Water-Use Concepts

Water-use terms and concepts used in this chapter are defined in the “Glossary” section and are shown in figure 1. The core concept of water use is the water withdrawal from groundwater or surface water to use for a specific purpose and the return flow back to the local environment. Water is typically moved or conveyed through one or more pipes or canals, or for some larger systems, through tunnels or aqueducts. Water use is typically categorized by type (category) of use, such as public supply, thermoelectric power, irrigation, domestic, or industrial use. Consumptive use is the part of water withdrawn that is evaporated, transpired, incorporated in products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Water that is withdrawn but has not been removed from the local environment is returned to groundwater or surface water as return flow (or effluent), which can occur through various means such as outfall pipes from wastewater treatment or industrial facilities or on-site septic systems. In some areas, often but not always where freshwater resources are scarce, water after treatment, referred to as “reclaimed wastewater” or “reused water,” might be used for potable or non-potable purposes (such as to irrigate crops, lawns, or golf courses) or as cooling water for thermoelectric powerplants. Effluent from wastewater treatment facilities is typically returned to streams and may help sustain minimal flow for ecological purposes and furnish water for downstream withdrawals. Because return flow is available for further instream or offstream use, any chemical or thermal alteration resulting from use has implications for water quality and stream ecology. As water moves through pipes or other conveyances, water volumes can increase through infiltration or inflow, or can decrease through conveyance losses, such as leaks or broken pipes. Open conveyances like canals are subject to losses from evapotranspiration.

Water-use terminology is neither static nor universal. The categorization and reporting of water-use information by the USGS water-use program has changed over time. Some organizations or agencies outside the USGS use different terms for water-use concepts or have a different definition for a term used by the USGS. For example, the USGS uses “consumptive use” or “consumption” to mean water that is not readily available for another use locally. Other organizations use the term differently. For example, the Bureau of Reclamation refers to water “consumption” similarly to the USGS except that the term also includes interbasin transfers (Bruce and others, 2018). The South Florida Water Management District issues consumptive water-use permits for water withdrawals. “Water use” and “water withdrawal” can be used interchangeably in many situations, although water use is typically best understood in the context of the category for which it is being used (for example, irrigation or domestic water use) and water withdrawal in the context of removing water from its source (groundwater or surface water).

Public-Supply

This section defines terms and concepts related to public-supply water use by the USGS; terminology associated with self-supply water use is included because it completes the representation of water use for categories such as domestic, industrial, and thermoelectric power. Public-supply water use is defined by the USGS as water withdrawn by public and private water suppliers that furnish water to at least 25 people or have a minimum of 15 connections. The U.S. Environmental Protection Agency uses the same definition for a public water system, which they further classify based on whether or not the populations served are for communities and whether populations are transient or non-transient. Public suppliers provide water for various uses such as domestic, commercial, industrial, thermoelectric power, and public use; the transfers to these water users are referred to as public-supply deliveries. The difference between water withdrawals by public suppliers and deliveries to billed water users is non-revenue water, which includes leakage, meter errors, and public uses of water such as firefighting, street and sewer cleaning, flushing of water lines, irrigation of parks and public lands, and other municipal purposes. Non-revenue water has not historically been accounted for by USGS other than as a calculation of the difference between reported withdrawals and reported or estimated deliveries, resulting in an estimate of “all other uses and losses.” Other terms commonly used outside the USGS to describe public-supply water use are “municipal” or “community” water use.

The phrase, self-supplied water, refers to water used by (1) irrigation, mining, livestock, and aquaculture facilities; and (2) domestic, commercial, and industrial users and thermoelectric-power facilities that is not furnished by a public supplier. For categories that do not receive public-supply water, the term “self-supplied” is often dropped. Water used for crop irrigation is typically self-supplied. Total water use for a given category of use is the sum of water delivered by a public supplier and water that is self-supplied, and for some categories (such as irrigation and thermoelectric) might include reclaimed wastewater.

More information is available for public-supply water use than for self-supplied water use because public suppliers are subject to Federal and State regulations, which typically require some form of data reporting. In contrast, self-supplied water users often have fewer reporting requirements, depending on State or regional regulations. Importantly, although public suppliers generally meter deliveries of water to customers for billing, planning, reporting, and regulatory purposes, metered volumetric data are not always publicly shared. Some self-supplied data are available from States that regulate or require reporting of all types of water withdrawals or withdrawals greater than a designated volumetric threshold or other criteria.

Crop-Irrigation Withdrawals and Consumptive Use

Crop irrigation accounted for the largest withdrawals of freshwater across the CONUS during water years 2010–20 (fig. 4). Average water withdrawals and consumptive use for crop irrigation during 2010–20 were 105,497 and 75,698 Mgal/d (12,147 and 8,716 Mm³/mo), respectively (table 1). Model estimates for water withdrawals and consumptive use for crop irrigation for the CONUS in water year 2020 were 108,723 and 78,400 Mgal/d (12,526 and 9,027 Mm³/mo), respectively. Model estimates for crop-irrigation withdrawals and consumptive use have a nearly identical pattern (fig. 11) because irrigation withdrawals are calculated from modeled irrigation consumptive use and irrigation efficiency (Haynes and others, 2024). Modeled crop-irrigation consumptive use for hydrologic regions varied from 59 to 84 percent of the estimated crop-irrigation withdrawals, with largest percents in the Northeast through Midwest aggregated hydrologic regions and smallest percents in the Western aggregated hydrologic regions and a national average of 72 percent (tables 1 and 5; Martin and others, 2023; Haynes and others, 2024).

In addition to water applied by an irrigation system to grow crops and pastures, model estimates of crop-irrigation water withdrawals include water losses from irrigation systems and conveyance losses (Haynes and others, 2024). Estimates of irrigation water use made using previous USGS approaches also included pre-growing season applications, frost protection, chemical application, weed control, field preparation, crop cooling, harvesting, dust suppression, and leaching salts from the root zone (Dieter and others, 2018a). In the CONUS in 2017, crops with the largest number of irrigated acres, in descending order, were corn for grain, soybeans, hay and alfalfa, orchards, and cotton (U.S. Department of Agriculture, 2019).

Crop-irrigation water use is largely a function of climate variables such as precipitation and evaporative demand (Nie and others, 2021). Crop-irrigation withdrawals and consumptive use are generally inversely related to precipitation (fig. 11; the correlation coefficient for precipitation and crop-irrigation consumptive use is −0.77). A severe multi-year drought across much of the United States during 1999–15 was most intense in 2012 (Hoerling and others, 2014; McCabe and others, 2023). Estimates of annual crop-irrigation withdrawals and consumptive use during 2012 increased by more than 28 and 43 percent, respectively, compared to the wettest year (2019) and crop-irrigation withdrawals were 13 percent greater than the next driest year (2011) during 2010–20 (fig. 11).

Crop-irrigation water withdrawals during water year 2012 compared to the average of water years 2010−20 were not uniform across the CONUS (fig. 12). Compared to average May crop-irrigation withdrawals, water year 2010−20 withdrawals in May 2012 were about 14 and 9 times higher in the Mississippi embayment and Central High Plains hydrologic regions, respectively (fig. 12). In contrast, the Pacific Northwest, Columbia–Snake, Texas, and Florida hydrologic regions had smaller crop-irrigation withdrawals in May 2012 compared to water years 2010−20 (fig. 12). Other factors besides climate (such as irrigation management, irrigation infrastructure, and crop type) also highly influence crop-irrigation water withdrawals (Ketchum and others, 2023).

Satellite data show that for areas that grow crops, irrigated-land footprints vary from year to year, with an overall increasing trend in total area of irrigated land in the United States since 1997 (Xie and others, 2021). During drought, even with less irrigated land, crop needs for irrigation are greater than during normal or wet years and more water is lost as consumptive use to evapotranspiration. The percentage of crop-irrigation consumptive use to withdrawals in 2012 was 73, compared to the lowest percentage of 70.4 percent in 2010 (Martin and others, 2023; Haynes and others, 2024).

Monthly estimates of crop-irrigation water use at the HUC12 scale during 2010–20 show that irrigation water is used most heavily in the Central Valley of California, the Snake and Yakima River Basins in Idaho and Washington, and southern Florida and Texas, as well as the Central High Plains, Southern High Plains, and Mississippi Embayment hydrologic regions, and that most crop-irrigation use occurs from May to October (fig. 13). Crop-irrigation withdrawals generally increase northward as temperatures warm and decrease again in late autumn after crops are harvested. Some parts of the country have a climate that is conducive for growing crops in all seasons. For example, grains, hay, cotton, tomatoes and other row crops, citrus, nuts (almonds, walnuts, and pistachios), and grapes are grown year-round in Fresno County in the Central Valley of California (Fresno County Department of Agriculture, 2010). Because crop irrigation accounts for the largest volume of water use across the CONUS, and withdrawals from some small watersheds (HUC12 scale) in some parts of the country during summer are very large (more than 10 Mgal/d; fig. 13), the absolute and relative volumes of crop-irrigation withdrawals and consumptive use are important to water-availability assessments at small and large spatial scales.

The largest estimated water use for crop irrigation for the CONUS occurred in July. Median modeled estimates for July crop-irrigation withdrawals, summed to hydrologic regions during water years 2010–20, ranged from 650 Mgal/d in the Northeast hydrologic region to 61,328 Mgal/d in the California–Nevada hydrologic region (fig. 14A; 75 to 7,065 Mm³/mo). Estimates of crop-irrigation consumptive use are similarly framed by a low estimate of 527 Mgal/d in the Northeast and a high of 41,212 Mgal/d in the California–Nevada hydrologic region (fig. 14A; 61 to 4,748 Mm³/mo).

Normalizing by area and expressing as a depth (volume divided by area) provides an indication of the intensity of crop-irrigation withdrawals and consumptive use within each region, which influences regional water availability. More intense withdrawals and consumptive use place a greater degree of hydrologic stress on the region. The Northeast hydrologic region has the least intense crop-irrigation withdrawal, 0.000016 feet per year (ft/yr), and the Mississippi Embayment hydrologic region has the most intense average July crop-irrigation withdrawal, 0.0034 ft/yr—more than double the average July withdrawal of 0.0015 ft/yr for the next most intense region, the Central High Plains (0.005, 1.04, and 0.46 millimeters per year, respectively; fig. 14B). Normalized consumptive use estimates for crop irrigation follow the same pattern as normalized withdrawals.

Why are normalized withdrawals and consumptive use so much higher in the Mississippi Embayment than other parts of the country? The Mississippi Embayment hydrologic region, substantially overlapping with the Mississippi Alluvial Plain aquifer system, is one of the most productive agricultural regions in the Nation and depends largely on groundwater for irrigating rice, a water intensive crop, and other crops. In the Mississippi Embayment hydrologic region, which covers a relatively small area (43,000 square miles [mi²]) compared to most of the other hydrologic regions, cultivated cropland accounts for about 45 percent of the land area with 7 percent used for rice production (Karaba and others, 2007). The combination of small area and large withdrawals for crop-irrigation needs can explain the amplified intensity of crop-irrigation withdrawals from the Mississippi Embayment hydrologic region and concomitant water stress (chap. F, Stets and others, 2025b).

Thermoelectric Power Withdrawals and Consumptive Use

Thermoelectric-power water use is characterized by large withdrawals and relatively low consumptive use (Diehl and Harris, 2014; Harris and Diehl, 2019). Model estimates for withdrawals within the CONUS for thermoelectric power in water year 2020 were 61,399 Mgal/d from fresh water and 19,033 Mgal/d from saline water, totaling 80,432 Mgal/d (7,099, 2,194, and 9,293 Mm³/mo, respectively). Average withdrawals from fresh water for thermoelectric power during water years 2010–20 were 82,656 Mgal/d and from saline water were 21,224 Mgal/d (9,952 and 2,497 Mm³/mo, respectively). Different types of cooling systems use vastly different amounts of water. Consumptive use for thermoelectric power, overwhelmingly fresh water, was 2,382 Mgal/d in 2020 and 2,904 Mgal/d averaged over water years 2010–20 for the CONUS, or 4 percent of thermoelectric freshwater withdrawals.

Two broad types of cooling systems are once-through and recirculating. Once-through cooling systems withdraw large volumes of water that circulate through powerplant condensers to condense the steam used to generate electricity. Heated water is discharged back to the source; a relatively small amount of that water is consumed through evaporation. Recirculating cooling systems reuse water within the cooling system multiple times and consequently withdraw less from a water source but consume, through evaporation, a larger percentage of the water withdrawn as compared with once-through cooling systems. Consumptive-use rates in plants with recirculating systems can be as much as or greater than 70 percent of withdrawals (Harris and Diehl, 2019). During 2010–20, an overall shift occurred in powerplant infrastructure from once-through cooling systems towards recirculating cooling systems and, as a consequence, withdrawals for thermoelectric power have decreased while the relative amount of consumptive use to withdrawals has increased (Harris and others, 2025).

The type of cooling system for thermoelectric power is directly relevant to understanding water availability. Although withdrawals from thermoelectric powerplants with once-through cooling systems can dominate total water withdrawals across hydrologic regions or States (Dieter and others, 2018a), withdrawals occur at point locations and are much more acutely manifest in the context of water availability at smaller scales such as HUC12. Other than those that use municipal water or reclaimed wastewater, most thermoelectric powerplants are purposefully built near a source of water that can be used for cooling. Unlike with public-supply or crop-irrigation water use, the need to account for interbasin transfers of water for thermoelectric-power water use is negligible. Because the place of use is close to the withdrawal, consumptive use for thermoelectric power also occurs at the location of the plant. This means that locations with plants with recirculating towers, which consume relatively larger volumes of water than other types of cooling systems, have less water available for other uses than locations without these types of plants.

Although included in the USGS thermoelectric power water-use model, discussions of thermoelectric-power water use in this chapter do not include water from public-supply (referred to as “municipal” water sources in Galanter and others, 2023) or reclaimed wastewater. Public-supply and reclaimed wastewater sources contributed water for cooling to about 24 percent of powerplants that were modeled, which generated about 12 percent of total electricity; however, powerplants with these sources of water accounted for a small fraction of thermoelectric withdrawals (0.4 percent) and consumptive use (9 percent) of totals within the CONUS (Galanter and others, 2023). Although these water sources may be important locally, they do not affect our large-scale assessments of water use at the regional and CONUS scale.

Model 2020 estimates of thermoelectric power water withdrawals and consumptive use and their relative percentages—which provide inherent information about the type of cooling system—are shown in figure 15. Figure 16 shows summaries for water years 2010–20. Freshwater withdrawals and the number of powerplants are greatest in the Eastern United States (figs. 15A and 16C), where surface-water availability is greater and once-through cooling systems, characterized by large withdrawal and small consumptive use rates, are more common than in the West. The western CONUS is dominated by thermoelectric powerplants that recirculate cooling water; have relatively large consumptive use rates; and are likely to use groundwater, municipal water, reclaimed wastewater, or a combination thereof (Galanter and others, 2023). These regional patterns are shown by the higher ratio of consumptive use to withdrawals and fewer thermoelectric power plants in the West compared to the East (fig. 15B, 15C).

Net power generation, a factor affecting thermoelectric water use, is greatest in the Eastern United States, particularly in the Florida, Atlantic Coast, and Northeast hydrologic regions, where thermoelectric withdrawals are greatest and where most of the country’s population resides (fig. 16B; Galanter and others, 2023). The Florida and Northeast hydrologic regions are also where withdrawals of saline surface water for thermoelectric power (on an absolute and normalized by area basis) are greatest (fig. 16C). Withdrawals from surface-water saline sources for thermoelectric power tend to be relatively large and consumptive use, not explicitly modeled for saline plants, is negligible because surface-water, saline-sourced plants often have once-through cooling systems (Galanter and others, 2023). Saline withdrawals are not relevant for freshwater-availability assessments.

As temperatures warm and the composition of the electrical grid changes in the United States, water use at thermoelectric powerplants will continue to change. The decrease in water withdrawals at thermoelectric powerplants can be largely attributed to a couple of trends. The share of total U.S. electricity generated by coal-fired plants (historically baseload powerplants using once-through freshwater cooling systems) is declining, and many of these plants are being retired; powerplants with once-through saline cooling systems are also being retired. Additionally, more of the electrical grid is being supplied by energy-efficient natural gas combined cycle plants paired with water-efficient recirculating cooling towers (Gorman Sanisaca and others, 2023). Conversely, thermoelectric consumptive use (the evaporative loss of water through the cooling system), which is sensitive to ambient water temperatures (once-through cooling systems) and air temperatures (recirculating tower cooling systems), could increase in response to heat waves and warming climates (Diehl and Harris, 2014).

Self-Supplied Industrial Withdrawals and Total Industrial Water Use

In 2015, withdrawals from fresh water for self-supplied industrial use were 14,000 Mgal/d and accounted for about 5 percent of total freshwater withdrawals in the United States (Dieter and others, 2018a). In 2015, 786 Mgal/d also were withdrawn from saline sources for industrial use, accounting for 2 percent of total saline withdrawals. Groundwater was the source of 2,670 Mgal/d and surface water the source of 11,300 Mgal/d of freshwater withdrawals for industrial use (19 percent and 81 percent, respectively). The USGS did not estimate public-supply deliveries to industrial water users in 2015. The most recent estimate of industrial deliveries was made in 1995, when deliveries were about 19 percent of total industrial water use, self-supplied withdrawals were 81 percent of total industrial water use, and deliveries to industrial users represented about 12 percent of total withdrawals for public supply (Solley and others, 1998).

Indiana and Louisiana in 2015 together accounted for 32 percent of withdrawals from fresh water for industrial use in the country, with Lake County, Indiana, (which includes the city of Gary) accounting for 52 percent of Indiana’s industrial freshwater withdrawals (Dieter and others, 2018b). This single county also accounted for 8 percent of total industrial freshwater withdrawals in the country. Leading sectors that contributed to industrial water use in Indiana were automotive, pharmaceuticals, and steelmaking; in Louisiana, these sectors were petroleum refining, chemicals, and petrochemicals. Throughout most of predominantly rural Maine, industrial use accounted for more water use than all other categories in 2015 (fig. 19), primarily because of water demand from the pulp and paper industry.

Self-Supplied Domestic Withdrawals and Total Domestic Water Use

Nationwide in 2015, domestic water users received most of their water from public suppliers. Eighty-eight percent (23,300 Mgal/d) of water used for domestic purposes came from public suppliers and 12 percent (3,260 Mgal/d) were self-supplied (Dieter and others, 2018a). Domestic self-supplied withdrawals accounted for about 1 percent of total withdrawals in the United States in 2015. Of the 3,260 Mgal/d of self-supplied withdrawals for domestic use, the source for 49.1 Mgal/d (2 percent) was groundwater and for 3,210 Mgal/d (98 percent) was surface water.

Domestic water use (also referred to as residential or household water use) is water used for indoor household purposes such as drinking; food preparation; bathing; washing clothes and dishes; flushing toilets; and outdoor purposes such as watering lawns and gardens, washing vehicles, and filling pools. Domestic self-supplied water users usually live where public water suppliers are not available (that is, outside cities, metropolitan areas, and towns), although some populations in urban or suburban areas are self-supplied and some rural populations are served by small public suppliers.

Estimates for domestic water use directly relate to population. For historical USGS water-use estimates, the population of domestic self-supplied water users was typically estimated as the difference between total county population and the population served by public suppliers (Dieter and others, 2018a), sometimes adjusted based on local understanding of factors such as population distribution for multi-county public supply systems and seasonal shifts in population. Self-supplied population was multiplied by a Statewide or countywide per-capita residential water-use coefficient, which, in 2015, was usually extrapolated from reported data or carried over from previous estimates (Luukkonen and others, 2021). In 2015, per-capita coefficients for domestic self-supplied use ranged from 36 gallons (gal) per capita per day in Connecticut to 186 gal per capita per day in Nevada, with a national average of 77 gal per capita per day (Dieter and others, 2018a).

States with total domestic use (the combination of public-supply deliveries to domestic users and self-supply domestic use) greater than 1,000 Mgal/d in 2015 were California, Texas, Florida, New York, and Illinois (Dieter and others, 2018a). States with the largest self-supplied withdrawals for domestic use were Pennsylvania, Michigan, and New York. On a per-capita basis, the largest total domestic water use occurred in Idaho, Utah, Arizona, and Hawaii. Prince George’s County in Maryland was the county with the largest self-supplied domestic population and withdrawals (0.7 percent of the national total). The county with the largest volume of public-supply deliveries to domestic users was Los Angeles County, California (3.5 percent of the national total). Virginia and Michigan have the most counties where domestic self-supplied use is larger than any other category of water use (fig. 19; Dieter and others, 2018b) .

Self-Supplied Commercial Withdrawals and Total Commercial Water Use

Commercial water use (self-supplied withdrawals plus deliveries from public supply) was most recently compiled nationwide in 1995, when it represented about 3 percent of total freshwater use (Solley and others, 1998). Self-supplied withdrawals for commercial use (all fresh water) were 2,890 Mgal/d and deliveries to commercial water users from public supply were 6,690 Mgal/d. Withdrawals for self-supplied commercial use accounted for less than 1 percent of total freshwater withdrawals in the United States in 1995. Groundwater was the source of 939 Mgal/d and surface water the source of 1,950 Mgal/d of freshwater withdrawals for commercial use (32.5 percent and 67.5 percent, respectively).

Commercial water use includes water used for motels, hotels, restaurants, office buildings, other commercial facilities, military and nonmilitary institutions, and (for 1990 and 1995) offstream fish hatcheries. In 1995, California, Oregon, and New York had the largest total commercial use, and Oregon, California, and Idaho had the largest self-supplied withdrawals for commercial water use (Solley and others, 1998). Although a few State agencies furnished data from reported or permitted withdrawals for commercial water use to the USGS for the 1995 water-use report, most States estimated commercial withdrawals from coefficients related to the particular type of commercial establishment, such as the number of students at a university, workers in an office building, or beds in a hotel or hospital.

Self-Supplied Livestock Water Use

Withdrawals for livestock water use, all from fresh water, were 2,000 Mgal/d and accounted for less than 1 percent of total freshwater withdrawals in the United States in 2015 (Dieter and others, 2018a). About 62 percent (1,240 Mgal/d) of withdrawals for livestock water use were from groundwater and 38 percent (760 Mgal/d) were from surface water.

The livestock category is defined as water used for livestock watering, feedlots, dairy operations, and other on-farm needs and does not include water used to grow feed crops. Types of livestock include dairy cows and heifers, beef cattle and calves, sheep and lambs, goats, hogs and pigs, horses, and poultry. About 14 percent of total water withdrawals for livestock in the United States in 2015 occurred in Texas, with California and Iowa combined contributing another 17 percent. A large part of withdrawals for livestock were for cattle (Dieter and others, 2018a). Livestock water withdrawals are typically estimated using county-level animal population data provided by the U.S. Department of Agriculture Census of Agriculture, produced every 5 years, and average water-use coefficients, in gallons per head per day, for each animal type (Lovelace, 2009b).

Self-Supplied, Mining-Water Use

Water used for mining in the United States includes fresh water and saline water. In 2015, withdrawals for mining from fresh water were 1,880 Mgal/d and from saline water were 2,120 Mgal/d, accounting for less than 1 percent and 5 percent of total withdrawals in the U.S. for fresh water and saline water, respectively (Dieter and others, 2018a). About 54 percent (1,010 Mgal/d) of withdrawals from fresh water for mining were from groundwater and 46 percent (877 Mgal/d) were from surface water. About 88 percent (1,860 Mgal/d) of withdrawals from saline water for mining water use were from groundwater and 12 percent (256 Mgal/d) were from surface water.

Mining water use includes water used for the extraction of naturally occurring minerals including solids (such as coal, sand, gravel, and ores), liquids (such as crude petroleum), and gases (such as natural gas). It includes uses associated with quarrying, milling of mined materials, injection of water for secondary oil recovery or for unconventional oil and gas recovery (such as hydraulic fracturing), and other operations associated with mining activity.

The largest withdrawals of fresh water for mining were in Nevada (10 percent of the U.S. total). Eureka County, Nevada (fig. 19) used 77.4 Mgal/d of fresh water in 2015 for mining, with primary products of silver and gold, and other ores such as lead, copper, and zinc (Burger and others, 2018; Muntean and Micander, 2023). Eureka County accounted for 4.3 percent of total mining withdrawals from fresh water in the country and 40 percent of withdrawals for mining in Nevada in 2015. Tooele County, Utah (fig. 19), had the largest total county scale withdrawal from mining that included saline water of 131.4 Mgal/d in 2015. Texas, Florida, Ohio, and Indiana each had similar withdrawal volumes of about 130 Mgal/d and together accounted for 27 percent of freshwater withdrawals for mining nationwide. More than 200 Mgal/d of saline water were withdrawn for mining in Texas, California, and Utah.

Self-Supplied, Golf-Course-Irrigation Water Use

In the 2015 and previous USGS water-use reports, irrigation water use included water used for crops and recreational land including golf courses. USGS staff who provided State-based information for the national water-use reports had the option of either differentiating golf-course-irrigation water use from crop irrigation or of reporting the two types as a single value. Based on information from 36 States that reported golf-course irrigation separately from crop irrigation, withdrawals for golf-course water use accounted for less than 1 percent of irrigation withdrawals in the United States in 2015 (Dieter and others, 2018b). Reported withdrawals for golf-course irrigation totaling 1,039 Mgal/d were all from fresh water and accounted for less than 1 percent of total freshwater withdrawals in the United States in 2015 (Dieter and others, 2018b). About 47 percent (488 Mgal/d) of withdrawals for golf-course-irrigation water use were from groundwater and 53 percent (551 Mgal/d) were from surface water.

In the States with reported golf-course-irrigation use, Maricopa County, Arizona (fig. 19), had the largest total withdrawal from fresh water for golf-course irrigation (83.8 Mgal/d; 58 percent from groundwater and 42 percent from surface water) by almost three times the next largest county, Riverside County, California (29.3 Mgal/d; 69 percent from groundwater and 31 percent from surface water; fig. 19). Maricopa County also used the largest amount of reclaimed wastewater for golf-course irrigation (25 Mgal/d or 23 percent of total golf-course-irrigation water use) and had the largest consumptive use for golf-course irrigation (87 Mgal/d) of all counties in the country with reported use. Florida, California, and Arizona had the largest statewide withdrawals for golf-course irrigation and accounted for a total of 43 percent of golf-course withdrawals for reporting States. These States also had the largest amounts of reclaimed wastewater and consumptive use for golf-course irrigation. Ninety-nine percent of golf-course irrigation used sprinkler types of systems; the remaining 1 percent used micro irrigation or surface (flood) irrigation methods (Dieter and others, 2018b).