Nov 05, 2014

National Water Use at Lowest Levels in 45 Years

Numbers show positive trends in conservation

USGS, Water Use, Decrease, United States

Water use across the country has reached its lowest recorded level in nearly 45 years. According to a new USGS report, about 355 billion gal per day (gpd) were withdrawn for use in the entire U.S. during 2010.

This represents a 13% reduction in water use from 2005, when about 410 billion gpd were withdrawn, and the lowest level since before 1970.

“Reaching this 45-year low shows the positive trends in conservation that stem from improvements in water use technologies and management,” said Mike Connor, U.S. deputy secretary of the interior. “Even as the U.S. population continues to grow, people are learning to be more water conscious and do their part to help sustain the limited freshwater resources in the country.”

In 2010, more than 50% of the total withdrawals in the U.S. were accounted for by 12 states. In order of withdrawal amounts, they are California, Texas, Idaho, Florida, Illinois, North Carolina, Arkansas, Colorado, Michigan, New York, Alabama and Ohio.

California accounted for 11% of the total withdrawals for all categories, and 10% of total freshwater withdrawals for all categories nationwide. Texas accounted for about 7% of total withdrawals for all categories, predominantly for thermoelectric power, irrigation and public supply.

Florida had the largest saline withdrawals, accounting for 18% of the total in the country, mostly saline surface-water withdrawals for thermoelectric power. Oklahoma and Texas accounted for about 70% of the total saline groundwater withdrawals in the United States, mostly for mining.

“Since 1950, the USGS has tracked the national water use statistics,” said Suzette Kimball, acting director of USGS. “By providing data down to the county level, we are able to ensure that water resource managers across the nation have the information necessary to make strong water use and conservation decisions.”

A number of factors can be attributed to the 20% decline in thermoelectric-power withdrawals, including an increase in the number of power plants built or converted since the 1970s that use more efficient cooling system technologies, declines in withdrawals to protect aquatic habitats and environments, power plant closures and a decline in the use of coal to fuel power plants.

"Irrigation withdrawals in the United States continued to decline since 2005, and more croplands were reported as using higher-efficiency irrigation systems in 2010,” said Molly Maupin, USGS hydrologist. “Shifts toward more sprinkler and micro-irrigation systems nationally, and declining withdrawals in the West have contributed to a drop in the national average application rate from 2.32 acre-ft per acre in 2005 to 2.07 acre-ft per acre in 2010."

For the first time, withdrawals for public water supply declined between 2005 and 2010, despite a 4% increase in the nation’s total population. The number of people served by public supply systems continued to increase, and the public supply per capita use declined to 89 gpd in 2010 from 100 gpd in 2005.

Declines in industrial withdrawals can be attributed to factors such as greater efficiencies in industrial processes, more emphasis on water reuse and recycling, and the economic recession, resulting in lower industrial production in major water-using industries.

In a separate report, USGS estimated thermoelectric power withdrawals and consumptive use for 2010, based on linked heat and water budget models that integrated power plant characteristics, cooling system types and data on heat flows into and out of 1,290 power plants in the U.S. These data include the first national estimates of consumptive use for thermoelectric power since 1995, and the models offer a new approach for nationally consistent estimates.

In August, USGS released the 2010 water use estimates for California in advance of the national report. The estimates showed that in 2010, Californians withdrew an estimated total of 38 billion gpd, compared with 46 billion gpd in 2005. Surface water withdrawals in the state were down, whereas groundwater withdrawals and freshwater withdrawals were up. Most freshwater withdrawals in California are for irrigation.