A new study warns that drilling for natural gas in the sliver of Marcellus Shale that stretches across Western Maryland could cause significant problems for the region's forests, water quality and water quantity.

The study, commissioned by the Maryland Department of the Environment, comes as the state determines whether to allow drilling in its western reaches, which include the mountainous terrain and clean rivers of Allegany and Garrett counties — home to the state's ski resorts and its Deep Creek Lake vacation area.

"We believe that it is inevitable that there will be negative impacts from Marcellus Shale Gas Drilling in Western Maryland (and perhaps beyond the state's borders) and that a significant portion of these 'costs' will be borne by local communities," the report said. "Heavy truck traffic on local roads, noise and odors emanating from drilling sites, conflicts with outdoor recreation, diminished tourism, reduced biodiversity, and deterioration of air and water quality are some examples of the types of impacts that are likely even under the best of circumstances."

The report, which the University of Maryland Center for Environmental Science prepared, does not take a stand on whether to allow drilling. Instead, it makes several recommendations on best practices to help Maryland avoid problems that have surfaced in Pennsylvania. Those include well explosions, major disturbance of habitat, fish kills, discharges of toxic-laden wastewater into rivers, dead farm animals and contaminated drinking water.

Drilling for natural gas has become controversial because of a process known as fracking. The drillers bore down thousands of feet into the shale, then turn the drill horizontally to bore along the gas-rich shale layer. Next, they then pump in, under high-pressure, close to one million gallons of water laden with chemicals to fracture and lubricate the rock, and then pump out the drilling fluids, suck out the gas, compress it and deliver it.

The water pumped out of the well, which the industry calls "produced water," includes a lot of chemicals known to be toxic — including benzene, methanol and hydrochloric acid. The water is also filled with naturally occurring chemicals and elements such as uranium that, before the fracking process, remained deep underground but once exposed can prove harmful.

New York is coming to the end of a five-year moratorium on natural gas drilling, which the legislature passed because of concerns over water quality and uranium contamination. Much of the Marcellus Shale in New York is in areas that feed New York City's water supply.

A gas company drilled its first well in Pennsylvania in 2004, but drilling really got under way in the Keystone State in 2008. Since then, nearly 9,000 wells have been drilled. But the Department of Environmental Protection has issued more than 3,000 violations for gas-drilling activities, according to National Public Radio news — some for minor paperwork violations, but others for major explosions, fires or spills.

The Maryland report recommends ways to avoid the problems experienced by other states. One practice it touts is a comprehensive drilling plan, where a driller clusters a few wells in one place and disturbs only 1–2 percent of the land in construction. It suggests comprehensive mapping before drilling — something not always done in Pennsylvania — so drillers can avoid subterranean voids and water surfaces. It also recommends that Maryland not allow drilling within 2,000 feet of underground drinking water sources. And, it strongly advocates for recycling wastewater and abolishing the storage of fracking waste in open pits, a practice that has made animals sick in several states.

Pennsylvania allowed several municipal wastewater plants to take fracking waste, even though the plants did not have the ability to take out the toxic chemicals. At least one of those plants discharged the toxic-laden waste into the Susquehanna.

"Under no circumstances should Maryland allow discharge of any untreated or partially treated brine, or residuals from brine treatment facilities, into the waters of the state," the report said. "To protect its water supplies, Maryland should establish a goal of 100 percent recycling of wastewater in permitting any Marcellus Shale Gas Drilling within the state and have a very strong preference for on-site recycling of wastewater."

Keith Eshleman, who wrote the 172-page study with his colleague Andrew Elmore, said the report was a huge challenge to complete because deep scientific studies on several Marcellus drilling problems have yet to be completed. The EPA, for example, is working on a comprehensive study on drilling's risk to drinking water. Also, Eshleman said, no researcher has studied the effects of surface runoff or erosion from well-pad construction, so they had to use urbanization as a surrogate.

"None of the practices we've identified are what I would call pie in the sky," Eshleman said. "We are calling for two years of site-specific monitoring data before you do anything. If you start to see problems, you can make adjustments. To get better, you have to have data."

Eshleman said that officials from the state's environment and natural resources departments reviewed the study and made some suggestions for revisions. But, he said, "I've not gotten pressure one way or another to do anything."

Meanwhile, several legislators in Annapolis put in bills to stop fracking from coming to Maryland. Those bills failed.

That didn't surprise Drew Cobbs, executive director of the Maryland Petroleum Institute, who called any legislation to ban the practice "premature." Gov. Martin O'Malley has set up a Marcellus Shale Commission to review the studies before any drilling begins.

"You have the commission doing the work, and the threat that fracking was going to occur before they finished the work wasn't a realistic argument," said Cobbs, who added he hadn't read Eshleman's entire report.

He said that he was "cautiously optimistic" drilling would come to the state.

"If Maryland goes forward, it's going to set the gold standard," he said.

But Del. Shane Robinson of Montgomery County, who introduced and then withdrew a bill to ban fracking, said that he sees three problems with fracking: the amount of water used, the emissions of methane from the wells and the fact that Maryland has such a small amount of shale but will spend a large amount of time and money developing a regulatory structure for drilling and then enforcing it.

"It uses way too much water," he said. "And I think it's bad policy to trade a priceless resource for a cheap energy source."

Environmental activists continue to campaign against the practice of fracking. They are planning an event for this summer, possibly in Baltimore, so that legislators and the public can hear from farmers in Pennsylvania who have wrestled with the negative side of gas drilling.

"I think fracking is more risky than it's worth, overall, and I think we need to have a serious conversation about the real costs," said Tommy Landers, executive director of Environment Maryland. "That is part of the conversation that has just not been loud enough in Maryland."