CHARLESTON, W.Va. (AP) - Coal slurry will not be allowed to be injected at new underground sites in West Virginia after the state's Department of Environmental Protection issued a moratorium on the practice Wednesday.

However, mine operators in the nation's No. 2 coal-producing state will be allowed to continue pumping a mix of chemicals, coal and dirt into about 15 underground mines where it already is done, the agency said.

Slurry is created when coal is washed with water and chemicals to separate clay, rock and other impurities that keep the carbon from burning efficiently. Underground injection is one way companies can legally dispose of it. They also can store it in massive impoundments, or bury it after it's dried.

The department also released a largely inconclusive 80-page report to the Legislature on the effect of coal slurry injection on water quality. Lawmakers ordered the report in 2006 and told the agency to have it in their hands well over a year ago.

Tests at four slurry injection sites found chemicals, including some used to remove impurities from coal, showed up in underground pools, according to the report. But none showed up in surface or groundwater samples taken during the site-specific investigation.

Tests also turned up elevated levels of strontium, which is a metal, along with sodium, sulfate and high alkalinity, but again the report said it's difficult to tell whether slurry injection, mining or other activities caused the levels.

"None of the sites chosen for the hydrologic assessment showed water quality impacts to surface waters caused by coal slurry injection alone," Department of Environmental Protection Secretary Randy Huffman said in a statement. "However, the study did point out areas where improvements can be made."

CHARLESTON, W.Va. (AP) - Coal slurry will not be allowed to be injected at new underground sites in West Virginia after the state's Department of Environmental Protection issued a moratorium on the practice Wednesday.

However, mine operators in the nation's No. 2 coal-producing state will be allowed to continue pumping a mix of chemicals, coal and dirt into about 15 underground mines where it already is done, the agency said.

Slurry is created when coal is washed with water and chemicals to separate clay, rock and other impurities that keep the carbon from burning efficiently. Underground injection is one way companies can legally dispose of it. They also can store it in massive impoundments, or bury it after it's dried.

The department also released a largely inconclusive 80-page report to the Legislature on the effect of coal slurry injection on water quality. Lawmakers ordered the report in 2006 and told the agency to have it in their hands well over a year ago.

Tests at four slurry injection sites found chemicals, including some used to remove impurities from coal, showed up in underground pools, according to the report. But none showed up in surface or groundwater samples taken during the site-specific investigation.

Tests also turned up elevated levels of strontium, which is a metal, along with sodium, sulfate and high alkalinity, but again the report said it's difficult to tell whether slurry injection, mining or other activities caused the levels.

"None of the sites chosen for the hydrologic assessment showed water quality impacts to surface waters caused by coal slurry injection alone," Department of Environmental Protection Secretary Randy Huffman said in a statement. "However, the study did point out areas where improvements can be made."

Representatives of the West Virginia Coal Association did not immediately respond to requests for comment.

Maria Lambert of the Ohio Valley Environmental Coalition's sludge safety project said the group is pleased that the DEP admits slurry is dangerous, but said the agency must do more.

"The DEP's recommendations are inadequate because people are going to be left with the same health issues for as long as companies are allowed to inject slurry under existing permits," Lambert said in a statement. "The solution the DEP has come up with is inadequate because it does not stop the injection of slurry going on right now. There is one solution to fixing the problem of coal slurry contamination in West Virginia: a ban on all slurry."

Slurry injection is used in a number of coal producing states across the country and in some cases regulated by the Environmental Protection Agency and in others by individual states.

Injecting slurry into old mines was common across Appalachia for decades. But it's also led to lawsuits filed by people who claim the practice has polluted their drinking water with toxins including arsenic, lead and manganese.

Now that DEP has finished its portion of the study, the state Department of Health and Human Resources has a year to develop recommendations.

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On the Net: www.wvdep.org/dmr/slurrystudy.