* EPA inspected well pads and compression stations
* "Legitimate concerns" have been raised-EPA
* Investigation to be completed in a "couple of months"
WASHINGTON, Feb 14 (Reuters) - U.S. environmental regulators are investigating possible violations of federal pollution laws at natural gas operations in a Pennsylvania county that is in the midst of a shale gas drilling boom.
The Environmental Protection Agency conducted inspections at well pads and compressor stations in Washington County, Pennsylvania, in late September and early October, agency spokeswoman Bonnie Smith said.
The agency is now analyzing the results of those inspections and expects to wrap up its probe in a couple of months, Smith said.
Investigations, such as the one being conducted in Washington County, are aimed at ensuring that companies are in compliance with various federal regulations for air, water and hazardous waste.
"While natural gas operators employ various safeguards to minimize the risks inherent to the industry, legitimate concerns have emerged regarding potential environmental impacts," the EPA said.
The EPA said it would not identify the names of the facilities that were inspected until the investigation is complete.
EPA enforcement probes that cover multiple environmental laws can target a single facility, an entire company or be geographically based.
Washington County, a hub of Marcellus shale drilling, was chosen for inspections because it is home to a significant amount of oil and gas production, the EPA said.
The county is also being analyzed as part of a separate study being conducted by the EPA on the impact of hydraulic fracturing, or fracking, on drinking water. The initial results of that report, which was commissioned by Congress, are to be released later this year.
Shale gas production has skyrocketed in recent years thanks to advances in fracking, which involves injecting a cocktail of water, sand and chemicals into the ground to extract fuel.
The rapid expansion of shale gas development has also prompted complaints from green groups and some landowners that the drilling is harming the air and water.
Supporters of the production argue that industry is working hard to manage any environmental concerns and that the Obama administration is unfairly targeting shale gas drillers.
The EPA angered many in the industry last year when it released a draft report that said fracking fluids likely polluted an aquifer that supplies public drinking water in Wyoming. Detractors contend the agency's findings were faulty.
The agency is also trucking drinking water to four homes in Dimock, Pennsylvania, after receiving data from residents suggesting the water has been polluted by drilling. (Editing by Lisa Shumaker)