Brunner Island

The Brunner Island power plant along the Susquehanna River near York Haven, York County.

The Brunner Island power plant — often scorned as one of the most polluting electricity producers in the United States — has agreed to stop using coal by the end of 2028.

Instead, the plant will produce power almost entirely with natural gas. The York County facility along the Susquehanna River across from Bainbridge, Lancaster County, had partially switched to natural gas in the last year.

The Sierra Club, which had announced an intent to sue the facility for air and water pollution, said it had reached a settlement with owner Talen Energy, which confirmed the agreement.

Under the terms of the settlement, the 57-year-old plant will stop burning coal from May through September — the peak smog season — by 2023, except for burning coal in case of power shortage emergencies.

Coal will be phased out completely by 2028.

The Brunner Island Steam Electric Station is often cited as a significant factor in poor air quality in Lancaster County.

From 2012 through 2014, the county had the worst soot levels in the state, according to the American Lung Association. Soot comes mainly from coal-fired power plants, combusion in vehicles and from  industries.

The Sierra Club and Talen officials said they will execute the settlement through a court-enforceable consent decree.

"While we still have a few years until these protections will go into effect, stopping coal burning at Brunner Island will end the creation of many harmful toxins and help surrounding states meet the federal air pollution limits set by the Clean Air Act," said Mark Kresowik, of The Sierra Club's Beyond Coal campaign.

Both Delaware and Connecticut in recent years had requested the federal Environmental Protection Agency force Brunner Island to cut down on smog pollutants, claiming the power plant's nitrogen oxide emissions were causing unhealthy air in their states.

Connecticut ended up suing EPA and last week a U.S. District Court judge ordered the agency to make a decision on cleaning up the Brunner Island power plant within 90 days.

A Talen spokesman said the settlement with The Sierra Club will give Brunner island "a clear path forward to sustainable operation."

Todd Martin, spokesman for the Allentown-based utility, said the settlement "resolves all current and future claims against the plant. "We are pleased the parties reached an agreement that eliminates the distraction of litigation or objections to permitting and enables Brunner Island to focus on the safe, efficient and reliable generation of electricity for our customers," he said.

Brunner Island produces enough electricity to power about 1 million homes.

Talen and its former owner, PPL, had spent $800 million in air pollution upgrades to conform to limits on mercury, sulfur dioxide and other air toxins.

In 2015, Brunner Island was singled out by The Sierra Club as the largest single source of smog-causing nitrogen oxides in southeastern Pennsylvania. In 2013, Brunner Island had been ranked as the 59th-worst power plant in the country for emissions of carbon dioxide, widely recognized as contributing to climate change.

Burning of natural gas emits no precursors of acid rain or mercury. Nitrogen oxides are significantly lower than burning coal and carbon dioxides are cut in half.

But Brunner Island has still been out of compliance with state and federal regulations on heated water discharged into the Susquehanna as well as nutrients from wastewater that empty into the river.

Some of those pollutants stem from coal ash basins at the plant site, according to The Sierra Club.

Closures of coal-fired power plants have accelerated across the U.S. in recent years.