Overall Water Usage Declines in the U.S.

By Kelli Foy

Those of us living in the Great Lakes region might take it for granted, but water conservation is an important part of creating a secure environment. A recent U.S. Geological Survey (USGS) report boasts some good news on this front for sustainability experts.

Estimated water use in 2010, the last year records were available, was 13% less than that used in 2005 and total water withdrawals are at their lowest level since before 1970. The dramatic shift in usage was caused by significant declines in the largest water use categories, including thermoelectric power, irrigation, public supply and industrial. Although usage in the mining and aquaculture categories increased, the low overall usage in these categories did not offset the declines seen in the other large categories. The USGS provides in depth information on each of the eight categories reported: public supply, domestic, irrigation, livestock, aquaculture, industrial, mining and thermoelectric power.

WaterThe public supply category encompasses water withdrawals by public and private water suppliers that provide water to at least 25 people or have a minimum of 15 connections that are used for domestic, commercial or industrial purposes. It also includes water used for public services and system losses. However, the largest component of the category is domestic deliveries, which account for 57% of the total public-supply withdrawals nationally. In 2010, approximately 86% of the total U.S. population received potable water from public-supply facilities, which remained unchanged from 2005. Despite the stagnant percentage of users, the withdrawals in 2010 dropped 5% to 42,000 million gallons per day (Mgal/d). Notably, this is the first time this category has declined since the USGS began reporting water use numbers in 1950.

Domestic use, as the USGS defines it, considers indoor and outdoor residential water use. Of domestic water use in 2010, 3,600 Mgal/d were self-supplied and 23,800 Mgal/d came from public suppliers, for a combined total of 27,400 Mgal/d. The combined national average per capita usage was 88 gallons per capita daily (gpcd). The corresponding per capita usage for 2005 was 98 gpcd. Illinois fell below the 2010 national average in this category with a per capita usage of 80 gpcd.

Irrigation—which includes agricultural and horticultural practices as well as watering of open spaces like golf courses, parks and cemeteries—was also down. Total irrigation withdrawals for 2010 were 115,000 Mgal/d, which represented a 9% decline from the 2005 numbers and the lowest usage level since before 1965. The study saw the second consecutive 5-year period of decline and placed the 2010 withdrawals 23% lower than withdrawals in 1980, when irrigation was at peak usage levels. Incredibly, this decrease in water use occurred despite the addition of 950 thousand acres of irrigated land over the five-year period. This can be attributed to more water-efficient irrigation systems, including sprinkler systems, up 3% from 2005, and micro-irrigation systems, up 14% from 2005.

Industrial water usage includes withdrawals for fabricating, processing, washing, diluting, cooling or transporting a product. It also includes incorporating water into a product and sanitation needs within a manufacturing facility. In 2010, industrial withdrawals were 15,900 Mgal/d, a 12% decline over 2005. Notably, only three states (Indiana, Louisiana and Texas) account for 35% of the total industrial withdrawals.

water_sidebarThermoelectric power withdrawals were 161,000 Mgal/d in 2010, which accounted for the majority of total water use at 45%. In 2010, an average of 19 gallons were used to produce one kilowatt-hour of electricity compared to almost 23 gallons in 2005. Estimated withdrawals in this category decreased by 20% from 2005, which was the largest drop-off seen in any category in the study. Possible reasons for the sharp decline include plant closures, use of linked heat and water budget model data, decrease in use of coal and increase in use of natural gas and new power plants using more water-efficient cooling technology. Illinois led the nation in water use at power plants with a total of 10,700 Mgal/d, just ahead of Texas.

The estimated water withdrawals for livestock uses in 2010 went down by 7% over withdrawals for this category in 2005 while two categories, mining and aquaculture, saw a rise in water use. The aquaculture sector has expanded over the last decade, and water use has seen a corresponding uptick. Total aquaculture water use in 2010 accounted for 3% of total water withdrawals and an increase of 7% from 2005. In this category, only four states (Idaho, North Carolina, California and Oregon) were responsible for 63% of the total withdrawals.

In 2010, total mining withdrawals equaled an estimated 5,320 Mgal/d, which accounted for only about 1% of total withdrawals. While freshwater withdrawals were slightly down, total water use in the mining industry increased by 39% since 2005. The overall increase was the result of a 97% climb in saline-water withdrawals. Though that number is staggering, it may be partially attributed to increased accounting of water produced as a by-product of oil and gas extraction that is re-injected for secondary oil and gas recovery.

The USGS study indicates that strides are being made to successfully reduce water withdrawals. Declines were seen in all but two categories reported in the 2010 study. Hopefully, the trends will continue for the 2015 report due to the advent of new technology and continued conservation efforts.

Image: U.S. Army Corps of Engineers

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