Mine drainage turns Montour Run milky green

Tributaries also affected by mine

Pittsburgh Post-Gazette

A high concentration of dissolved aluminum in mine drainage was believed to be responsible for a milky discoloration found Monday throughout Montour Run and its tributaries.

State and Allegheny County environmental officials said the substance appeared to be present in concentrations that had the potential to harm fish, insects and microorganisms. No alert was issued along the Allegheny County stream that flows from points near Pittsburgh International Airport to its confluence with the Ohio River at Coraopolis.

The state Department of Environmental Protection, the Fish and Boat Commission and the Allegheny County Conservation District were investigating.

“I was with Allegheny County Conservation District [staff] when we tested the stream,” said Matthew A. Raetsch, a waterways conservation officer with the state Fish and Boat Commission. “Our best guess is [the cause was] mine drainage because of all the torrential rains we’ve had. We don’t know the impact yet. We’re looking into it.”

Mr. Raetsch said he saw no evidence of dead or distressed fish or insects. A detailed lab report was expected within a couple of days.

In its 37 square miles, the Montour Run watershed is fed by tributaries that cross long-abandoned mines from the Pittsburgh No. 8 coal seam. The mine entrances were sealed long ago, said Robert C. Dolence, a board member of the Montour Run Watershed Association, but they can overflow following periods of heavy rain.

The greenish white discharge, he said, was the result of a chemical reaction.

“The sulfur in the coal seam oxidizes when it’s exposed to air in the mine,” he said. “When the oxidized sulfur meets water, it creates dissolved iron particles and sulfuric acid, which dissolves aluminum and other minerals. The mine drainage including the dissolved aluminum mixes with alkaline, giving the water a milky appearance.”

Montour Run is parallel to the Montour Trail, which rolls from Coraopolis to the Library section of South Park Township. The creek flows through several community parks.

Montour Run is stocked with trout from the mouth of Trout Run to Ewings Mill Road. State stockings of brown and rainbow trout are scheduled for April 12 and April 16. The statewide trout season opens April 14. Mr. Raetsch said mine discharges can delay or force the cancellation of fish stockings.

John Bodner of Cecil, who coordinates private stockings of Montour Run by the Forest Grove Sportsmen’s Club, said the group had planned to stock 1,200 brook, brown, rainbow and golden rainbow trout, many of trophy size, for an upcoming tagged-fish contest.

“There have been mine overflows before, but it’s never happened like this on this creek. Never this much,” said Mr. Bodner, who has been involved in Montour Run rehabilitation projects for 30 years. “[The milky discharge] is in the headwaters, tributaries, the main stem. It’s everywhere.”

In December, Mr. Bodner said, Montour Run was “loaded” with forage fish and insects.

“Now we’ll have to see,” he said.