Natural gas development in the Marcellus Shale poses a danger to the Susquehanna River and its tributaries, which supply almost half of the fresh water resources in the Chesapeake Bay, American Rivers said Tuesday.

American Rivers publishes an annual list of the "most endangered rivers" in the country. The Susquehanna River is at the highest risk because of the dangers from contaminated water from gas drilling operations, it said in its latest report. The Susquehanna and its tributaries flow over the Marcellus Shale region in New York, Pennsylvania and Maryland.

The "threat of contamination is high" to the Susquehanna River because some of the water used to hydraulically fracture (frack) the Marcellus Shale returns to the surface and "requires specialized treatment, but at this time only a limited number of wastewater treatment facilities have the capacity to handle it."

Pennsylvania and New York, the authors noted, are working to improve clean water safeguards for gas development but "they fall short of adequately protecting the water supply for millions of Americans." Because of the lack of safeguards, these states and the Susquehanna River Basin Commission (SRBC) should "analyze all of the potential cumulative impacts that could result from natural gas extraction and ensure proper regulations are in place and capable of being enforced before development is allowed to continue."

The Harrisburg, PA-based SRBC manages the water resources of the Susquehanna River Basin, which provides about 45% of the fresh water in Chesapeake Bay. The Susquehanna River starts in Cooperstown, NY, and flows 444 miles to Havre de Grace, MD, where the river meets the Chesapeake Bay.

American Rivers urged the states and the SRBC to "announce a complete moratorium on water withdrawals and hydraulic fracturing until there are comprehensive regulations in place for natural gas development or they will put public health and drinking water at risk."

Late last year the SRBC said it would install real-time monitoring stations in 10 watersheds in the Southern Tier of New York as an early warning system for potential gas drilling incidents (see Shale Daily, Dec. 2, 2010). In April the Chesapeake Bay Foundation urged the Obama administration to authorize a comprehensive study on fracking in the Marcellus Shale and its potential effects on the Chesapeake Bay watershed (see Shale Daily, April 5).

Several frack-related spills have affected the Susquehanna River's tributaries in the past few years. Chesapeake Energy Corp. last week resumed completion activities in the Marcellus after voluntarily halting operations in April following a well blowout, which released thousands of gallons of fracking fluid into a tributary of the Susquehanna River (see Shale Daily, May 16; April 25).

The spill led the Pennsylvania Department of Environmental Protection to launch an investigation and to issue a notice of violation (see Shale Daily, April 26). The state of Maryland also has filed a lawsuit against the company (see Shale Daily, May 4).

At No. 7 on the American Rivers list is the Hoback River in Wyoming, which also is said to be threatened by gas drilling.

The Hoback flows through the Bridger-Teton National Forest in the Wyoming Range. In May the U.S. Forest Service withdrew a decision to not permit oil and gas drilling in the forest (see Daily GPI, May 9). In the reversal U.S. Forest Supervisor Jacqueline A. Buchanan said a more thorough analysis needs to be conducted before a final decision on drilling is made.

"In addition to significant sedimentation risk from well construction and other development, the river's clean water is threatened by industrial chemicals and toxic wastewater from the hydraulic fracturing...process," the authors said of the Hoback's designation on the list.