WASHINGTON — A new US Geological Survey (USGS) report says that despite a 30 percent population increase in the United States during the past 25 years, overall water use has remained “fairly stable,” according to an October 29 government news release.

The study looked at water consumption during the five-year period ending 2005 and found that in 2005 the country used slightly less total water than during the peak years of 1975 and 1980.

Released October 29 by Assistant Secretary of the Interior Anne Castle at The Atlantic’s Water Summit in the National Press Club here, the report notes that in 2005 Americans used 410 billion gallons per day, slightly less than in 2000. The declines are attributed to the increased use of more efficient irrigation systems and alternative technologies at power plants.

Water withdrawals for public supply have increased steadily since 1950 — when USGS began the series of five-year trend reports — along with the population that depends on these supplies, the release said.

Nearly half (49 percent) of the 410 billion gallons per day used by Americans was for producing electricity at thermoelectric power plants; irrigation accounted for 31 percent; and public supply 11 percent of the total. The remaining 9 percent of the water was for self-supplied industrial, livestock, aquaculture, mining and rural domestic uses.

According to Castle, the report “underscores the importance of recognizing the limits of the drinking water supplies on which our growing population depends. While public-supply withdrawals have continued to increase overall, per capita use has decreased in many states during recent decades.”

The four states accounting for more than one-fourth of all fresh and saline water withdrawn in the United States in 2005 are California, Texas, Idaho and Florida, the report says. The states with the largest fresh surface-water uses were California, Texas, Idaho and Illinois. The states with the largest fresh groundwater uses were California, Texas, Nebraska and Arkansas.

In its own analysis of the USGS data, the Oakland, CA-based think tank Pacific Institute said in an October 29 news release that the drop in total water consumption means that per-capita water use in the United States has decreased to 1,383 gallons per person per day — a level not seen since the 1950s.

The organization warned that when population growth in drier regions, climate change and tensions over sources are considered, there still is “tremendous untapped potential for improving efficiency in homes and businesses.”

Freshwater expert Dr. Peter Gleick, president of the Pacific Institute, is quoted in the release saying, “Even with the improvements we’ve seen, our rate of population growth and regional water usage is not sustainable. In many regions we are past the point of peak ecological water use, where current levels are damaging the health of our rivers, lakes, and groundwater aquifers. We have the tools to further reduce our water footprints dramatically. We need the will to make the changes and rethink how we manage our freshwater resources at every level.”

According to the USGS report, the largest uses of fresh surface water were power generation and irrigation, and the largest use of fresh groundwater was irrigation.

To read the news release, click here.

To access the full report, click here.

To read the Pacific Institute release, click here.

For related information, click here.