Naturally occurring methane in New York water wells could serve as a baseline to measure the quality of the water supply if and when natural gas drilling is expanded and high-volume hydraulic fracturing (fracking) is allowed, the U.S. Geological Survey (USGS) said in a new report. New York Gov. Andrew Cuomo is expected to announce any day a decision about whether to allow more gas drilling to proceed.

According to the report, “in order to manage water resources in areas of gas well drilling and hydraulic fracturing in New York, the natural occurrence of methane in the state’s aquifers needs to be documented.” The brief, done in cooperation with the New York Department of Environmental Conservation, “presents a compilation of data on dissolved methane concentrations in the groundwater of New York” available from the USGS National Water Information System.

Since 2002 the USGS has conducted groundwater quality monitoring assessments in major river basins of New York. Between 1999 and 2011 methane had been sampled in eight of the 14 major river basins, and the data, combined with those from groundwater age-dating analyses, yielded dissolved methane concentrations from water wells at 239 locations in the state, said researchers William Kappel and Elizabeth Nystrom.

Most of the methane levels in the water wells (91%) either registered no dissolved methane or had levels below the threshold that would require monitoring. The rest of the wells sampled (9%) indicated methane levels that were high enough to warrant monitoring or steps “to avoid possible explosive conditions,” the USGS said.

“Methane in groundwater has been much in the news on account of the potential association with unconventional energy development, but citizens need to be aware that methane occurs naturally in some groundwater systems,” said USGS Director Marcia McNutt. “When present, methane can be dangerous and yet difficult to detect by the consumer, hence the importance of testing groundwater for the presence of this dissolved gas.”

Nearly one-third of New York’s population, or about six million people, gets its drinking water from wells, federal officials said. That figure is similar to other northeastern states in USGS studies on groundwater quality, they said.

Seven percent of the 200-plus wells tested by the USGS had methane levels above 10 milligrams per liter (mg/l), which is high for owners to monitor or fix the problem, the report said. Another 2% of the wells contained methane at levels higher than 28 mg/l, “a level that requires removal of any potential ignition source and venting the gas away from confined spaces to avoid possible explosive conditions.”

The governor’s spokesman said Friday a decision on lifting the fracking moratorium had not been made. A spokeswoman for the New York Department of Conservation said in August the review of high-volume fracking was “continuing” and no decisions had been made (see Shale Daily, Aug. 8). Emily DeSantis said at the time, “It is premature to talk about options until the review of the science and the facts is complete.”