August 1, 2004

Utah Water Use

Every five years, the U.S. Geological Survey releases data on water usage by state. The data detail the amount of water used for agriculture, municipal and industrial uses (M&I- public or private water utility providers), mining, private industrial wells and thermoelectric generation. The data also provide a look at the sources of water within the state, either surface sources, such as lakes, reservoirs and rivers or ground sources — wells and springs. The release of these data is slow, and data from 2000 have just recently been published. Along with previous reports from 1985, 1990 and 1995, these data provide a time series of water usage in Utah and other states. According to the 2000 data, Utahns used 4.76 billion gallons of water per day. Figure 1 shows the breakout of water use by category in percentage terms. Irrigation remains Utah’s largest use category and the percentage of water used for this purpose is up slightly from 79.2% in 1995.

Figure 1: Utah Fresh Water Usage by Category, 2000

In addition to the increase in the percentage of water used for irrigation purposes, the consumption of municipal water per capita in Utah also increased from 1995 to 2000. In 1995, 269 gallons were used per person per day in the state. In 2000, that climbed to 293 gallons. This was one of the largest increases in the country. Only four states, Colorado, Hawaii, Texas and Louisiana had larger increases in the amount of municipal water used per person. Drought conditions in all these states undoubtedly contributed to this increase as did the increasing urbanization of these areas. The table in Figure 2 shows the per capita use of M&I water for all states since 1985 and the percent change and ranking over the time period. Utah ranks 20th in the nation in terms of growth while Alabama saw the greatest growth in per capita water consumption and Pennsylvania saw the greatest decline.

Figure 2: M&I Water Use by State, 1985-2000 Source: U.S. Geological Survey

Sources of Utah Water

Water is classified to have one of two sources of origin. Water comes from either surface sources — lakes, rivers and streams or from ground sources — springs and wells. In Utah, 78.6% of total water withdrawals are from surface sources. However, for public drinking water supplies, 57.1% comes from ground water sources. Ground water tends to be of a higher quality and requires less treatment to reach drinking water quality. Utah’s 57.1% ranks the state 10th in the nation for the percentage of public drinking that originates from ground sources. Figure 3 details ground water withdrawals for M&I use by state. Perhaps the most interesting comparisons are with Utah’s neighboring states. For example, Colorado is one of the lowest ground water users in the nation; only 6% of Colorado’s publicly supplied drinking water originates from ground sources. Conversely, both Idaho and New Mexico receive over 88% of their drinking water from ground sources. In the case of New Mexico, there is little potable surface water to utilize in public systems. In Idaho, it appears to be a case of water rights. Most of the surface water in the state goes for irrigation. Municipalities in that state need to search elsewhere for water resources.

Figure 3: Public Supply by State and Source, 2000 Source: U.S. Geological Survey

An ongoing concern about ground water usage is that the water is not as readily replenished as surface water and that over-usage of this resource will dry up deep aquifers, some of which are the source of surface waters. Nationally, there seems to be an increase in the proportion of ground water used. In the Intermountain West as well as in Utah, ground water usage has fluctuated over the time series with a peak in 1990, as shown in Figure 4.

Figure 4: Utah, Intermountain Region and U.S. Groundwater Usage as a Percent of Total Water Withdrawals, 1985-2000

Utah Surface Water Quality

This shift to a greater reliance on ground water can, in part, be attributed to concerns over surface water quality. The U.S. Environmental Protection Agency provides analysis of surface water quality for states. The quality assessments go beyond whether or not surface water can be used in drinking water to include considerations like fish and wildlife protection, recreational use, navigation and agriculture use. Assessments are performed on all types of surface water including lakes, rivers, reservoirs, bays and estuaries, near shore and off shore oceanic water quality. Figure 5 provides summary information on rivers and lakes/reservoirs for those states that have submitted assessment information to the EPA. The figure includes the percentage of rivers and lakes that were classified as “good” and each state’s ranking relative to the other states. For this summary, bay, estuary and ocean data were not analyzed, since those water sources do not typically provide water for municipal systems. As the figure shows, Utah’s water quality rates fairly well, ranking 8th on river quality and 7th for lake/reservoir quality. Most of the intermountain states rank high at least on one indicator. Colorado ranks second in the nation for both river and lake quality. Montana is the overall lowest performing state, due to surface water pollution from mining activities. The overall good ratings of the Intermountain West are due in large part again to geography and demographics. Many of the nation’s rivers have their genesis in the Rocky Mountains and the low population density of these areas means that waters exiting the intermountain states are relatively clean.

Figure 5: Surface Water Quality Ranking by State, 2000 Source: U.S. Environmental Protection Agency, compiled from states’ individual 305(b) reports