RENO -- Overall releases of toxic chemicals to the environment by industry in Nevada decreased 8 percent in 2009 to 184 million pounds compared with the previous year, federal regulators reported Thursday.
Mining companies accounted for 97 percent of the releases to air, water and land covered in its annual Toxics Release Inventory, according to the U.S. Environmental Protection Agency.
The report, which also covers offsite transfers for disposal, lists arsenic, lead, zinc, manganese, antimony and mercury as the most common forms of chemical pollution in Nevada.
Air releases increased 5 percent to 1.6 million pounds, onsite land releases decreased 9 percent to 179,536 million pounds and offsite transfers for disposal climbed 27 percent to 2.3 million pounds, according to the report.
Overall releases of mercury and mercury compounds decreased 3 percent to 5.2 million pounds in Nevada.
Justin Hayes of the Idaho Conservation League hailed a roughly 50 percent reduction in airborne mercury emissions from Nevada gold mines to 2,523 pounds in 2009, saying it was good news for people in Nevada, Idaho and Utah living down wind from the mines.
The emissions have been suspected of making some fish and waterfowl in the states so polluted with methylmercury they are unsafe to eat. Children and women of child-bearing age are most at risk.
"This reduction is the single most significant reduction reported in the Toxics Release Inventory this year, and has the most profound effect on the health of people and the quality of the environment," Hayes said.
Nevada's top five polluters were Newmont Mining Corp. mines in Golconda, Carlin and Battle Mountain, and Barrick Gold Corp. mines in Elko and Crescent Valley, the report said.
Newmont's Twin Creek Mine in Golconda led the state with nearly 48 million pounds of total releases, followed by Barrick's Goldstrike Mine in Elko with 41 million pounds. Mining unearths lead and mercury naturally, or can produce it as a byproduct.
Mining officials have maintained EPA's figures are misleading. While the agency considers the chemicals to be released because they are displaced, most often the elements are fully contained in waste rock or soils, they said.
Louis Schack, spokesman for Barrick Gold of North America, said his company had not had time to review the report and could not draw any immediate conclusions from it.
"As responsible mine operators, we have worked for many years to reduce impacts, enhancing the protection of both people and the environment," he said. "We continue making significant progress in controlling mercury emissions."
The state of Nevada began requesting voluntary reductions in mercury emissions in 2001 and adopted mandatory controls in 2006 at 15 gold facilities in the state. The federal EPA also is moving ahead with plans to cut mercury emissions from Nevada gold mines.
John Hadder, director of the Reno-based conservation group Great Basin Research Watch, said the reduction in airborne mercury from mines shows the state program is working.
"Our position is we want to see mercury emissions reduced as low as possible," he said. "The Nevada program is producing good results and we hope it'll continue to produce even better results as time goes by. If the EPA standards can improve on that, that's great."
But Hadder questioned Nevada's reported 8 percent overall reduction in toxic chemicals in 2009, saying it could stem from a production slowdown instead of cleaner manufacturing processes.