SALT LAKE CITY — U.S. water withdrawals are at their lowest overall level in 45 years, experiencing signficant declines in the largest use areas like public water supply, irrigation, industry and thermoelectric power.
A report released this week by the U.S. Geological Survey said those categories experienced significant declines and that the 355 billion gallons of water used per day in the United States is at a consumptive level not seen since before 1970.
It means the country is developing ways to use water more efficiently and has improved conservation efforts.
Overall, that 2010 U.S. withdrawal is 13 percent less than in 2005, according to the report released Wednesday. Mining — which includes the oil and gas industry — experienced the most dramatic increase of 39 percent, while aquaculture ramped up 7 percent more than in 2005. Aquaculture includes fish hatcheries and farming of finfish and shellfish.
Across the country, 268 million people rely on a public water supply via water districts and other public delivery systems — or 86 percent of the population. The remainder rely on "self-supplied" systems that derive the majority of water used from springs and wells.
The report, "Estimated Water Use in the United States," represents the most comprehensive water-use data compiled by a federal agency and has been released every five years since 1950.
A number of factors are cited in the U.S. Department of Interior report that would lead to the substantial declines in large usage categories. The report points to the implementation of water saving measures in communities as the public and politicians become more savvy about conservation and increases in industrial reuse and recycling of wastewater.
While thermoelectric power and irrigation remained the two largest uses of water in 2010, both were notably less in 2010 than in 2005. Thermoelectric power water usage was 20 percent lover in that time period — dropping to a pre-1970 level ,and irrigation was 9 percent less in 2010 over 2005 and at the lowest volume since before 1965.
Thermoelectric power plants are using new cooling system technologies, are turning to natural gas over coal or have experienced closures, while farmland acreage is increasingly moving to sprinkler or micro-irrigation systems, the report said.
Public water supply withdrawals are down 5 percent (even though population was up 4 percent) between 2010 and 2005, and represent the first time since the five-year reporting began in 1950 that a decrease has been documented.
About 35 percent of all public water supply withdrawals came from the four states with the largest populations: California, New York, Florida and Texas. In total, 12 states accounted for 50 percent of all the withdrawals in the United States.
Even though mining use of water constituted the largest percentage of increase from 2005 to 2010 — 39 percent — the escalation of usage had minimal impact because it represents such a small percentage of the overall use, just 1 percent, according to the report.
The report shows Utah among the seven highest states for water withdrawals for mining in 2010 — at 250 million gallons per day, with 246 million gallons of that water derived from a saline supply, rather than freshwater.
Increased water usage in the mining category is reflective of the accelerated domestic oil and gas activity in the country. While freshwater withdrawals were only 1 percent less in 2010 than in 2005, saline water withdrawals were 97 percent more. The report notes that some of the increase in saline water usage is attributed to the increased accounting of water produced as a byproduct during oil and gas extraction and then reinjected for secondary oil and gas recovery.
Utah and Alaska, according to the report, accounted for 100 percent of the saline surface water withdrawals.
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