RRI Energy's Seward electric power plant along the Conemaugh River in southern Indiana County has violated toxic pollution and river temperature limits thousands of times in the last five years, according to environmental groups.

The groups -- PennEnvironment, the Sierra Club, PennFuture and Defenders of Wildlife -- announced Monday that they will file a formal 60-day notice of their intent to sue the company in federal court for its repeated violations of the Clean Water Act.

The groups said RRI's own reports to the state Department of Environmental Protection show water discharges into the river from a coal refuse site at the plant exceeded permitted limits of iron, aluminum, manganese and acidic water on 400 separate days and for every month since 2005.

The company's monitoring reports also show pollutants, including toxic heavy metals, are leaching from the refuse pile and contaminating the river and groundwater in the area, violating the federal Clean Water Act and state Clean Streams Law, the environmental groups say.

In addition, the hot, polluted wastewater discharged by the 521-megawatt waste-coal burning power plant 60 miles east of Pittsburgh has often caused river water temperatures to spike by 12, 14, and even 20 degrees in less than an hour. The power plant's permit limits river temperature changes to 2 degrees, but it has exceeded that limit more than 600 times, the groups said.

The large and quick river temperature fluctuations threaten aquatic life, said Lisa Widawsky, an attorney with the Environmental Integrity Project, a Washington, D.C.-based group representing four other environmental groups.

Laurie Fickman, a spokeswoman for Houston, Texas-based RRI, said Monday that the company needs to review the formal notice before it can respond to the allegations of permit violations.

Josh Kratka, senior attorney at the National Environmental Law Center, who also worked on the notice, said the environmental groups decided to take action on the pollution violations because the DEP, which has primary enforcement responsibility, has not.

"I understand that the department is totally under-resourced and understaffed, to the extent it's trying to stop a flood with a teaspoon," Mr. Kratka said. "But when there are this many violations there should be some sort of red flag raised."

Heather Sage, vice president of PennFuture, said "for decades, we've been paying dearly for the cost of coal mining and burning -- with polluted air, land, and streams, poor health and a devastated economy.

"We simply cannot compete in the 21st-century green economy while shackled by the pollution from a technology whose time is past."

The $800 million Seward plant was built by Reliant Energy, now RRI, in 2004 to use low-grade "waste" coal. It uses about 3.5 million tons of waste coal annually.

David Masur, state director for PennEnvironment, said a review of RRI's discharge monitoring reports by environmental groups uncovered more than 12,000 permit violations over the last five years by reviewing discharge monitoring reports required by those consent agreements, and the violations are ongoing.

Helen Humphreys, a DEP spokeswoman, said the department has records of just 212 violations at the Seward plant since 1999 -- 210 covered by a September 2000 consent order and two amendments to that order that went into effect in 2001.

In the 2000 consent order, Reliant, now RRI, had agreed to remediate the coal refuse site, its runoff and groundwater contamination when it built the new power plant in 2004.

RRI's five-year National Pollutant Discharge Elimination System permit for Seward, renewed in June 2001, expired in 2006 but was "administratively extended" by the DEP, said Ms. Humphreys. She said the DEP and RRI are negotiating a discharge permit renewal and it could be issued later this year.

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