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Water Use in the United States |
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Background
Thermoelectric
Irrigation
Public
Supply
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Industrial
Other
Trends
in Water Use
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We use water every day—for drinking, for watering our
lawns and gardens, for recreation, and for many uses that we don't
necessarily see but which are critical to our lives. Large
quantities of water are used to generate power and to cool electricity-generating
equipment. Water is used for irrigation, aquaculture, and
for many industrial processes and commercial uses. Our nation's
underground and surface waters are vitally important to our everyday
life.
Since 1950, the U.S. Geological Survey (USGS) has compiled data
on amounts of water used in homes, businesses, industries, and
on farms throughout the United States, and has described how that
use has changed with time. Water-use data are collected at
five-year intervals. These data, combined with other USGS
information, have facilitated a unique understanding of the effects
of human activity on the Nation's water resources. Water
availability has emerged as an important issue for the 21st century
and, as a result, the need is increasing for consistent, long-term
water-use data to support wise use of this essential natural resource.
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Background |
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Between 1950 and 1980 there was a steady increase in water use
in the United States. During this time, the expectation was
that as population increased, so would water use. Contrary to expectation,
reported water withdrawals declined in 1985 and have remained relatively
stable since then in spite of a steady increase in United States
population. Changes in technology, in State and Federal laws,
and in economic factors, along with increased awareness of the
need for water conservation, have resulted in more efficient use
of the water from the Nation's rivers, lakes, reservoirs, and aquifers.
Estimates of water use for 2000 indicate that about 408 billion
gallons per day (abbreviated Bgal/d) were withdrawn for all uses
during the year. This total has varied less than 3 percent
since 1985 as withdrawals have stabilized for the two largest uses—thermoelectric
power and irrigation. Freshwater withdrawals were about
80 percent of the total, and the remaining 20 percent was saline
water. Saline water is defined as water with 1000 mg/L or
more of dissolved solids; it is usually undesirable for drinking
and for many industrial uses.
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Thermoelectric Water Use |
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Cooling towers, Burke County, Georgia.
Credit: U.S. Geological SurveyThermoelectric
power accounts for about half of total water withdrawals. Most
of the water is derived from surface water and used for once-through
cooling at power plants. About 52 percent of fresh surface-water
withdrawals and about 96 percent of saline-water withdrawals are
for thermoelectric-power use.
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Irrigation Water Use |
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Grated-pipe flood irrigation, Fremont
County, Wyoming.
Credit: USDA, Natural Resources Conservation
Service Irrigation accounts for about a third of
water use and is currently the largest use of fresh water in
the United States. Irrigation water use includes water used for
growing crops, frost protection, chemical applications, weed
control, and other agricultural purposes, as well as water used
to maintain areas such as parks and golf courses. Historically,
more surface water than ground water has been used for irrigation.
However, the percentage of total irrigation withdrawals from
ground water has continued to increase, from 23 percent in 1950
to 42 percent in 2000. Irrigated acreage more than doubled between
1950 and 1980, then remained constant before increasing nearly
7 percent between 1995 and 2000. The number of acres irrigated
with sprinkler and microirrigation systems has continued to increase
and now comprises more than one-half the total irrigated acreage.
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Public Supply Water Use |
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Public supply water intake, Bay County,
Florida.
Credit: U.S. Geological Survey Public-supply
water is water withdrawn by public and private water suppliers,
in contrast to self-supplied water, which is water withdrawn by
a user. Public-supply water may be used for domestic, commercial,
industrial, thermoelectric power, or public-use purposes. In
1950, only 62 percent of the United States population obtained
drinking water from public suppliers, but by 2000 about 85 percent
did. Public-supply water use has increased steadily since
1950 and accounted for about 11 percent of water use in 2000. |
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Industrial Water Use |
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Self-supplied industry.In 2000,
self-supplied industrial water withdrawals accounted for about
5 percent of water use. Industrial water use includes water
used for fabrication, processing, washing, and cooling, and also
includes water used by smelting facilities, petroleum refineries,
and industries producing chemical products, food, and paper products.
Industrial water use has declined 24 percent since 1985 and in
2000 was at the lowest level since reporting began in 1950. |
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Other Water Use |
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Combined withdrawals for self-supplied domestic, livestock, aquaculture,
and mining activities represented about 3 percent of total water
withdrawals for 2000. Self-supplied domestic withdrawals
include water used for household purposes which is not obtained
from public supply. About 43 million people in the United
States self-supply their domestic water needs, usually from wells. Livestock
water use includes watering, feedlots, and other on-farm needs
for animals such as cattle, sheep, pigs, horses, and poultry. Aquaculture
use is water used for fish hatcheries, fish farms, and shellfish
farms. Mining water use encompasses water used for the extraction
of minerals, including solids such as coal and ores, liquids such
as crude petroleum, and gases such as natural gas. Also included
is water used for processes done as part of the mining activity. Nearly
all of saline ground-water withdrawals in 2000 were for mining.
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Domestic well, Early County, Georgia; Livestock watering, Rio Arriba
County, New Mexico; Trout farm, Buhl, Idaho.
Credits: U.S. Geological Survey; USDA, Natural Resources Conservation
Service; Clear Springs Foods, Inc. |
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Trends in Water Use |
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Estimates
of water use show total withdrawals increased steadily from 1950
to 1980, declined more than 9 percent from 1980 to 1985, and have
varied less than 3 percent since 1985. Total withdrawals
peaked during 1980, although total U.S. population has increased
steadily since 1950. Estimates of water use peaked during
1980 because of large industrial, irrigation, and thermoelectric-power
withdrawals. Total withdrawals for 2000 were similar to the
1990 total withdrawals, although the U.S. population had increased
13 percent since 1990. |
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Trends in population and freshwater withdrawals by source, 1950-2000.
Source: U.S. Geological Survey |
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Total withdrawals have remained about 80 percent surface water
and 20 percent ground water since 1950. The portion of surface-water
withdrawals that was saline increased from 7 percent for 1950 to
20 percent for 1975 and has remained about 20 percent since. The
percentage of ground water that was saline never exceeded about
2 percent. The percentage of total withdrawals that was saline
water increased from a minor amount in 1950 to as much as 17 percent
during 1975 and 1990.
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Trends in total water withdrawals by water-use category, 1950-2000.
(Total withdrawals for rural domestic and livestock and for "other
industrial use" are not available for 2000.)
Source: U.S. Geological Survey |
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More detailed information on water-use and water-use trends is
available in the U.S. Geological Survey publication Estimated
Use of Water in the United States in 2000. Water basics
and additional water-use information can be found in USGS:
Water Science for Schools, especially the Water Questions
& Answers.
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