore, pig, or scrap; alloying metals; manufacturing nails, spikes, and insulated wire and cable


Irrigation refers to any withdrawal of water for application to vegetation. This includes application to field crops such as rice, corn, cotton, fruit crops, nurseries, and special applications such as the watering of golf courses and sporting fields.

Livestock Withdrawal

Livestock withdrawal to water withdrawn for use in the production of cattle, horses, sheep, swine, poultry, and other animals. The water can be used for livestock consumption, sanitation, and other on-farm needs.

Power Generation Withdrawal

Power generation withdrawal refers to water withdrawn for thermoelectric power-generation purposes such as cooling, sanitation, washing, and steam generation. Use of water for hydroelectric power generation is considered an instream use and not a withdrawal. Therefore, hydroelectric power-generation use is not included in surface-water withdrawals in this report, but is reported as an instream use.

Public-Supply Withdrawal

Public-supply withdrawal refers to water withdrawn and delivered to a group of users by public and private water suppliers. Typically a public water supply is one that serves 25 people or 15 connections year round. The water is used for a variety of purposes such as domestic, commercial, industrial, and public water use. In addition, a portion of public-supply withdrawals are conveyed to a large industrial facility that does not have its own water supply.

Rural Domestic Withdrawal

Rural domestic withdrawal refers to water withdrawn by a person or family for personal home use. These users are often in rural areas where public supplies are unavailable.

Units of Measurement

Water use is usually expressed as a rate, that is, a volume of water over a period of time. Common rates for water use are thousand gallons or 100 cubic feet, ccf, (as in a meter reading), gallons per minute, gpm, (as in pumpage), gallons per day, gpd, (as in per person or per household); million gallons per day, Mgal/d, (as in per facility or per geographically or politically bounded area); billion gallons per day, bgd, (as in a national total); or acre-foot, acre-ft, (more commonly used for irrigation water use and in the western United States).

Water Use

Water use is water withdrawn or diverted from a ground or surface water source and used for public supply, industry, power generation, rural domestic, livestock, irrigation, and aquaculture purposes.

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Page last modified: January 13, 2017 8:16:21