Americans began using less water even before this summer's drought curtailed supplies, according to a study by the U.S. Geological Survey.

The USGS analysis attributes at least part of the reduction in use to a decline in the water available, stemming from the volume of water consumed across the nation in prior years.Utah's daily water use per resident was 2,540 gallons in 1985 and 3,100 in 1980, the USGS said.

The overall picture remains bright as far as total water available is concerned, the study reports. But that doesn't mean there is enough in every place for every use.

The USGS found that the amount of water drawn from lakes, streams, reservoirs, wells and springs fell 10 percent between 1980 and 1985.

The water analysis, the eighth done since 1950, was the first to disclose a decline in national water usage.

The 1985 total was 399 billion gallons per day, including 338 billion gallons of fresh water. That amounted to 1,400 gallons of fresh water used daily for every American, down from 1,600 in 1980.

The decreases were widely spread across the nation, with a majority of states reporting less water use during 1985 when compared with 1980, Wayne Solley, a survey hydrologist and senior author of the report, said in a statement accompanying the survey's release Monday.

Spot sampling during the current drought indicates some increases in use of water from various sources, but the agency said it did not have enough information to make national estimates. It took two years to compile all the data for the 1985 analysis.

The agency said a number of factors likely contributed to the decline in water use in the first half of this decade, not the least of which was that previous usage left less water available.