It has had a number of improvements made over the years to reduce the level of environmental pollution, especially measures to cut down acidic emissions of nitrogen and sulphur oxides.

In 2009 a wet flue-gas desulfurization system was put in place to reduce sulfur dioxide and heavy metal emissions.

The plant has a continuous emissions monitoring system in the stack which must adhere to very rigid accuracy and reliability requirements established by the Commonwealth of Pennsylvania.

PSEG Fossil owns a 22.84 percent share (391 net MW with peaker), while Reliant Resources, operates it.

The plant is basically a twin of the Conemaugh Generating Station, also partially owned by PSEG Fossil.

Fuel: Coal Commercial Operation: Unit 1: 1967, Unit 2: 1968 Ownership: 22.84% PSEG Fossil (partial list of 78.26%) Keystone was outfitted with a wet limestone scrubber system in late 2009 to partially remove heavy metals and sulfur dioxide from the emitted flue gas.

While the plant has had SCR technology in place since 2003 to reduce emissions of nitrogen oxides, after 2010 operation of this equipment during the ozone season (May – September) was severely curtailed.