GILLETTE - Coalbed methane water discharges have degraded the water quality of the Powder River, according to a study commissioned by the Powder River Basin Resource Council.

Results of the two-year study indicate that "salt-loading" has significantly elevated the sodium adsorption ratio (SAR) in areas of the Powder, making it less useful for irrigation and more prone to noxious weed invasions on its banks.

Higher SAR values and other pollutants from coalbed methane discharges also threaten several fish populations in the greater Powder River watershed, according to the study conducted by Montana-based Confluence Consulting, Inc.

Industry members dispute the results of the study, noting that not enough baseline information existed on the Powder River and other streams in the area before coalbed methane development began in the region. That makes it difficult to know for sure whether coalbed methane discharges are to blame for any measured degradation.

"It makes it a difficult case to prove what they are saying, and they are blaming the industry for what may be naturally occurring," said John Robitaille, vice president of the Petroleum Association of Wyoming.

PRBRC officials said that very argument is one reason why it commissioned a study of the rivers.

PRBRC board member Clay Rowley said the study helps to fill "data gaps" in the overall understanding of the ecological health of the Powder River watershed.

"While we can guess and make inferences from what we see happening, there is no body of scientific data that analyzes all the parameters in a systematic way," Rowley said.

"I just wish the state or the BLM (Bureau of Land Management) had done this kind of analysis earlier so we'd have some pre-CBM baseline information," Rowley said.

The Wyoming Department of Environmental Quality is responsible for issuing permits to discharge coalbed methane water. In issuing a permit, the agency sets limits for SAR and various pollutants in the hopes of protecting the integrity of existing surface waters for fish, wildlife and agricultural uses.

However, due to a lack of baseline information, those parameters are largely based on best guesses, said John Wagner, administrator of DEQ's Water Quality Division.

"Admittedly, when we put those limits in the permits they are based on theoretical assumptions," Wagner said.

The DEQ did complete a whole effluent toxicity (WET) test of coalbed methane water from the Big George coal seam last year and determined the water could potentially be toxic to a number of aquatic organisms.

DEQ officials said the results persuaded them to impose more stringent pollution limits for certain areas.

Industry estimates that nearly 70 percent of the coalbed methane resource in the basin will come from the Big George coal seam.

Wagner said so far, no regulatory agency has measured a degradation of the overall health of the Powder River. A multi-agency monitoring group is still organizing a program to measure the impacts of coalbed methane development on surface waters, but it has not produced any results yet.

Agencies governing the coalbed methane gas industry have said they have adopted an "adaptive management" plan so they can adjust regulations as they see impacts from the development.

Confluence, the firm that conducted the PRBRC study, concluded that an adaptive management approach is a good idea because it will allow "continual refinement of management activities."

In the meantime, results of the study suggest that the Powder and its connecting waters are already being impacted.

"Confluence found that the Powder River, in spite of its natural turbidity and tolerance for salt leaching from clay soils, is showing "the marked effects of water quality degradation" brought about by increased loading of salts from CBM discharge water and from other toxic constituents

of the water, including arsenic," the PRBRC stated in a press release.

The American Rivers organization listed the Powder among its "Most Endangered Rivers of 2002."