Glad You Asked: Does Utah Really Use More Water Than Any Other State?

by Mark Milligan

Current USGS water use reporting categories and total gallons used per day in 2010
(the most recent year of available data)

Public Supply–42 Billion U.S. / 673 Million Utah.
Water withdrawn by public and private water suppliers that furnish water to at least 25 people or have a minimum of 15 connections. Public suppliers provide water for a variety of uses, such as domestic, commercial, industrial, thermoelectric-power, and public water use.

Domestic–6 Billion U.S. / 8.44 Million Utah (self-supplied only).
Water used for indoor and outdoor household purposes such as drinking, food preparation, flushing toilets, and watering lawns. As a reporting category it includes water provided by public water suppliers and self-supplied water such as private wells. Reported uses may only include self-supplied water to avoid double counting with the Public Supply category.

Irrigation –115 Billion U.S. / 3.22 Billion Utah.
Water used for crop production and recreational lands such as parks and golf courses.

Livestock –2 Billion U.S. / 16.5 Million Utah.
Water used for livestock watering, feedlots, dairy operations, and other on-farm needs.

Aquaculture –42 Billion U.S. / 97.1 Million Utah.
Water used for offstream fish hatcheries and the farming of finfish, shellfish, and other organisms that live in water.

Industrial–16 Billion U.S. / 118.2 Million Utah.
Water used for fabrication, processing, washing, and cooling.  Includes industries such as chemical, food, mining, paper, petroleum refining, and steel.

Mining–32 Billion U.S. / 250.19 Million Utah.
Water used for extracting commodities such as minerals, coal, oil, gas, sand, gravel, and stone.

Power–160 Billion U.S. / 80.9 Million Utah.
Water used in the process of generating electricity with steam-driven turbine generators (thermoelectric power). This includes almost all coal, nuclear, and geothermal power plants as well as some solar and many natural gas power plants. Thermoelectric power generation accounted for 45 percent of total (fresh and saline) and 38 percent of fresh water use nationally in 2010.

A Tricky Question

Water in the U.S. and especially in the American West is a complex matter, and even a question as seemingly simple as how much water a state uses can be confusing. A different answer can be reached depending on caveats such as total versus per capita use; consideration of salt water use; surface water versus groundwater use; intended use of the water such as domestic, mining, or power generation; and if the water is delivered by a public supplier. So, what about claims that Utah uses more water than any state?

To investigate various claims and caveats of water use, one must rely on reports published by the U.S. Geological Survey (USGS). In compiling water use reports, the USGS utilizes data derived from different sources and methods and thus has varying levels of accuracy from state to state. For example, as part of continuing efforts to improve their data for Utah, the Utah Division of Water Resources recently released a report which stated they may be underestimating unmetered irrigation (secondary water) water use by as much as 34 percent for large water districts (for details see https://water.utah.gov/WaterUseCollectionReportFINAL1_29.pdf). So when ranking states, the margin of error could be greater than the reported differences in water use. Nevertheless, the USGS reports are the best and most reliable source for comparing states’ water use.

Since the 1950s the USGS has published water use reports for years ending in “0” and “5.” Unfortunately, although limited data are currently available, the full 2015 report is not expected to be released until fall of 2019. This article uses the most recent data available whether from 2010 or 2015. Since 2000 the USGS has categorized water use as public supply, domestic, irrigation, livestock, aquaculture, industrial, mining, or power generation (see side bar for details).

Some Answers

Which state uses the most total water? California.
In 2010 when considering all sources and uses of water California led the nation in water use with an average of 38 billion gallons per day! Utah’s 4.46 billion gallons per day pales in comparison and ranks us 30th on this list. California may have consumed the most total water, but it had an enormous population of 37.3 million while Utah had only 2.76 million people, which is why it may be preferable to compare per capita use.

Which state uses the most total water per person? Idaho.
In 2010 Idaho’s 1.57 million people used 10,955 gallons per capita per day (GPCD) (82 percent was used for irrigation)! Utah used 1,616 GPCD day ranking us 12th on this list. Total water includes categories of commodities that may use water in one state for a product that is consumed or utilized in another state. For example, if Utah water is used to generate electricity sold to California, should the water be legered against the producing state or consuming state? Conversely, California grows many crops that are shipped to Utah, and in this case some of California’s water is shipped to Utah in fruits and vegetables. This may be a reason the USGS does not highlight per capita total use in its report.  It does, however, highlight the use of domestic water per capita, water which is locally produced and consumed.

Which state uses the most domestic water per capita? Idaho.
In 2015 when considering per capita use of domestic water (both public supply and self-supplied), Idaho topped the nation by using 184 GPCD. Utah was a close second using 178 GPCD. The national average was 82 GPCD. While national domestic water use continues to drop, Idaho and Utah continue to use more. In 2010 the national average was 88 GPCD while Idaho and Utah used a reported 168 and 167 GPCD, respectively.

Which state’s public supply customers use the most water per capita? Utah.
In 2010 Utah’s public supply customers used 248 GPCD, ranking us number 1 on this list. Nevada ranked second, using 229 GPCD. How did Utah surpass Idaho which used 210 GPCD and is ranked 5th on this list, behind Wyoming and Hawaii? Although Idahoans’ water use tops the two previous lists, only one percent of the state’s use is categorized as public supply. The very small number of public supply customers apparently do not use as much water as the vast majority of Idahoans who supply their own water through private wells or surface diversions.

What Does It All Mean?

An internet search will yield many articles from mainstream, reputable media that have some form of the claim that at 248 GPCD, Utah has the highest per capita water use in the nation. While correct, the claim is only true for public supply customers, a consideration generally not addressed by the media. Interestingly, the 2010 USGS report does not explicitly give any per capita public supply use numbers or rankings, in spite of having the data to do so.

Although state rankings are good for creating attention-grabbing headlines that inspire water-use awareness, they have little to no scientific merit. Arid states typically use more water for landscape and crop irrigation. Farmers usually grow crops that yield higher profit margins and those crops, especially the abundant grass hay and alfalfa hay grown in Utah and Idaho, use a lot of irrigation water. Indeed, irrigation (not including irrigation water delivered from a public supply) accounts for 72 and 82 percent of Utah’s and Idaho’s 2010 water use, respectively.

Utah has historically used copious amounts of water to irrigate valley crops and for landscaping during our dry summer growing seasons. This has largely been possible because adjacent mountains receive ample precipitation. For example, the town of Alta, in the Wasatch Range above Salt Lake Valley, averages over 54 inches of precipitation a year, slightly more than Seattle and Salt Lake City combined. Despite elevated mountain precipitation, many areas in Utah have been supplementing surface water supplies by pumping groundwater at rates that exceed recharge, and some are starting to be impacted.  For instance, the need to deepen or replace old shallow wells is a common occurrence in some aquifers. Also, ground-subsidence cracks attributed to land subsidence caused by decreasing groundwater levels have damaged infrastructure and houses in Cedar Valley, Iron County (for more information, see Survey Notes, v. 43, no. 1, p. 1-3.).

Increasing per capita water use coupled with rapid population growth and projected reductions in both snowpack and streamflow due to changing climate is not sustainable. Nearly 3 million people currently live in Utah and that number is expected to swell to roughly 5.5 million by 2050. To sustain such growth Utah will soon need to make big decisions about conservation measures, water management, and the potential development of costly new supply projects.

For More Information

USGS Estimated Use of Water publications can be found at https://water.usgs.gov/watuse/50years.html.

Information on future water supplies can be found at the Utah Division of Water Resources, https://water.utah.gov and in a report by the Utah Foundation, a non-partisan and non-profit, public policy research group: https://cicwcdorg.files.wordpress.com/2018/01/2014-09-flowing-toward-2050-utah-foundation-rpt-723-2014-09-2.pdf.

Survey Notes, v. 50 no. 2, May 2018