Sulfate contamination in the Monongahela River has been reduced and it is no longer listed as impaired, a state water quality assessment reveals.

Pennsylvania's 2014 Integrated Water Quality Monitoring and Assessment Report was approved by the U.S. Environmental Protection Agency (EPA) at the end of the year.

Produced by the state Department of Environmental Protection (DEP), the report said that since 2012 a total of 333 miles of previously impaired flowing waters and 853 lake acres have been restored. In addition, fish consumption advisories were removed from 11,592 lake acres.

Two major changes are listed in the 2014 report.

The Monongahela River was previously classed as impaired for potable water use, but the in-stream level of sulfates now meets Pennsylvania's water quality standards.

However, the lower main stem of the Susquehanna River will be added to the fish consumption impairment list for channel catfish larger than 20 inches due to polychlorinated biphenyls (PCBs). As a result, people are recommended to eat no more than one meal of the fish per month.

PCBs were subject to a nationwide ban in 1979 but have lingered in the environment and it will be hard to pinpoint the source of the chemicals that have made their way into the catfish, PennLive.com reported.

Improvements in the Monongahela River follow the elimination of wastewater discharges into the river from Marcellus Shale gas drilling, as well as the closure of several coal-burning power plants along the river, Dave Spotts, head of the state Fish and Boat Commission's Division of Environmental Services, told the Pittsburgh Post-Gazette.