WASHINGTON • A study released Thursday finds that 39 sites in 21 states where coal-fired power plants dump their coal ash are contaminating water with toxic metals such as arsenic and other pollutants, and that the problem is more extensive than previously estimated.

The analysis of state pollution data by the Environmental Integrity Project, the Sierra Club and Earthjustice comes as the Environmental Protection Agency is considering whether to impose federally enforceable regulations for the first time. An alternative option would leave regulation of coal ash disposal up to the states, as it is now.

The EPA will hold the first of seven nationwide hearings about the proposed regulation Monday in Arlington, Va. A public comment period ends Nov. 19.

Concerns over coal ash have ignited in Franklin County, where residents of Labadie are fighting a plan to develop a 400-acre coal ash landfill. The AmerenUE facility would dispose of waste from the Labadie Power Plant, which generates about 350,000 tons of coal ash a year.

The electric power industry is lobbying to keep regulation up to individual states. Environmental groups say the states have failed to protect the public and that the EPA should set a national standard.

"This is a huge and very real public health issue for Americans," said the director of the study, Jeff Stant of the Environmental Integrity Project. "Coal ash is putting drinking water around these sites at risk."

EIP is a nonpartisan organization that advocates for enforcement of environmental laws.

Of the 39 sites analyzed, 35 had groundwater monitoring wells. All of them showed concentration of heavy metals such as arsenic and lead that exceeded federal health standards.

The other four had only water monitoring data from rivers or lakes where the waste sites discharged water. Scientists found contamination that damaged aquatic life.

The report, following a previous study by the environmental groups and EPA's own tally, brings the number of contaminated coal waste sites to 137 in 34 states.

The Post-Dispatch contributed to this report.