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A new United States Geological Survey (USGS) report indicates that water use across the country has fallen to its lowest recorded level in 45 years. The report found that 322 billion gallons of water per day (Bgal/d) were withdrawn for use in the United States during 2015 versus 1970’s consumption of 370 Bgal/d.
The 2015 levels also represent a nine percent reduction of water use from 2010 when about 354 Bgal/d were withdrawn. Reductions in water use were first observed in 2010 and the trend is continuing.
“The downward trend in water use shows a continued effort towards efficient use of critical water resources, which is encouraging,” said Tim Petty, assistant secretary for Water and Science at the Department of the Interior (DOI). “Water is the one resource we cannot live without, and when it is used wisely, it helps to ensure there will be enough to sustain human needs, as well as ecological and environmental needs.”
Twelve states accounted for 50 percent of the total water withdrawals in 2015 within the U.S. Of the 50 percent of withdrawn water (in order of withdrawal amounts in descending order) to top 12 states are: California, Texas, Idaho, Florida, Arkansas, New York, Illinois, Colorado, North Carolina, Michigan, Montana, and Nebraska. The USGS did not provide a ranking of per capita use or account for population or states with high volumes of agricultural water use.
Total water withdrawals were assessed in five categories: public supply, irrigation, industrial, thermoelectric power and other (incl. aquaculture, livestock, mining and self-supplied domestic). California and Texas accounted for approximately 16 percent of total withdrawals for all categories at nine and seven percent respectively. The majority of California’s use was for irrigation (likely due to the agricultural Central Valley) while use in Texas was a cross between thermoelectric power generation, irrigation and public supply.
Florida posted the largest share of saline withdrawals — accounting for 23 percent of the total in the country – due mostly to saline surface-water withdrawals for thermoelectric power generation. Texas and California accounted for 59 percent of the total saline groundwater withdrawals in the United States, mostly for mining.
For the first time since 1995, the USGS estimated consumptive use for two categories — thermoelectric power generation and irrigation. Consumptive use is the fraction of total water withdrawals that is unavailable for immediate use because it is evaporated, transpired by plants, or incorporated into a product. The USGS estimated a consumptive use of 4.31 Bgal/d, or three percent of total water use for thermoelectric power generation in 2015. In comparison, consumptive use was 73.2 Bgal/d, or 62 percent of total water use for irrigation in 2015.
“Consumptive use is a key component of the water budget. It’s important to not only know how much water is being withdrawn from a source, but how much water is no longer available for other immediate uses,” said USGS Hydrologist Cheryl Dieter.
Water withdrawn for thermoelectric power generation was the largest use nationally at 233 Bgal/d, with irrigation and public supply as the next two leading uses, respectively. Collectively, these three uses represented 90 percent of total withdrawals. Withdrawals declined for thermoelectric power generation and public supply but increased for irrigation. Specifically, thermoelectric power decreased 18 percent from 2010, the largest percent decline of all categories while irrigation withdrawals (all freshwater) increased 2 percent. Public-supply withdrawals decreased 7 percent.
“The USGS is committed to providing comprehensive reports of water use in the country to ensure that resource managers and decision makers have the information they need to manage it well,” said USGS Director Jim Reilly. “These data are vital for understanding water budgets in the different climatic settings across the country.”
