Water Use

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Chapter 2
Water Use

Water is used in every society. Individuals use water for drinking, cooking, cleaning, and recreation. Industry uses it to make chemicals, manufacture goods, and clean factories and equipment. Cities use water to fight fires, clean streets, and fill public swimming pools and fountains. Farmers give water to their livestock, clean their barns, and irrigate their crops. Hydroelectric power stations use water to drive generators, and thermonuclear power stations use it for cooling. No plant or animal can survive without water. Water is vital to life, yet, as Chapter 1 describes, it is a finite (limited) resource. There is no more water today than was on Earth four billion years ago.


Most human and land-based animal and plant activities that use water require freshwater. In the vast majority of cases, saline or saltwater cannot be used without treating it to remove the salt. The U.S. Geological Survey (USGS) notes in Where Is Earth's Water Located? (August 28, 2006, http://ga.water.usgs.gov/edu/earthwherewater.html) that the world's total water supply is about 332.5 million cubic miles, but freshwater comprises only about 3% of this water. (See Figure 1.2 in Chapter 1.) If this water were distributed equally over the planet relative to population density and animal and plant needs, it would be more than enough to sustain all life. This, however, is not the case.

Freshwater supplies vary not only from region to region on Earth but also from year to year within regions. Within the continental United States some parts of the country do not have adequate supplies at the same time that other areas may be experiencing floods. For example, the National Climatic Data Center, in Climate of 2006In Historical Perspective: Annual Report (January 9, 2007, http://www.ncdc.noaa.gov/oa/climate/research/2006/ann/ann06.html), reports that as rains flooded western Washington State in November 2006, parts of Arizona and Minnesota were experiencing a severe drought.

The first human settlements were based on the availability of water. Where water was plentiful, large numbers of people flourished; where water was scarce, small groups eked out a living. Villages and cities thrived in areas of constant water supply. In more arid regions nomads wandered in search of water. Great nations grew up along the Nile River in Egypt, the Tigris and the Euphrates rivers in western Asia, the Indus River in India, and the Yellow River in China.

Modern societies, which have more control over the water supply than did ancient societies, have developed technologies that bring water to arid regions and divert water from areas likely to flood. Modern, elaborate irrigation systems have made it possible for cities to exist in places where two centuries ago only the hardiest plants and animals could survive. For example, without these water systems Los Angeles would be a semiarid desert.


Freshwater that is potable (safe to drink) is the most crucial resource for the maintenance of human societies. Freshwater, however, is limited in total supply, unevenly distributed, and often of unacceptable quality, particularly in areas where the supply is limited.

Most people in the United States obtain water through water utility companies, also called water purification and distribution plants. Utility companies are those that serve the public, such as an electric company, sewage treatment plant, or water purification and distribution plant. Utility companies may be owned by cities, towns, or private entities.

Water utility companies withdraw water from either surface or groundwater sources to supply their customers. The customers pay the utility companies for the water they use. Water may also be self-supplied, that is, withdrawn directly from wells, lakes, or rivers by those users who have the equipment, technology, and water rights necessary to withdraw and process water for their individual and family use.

As described in Chapter 1, water cycles naturally within the environment. (See Figure 1.3 in Chapter 1.) Water withdrawn from surface or groundwater sources by humans eventually returns to the water cycle, but sometimes it is returned in a condition different from which it was withdrawn. The water's condition can greatly affect the ability to reuse the water. For example, water used for irrigation may end up as agricultural runoff containing pesticides and fertilizers, making it unfit for other uses such as drinking. Water used to flush a toilet mixes with body wastes, making it unfit for other uses as well.

Figure 2.1 shows a flowchart of water use activities. The phrase water use means human activities that use and transfer both surface and groundwater. Water use begins when water is withdrawn from groundwater or surface water. It may be withdrawn and used directly, such as when a person has a well serving the home, or it may be withdrawn, treated, and distributed by a water utility company. After use, water that is not consumed is called wastewater, and it is returned to a river or to a wastewater treatment plant where, after treatment, it is discharged into a river. Consumed water is that which evaporates during water use or is used in a way that makes it unavailable for other uses, such as water incorporated into a product being manufactured. Unaccounted-for water includes public water use (firefighting, street washing, water treatment plant back flushing of filters, and municipal parks and swimming pools), leakage (conveyance loss), and meter errors.


Water use in the United States is monitored and reported by the USGS, which classifies water use as in-stream or off-stream. In-stream use means that water is used at its sourceusually a river or streamand the vast majority of that water is returned immediately to the source. Little or no water is consumed. Examples are a hydroelectric plant where water flows through turbines, which drive generators, and old mills where flowing water turns a wheel, which moves grinding stones. In the hydroelectric plant, the flowing water immediately returns to the river from which it came. In the old mill, the water never leaves the river. Off-stream use means that the water is withdrawn from a surface or ground-water source and conveyed to the place where it is used.

Off-Stream Use

Table 2.1 shows total off-stream water use by source, type, and state for 2000. Nationwide, off-stream water use was 408 billion gallons per day (Bgal/d). Susan S. Hutson et al., in Estimated Use of Water in the United States in 2000 (2004, http://pubs.usgs.gov/circ/2004/circ1268/pdf/circular1268.pdf), the most recent info available, note that this was slightly more than the 402 Bgal/d in 1995. Of the water involved in off-stream use, 345 Bgal/d (84%) was freshwater in 2000.

At 51.2 Bgal/d, California used more water than any other state by a large margin. (See Table 2.1.) Texas was the second-largest water user at 29.6 Bgal/d. Figure 2.2 shows a map of total off-stream water use by state for 2000. This presentation of the data makes it easier to compare water use among states. It is easy to see that California, Texas, and Florida are the largest water-users in the nation.

In many cases off-stream use results in substantial consumptive use of water. Consumptive use is of two types: quantitative or qualitative. Quantitative consumption means that part of the water withdrawn has evaporated, been transpired (given off) by plants, been incorporated into products or crops, been consumed by humans or livestock, or otherwise removed from the immediate water environment so that the quantity returned to the source is substantially less than the quantity of water withdrawn. An example of consumptive use is spray irrigation. According to the USGS, in "Irrigation Techniques" (August 30, 2005, http://ga.water.usgs.gov/edu/irmethods.html), about 60% of the water used to irrigate crops is returned to the source. The other 40% of the water evaporates, is incorporated into plant structure, or is transpired by plants.

Total water use by source and state, 2000
[Figures may not sum to totals because of independent rounding]
StatePopulation (in thousands)Withdrawals (in million gallons per day)Withdrawals (in thousand acre-feet per year)
By source and typeTotal
GroundwaterSurface waterTotal
Source: Susan S. Hutson et al., "Table 1. Total Water Withdrawals by Source and State, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia5720009.8709.879.8709.8711.1011.1
New Hampshire1,24085.2085.23627611,1204477611,2105018541,350
New Jersey8,41058405841,5903,3904,9802,1703,3905,5602,4303,8006,230
New Mexico1,8201,54001,5401,71001,7103,26003,2603,65003,650
New York19,00089308936,1905,01011,2007,0805,01012,1007,9405,61013,600
North Carolina8,05058005809,1501,62010,8009,7301,62011,40010,9001,81012,700
North Dakota64212301231,02001,0201,14001,1401,28001,280
Rhode Island1,05028.6028.6110290400138290429155326481
South Carolina4,01033003306,84006,8407,17007,1708,04008,040
South Dakota7552220222306030652805285920592
Washington5,8901,47001,4703,80039.93,8405,27039.95,3105,91044.7 5,960
West Virginia1,81090.9090.95,06005,0605,15005,1505,77005,770
Puerto Rico3,81013701374832,1902,6706202,1902,8106952,4603,150
U.S. Virgin Islands1091.0301.0310.613614711.613614813.0153166

Qualitative consumption occurs when the quality of the water is substantially altered so that it is no longer acceptable by downstream users, but the quantity remains substantially unchanged. An example would be discharge of industrial wastewater into a body of water that renders the water unfit for drinking. Many water withdrawals result in both quantitative and qualitative consumption.

Off-stream use is further divided into eight categories:

  • Public supply
  • Domestic
  • Irrigation
  • Livestock
  • Aquaculture
  • Industrial
  • Mining
  • Thermoelectric power

Table 2.2 shows the total amount of water withdrawn for each category by state. The two activities that use the most freshwater are irrigation (137 Bgal/d nationally in 2000) and thermoelectric power (136 Bgal/d nationally in 2000). Thermoelectric power is the generation of electricity by means of steam-driven turbine generators. No other category of use comes close to using the amount of freshwater that is used for irrigation and thermoelectric power.


Public-supply water use is water withdrawn by public and private water suppliers (utility companies) and delivered for domestic, commercial, industrial, and thermoelectric power uses. It may be used for public services such as filling public pools, watering vegetation in parks, supplying public buildings, firefighting, and street washing. In 2000 water utility companies supplied 43.3 Bgal/d. (See Table 2.2.) The rest of the water shown in Table 2.2 under the various other categories was self-supplied. That is, the water was withdrawn from groundwater or surface water sources by the users, not by water utility companies.

Total water use by state and usage category, 2000
[Figures may not sum to totals because of independent rounding. All values are in million gallons per day.]
StatePublic supplyDomesticIrrigationLive-stockAqua-cultureIndustrialMiningThermoelectric powerTotal
Source: Susan S. Hutson et al., "Table 2. Total Water Withdrawals by Water-Use Category, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia00.18009.6909.8709.87
New Hampshire97.141.04.7516.344.906.802367614477611,210
New Jersey1,05079.71401.686.46132011006503,3902,1703,3905,560
New Mexico29631.42,86010.5056.403,26003,260
New York2,57014235.529704,0405,0107,0805,01012,100
North Carolina9451892871217.88293036.407,8501,6209,7301,62011,400
North Dakota63.611.914517.6090201,14001,140
Rhode Island1198.993.454.2802.40290138290429
South Carolina56663.526756505,71007,17007,170
South Dakota93.39.5337342.05.1205.2405280528
West Virginia19040.4.0496803,95005,15005,150
Puerto Rico513.8894.511.2002,1906202,1902,810
U.S. Virgin Islands6.091.69.503.340013611.6136148

According to Hutson et al., public suppliers serviced about 242 million people in 2000 (about 85% of the total U.S. population of 285 million at that time). (See Table 2.3.) This figure represents an 8% increase over the number of people supplied with water by public suppliers in 1995. Of the 43.3 Bgal/d of water that public suppliers withdrew, 27.3 Bgal/d (63%) came from surface sources and 16 Bgal/d (37%) from groundwater sources. Figure 2.3 shows that California, Texas, Illinois, New York, and Florida accounted for a majority of U.S. public-supply withdrawals in 2000.

Public supply water use, 2000
[Figures may not sum to totals because of independent rounding]
StatePopulation (in thousands)Withdrawals (in million gallons per day)Withdrawals (in thousand acre-feet per year)
TotalServed by public supplyBy sourceTotalBy sourceTotal
PopulationPopulation (in percent)Ground-waterSurface waterGround-waterSurface water
Source: Susan S. Hutson et al., "Table 5. Public-Supply Water Withdrawals, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia572572100000000
New Hampshire1,2407566133.
New Jersey8,4107,460894006501,0504497291,180
New Mexico1,8201,4608026233.829629437.9332
New York19,00017,100905831,9802,5706532,2202,880
North Carolina8,0505,350661667799451868731,060
North Dakota6424937732.431.263.636.335.071.3
Rhode Island1,0509228816.910211919.0115134
South Carolina4,0103,16079105462566117517635
South Dakota7556258354.239.193.360.743.9105
West Virginia1,8101,3007241.614919046.6167213
Puerto Rico3,8103,80010088.542551399.2476576
U.S. Virgin Islands10953.449.525.576.09.586.246.83


Domestic water use includes water for typical household purposes, such as drinking; food preparation; bathing; washing clothes, dishes, and cars; flushing toilets; and watering lawns and gardens. Although people need to take in about two quarts of water a day from what they eat or drink to replace water loss, water needs for household use (indoor and outdoor) add to the amount of water people require each day.

In the report Residential End Uses of Water Study (1999, http://www.awwarf.org/research/topicsandprojects/execSum/241.aspx), Peter W. Mayer et al. studied residential end uses of water in twelve hundred single-family homes in twelve North American locations from 1996 to 1998. They conclude that flushing the toilet uses the most water (20.1 gallons per person per day) of all indoor household water uses in homes not equipped with water-efficient fixtures. Laundering clothes ranked second in water use (15 gallons per person per day), and taking showers (13.3 gallons per person per day) ranked third. In addition, the U.S. Environmental Protection Agency (EPA) reports in the fact sheet "Safe Drinking Water Act 30th Anniversary: Water Facts" (June 2004, http://www.epa.gov/ogwdw/sdwa/30th/factsheets/waterfacts.html) that outdoor household water use for activities such as filling swimming pools, watering lawns, and washing cars accounts for 50% to 70% of total household water usage. Each American, on average, uses over one hundred gallons of water per day.

In 1992 Congress passed the Energy Policy and Conservation Act. This legislation established uniform national standards for manufacture of water-efficient plumbing fixtures, such as low-flow toilets and showers. The purpose was to promote water conservation by residential and commercial users. Since that time many water suppliers have sponsored programs offering rebates on water bills and other incentives to encourage the use of these devices to reduce water use.


Aquaculture is the practice of raising animals that live in watersuch as finfish and shellfishfor food, restoration, conservation, or sport. According to Table 2.4, aquaculture use accounted for 3.7 Bgal/d of water use nationally in 2000. Surface water was the source for 2.6 Bgal/d (70%) of this total. Idaho alone accounted for nearly 2 Bgal/d (53%) of the aquaculture water use reported.


The word irrigation usually brings to mind arid or semiarid deserts transformed into lush green fields of crops by the turn of a handle, bringing life and prosperity where before there had been only sagebrush and cactus. To some extent this is true. Many parts of the American West and Midwest do not average enough yearly rainfall to sustain the crops that are grown there; the cultivation of those crops is made possible only with the water supplied by irrigation. Irrigation is also used to supplement rainfall in areas with adequate water supplies to increase the number of plantings per year, improve yield, and reduce the risk of crop failure during drought years.

According to Hutson et al., irrigation accounted for 137 Bgal/d of freshwater withdrawals for all off-stream categories in 2000. (See Table 2.2.) Approximately 80 Bgal/d of withdrawals (58%) were from surface water sources, and the remaining 56.9 Bgal/d (42%) were from groundwater sources. (See Table 2.5.) The quantity of freshwater used for irrigation varies greatly from region to region. Irrigation is by far the largest water use category in the West. (See Figure 2.4.) California alone used 30.5 Bgal/d (22%) of all irrigation water in 2000. (See Table 2.5.)

Water use for aquaculture, 2000
[Figures may not sum to totals because of independent rounding]
StateWithdrawals (in million gallons per day)Withdrawals (in thousand acre-feet per year)
By sourceTotalBy sourceTotal
GroundwaterSurface waterGroundwaterSurface water
Source: Susan S. Hutson et al., "Table 9. Aquaculture Water Withdrawals, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia
New Hampshire3.1213.116.33.5014.718.2
New Jersey6.4606.467.2407.24
New Mexico
New York
North Carolina7.8807.888.8308.83
North Dakota
Rhode Island
South Carolina
South Dakota
West Virginia
Puerto Rico
U.S. Virgin Islands

Hutson et al. note that irrigation has the highest consumptive use of any of the eight categories of off-stream water use. In many irrigated areas about 75% to 85% of the irrigation water is lost to evaporation, transpiration, or retained in the crops. The remaining 15% to 25% either slowly makes its way through the soil to recharge (replenish) groundwater, a process called irrigation return flow, or is returned to nearby surface water through a drainage system. The average quantities of water applied range from several inches to more than twenty inches per year, depending on local conditions.

Acres of land being irrigated by state, 2000
[Figures may not sum to totals because of independent rounding]
StateIrrigated land (in thousand acres)Withdrawals (in million gallons per day)
By type of irrigationTotalBy sourceTotal
SprinklerMicro-irrigationSurfaceGroundwaterSurface water
Source: Adapted from Susan S. Hutson et al., "Table 7. Irrigation Water Withdrawals, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia.32 000.320.18.18
New Hampshire6.0806.08.504.254.75
New Jersey10915.73.7012822.8117140
New Mexico4617.175309981,2301,6302,860
New York70.08.731.8480.623.312.135.5
North Carolina1933.70019665.8221287
North Dakota200026.722772.273.2145
Rhode Island4.
South Carolina1663.6617.5187106162267
South Dakota276078.3354137236373
West Virginia2.210.983.
Puerto Rico15.533.05.3553.836.957.594.5
U.S. Virgin Islands.2000.

Significant changes in water quality can be caused by irrigation. The water lost in evapotranspiration is relatively pure because nonwater chemicals are left behind, precipitating as salts and accumulating in the soil. The salts continue to accumulate as irrigation continues. Accumulation of salts in the soil can cause the concentration of salts in the irrigation return flows to be higher than in the original irrigation water. Excessive salts in the soil can also interfere with crop growth, sometimes resulting in soil unsuitable for crop growth. To stop excessive buildup of salts in the soil, extra irrigation water is often used to flush the salts from the soil and transport them into the groundwater. In locations where these dissolved salts reach high concentrations, the recharge of the groundwater from irrigation return flow can reduce the quality of groundwater and the surface water to which the groundwater discharges.


Livestock water use includes drinking water for livestock, dairy and feedlot operations, and other on-farm needs. Hutson et al. indicate that 1.8 Bgal/d of water was used for these purposes in 2000. (See Table 2.2.) Total withdrawals for livestock increased slightly between 1995 and 2000 for the twenty-two states that reported data for both years. However, withdrawals actually increased only in eight of the twenty-two reporting states. Combined, California, Texas, and Oklahoma accounted for 868 million gallons per day (Mgal/d; 49%) of the U.S. total livestock water use in 2000, and 556 Mgal/d (66%) of the surface water used. (See Table 2.6.)


Even those industries that do not use water directly in their products may use substantial quantities of water during operations. Water for industrial use is commonly divided into four categories: cooling water, process water, boiler feed water, and sanitary and service water (for personal use by employees, for cleaning plants and equipment, and for the operation of valves and other equipment). Industries that use the most water include steel, chemical and allied products, paper and related products, and petroleum refining.

According to Hutson et al., water supplied for industrial use in 2000 totaled 19.7 Bgal/d, 11% less than in 1995. Approximately 16.2 Bgal/d (82%) was withdrawn from surface water. (See Table 2.7.) Louisiana, Indiana, and Texas together consumed 7.4 Bgal/d (37%) of the nation's industrial water withdrawals.

Most manufacturers use processed water at some point in the course of making a product. Water is the solvent (the substance in which other substances are dissolved) in many chemical processes. In some plants the item being manufactured is in contact with water at almost every step in its conversion from raw materials to finished product. For example, in the production of pulp and paper, water is used for removing bark from pulpwood, moving the ground wood and pulp from one process to another, cooking the wood chips for removal of lignin (the woody pulp of plant cells), and washing the pulp. Another example is the food industry, which uses huge quantities of water for cleaning and cooking vegetables and meat, canning and cooling canned products, and cleaning equipment and facilities.

The need for large quantities of easily accessible water has led to industrial development around or near coastlines, rivers, and lakes. The Great Lakes region and the Ohio River Valley are examples. This development has often caused serious deterioration of water quality in the area because, after it is used, water may be returned to its source carrying pollutants.

Water use for livestock by state, 2000
[Figures may not sum to totals because of independent rounding]
StateWithdrawals (in million gallons per day)Withdrawals (in thousand acre-feet per year)
By sourceTotalBy sourceTotal
GroundwaterSurface waterGroundwaterSurface water
Source: Susan S. Hutson et al., "Table 8. Livestock Water Withdrawals, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia
New Hampshire
New Jersey1.6801.681.8801.88
New Mexico
New York
North Carolina89.132.312199.936.2136
North Dakota
Rhode Island
South Carolina
South Dakota16.925.242.018.928.247.1
West Virginia
Puerto Rico
U.S. Virgin Islands


Mining is the extraction of naturally occurring materials, including petroleum, from the earth's crust. Water is used for washing and milling (processing). All water for mining operations is self-supplied and may come from a freshwater or saline source. Hutson et al. classify water as saline if it contains more than one thousand milligrams per liter or more of dissolved solids (salts).

Industrial water use by state, 2000
[Figures may not sum to totals because of independent rounding]
StateWithdrawals (in million gallons per day)Withdrawals (in thousand acre-feet per year)
By source and typeTotal
GroundwaterSurface waterBy type
Source: Susan S. Hutson et al., "Table 10. Industrial Self-Supplied Water Withdrawals, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
District of Columbia000000000000
New Hampshire6.9506.9537.9037.944.9044.950.3050.3
New Jersey65.3065.366.2066.213201321470147
New Mexico8.8008.801.6701.6710.5010.511.7011.7
New York1450145152015229702973330333
North Carolina25.6025.6267026729302933290329
North Dakota6.8806.8810.7010.717.6017.619.7019.7
Rhode Island2.1902.192.0902.094.2804.284.8004.80
South Carolina50.9050.9514051456505656330633
South Dakota3.1603.161.9601.965.1205.125.7405.74
West Virginia9.7009.70958095896809681,09001,090
Puerto Rico11.2011.200011.2011.212.5012.5
U.S. Virgin Islands.220.223.1203.123.3403.343.7403.74

Hutson et al. estimate that 3.5 Bgal/d of water was withdrawn for mining in 2000, down from 3.8 Bgal/d in 1995. Most water used for mining purposes was in the Texas Gulf area, followed by the Great Lakes region. Texas, Minnesota, and Wyoming together accounted for 1.6 Bgal/d (46%) of the mining withdrawals reported.

Acid mine drainage is a byproduct of mining activity. It is the drainage that results from the activity of removing and processing large amounts of rock to recover desired ores of heavy metals, minerals, and coal. Thousands of miles of streams are severely affected by drainage and runoff from abandoned coal mines, which are the single largest source of adverse water-quality impacts to both surface and groundwater in the United States.

Total water use by usage category, 2000
Source: Adapted from Susan S. Hutson et al., "Figure 1. Total Water Withdrawals by Category, 2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
Public supply11
Thermoelectric power48


Thermoelectric power plants are those that use turbines or similar devices to convert pressurized steam into electricity. Hydroelectric power plants use moving water to produce electricity, and nuclear power plants use water to cool nuclear reactors. Only the thermoelectric plants remove water for off-stream use. The water used in hydroelectric plants and nuclear power plants is in-stream use, so it is not included here.

Water used for thermoelectric power generation accounted for almost half (48%) of all withdrawals for off-stream use in 2000. (See Table 2.8.) Hutson et al. note that the largest total withdrawals were in Texas. States in the eastern portion of the country accounted for about 83% of the total thermoelectric water use. Figure 2.5 shows the geographic distribution of total, total freshwater, and total saline water withdrawals for thermoelectric power. These maps also visually show that California, Texas, and states in the eastern United States use the most off-stream water to produce electricity. By contrast, the Pacific Northwest uses hydroelectric power generation (an in-stream use) to supply a substantial part of the regional demand for electricity.


Water has been used to dilute and disperse waste since the earliest human settlements. If the wastewater is properly treated, the water environment can dilute, disperse, and assimilate waste products without harm to water quality or aquatic communities. The first step in the process is to identify the total maximum daily load of individual pollutants that particular water bodies can receive and not violate state water quality standards. The next step is to design, construct, and operate waste-water treatment facilities that provide the necessary level of treatment before discharging wastewater.

For the first (and last) time, the USGS reports in Estimated Use of Water in the United States in 1995 (1998, http://water.usgs.gov/watuse/pdf1995/pdf/wastewater.pdf) the wastewater releases and return flow in 1995. This category includes facilities that collect, treat, and dispose of water through sewer systems and wastewater treatment plants, generally to surface waters. Over 16,400 publicly owned treatment facilities released 41 Bgal/d of treated wastewater nationwide in 1995. The annual average was one to two million gallons of treated water per facility per day. The largest wastewater return flows occurred in regions with large populations. Illinois (4.8 Bgal/d) and Ohio (4.7 Bgal/d) reported the largest releases of treated wastewater.

Not all treated wastewater is return flow. Because of the increasing demand for water and the cost of treating drinking water, more emphasis is being placed on water conservation and water reclamation (reuse). Reclaimed water is wastewater that has been treated for uses such as irrigation of golf courses or public parks instead of being discharged back to source waters. Florida (271 Mgal/d), California (216 Mgal/d), and Arizona (209 Mgal/d) reported large uses of reclaimed wastewater in 1995.


The off-stream water-use categories described earlier are generally recognized as representing the most essential human uses of water. Sometimes there is not enough water available at a given location to meet all the demands for it. In these situations, who owns the water?

Water rights are held in trust by the states (held by the state for the benefit of the state's residents) and may be assigned to individuals and corporations according to statutes (laws) regulating water use. A state may also challenge water use to ensure public access to water that lies within or along its boundaries. State laws, regulations, and procedures establish how an individual, company, or other organization obtains and protects water rights. When water rights are disputed, particularly in the West, the question is often resolved through a judicial determination known as adjudication. According to the U.S. Fish and Wildlife Service (USFWS; April 29, 1993, http://www.fws.gov/policy/403fw2.html), adjudications may determine "all rights to use water in a particular stream system or watershed to establish the priority, point of diversion, place and nature of use, and the quantity of water used among the various claimants." When the water involved crosses state boundaries, states enter into agreements for water sharing. When agreement cannot be reached between states, the matter is usually settled in the federal courts, or in some cases by an act of Congress.

Riparian Rights

The right of private landowners to use the water next to their property in streams, lakes, ponds, and other bodies of water is known as a riparian right, and this right underlies the laws regulating water in most states in the eastern part of the country. Even though local statutes are often written to pertain specifically to the bodies of water they regulate, the riparian system generally assigns each landowner an equal right to reasonable use of the water. Defining reasonable use can lead to disputes among neighboring landowners, but it typically allows common agricultural and private uses that do not involve holding water in storage.

Doctrine of Prior Appropriation

The relative scarcity of water in the West has led to a unique set of laws regulating water use, based on what is known as the doctrine of prior appropriation. Covering both surface and groundwater, the appropriation doctrine determines water rights by applying two standards: the timing of water claims and the nature of the water use. Rather than assigning rights based on landownership, the doctrine of appropriation considers both when and why water is used. The earliest water user is considered to hold a claim to the water, and the extent of those rights are judged by whether or not that use is considered beneficial. To determine beneficial use, two areas are considered: the purpose of the use and its efficiency (i.e., that the use is not wasteful). Individual states define the scope of beneficial uses within their boundaries.

A notable difference from the riparian (landowner-ship) system is that under the doctrine of appropriation, water rights may be forfeited if the rights holder fails to use the water in a manner approved by the state or discontinues beneficial use for a designated length of time.

Another feature of the appropriation system is that rights are not shared equally among all users of a body of water. According to the USFWS, "Priority determines the order of rank of the rights to use water in a system. [The] person first using water for a beneficial purpose has a right superior to those commencing their use later." Therefore, when water shortages occur, all rights holders are not affected equally as they are under the riparian system. Prior claims take precedence. However, because water shortages in the West can affect community water needs, priority may be awarded to some vital uses regardless of the date of first claim.

Conflicts over Federal Water Rights

Sometimes conflicts over water rights arise that involve the federal government, and since the 1990s the federal government has been involved in several long court battles to determine the precedence of water claims in the West. In Tulare Lake Basin Water Storage District v. U.S. 49 Fed. Cl. 313 (2001), Judge John Wiese found that even though the federal government had a right to withhold water from farmers for irrigation to preserve salmon and smelt in California, by doing so the government had deprived farmers in the San Joaquin Valley of their rightful use of water. In December 2004 the Bush administration agreed to pay $16.7 million to compensate the farmers for their loss. The case was considered to have negative implications for environmental projects in the West, where the high costs associated with preservation efforts might make them untenable. Previously, the protection of endangered species was considered a higher priority than individual rights to water access.

In another case involving the federal government, Trout Unlimited v. U.S. Department of Agriculture (D.C. No. 96-WY-2686-WD), a conservation organization challenged the approval by the U.S. Forest Service of access to the Long Draw Reservoir in Colorado that did not establish bypass flow regulations for water projects. A bypass flow is the minimum amount of water needed to flow freely around a dam or diversion to sustain the area's aquatic life. On April 30, 2004, a federal judge determined that the Forest Service had not only the authority but also a responsibility to consider the protection of wildlife when issuing permits for water projects on federal lands.


Since the enactment of the Clean Water Act in 1972, with its emphasis on maintaining the physical, chemical, and biological characteristics of the nation's waters, there has been an increasing awareness of the need to protect and maintain the insects, plants, and animals that make up the ecosystem of surface water bodies. Because life on Earth began in the ancient seas, aquatic life has been an integral part of overall water resources. This fact has frequently been ignored as human civilizations evolved, resulting in widespread change in and annihilation of aquatic systems.

In the United States, allocating water to maintain aquatic systems was rarely recognized as a legitimate use until the last two decades of the twentieth century. Before that time dam construction frequently disrupted whole ecological systems by reducing the water available to aquatic life in large stretches of rivers and streams below dams, interfering with the life cycles of migrating fish and other organisms and flooding habitats. In some river systems, such as the Colorado River, the entire flow was allocated and appropriated, resulting in drastic changes to the lush waterscape observed decades before at the delta of the Sea of Cortez, where the Colorado River deposited its rich silt. Rivers and streams have been lined with impermeable surfaces such as concrete or channelized to conserve water, control flooding, or provide passage for boats.

These practices are slowly changing. Permits issued for dam construction or reissued for dam operation are beginning to contain a provision for maintenance of minimum flow below the dam at a level sufficient to protect the natural system. In several cases this has required reduction in the water allocated to other users. Many states have programs to restore natural systems by removing abandoned or obsolete dams and other waterway obstructions and by constructing fish ladders to facilitate fish passage. Water allocation decisions in areas where water is a scarce resource are increasingly designating a portion for aquatic life protection. Proposals to divert or use water are more closely scrutinized to avoid adverse impacts to aquatic life. Recognizing aquatic life protection as a legitimate water use will have a profound effect on future water allocation decisions.

Except for a few rare instances, water is owned by the states, not the federal government. Therefore, the USFWS has adopted a policy of obtaining water rights. The objective is to obtain water supplies of adequate quantity and quality and the legal rights to use that water from the states, for development, use, and management of USFWS lands and facilities and for other congressionally authorized objectives, such as protection of endangered species and maintenance of in-stream flows.

The following are some examples of the evolving recognition of aquatic life protection as a legitimate water use:

  • In May 2004 President George W. Bush issued an executive order that created a federal Great Lakes Interagency Task Force that would work to improve the deteriorating health of the Great Lakes. This task force and other regional groups convened in December 2004 and developed the Great Lakes Regional Collaboration Strategy to Restore and Protect the Great Lakes (December 12, 2005, http://www.glrc.us/documents/strategy/GLRC_Strategy.pdf). This strategy includes plans to stop the overflow of untreated sewage into the lakes, reduce agricultural runoff, protect wetlands, and control foreign species such as zebra mussels that are disrupting the aquatic food chain. As of March 2007, project activities were just beginning.
  • A February 26, 2003, news report issued by the National Marine Fisheries Service stated that for the second consecutive year federal agencies had made substantial progress in implementing the National Marine Fisheries Service's 2000 Biological Opinion for the Federal Columbia River Power System. These efforts have resulted in the protection of hundreds of miles of habitat and in a record return of adult fish to the Columbia River in 2002.
  • In "Region 9: Progress Report 2002" (February 26, 2007, http://www.epa.gov/region09/annualreport/02/water.html), the EPA discusses the success of the salmon recovery project in Northern California's Butte Creek. The project, which was undertaken by the CALFED Bay-Delta Program, has resulted in an average spring salmon spawning of about six thousand fishup from about one thousand fish per spring from the 1960s through the 1990s. The removal of four small dams that had blocked salmon passage was funded by the local Western Canal Water District and Southern California's Metropolitan Water District.
  • According to the Connecticut River Coordinator's Office (March 26, 2007, http://www.fws.gov/r5crc/Habitat/fish_passage.htm) of the USFWS, removal of the New England Box Company dam on the Ashuelot River in Winchester, New Hampshire, in 2002 restored approximately fifteen miles of the river to free-flowing for the first time in one hundred years. The project was part of a river restoration plan intended to help bring back thousands of American shad, blueback herring, and Atlantic salmon to the river. As one of New Hampshire's major tributaries to the Connecticut River, the Ashuelot is historically important for migratory fish.
  • In March 2000 Judge Richard Hicks of the Thurston County Superior Court ruled that the Washington Department of Ecology had to implement a 1993 statute requiring metering of water use throughout the state. The implementation had to include both surface and groundwater. The water metering statute was adopted as part of a larger salmon recovery package and was seen as an essential element in the wise management of the state's water resources for both people and salmon. Metering is viewed as an effective way to get the basic information about who is using the water and how much.


After continual increases in U.S. total water withdrawals since the USGS began reporting in 1950, water use peaked in 1980, declined through 1990, and has remained relatively stable since then. (See Table 2.9, Figure 2.6, and Figure 2.7.) From 1995 to 2000 (the latest data available), a period that experienced a 7% increase in U.S. population, total off-stream water use increased only 2%. Water use for public supply increased by 8%, irrigation by 2%, and thermoelectric power use by 3%.

Hutson et al. state that the general increase in water use from 1950 to 1980 and the decrease from 1980 to 2000 can be attributed to several factors, including:

  • Expansion of irrigation systems and increases in energy development from 1950 to 1980.
  • The development and increasing use of two irrigation methodscenter-pivot irrigation systems and drip irrigation (the application of water directly to the roots of plants)that are more efficient in delivering water to crops than the traditional sprayer arms that project the water into the air, where much is lost to wind and evaporation.
  • Higher energy prices in the 1970s and a decrease in groundwater levels in some areas increased the cost of irrigation water.
  • A downturn in the farm economy in the 1980s, which reduced demands for irrigation water.
  • New industrial technologies requiring less water, improved efficiency, increased water recycling, higher energy prices, and changes in the law to reduce pollution.
  • Active conservation programs and increased awareness by the general public of the need to conserve water.
Water use trends, selected years 19502000
[In billion gallons per day (thousand million gallons per day); rounded to two significant figures for 195080, and to three significant figures for 19852000; percentage change is calculated from unrounded number]
YearPercentage change 19952000
a48 states and District of Columbia, and Hawaii.
b48 states and District of Columbia.
c50 states and District of Columbia, Puerto Rico, and U.S. Virgin Islands.
d50 states and District of Columbia, and Puerto Rico.
eFrom 1985 to present this category includes water use for fish farms.
fData not available for all states; partial total was 5.46.
gCommercial use not available; industrial and mining use totaled 23.2.
hData not available.
Source: Susan S. Hutson et al., "Table 14. Trends in Estimated Water Use in the United States, 19502000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, 2004, http://pubs.usgs.gov/circ/2004//circ1268/pdf/circular1268.pdf (accessed January 2, 2007) and revision data February 7, 2005, http://pubs.usgs.gov/circ/2004//circ1268/control/revisions.html (accessed January 2, 2007)
Population, in millions150.7164.0179.3193.8205.9216.4229.6242.4252.3267.1285.3+7
Offstream use:
    Total withdrawals180240270310370420440399408402408+2
    Public supply1417212427293436.538.540.243.2+8
Rural domestic and livestock:
Self-supplied domestic2.
Livestock and aquaculture1.
Thermoelectric-power use4072100130170200210187195190195+3
Other industrial use3739384647454530.529.929.1g
Source of water:


The usefulness and availability of water can fluctuate dramatically in natural systems. Both the quality and quantity of water resources need to be protected for the nation's present and future generations. Furthermore, even though current water use can be determined, total water needs for most uses are changing. Water use is dependent on prices, technology, customs, and regulations. As such, water use data are good indicators of where and how the nation consumes water, but they are not necessarily good predictors of future water use trends.

Although the United States is not running out of water, the era of free and easily developed water supplies has ended for much of the country; in some areas water use is approaching or has exceeded the available supply.

Projections of freshwater usage by use-category are presented by Thomas C. Brown in Past and Future Freshwater Use in the United States (December 1999, http://www.fs.fed.us/rm/pubs/rmrs_gtr039.pdf). According to Brown, by 2040 freshwater usage in the United States will reach 364 Bgal/d. This figure represents a 7% increase over the 1995 usage rate of 340 Bgal/d.

Brown's projections anticipate increased freshwater usage for livestock and domestic and public water services. (See Figure 2.8.) Water usage for thermoelectric generation will rise slightly. The dark bars in Figure 2.8 indicate past withdrawals and the light bars indicate future withdrawals (projected as of 1999). The dots show levels of related factors, with dark dots showing past levels and light dots future levels. The related factor and its scale is on the right.

Freshwater usage for livestock and domestic and public water services is projected to increase at about the same rate as the U.S. population. Water usage for thermoelectric generation will rise only slightly, even though the kilowatt hours generated will increase much more substantially. In 1995 freshwater withdrawals for thermoelectric use were 132 Bgal/d; in 2040 the withdrawals are estimated at 142 Bgal/d. Although water withdrawals per day are projected to be higher in 2040 than they were in 1995, the increased kilowatt hours produced will result in a decreasing water withdrawal per kilowatt hour of electricity that will be produced.

The quantity of water used by industry and for commercial applications is anticipated to remain stable through 2040. (See Figure 2.8.) David G. Lenze and Kathy Albetski report in "State Personal Income 2006" (March 27, 2007, http://www.bea.gov/newsreleases/regional/spi/2007/pdf/spi0307.pdf) that per capita income grew 5.2% in 2006, up from 4.2% in 2005. With continued annual growth in per capita income and with industrial and commercial withdrawals remaining stable, the result will be a decrease in water withdrawals for industrial and commercial uses per dollar of income.

Through 2040 the amount of irrigated acreage is expected to increase modestly, from 57.9 million acres in 1995 to 62.4 million acres in 2040. (See Figure 2.8.) Water withdrawals, however, are expected to decline modestly, from 134 Bgal/d in 1995 to 130 Bgal/d in 2040.

Overall, per capita freshwater withdrawals are projected to decline through 2040, although the net change will be an increase of about 7%. (See Figure 2.8.) Several factors are expected to contribute to the lower per capita freshwater usage rates. According to Brown, the two most prominent factors are improved efficiencies projected for the municipal, industrial, and thermoelectric generating sectors, and reduced irrigation withdrawals.

Increasing awareness among the traditional users of water and the general public of the finite nature of clean water supplies, particularly freshwater, has resulted in growing conservation efforts and innovative approaches to water conservation and reclamation. Water conservation is the careful use and protection of water resources. Water reclamation, also called water recycling, is the treatment of wastewater so that it can be reused for certain purposes, such as landscape irrigation.

Water Conservation

Water conservation and reclamation efforts take place all over the United States. The following are a few examples to show the types of activities that have been undertaken and their outcomes.

In "How We Can Do It" (Scientific American, February 2001), Diane Martindale and Peter H. Gleick describe a massive water conservation project undertaken in New York City. To prevent a pending water crisis in the early 1990s, New York City needed an extra ninety million gallons of water per day, about 7% of the city's total daily use. Faced with the need to raise $1 billion for a new pump station to bring additional water from the Hudson River, the city came up with a cheaper alternative: reduce the demand on the current supply. Using a three-year toilet rebate program, budgeted at $295 million for up to 1.5 million rebates, the city sought to replace about one-third of the existing toilets that used five gallons per flush with the water-saving models that did the same job with less than two gallons. By the end of the program in 1997, 1.3 million inefficient toilets in 110,000 buildings had been replaced with low-flow toilets. The result was about a 29% reduction in water use per building per year. The low-flow toilets were estimated to save about seventy to ninety Mgal/d.

New York City saved thirty to fifty Mgal/d of water from its leak detection program, two hundred Mgal/d from meter installation, and four Mgal/d from home inspections.

Concurrently, New York City had a water audit program under which property owners who wanted to reduce water use to keep bills down could request a free water efficiency survey from the company that oversaw the city's audit program. Inspectors checked for leaky plumbing, offered advice on retrofitting with water-efficient fixtures, and distributed low-flow showerheads and water-efficient faucet aerators. Low-flow showerheads use about half the water of the old units. Faucet aerators, which replace the screen in the faucet head and add air to the spray, can reduce the flow from four gallons per minute to one gallon per minute. The company made hundreds of thousands of these inspections, saving an estimated eleven Mgal/d of water.

Overall, the program shows that water conservation works. Per person water use in New York City dropped from 195 to 169 gallons per person per day between 1991 and 1999, even though the city's population continued to grow.

In Cases in Water Conservation: How Efficiency Programs Help Water Utilities Save Water and Avoid Costs (July 2002, http://www.epa.gov/watersense/docs/utilityconservation_508.pdf), the EPA reports on conservation methods and incentives adopted by New York City and sixteen other North American locations. Each location was beset by problems such as a strain on the water supply, unaccounted-for water loss, and water shortages. One of the more significant conservation efforts took place in Gallitzin, Pennsylvania. In the mid-1990s the Gallitzin Water Authority reported water losses exceeding 70%. After identifying the major problems (high water loss, recurring leaks, high overall operational costs, low-pressure complaints, and unstable water entering the distribution system), the water authority developed accurate water production and distribution records using seven-day meter readings at its water plant and pump systems. Then it developed a system map to locate leaks. A leak detector located 95% of leaks in the water system. After repairs were made there was an 87% drop in unaccounted-for water loss and savings of $5,000 on total chemical costs and $20,000 on total annual power costs from 1994 to 1998.

Water Reclamation

The water department in Tampa, Florida, has been working to maximize the yield from its water supply. The South Tampa Area Reclaimed water project featured the use of high-quality reclaimed water from the Howard F. Curran Wastewater Treatment Facility to satisfy the demands of high-volume irrigation users in South Tampa. Water would be made available through a water system that would be separate from the drinking water supply to prevent any possibility of cross contamination. The project began as a grassroots effort by Westshore residents concerned about future water supplies. Important conditions of the project were voluntary participation in it, only citizens who wanted reclaimed water would have to participate in the project, and user fees would make the project self-supporting.

In the first four months of the project sign-up, forty-five hundred homeowners and businesses enrolled. Construction of Phase I began in 2002 and was near completion in 2005 at a cost of $28 million. The first users began drawing water from the system in July 2004. Recommended uses for reclaimed water are crop irrigation, lawn and landscape watering, washing cars, and general cleaning. In "Fast Facts" (2007, http://www.tampagov.net/dept_water/starproject/Fast_Facts.asp), the water department estimates that when fully operational, Phase I would save more than 3.2 Mgal/d of potable water each day during the dry season, and additional phases are planned to extend the project to a wider geographical area.

The San Diego County Water Authority (2006, http://www.sdcwa.org/manage/recycled-facilities.phtml) operates the San Pasqual water reclamation plant, which is located in the San Pasqual Valley near Escondido, California. The purpose of the plant, which can treat up to one Mgal/d of water, is to supply reclaimed water to the community. The wastewater received at the treatment facility is treated to the primary level when solids are removed. The screened primary effluent is then fed into as many as twenty-four aquatic treatment ponds, where the wastewater is biologically stabilized. The ponds are stocked with water hyacinth, mosquito fish, crayfish, and other organisms to create an aquatic ecosystem that removes pollutants from wastewater. Water hyacinths grow quickly in the ponds. About 50% of the plants are harvested weekly from the ponds, dried for composting, and sold for reuse as a soil amendment. After the water passes through the aquatic treatment ponds, it is clarified, filtered, and disinfected for use in irrigation and research.

Water Crisis Looming in the West?

Table 2.10 shows cumulative estimates of population change for states and regions of the United States from 2000 to 2006. During this period the West was the fastest-growing portion of the country by percentage. However, the South was the region of the country that gained the most people. Thus, both the West and the South vie for first and second place as the fastest-growing regions of the United States.

Percentage-wise, Nevada (24.9%) was the state that grew the most from 2000 to 2006, followed by Arizona (20.2%), Georgia (14.4%), Utah (14.2%), Idaho (13.3%), Florida (13.2%), Texas (12.7%), Colorado (10.5%), North Carolina (10.1%), and Delaware (8.9%), respectively. (See Table 2.10.) The state that grew the most in numbers of new residents was Texas (2.6 million), followed by California (2.5 million), Florida (2.1 million), Georgia (1.1 million), Arizona (1 million), North Carolina (810,000), Virginia (564,000), Washington (501,000), Nevada (497,000), and Colorado (451,000), respectively. Louisiana lost population during this period, with much of that decline attributed to Hurricane Katrina and its aftermath.

According to the U.S. Bureau of the Census, in "Louisiana Loses Population; Arizona Edges Nevada as Fastest-Growing State" (December 22, 2006, http://www.census.gov/Press-Release/www/releases/archives/population/007910.html), Arizona was the fastest-growing state with its population growing 3.6% in 2006. Nevada was a close second with its population growing 3.5%. The West was the fastest-growing region that year; its population grew by 1.5%. The South was the next fastest-growing region with a population increase of 1.4% In contrast, the population increase in the Midwest was 0.4% and in the Northeast was 0.1%

In Interim State Population Projections, 2005 (April 21, 2005, http://www.census.gov/population/projections/PressTab7), Census Bureau projections show that population growth in the United States for the first thirty years of the twenty-first century will be concentrated in states in the West and South, especially Texas, Florida, Georgia, Washington, Arizona, Idaho, Oregon, Nevada, and North Carolina, which are expected to each experience at least a 40% gain in their populations by 2030. Florida alone is expected to leap by nearly thirteen million during this periodthe nation's biggest numerical gainfollowed closely by California and Texas. With the casino building boom in Las Vegas and the surrounding areas, Marc J. Perry and Paul J. Mackun note in "Population Change and Distribution, 1990 to 2000: Census 2000 Brief" (April 2001, http://www.census.gov/prod/2001 pubs/c2kbr01-2.pdf) that Nevada became the fastest-growing state in the 1990s and Las Vegas the fastest-growing metropolitan area. This population growth is expected to put enormous pressure on natural resources, including water, and to force huge changes in water consumption practices and prices.


As usable water becomes rarer because of increasing population and the pollution of water supplies, it is expected to become a commodity such as iron or oil. Peter Allison, in "World Overview: Water WarsThe Global Viewpoint" (2006, http://www.itt.com/waterbook/world.asp), states that "over 20 countries depend on the flow of water from other nations for much of their supply. And more than 300 of the world's river basins are shared by two or more countries." All are potential objects of world political power struggles over this critical resource.

Africa, the Middle East, and South Asia are three areas of the world that are particularly short of water. Other dry areas include the southwest of North America, limited areas in South America, and large parts of Australia.

The rivers in the Middle East are the lifeblood of an arid region. Freshwater has never come easily to this area. Rainfall occurs only in winter and drains quickly through the parched land. Most Middle Eastern countries are joined by common aquifers. The United Nations cautions that future wars in the Middle East can be fought over water.

Since April 2001 tensions between Israel and Lebanon have been escalating over the Lebanese construction of a pumping station along the Hasbani River. The Has-bani flows into the Sea of Galilee, which is Israel's primary freshwater reservoir. In 2001 Israel was undergoing a water crisis, and the sea was at its lowest level ever. Tensions periodically arise as droughts tighten supply in the area, but since mid-2005 the tensions between Israel and Lebanon regarding Lebanon's pumping of water from the Hasbani River have been handled diplomatically, with the assistance of the European Union and the United Nations.

TABLE 2.10
Estimates of population change by region, state, and Puerto Rico, 200006
Geographic areaPopulation estimatesChange, 2000 to 2006National ranking of states
July 1, 2006April 1, 2000 estimates baseNumberPercentPopulation estimatesChange, 2000 to 2006
July 1, 2006April 1, 2000 estimates baseNumberPercent
Note: The April 1, 2000 population estimates base reflects changes to the Census 2000 population from the count question resolution program and geographic program revisions. (X) Not applicable.
Source: "Table 2. Cumulative Estimates of Population Change for the United States, Regions, States and Puerto Rico and Region and State Rankings: April 1, 2000 to July 1, 2006," U.S. Census Bureau, Population Division, December 22, 2006, http://www.census.gov/popest/states/tables/NST-EST2006-02.xls (accessed January 2, 2007)
United States299,398,484281,424,60217,973,8826.4(X)(X)(X)(X)
District of Columbia581,530572,0599,4711.750504944
New Hampshire1,314,8951,235,78679,1096.441413418
New Jersey8,724,5608,414,347310,2133.71191630
New Mexico1,954,5991,819,046135,5537.536362916
New York19,306,18318,976,821329,3621.7331343
North Carolina8,856,5058,046,491810,01410.1101169
North Dakota635,867642,2006,3331.048475050
Rhode Island1,067,6101,048,31919,2911.843434642
South Carolina4,321,2494,011,816309,4337.724261714
South Dakota781,919754,84427,0753.646464433
West Virginia1,818,4701,808,35010,1200.637374849
Puerto Rico3,927,7763,808,603119,1733.1(X)(X)(X)(X)

The oil-rich Middle Eastern nation of Kuwait has little water, but it has the money to secure it. To use seawater, Kuwait has constructed six large-scale, oil-powered desalination plants. According to the U.S. Commercial Service, in "Water Resources Equipment (WRE)" (2007, http://www.buyusa.gov/saudiarabia/en/113.html), Saudi Arabia leads the world in desalination. In 2007 its thirty plants produced 30% of all the desalinated water in the world.

Water quality and water shortages are just two of the problems facing the world in the years to come. The September 11, 2001, terrorist attacks in the United States increased concerns about bioterrorism. On June 12, 2002, Congress passed the Public Health Security and Bioter-rorism Act of 2002. Title IV of the act (Drinking Water Security and Safety) mandates that every community water system that serves a population of more than thirty-three hundred people must:

  • Conduct a vulnerability assessment.
  • Certify and submit a copy of the assessment to the EPA administrator.
  • Prepare or revise an emergency response plan that incorporates the results of the vulnerability assessment.
  • Certify to the EPA administrator, within six months of completing the vulnerability assessment, that the system has completed or updated its emergency response plan.