PITTSBURGH -- High levels of an ultra-salty compound that could be linked to oil and gas drilling persist in the Allegheny River's Pittsburgh-area watershed, while the levels declined in the nearby Monongahela River, recent research shows.
Officials at public water utilities in both watersheds grew concerned in 2009 and 2010 when bromide levels soared during a surge of Marcellus Shale gas drilling. Although not considered a pollutant by themselves, the bromides combine with chlorine used in water treatment to produce compounds that can threaten public health.
A recent Pittsburgh Water and Sewer Authority report found that high levels of bromides persisted this year in the Allegheny just downstream from industrial brine treatment plants. The plants accept wastewater from oil and gas drilling and other industrial activities.
Also, preliminary research by a Duke University team found a similar problem in a tributary of the Allegheny, professor Avner Vengosh told The Associated Press on Monday. Vengosh said the source there appears to be from conventional oil or gas wells, not shale wells.
But on the Monongahela River, a Carnegie Mellon University team said last week, preliminary research found that bromide levels declined significantly this year, after Marcellus Shale gas drillers responded to warnings from scientists and environmental groups and voluntarily stopped taking waste to treatment plants there. The Monongahela merges with the Allegheny at Pittsburgh to form the Ohio River.
In early 2011, the Pennsylvania Department of Environmental Protection called on shale gas drillers to voluntarily stop taking wastewater to public water treatment plants along rivers, and major companies and industry groups agreed to the request. Now, most shale wastewater is sent to deep underground waste wells in Ohio or recycled.
The DEP wastewater request doesn't apply to conventional oil and gas well wastewater, and Vengosh said that doesn't make sense.