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.

FRESHWATER AVAILABILITY

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 2006—In 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.

HOW WATER IS SUPPLIED

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.

TYPES OF WATER USE IN THE UNITED STATES

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 source—usually a river or stream—and 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.

TABLE 2.1
Total water use by source and state, 2000
[Figures may not sum to totals because of independent rounding]
State	Population (in thousands)	Withdrawals (in million gallons per day)									Withdrawals (in thousand acre-feet per year)
		By source and type						Total			Withdrawals (in thousand acre-feet per year)
		Groundwater			Surface water			Total			Total
		Fresh	Saline	Total	Fresh	Saline	Total	Fresh	Saline	Total	Fresh	Saline	Total
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)
Alabama	4,450	440	0	440	9,550	0	9,550	9,990	0	9,990	11,200	0	11,200
Alaska	627	50.2	90.4	141	111	53.4	164	161	144	305	181	161	342
Arizona	5,130	3,420	8.17	3,430	3,300	0	3,300	6,720	8.17	6,730	7,530	9.16	7,540
Arkansas	2,670	6,920	.08	6,920	3,950	0	3,950	10,900	.08	10,900	12,200	.09	12,200
California	33,900	15,20	0152	15,400	23,200	12,600	35,800	38,400	12,800	51,200	43,100	14,300	57,400
Colorado	4,300	2,320	0	2,320	10,300	0	10,300	12,600	0	12,600	14,200	0	14,200
Connecticut	3,410	143	0	143	565	3,440	4,010	708	3,440	4,150	794	3,860	4,650
Delaware	784	115	0	115	466	741	1,210	582	741	1,320	652	831	1,480
District of Columbia	572	0	0	0	9.87	0	9.87	9.87	0	9.87	11.1	0	11.1
Florida	16,000	5,020	0	5,020	3,110	12,000	15,100	8,140	12,000	20,100	9,120	13,400	22,500
Georgia	8,190	1,450	0	1,450	4,960	91.7	5,060	6,410	91.7	6,500	7,190	103	7,290
Hawaii	1,210	433	.85	434	208	0	208	640	.85	641	718	.95	719
Idaho	1,290	4,140	0	4,140	15,300	0	15,300	19,500	0	19,500	21,800	0	21,800
Illinois	12,400	813	0	813	12,900	0	12,900	13,700	0	13,700	15,400	0	15,400
Indiana	6,080	656	0	656	9,460	0	9,460	10,100	0	10,100	11,300	0	11,300
Iowa	2,930	679	0	679	2,680	0	2,680	3,360	0	3,360	3,770	0	3,770
Kansas	2,690	3,790	0	3,790	2,820	0	2,820	6,610	0	6,610	7,410	0	7,410
Kentucky	4,040	189	0	189	3,970	0	3,970	4,160	0	4,160	4,660	0	4,660
Louisiana	4,470	1,630	0	1,630	8,730	0	8,730	10,400	0	10,400	11,600	0	11,600
Maine	1,270	80.8	0	80.8	423	295	718	504	295	799	565	330	895
Maryland	5,300	225	0	225	1,200	6,490	7,690	1,430	6,490	7,910	1,600	7,270	8,870
Massachusetts	6,350	269	0	269	783	3,610	4,390	1,050	3,610	4,660	1,180	4,050	5,220
Michigan	9,940	734	0	734	9,260	0	9,260	10,000	0	10,000	11,200	0	11,200
Minnesota	4,920	720	0	720	3,150	0	3,150	3,870	0	3,870	4,340	0	4,340
Mississippi	2,840	2,180	0	2,180	632	148	781	2,810	148	2,960	3,150	166	3,320
Missouri	5,600	1,780	0	1,780	6,450	0	6,450	8,230	0	8,230	9,220	0	9,220
Montana	902	188	0	188	8,100	0	8,100	8,290	0	8,290	9,300	0	9,300
Nebraska	1,710	7,860	4.55	7,860	4,390	0	4,390	12,200	4.55	12,300	13,700	5.10	13,700
Nevada	2,000	757	0	757	2,050	0	2,050	2,810	0	2,810	3,140	0	3,140
New Hampshire	1,240	85.2	0	85.2	362	761	1,120	447	761	1,210	501	854	1,350
New Jersey	8,410	584	0	584	1,590	3,390	4,980	2,170	3,390	5,560	2,430	3,800	6,230
New Mexico	1,820	1,540	0	1,540	1,710	0	1,710	3,260	0	3,260	3,650	0	3,650
New York	19,000	893	0	893	6,190	5,010	11,200	7,080	5,010	12,100	7,940	5,610	13,600
North Carolina	8,050	580	0	580	9,150	1,620	10,800	9,730	1,620	11,400	10,900	1,810	12,700
North Dakota	642	123	0	123	1,020	0	1,020	1,140	0	1,140	1,280	0	1,280
Ohio	11,400	878	0	878	10,300	0	10,300	11,100	0	11,100	12,500	0	12,500
Oklahoma	3,450	771	256	1,030	990	0	990	1,760	256	2,020	1,970	287	2,260
Oregon	3,420	993	0	993	5,940	0	5,940	6,930	0	6,930	7,770	0	7,770
Pennsylvania	12,300	666	0	666	9,290	0	9,290	9,950	0	9,950	11,200	0	11,200
Rhode Island	1,050	28.6	0	28.6	110	290	400	138	290	429	155	326	481
South Carolina	4,010	330	0	330	6,840	0	6,840	7,170	0	7,170	8,040	0	8,040
South Dakota	755	222	0	222	306	0	306	528	0	528	592	0	592
Tennessee	5,690	417	0	417	10,400	0	10,400	10,800	0	10,800	12,100	0	12,100
Texas	20,900	8,470	504	8,970	16,300	4,350	20,700	24,800	4,850	29,600	27,800	5,440	33,200
Utah	2,230	1,020	26.5	1,050	3,740	177	3,920	4,760	203	4,970	5,340	228	5,570
Vermont	609	43.2	0	43.2	404	0	404	447	0	447	501	0	501
Virginia	7,080	314	0	314	4,880	3,640	8,520	5,200	3,640	8,830	5,830	4,080	9,900
Washington	5,890	1,47	0	0	1,470	3,800	39.9	3,840	5,270	39.9	5,310	5,910	44.7 5,960
West Virginia	1,810	90.9	0	90.9	5,060	0	5,060	5,150	0	5,150	5,770	0	5,770
Wisconsin	5,360	813	0	813	6,780	0	6,780	7,590	0	7,590	8,510	0	8,510
Wyoming	494	541	222	763	4,400	0	4,400	4,940	222	5,170	5,540	248	5,790
Puerto Rico	3,810	137	0	137	483	2,190	2,670	620	2,190	2,810	695	2,460	3,150
U.S. Virgin Islands	109	1.03	0	1.03	10.6	136	147	11.6	136	148	13.0	153	166
Total	285,000	83,300	1,260	84,500	262,000	61,000	323,000	345,000	62,300	408,000	387,000	69,800	457,000

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

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.

TABLE 2.2
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.]
State	Public supply	Domestic	Irrigation	Live-stock	Aqua-culture	Industrial		Mining		Thermoelectric power		Total
State	Fresh	Fresh	Fresh	Fresh	Fresh	Fresh	Saline	Fresh	Saline	Fresh	Saline	Fresh	Saline	Total
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)
Alabama	834	78.9	43.1	—	10.4	833	0	—	—	8,190	0	9,990	0	9,990
Alaska	80.0	11.2	1.01	—	—	8.12	3.86	27.4	140	33.6	0	161	144	305
Arizona	1,080	28.9	5,400	—	—	19.8	0	85.7	8.17	100	0	6,720	8.17	6,730
Arkansas	421	28.5	7,910	—	198	134	.08	2.78	0	2,180	0	10,900	.08	10,900
California	6,120	286	30,500	409	537	188	13.6	23.7	153	352	12,600	38,400	12,800	51,200
Colorado	899	66.8	11,400	—	—	120	0	—	—	138	0	12,600	0	12,600
Connecticut	424	56.2	30.4	—	—	10.7	0	—	—	187	3,440	708	3,440	4,150
Delaware	94.9	13.3	43.5	3.92	.07	59.4	3.25	—	—	366	738	582	741	1,320
District of Columbia	0	0	.18	—	—	0	0	—	—	9.69	0	9.87	0	9.87
Florida	2,440	199	4,290	32.5	8.02	291	1.18	217	0	658	12,000	8,140	12,000	20,100
Georgia	1,250	110	1,140	19.4	15.4	622	30	9.80	0	3,250	61.7	6,410	91.7	6,500
Hawaii	250	12.0	364	—	—	14.5	.85	—	—	0	0	640	.85	641
Idaho	244	85.2	17,100	34.9	1,970	55.5	0	—	—	0	0	19,500	0	19,500
Illinois	1,760	135	154	37.6	—	391	0	—	—	11,300	0	13,700	0	13,700
Indiana	670	122	101	41.9	—	2,400	0	82.5	0	6,700	0	10,100	0	10,100
Iowa	383	33.2	21.5	109	—	237	0	32.8	0	2,540	0	3,360	0	3,360
Kansas	416	21.6	3,710	111	5.60	53.3	0	31.4	0	2,260	0	6,610	0	6,610
Kentucky	525	27.5	29.3	—	—	317	0	—	—	3,260	0	4,160	0	4,160
Louisiana	753	41.2	1,020	7.34	243	2,680	0	—	—	5,610	0	10,400	0	10,400
Maine	102	35.7	5.84	—	—	247	0	—	—	113	295	504	295	799
Maryland	824	77.1	42.4	10.4	19.6	65.8	227	8.31	.02	379	6,260	1,430	6,490	7,910
Massachusetts	739	42.2	126	—	—	36.8	0	—	—	108	3,610	1,050	3,610	4,660
Michigan	1,140	239	201	11.3	—	698	0	—	—	7,710	0	10,000	0	10,000
Minnesota	500	80.8	227	52.8	—	154	0	588	0	2,270	0	3,870	0	3,870
Mississippi	359	69.3	1,410	—	371	242	0	—	—	362	148	2,810	148	2,960
Missouri	872	53.6	1,430	72.4	83.3	62.7	0	16.9	0	5,640	0	8,230	0	8,230
Montana	149	18.6	7,950	—	—	61.3	0	—	—	110	0	8,290	0	8,290
Nebraska	330	48.4	8,790	93.4	—	38.1	0	128	4.55	2,820	0	12,200	4.55	12,300
Nevada	629	22.4	2,110	—	—	10.3	0	—	—	36.7	0	2,810	0	2,810
New Hampshire	97.1	41.0	4.75	—	16.3	44.9	0	6.8	0	236	761	447	761	1,210
New Jersey	1,050	79.7	140	1.68	6.46	132	0	110	0	650	3,390	2,170	3,390	5,560
New Mexico	296	31.4	2,860	—	—	10.5	0	—	—	56.4	0	3,260	0	3,260
New York	2,570	142	35.5	—	—	297	0	—	—	4,040	5,010	7,080	5,010	12,100
North Carolina	945	189	287	121	7.88	293	0	36.4	0	7,850	1,620	9,730	1,620	11,400
North Dakota	63.6	11.9	145	—	—	17.6	0	—	—	902	0	1,140	0	1,140
Ohio	1,470	134	31.7	25.3	1.36	807	0	88.5	0	8,590	0	11,100	0	11,100
Oklahoma	675	25.5	718	151	16.4	25.9	0	2.48	256	146	0	1,760	256	2,020
Oregon	566	76.2	6,080	—	—	195	0	—	—	15.3	0	6,930	0	6,930
Pennsylvania	1,460	132	13.9	—	—	1,190	0	182	0	6,980	0	9,950	0	9,950
Rhode Island	119	8.99	3.45	—	—	4.28	0	—	—	2.40	290	138	290	429
South Carolina	566	63.5	267	—	—	565	0	—	—	5,710	0	7,170	0	7,170
South Dakota	93.3	9.53	373	42.0	—	5.12	0	—	—	5.24	0	528	0	528
Tennessee	890	32.6	22.4	—	—	842	0	—	—	9,040	0	10,800	0	10,800
Texas	4,230	131	8,630	308	—	1,450	907	220	504	9,820	3,440	24,800	4,850	29,600
Utah	638	16.1	3,860	—	116	42.7	5.08	26.3	198	62.2	0	4,760	203	4,970
Vermont	60.1	21.0	3.78	—	—	6.91	0	—	—	355	0	447	0	447
Virginia	720	133	26.4	—	—	470	53.3	—	—	3,850	3,580	5,200	3,640	8,830
Washington	1,020	125	3,040	—	—	577	39.9	—	—	519	0	5,270	39.9	5,310
West Virginia	190	40.4	.04	—	—	968	0	—	—	3,950	0	5,150	0	5,150
Wisconsin	623	96.3	196	66.3	70.2	447	0	—	—	6,090	0	7,590	0	7,590
Wyoming	107	6.57	4,500	—	—	5.78	0	79.5	222	243	0	4,940	222	5,170
Puerto Rico	513	.88	94.5	—	—	11.2	0	—	—	0	2,190	620	2,190	2,810
U.S. Virgin Islands	6.09	1.69	.50	—	—	3.34	0	—	—	0	136	11.6	136	148
Total	43,300	3,590	137,000	1,760	3,700	18,500	1,280	2,010	1,490	136,000	59,500	345,000	62,300	408,000

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.

TABLE 2.3
Public supply water use, 2000
[Figures may not sum to totals because of independent rounding]
State	Population (in thousands)			Withdrawals (in million gallons per day)			Withdrawals (in thousand acre-feet per year)
	Total	Served by public supply		By source		Total	By source		Total
	Total	Population	Population (in percent)	Ground-water	Surface water	Total	Ground-water	Surface water	Total
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)
Alabama	4,450	3,580	80	281	553	834	315	620	935
Alaska	627	421	67	29.3	50.7	80.0	32.9	56.9	89.7
Arizona	5,130	4,870	95	469	613	1,080	526	688	1,210
Arkansas	2,670	2,320	87	132	289	421	148	324	472
California	33,900	30,100	89	2,800	3,320	6,120	3,140	3,730	6,860
Colorado	4,300	3,750	87	53.7	846	899	60.2	948	1,010
Connecticut	3,410	2,660	78	66.0	358	424	74.0	402	476
Delaware	784	617	79	45.0	49.8	94.9	50.5	55.9	106
District of Columbia	572	572	100	0	0	0	0	0	0
Florida	16,000	14,000	88	2,200	237	2,440	2,470	266	2,730
Georgia	8,190	6,730	82	278	968	1,250	311	1,090	1,400
Hawaii	1,210	1,140	94	243	7.60	250	272	8.52	281
Idaho	1,290	928	72	219	25.3	244	245	28.3	274
Illinois	12,400	10,900	88	353	1,410	1,760	396	1,580	1,970
Indiana	6,080	4,480	74	345	326	670	386	365	751
Iowa	2,930	2,410	83	303	79.8	383	340	89.5	429
Kansas	2,690	2,500	93	172	244	416	193	273	466
Kentucky	4,040	3,490	86	71.0	455	525	79.5	510	589
Louisiana	4,470	3,950	88	349	404	753	392	453	844
Maine	1,270	726	57	29.6	72.5	102	33.2	81.3	115
Maryland	5,300	4,360	82	84.6	740	824	94.8	829	924
Massachusetts	6,350	5,880	93	197	542	739	220	608	828
Michigan	9,940	7,170	72	247	896	1,140	277	1,000	1,280
Minnesota	4,920	3,770	77	329	171	500	369	192	561
Mississippi	2,840	2,190	77	319	40.4	359	357	45.3	402
Missouri	5,600	4,770	85	278	594	872	311	666	978
Montana	902	664	74	56.1	92.4	149	62.9	104	167
Nebraska	1,710	1,390	81	266	63.8	330	299	71.6	370
Nevada	2,000	1,870	94	151	478	629	169	536	705
New Hampshire	1,240	756	61	33.0	64.1	97.1	37.0	71.9	109
New Jersey	8,410	7,460	89	400	650	1,050	449	729	1,180
New Mexico	1,820	1,460	80	262	33.8	296	294	37.9	332
New York	19,000	17,100	90	583	1,980	2,570	653	2,220	2,880
North Carolina	8,050	5,350	66	166	779	945	186	873	1,060
North Dakota	642	493	77	32.4	31.2	63.6	36.3	35.0	71.3
Ohio	11,400	9,570	84	500	966	1,470	560	1,080	1,640
Oklahoma	3,450	3,150	91	113	562	675	127	631	757
Oregon	3,420	2,730	80	118	447	566	133	501	634
Pennsylvania	12,300	10,100	82	212	1,250	1,460	237	1,400	1,640
Rhode Island	1,050	922	88	16.9	102	119	19.0	115	134
South Carolina	4,010	3,160	79	105	462	566	117	517	635
South Dakota	755	625	83	54.2	39.1	93.3	60.7	43.9	105
Tennessee	5,690	5,240	92	321	569	890	360	638	997
Texas	20,900	19,700	94	1,260	2,970	4,230	1,420	3,330	4,740
Utah	2,230	2,180	97	364	274	638	408	307	715
Vermont	609	362	59	19.5	40.6	60.1	21.8	45.6	67.4
Virginia	7,080	5,310	75	70.7	650	720	79.3	728	808
Washington	5,890	4,900	83	464	552	1,020	520	619	1,140
West Virginia	1,810	1,300	72	41.6	149	190	46.6	167	213
Wisconsin	5,360	3,620	67	330	293	623	370	329	699
Wyoming	494	406	82	57.2	49.4	107	64.1	55.3	119
Puerto Rico	3,810	3,800	100	88.5	425	513	99.2	476	576
U.S. Virgin Islands	109	53.4	49	.52	5.57	6.09	.58	6.24	6.83
Total	285,000	242,000	85	16,000	27,300	43,300	17,900	30,600	48,500

DOMESTIC USE

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

Aquaculture is the practice of raising animals that live in water—such as finfish and shellfish—for 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.

IRRIGATION

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.)

TABLE 2.4
Water use for aquaculture, 2000
[Figures may not sum to totals because of independent rounding]
State	Withdrawals (in million gallons per day)			Withdrawals (in thousand acre-feet per year)
	By source		Total		By source	Total
	Groundwater	Surface water	Total		Groundwater	Total	Surface 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)
Alabama	8.93	1.44	10.4	10.0	1.61	11.6
Alaska	—	—	—	—	—	—
Arizona	—	—	—	—	—	—
Arkansas	187	10.4	198	210	11.6	222
California	158	380	537	177	426	603
Colorado	—	—	—	—	—	—
Connecticut	—	—	—	—	—	—
Delaware	.07	0	.07	.08	0	.08
District of Columbia	—	—	—	—	—	—
Florida	7.81	.21	8.02	8.76	.24	8.99
Georgia	7.70	7.72	15.4	8.63	8.65	17.3
Hawaii	—	—	—	—	—	—
Idaho	51.5	1,920	1,970	57.7	2,150	2,210
Illinois	—	—	—	—	—	—
Indiana	—	—	—	—	—	—
Iowa	—	—	—	—	—	—
Kansas	3.33	2.27	5.60	3.73	2.54	6.28
Kentucky	—	—	—	—	—	—
Louisiana	128	115	243	144	129	273
Maine	—	—	—	—	—	—
Maryland	4.81	14.8	19.6	5.39	16.6	22.0
Massachusetts	—	—	—	—	—	—
Michigan	—	—	—	—	—	—
Minnesota	—	—	—	—	—	—
Mississippi	321	49.8	371	360	55.9	416
Missouri	2.01	81.3	83.3	2.25	91.2	93.4
Montana	—	—	—	—	—	—
Nebraska	—	—	—	—	—	—
Nevada	—	—	—	—	—	—
New Hampshire	3.12	13.1	16.3	3.50	14.7	18.2
New Jersey	6.46	0	6.46	7.24	0	7.24
New Mexico	—	—	—	—	—	—
New York	—	—	—	—	—	—
North Carolina	7.88	0	7.88	8.83	0	8.83
North Dakota	—	—	—	—	—	—
Ohio	1.36	0	1.36	1.52	0	1.52
Oklahoma	.29	16.1	16.4	.33	18.1	18.4
Oregon	—	—	—	—	—	—
Pennsylvania	—	—	—	—	—	—
Rhode Island	—	—	—	—	—	—
South Carolina	—	—	—	—	—	—
South Dakota	—	—	—	—	—	—
Tennessee	—	—	—	—	—	—
Texas	—	—	—	—	—	—
Utah	116	0	116	130	0	130
Vermont	—	—	—	—	—	—
Virginia	—	—	—	—	—	—
Washington	—	—	—	—	—	—
West Virginia	—	—	—	—	—	—
Wisconsin	39.8	30.4	70.2	44.6	34.1	78.7
Wyoming	—	—	—	—	—	—
Puerto Rico	—	—	—	—	—	—
U.S. Virgin Islands	—	—	—	—	—	—
Total	1,060	2,640	3,700	1,180	2,960	4,150

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.

TABLE 2.5
Acres of land being irrigated by state, 2000
[Figures may not sum to totals because of independent rounding]
State	Irrigated land (in thousand acres)				Withdrawals (in million gallons per day)
	By type of irrigation			Total	By source		Total
	Sprinkler	Micro-irrigation	Surface	Total	Groundwater	Surface water	Total
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)
Alabama	68.7	1.30	0	70.0	14.5	28.7	43.1
Alaska	2.43	0	.07	2.50	.99	.02	1.01
Arizona	183	14.0	779	976	2,750	2,660	5,400
Arkansas	631	0	3,880	4,510	6,510	1,410	7,910
California	1,660	3,010	5,470	10,100	11,600	18,900	30,500
Colorado	1,190	1.16	2,220	3,400	2,160	9,260	11,400
Connecticut	20.6	.39	0	21.0	17.0	13.4	30.4
Delaware	81.1	.71	0	81.8	35.6	7.89	43.5
District of Columbia	.32 0	0	0	.32	0	.18	.18
Florida	515	704	839	2,060	2,180	2,110	4,290
Georgia	1,470	73.8	0	1,540	750	392	1,140
Hawaii	16.7	105	0	122	171	193	364
Idaho	2,440	4.70	1,300	3,750	3,720	13,300	17,100
Illinois	365	0	0	365	150	4.25	154
Indiana	250	0	0	250	55.5	45.4	101
Iowa	84.5	0	0	84.5	20.4	1.08	21.5
Kansas	2,660	2.14	647	3,310	3,430	288	3,710
Kentucky	66.6	0	0	66.6	1.14	28.2	29.3
Louisiana	110	0	830	940	791	232	1,020
Maine	35.0	.95	.03	36.0	.61	5.23	5.84
Maryland	57.3	3.32	0	60.6	29.8	12.6	42.4
Massachusetts	26.6	2.35	0	29.0	19.7	106	126
Michigan	401	8.67	4.87	415	128	73.2	201
Minnesota	546	0	26.9	573	190	36.6	227
Mississippi	455	0	966	1,420	1,310	99.1	1,410
Missouri	532	1.43	792	1,330	1,380	48.1	1,430
Montana	506	0	1,220	1,720	83.0	7,870	7,950
Nebraska	4,110	0	3,710	7,820	7,420	1,370	8,790
Nevada	192	0	456	647	567	1,540	2,110
New Hampshire	6.08	0		6.08	.50	4.25	4.75
New Jersey	109	15.7	3.70	128	22.8	117	140
New Mexico	461	7.17	530	998	1,230	1,630	2,860
New York	70.0	8.73	1.84	80.6	23.3	12.1	35.5
North Carolina	193	3.70	0	196	65.8	221	287
North Dakota	200	0	26.7	227	72.2	73.2	145
Ohio	61.0	0	0	61.0	13.9	17.8	31.7
Oklahoma	392	1.50	113	507	566	151	718
Oregon	1,160	4.02	1,000	2,170	792	5,290	6,080
Pennsylvania	28.9	7.17	0	36.0	1.38	12.5	13.9
Rhode Island	4.48	.29	.05	4.82	.46	2.99	3.45
South Carolina	166	3.66	17.5	187	106	162	267
South Dakota	276	0	78.3	354	137	236	373
Tennessee	51.2	5.35	3.96	60.5	7.33	15.1	22.4
Texas	4,010	89.4	2,390	6,490	6,500	2,130	8,630
Utah	526	1.68	880	1,410	469	3,390	3,860
Vermont	4.95	0	0	4.95	.33	3.45	3.78
Virginia	64.3	13.9	0	78.2	3.57	22.8	26.4
Washington	1,270	49.9	252	1,570	747	2,290	3,040
West Virginia	2.21	0	.98	3.19	.02	.02	.04
Wisconsin	355	0	0	355	195	1.57	196
Wyoming	190	4.73	964	1,160	413	4,090	4,500
Puerto Rico	15.5	33.0	5.35	53.8	36.9	57.5	94.5
U.S. Virgin Islands	.20	0	0	.20	.29	.21	.50
Total	28,300	4,180	29,400	61,900	56,900	80,000	137,000

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

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.)

INDUSTRIAL

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.

TABLE 2.6
Water use for livestock by state, 2000
[Figures may not sum to totals because of independent rounding]
State	Withdrawals (in million gallons per day)			Withdrawals (in thousand acre-feet per year)
	By source		Total	By source		Total
	Groundwater	Surface water	Total	Groundwater	Surface water	Total
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)
Alabama	—	—	—	—	—	—
Alaska	—	—	—	—	—	—
Arizona	—	—	—	—	—	—
Arkansas	—	—	—	—	—	—
California	182	227	409	204	255	458
Colorado	—	—	—	—	—	—
Connecticut	—	—	—	—	—	—
Delaware	3.70	.22	3.92	4.15	.25	4.39
District of Columbia	—	—	—	—	—	—
Florida	31.0	1.51	32.5	34.7	1.69	36.4
Georgia	1.66	17.7	19.4	1.86	19.9	21.7
Hawaii	—	—	—	—	—	—
Idaho	27.7	7.20	34.9	31.0	8.07	39.1
Illinois	37.6	0	37.6	42.1	0	42.1
Indiana	27.3	14.6	41.9	30.6	16.4	47.0
Iowa	81.8	27.1	109	91.8	30.4	122
Kansas	87.2	23.5	111	97.7	26.3	124
Kentucky	—	—	—	—	—	—
Louisiana	4.03	3.31	7.34	4.52	3.71	8.23
Maine	—	—	—	—	—	—
Maryland	7.18	3.18	10.4	8.05	3.56	11.6
Massachusetts	—	—	—	—	—	—
Michigan	10.2	1.15	11.3	11.4	1.29	12.7
Minnesota	52.8	0	52.8	59.2	0	59.2
Mississippi	—	—	—	—	—	—
Missouri	18.3	54.1	72.4	20.5	60.6	81.1
Montana	—	—	—	—	—	—
Nebraska	76.0	17.4	93.4	85.2	19.5	105
Nevada	—	—	—	—	—	—
New Hampshire	—	—	—	—	—	—
New Jersey	1.68	0	1.68	1.88	0	1.88
New Mexico	—	—	—	—	—	—
New York	—	—	—	—	—	—
North Carolina	89.1	32.3	121	99.9	36.2	136
North Dakota	—	—	—	—	—	—
Ohio	8.20	17.1	25.3	9.19	19.2	28.4
Oklahoma	53.6	97.2	151	60.0	109	169
Oregon	—	—	—	—	—	—
Pennsylvania	—	—	—	—	—	—
Rhode Island	—	—	—	—	—	—
South Carolina	—	—	—	—	—	—
South Dakota	16.9	25.2	42.0	18.9	28.2	47.1
Tennessee	—	—	—	—	—	—
Texas	137	172	308	153	192	346
Utah	—	—	—	—	—	—
Vermont	—	—	—	—	—	—
Virginia	—	—	—	—	—	—
Washington	—	—	—	—	—	—
West Virginia	—	—	—	—	—	—
Wisconsin	60.3	6.02	66.3	67.6	6.75	74.4
Wyoming	—	—	—	—	—	—
Puerto Rico	—	—	—	—	—	—
U.S. Virgin Islands	—	—	—	—	—	—
Total	1,010	747	1,760	1,140	838	1,980

MINING

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).

TABLE 2.7
Industrial water use by state, 2000
[Figures may not sum to totals because of independent rounding]
State	Withdrawals (in million gallons per day)									Withdrawals (in thousand acre-feet per year)
	By source and type						Total			Withdrawals (in thousand acre-feet per year)
	Groundwater			Surface water			Total			By type
	Fresh	Saline	Total	Fresh	Saline	Total	Fresh	Saline	Total	Fresh	Saline	Total
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)
Alabama	56.0	0	56.0	777	0	777	833	0	833	934	0	934
Alaska	4.32	0	4.32	3.80	3.86	7.66	8.12	3.86	12.0	9.10	4.33	13.4
Arizona	19.8	0	19.8	0	0	0	19.8	0	19.8	22.2	0	22.2
Arkansas	67.0	.08	67.1	66.8	0	66.8	134	.08	134	150	.09	150
California	183	0	183	5.65	13.6	19.3	188	13.6	202	211	15.3	226
Colorado	23.6	0	23.6	96.4	0	96.4	120	0	120	135	0	135
Connecticut	4.13	0	4.13	6.61	0	6.61	10.7	0	10.7	12.0	0	12.0
Delaware	17.0	0	17.0	42.5	3.25	45.7	59.4	3.25	62.7	66.6	3.64	70.3
District of Columbia	0	0	0	0	0	0	0	0	0	0	0	0
Florida	216	0	216	74.7	1.18	75.9	291	1.18	292	326	1.32	328
Georgia	290	0	290	333	30	363	622	30.0	652	698	33.6	731
Hawaii	14.5	.85	15.4	0	0	0	14.5	.85	15.4	16.2	0.95	17.2
Idaho	35.8	0	35.8	19.7	0	19.7	55.5	0	55.5	62.2	0	62.2
Illinois	132	0	132	259	0	259	391	0	391	438	0	438
Indiana	99.7	0	99.7	2,300	0	2,300	2,400	0	2,400	2,690	0	2,690
Iowa	226	0	226	11.7	0	11.7	237	0	237	266	0	266
Kansas	46.6	0	46.6	6.74	0	6.74	53.3	0	53.3	59.8	0	59.8
Kentucky	95.2	0	95.2	222	0	222	317	0	317	356	0	356
Louisiana	285	0	285	2,400	0	2,400	2,680	0	2,680	3,010	0	3,010
Maine	9.90	0	9.90	237	0	237	247	0	247	277	0	277
Maryland	15.9	0	15.9	49.9	227	277	65.8	227	292	73.8	254	328
Massachusetts	10.7	0	10.7	26.2	0	26.2	36.8	0	36.8	41.3	0	41.3
Michigan	110	0	110	589	0	589	698	0	698	782	0	782
Minnesota	56.3	0	56.3	97.8	0	97.8	154	0	154	173	0	173
Mississippi	118	0	118	124	0	124	242	0	242	271	0	271
Missouri	29.2	0	29.2	33.5	0	33.5	62.7	0	62.7	70.3	0	70.3
Montana	31.9	0	31.9	29.3	0	29.3	61.3	0	61.3	68.7	0	68.7
Nebraska	35.5	0	35.5	2.60	0	2.60	38.1	0	38.1	42.7	0	42.7
Nevada	5.29	0	5.29	5.00	0	5.00	10.3	0	10.3	11.5	0	11.5
New Hampshire	6.95	0	6.95	37.9	0	37.9	44.9	0	44.9	50.3	0	50.3
New Jersey	65.3	0	65.3	66.2	0	66.2	132	0	132	147	0	147
New Mexico	8.80	0	8.80	1.67	0	1.67	10.5	0	10.5	11.7	0	11.7
New York	145	0	145	152	0	152	297	0	297	333	0	333
North Carolina	25.6	0	25.6	267	0	267	293	0	293	329	0	329
North Dakota	6.88	0	6.88	10.7	0	10.7	17.6	0	17.6	19.7	0	19.7
Ohio	162	0	162	645	0	645	807	0	807	905	0	905
Oklahoma	6.83	0	6.83	19.1	0	19.1	25.9	0	25.9	29.1	0	29.1
Oregon	12.1	0	12.1	183	0	183	195	0	195	218	0	218
Pennsylvania	155	0	155	1,030	0	1,030	1,190	0	1,190	1,330	0	1,330
Rhode Island	2.19	0	2.19	2.09	0	2.09	4.28	0	4.28	4.80	0	4.80
South Carolina	50.9	0	50.9	514	0	514	565	0	565	633	0	633
South Dakota	3.16	0	3.16	1.96	0	1.96	5.12	0	5.12	5.74	0	5.74
Tennessee	56.3	0	56.3	785	0	785	842	0	842	944	0	944
Texas	244	.50	244	1,200	906	2,110	1,450	907	2,350	1,620	1,020	2,640
Utah	34.3	5.08	39.4	8.38	0	8.38	42.7	5.08	47.8	47.8	5.69	53.5
Vermont	2.05	0	2.05	4.86	0	4.86	6.91	0	6.91	7.75	0	7.75
Virginia	104	0	104	365	53.3	419	470	53.3	523	526	59.7	586
Washington	138	0	138	439	39.9	479	577	39.9	617	647	44.7	692
West Virginia	9.70	0	9.70	958	0	958	968	0	968	1,090	0	1,090
Wisconsin	83.0	0	83.0	364	0	364	447	0	447	501	0	501
Wyoming	4.31	0	4.31	1.47	0	1.47	5.78	0	5.78	6.48	0	6.48
Puerto Rico	11.2	0	11.2	0	0	0	11.2	0	11.2	12.5	0	12.5
U.S. Virgin Islands	.22	0	.22	3.12	0	3.12	3.34	0	3.34	3.74	0	3.74
Total	3,570	6.51	3,580	14,900	1,280	16,200	18,500	1,280	19,700	20,700	1,440	22,100

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.

TABLE 2.8
Total water use by usage category, 2000
Category	Percent
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 supply	11
Irrigation	34
Aquaculture	<1
Mining	<1
Domestic	<1
Livestock	<1
Industrial	5
Thermoelectric power	48

THERMOELECTRIC POWER

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.

WASTE DISPOSAL

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.

RIGHT TO WATER USE

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.

PROTECTION OF AQUATIC LIFE

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 fish—up 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.

TRENDS IN WATER USE SINCE 1950

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 methods—center-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.

TABLE 2.9
Water use trends, selected years 1950–2000
[In billion gallons per day (thousand million gallons per day); rounded to two significant figures for 1950–80, and to three significant figures for 1985–2000; percentage change is calculated from unrounded number]
	Year											Percentage change 1995–2000
	1950^a	1955^b	1960^c	1965^d	1970^d	1975^c	1980^c	1985^c	1990^c	1995^c	2000^c	Percentage change 1995–2000
^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, 1950–2000," 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)
Population, in millions	150.7	164.0	179.3	193.8	205.9	216.4	229.6	242.4	252.3	267.1	285.3	+7
Offstream use:
Total withdrawals	180	240	270	310	370	420	440	399	408	402	408	+2
Public supply	14	17	21	24	27	29	34	36.5	38.5	40.2	43.2	+8
Rural domestic and livestock:
Self-supplied domestic	2.1	2.1	2.0	2.3	2.6	2.8	3.4	3.32	3.39	3.39	3.59	+6
Livestock and aquaculture	1.5	1.5	1.6	1.7	1.9	2.1	2.2	4.47^e	4.50	5.49	^f	—
Irrigation	89	110	110	120	130	140	150	137	137	134	137	+2
Industrial:
Thermoelectric-power use	40	72	100	130	170	200	210	187	195	190	195	+3
Other industrial use	37	39	38	46	47	45	45	30.5	29.9	29.1	^g	—
Source of water:
Ground:
Fresh	34	47	50	60	68	82	83	73.2	79.4	76.4	83.3	+9
Saline	^h	.6	.4	.5	1.0	1.0	.9	.65	1.22	1.11	1.26	+14
Surface:
Fresh	140	180	190	210	250	260	290	265	259	264	262	−1
Saline	10	18	31	43	53	69	71	59.6	68.2	59.7	61.0	+2

WATER USE—THE FUTURE

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 period—the nation's biggest numerical gain—followed 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.

WHERE WATER IS POWER—INTERNATIONAL WATER WARS?

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 Wars—The 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, 2000–06
Geographic area	Population estimates		Change, 2000 to 2006		National ranking of states
	Population estimates		Change, 2000 to 2006		July 1, 2006	April 1, 2000 estimates base	Number	Percent	Population estimates	Change, 2000 to 2006
	July 1, 2006	April 1, 2000 estimates base	Number	Percent	July 1, 2006	April 1, 2000 estimates base	Number	Percent
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 States	299,398,484	281,424,602	17,973,882	6.4	(X)	(X)	(X)	(X)
Northeast	54,741,353	53,594,784	1,146,569	2.1	4	4	4	4
Midwest	66,217,736	64,395,194	1,822,542	2.8	3	2	3	3
South	109,083,752	100,235,846	8,847,906	8.8	1	1	1	2
West	69,355,643	63,198,778	6,156,865	9.7	2	3	2	1
Alabama	4,599,030	4,447,351	151,679	3.4	23	23	27	34
Alaska	670,053	626,931	43,122	6.9	47	48	42	17
Arizona	6,166,318	5,130,632	1,035,686	20.2	16	20	5	2
Arkansas	2,810,872	2,673,398	137,474	5.1	32	33	28	22
California	36,457,549	33,871,653	2,585,896	7.6	1	1	2	15
Colorado	4,753,377	4,302,015	451,362	10.5	22	24	10	8
Connecticut	3,504,809	3,405,602	99,207	2.9	29	29	32	37
Delaware	853,476	783,600	69,876	8.9	45	45	37	10
District of Columbia	581,530	572,059	9,471	1.7	50	50	49	44
Florida	18,089,888	15,982,824	2,107,064	13.2	4	4	3	6
Georgia	9,363,941	8,186,816	1,177,125	14.4	9	10	4	3
Hawaii	1,285,498	1,211,537	73,961	6.1	42	42	36	20
Idaho	1,466,465	1,293,956	172,509	13.3	39	39	23	5
Illinois	12,831,970	12,419,647	412,323	3.3	5	5	11	36
Indiana	6,313,520	6,080,517	233,003	3.8	15	14	21	28
Iowa	2,982,085	2,926,382	55,703	1.9	30	30	40	41
Kansas	2,764,075	2,688,824	75,251	2.8	33	32	35	38
Kentucky	4,206,074	4,042,285	163,789	4.1	26	25	24	27
Louisiana	4,287,768	4,468,958	−181,190	−4.1	25	22	51	51
Maine	1,321,574	1,274,923	46,651	3.7	40	40	41	31
Maryland	5,615,727	5,296,506	319,221	6.0	19	19	14	21
Massachusetts	6,437,193	6,349,105	88,088	1.4	13	13	33	46
Michigan	10,095,643	9,938,480	157,163	1.6	8	8	26	45
Minnesota	5,167,101	4,919,492	247,609	5.0	21	21	19	23
Mississippi	2,910,540	2,844,656	65,884	2.3	31	31	38	40
Missouri	5,842,713	5,596,683	246,030	4.4	18	17	20	25
Montana	944,632	902,195	42,437	4.7	44	44	43	24
Nebraska	1,768,331	1,711,265	57,066	3.3	38	38	39	35
Nevada	2,495,529	1,998,257	497,272	24.9	35	35	9	1
New Hampshire	1,314,895	1,235,786	79,109	6.4	41	41	34	18
New Jersey	8,724,560	8,414,347	310,213	3.7	11	9	16	30
New Mexico	1,954,599	1,819,046	135,553	7.5	36	36	29	16
New York	19,306,183	18,976,821	329,362	1.7	3	3	13	43
North Carolina	8,856,505	8,046,491	810,014	10.1	10	11	6	9
North Dakota	635,867	642,200	−6,333	−1.0	48	47	50	50
Ohio	11,478,006	11,353,145	124,861	1.1	7	7	31	48
Oklahoma	3,579,212	3,450,654	128,558	3.7	28	27	30	29
Oregon	3,700,758	3,421,436	279,322	8.2	27	28	18	12
Pennsylvania	12,440,621	12,281,054	159,567	1.3	6	6	25	47
Rhode Island	1,067,610	1,048,319	19,291	1.8	43	43	46	42
South Carolina	4,321,249	4,011,816	309,433	7.7	24	26	17	14
South Dakota	781,919	754,844	27,075	3.6	46	46	44	33
Tennessee	6,038,803	5,689,262	349,541	6.1	17	16	12	19
Texas	23,507,783	20,851,790	2,655,993	12.7	2	2	1	7
Utah	2,550,063	2,233,198	316,865	14.2	34	34	15	4
Vermont	623,908	608,827	15,081	2.5	49	49	47	39
Virginia	7,642,884	7,079,030	563,854	8.0	12	12	7	13
Washington	6,395,798	5,894,140	501,658	8.5	14	15	8	11
West Virginia	1,818,470	1,808,350	10,120	0.6	37	37	48	49
Wisconsin	5,556,506	5,363,715	192,791	3.6	20	18	22	32
Wyoming	515,004	493,782	21,222	4.3	51	51	45	26
Puerto Rico	3,927,776	3,808,603	119,173	3.1	(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.

Water: No Longer Taken For Granted