HARRISBURG, Pa. (AP) -- The Environmental Protection Agency has asked Pennsylvania regulators to increase monitoring of wastewater discharges into rivers from the state's natural gas industry, which is booming from exploration of the Marcellus Shale rock formation.
In addition to producing gas, the thousands of wells now being drilled into the ancient sea bed produce large amounts of ultra-salty water tainted with metals like barium and strontium, trace radioactivity, and small amounts of toxic chemicals injected by energy companies.
Most big gas states require drillers to dump that waste into deep shafts to prevent it from contaminating surface water, but Pennsylvania allows the fluids to be discharged into rivers after partial treatment.
State regulators and the industry have insisted the practice is safe and adequately regulated, but an EPA regional administrator, Shawn Garvin, said in a letter to Pennsylvania's Department of Environmental Protection on Monday that it was concerned about the potential for harm to human health and the aquatic environment.
"Many of these substances are not completely removed by wastewater treatment facilities, and their discharge may cause or contribute to impaired drinking water quality for downstream users, or harm aquatic life," Garvin wrote.
He said Pennsylvania's drinking water utilities should start sampling immediately for radium, a naturally existing radioactive substance sometimes found in drilling water prior to treatment. Similar testing should be required at the treatment plants handling the waste, he said.
Garvin also asked the agency to re-examine permits previously issued to the treatment plants handling the waste, saying they currently lacked "critical provisions necessary for effective processing and treatment of wastewaters from drilling operations. He suggested in his letter that Pennsylvania officials had already, independently, expressed an interest in re-evaluating those permits -- a step he called "welcome."
Pennsylvania's acting environmental protection secretary, Michael Krancer, didn't immediately indicate whether he intended to take any of the actions requested by the EPA. He appeared to chafe, slightly, at the suggestion that the state wasn't doing enough to regulate the industry.
"We are reading and evaluating the letter, just like we do with all input that comes to us. We at DEP know what our responsibilities are," he said in a statement released by a spokeswoman.
"We will focus on protecting public safety and the environment and we will do that with facts and science. We will work with EPA to be sure that it is aware of everything we are doing in Pennsylvania in that regard."
The letter comes after EPA Secretary Lisa Jackson, under increasing political pressure, visited the agency's Region 3 offices in Philadelphia on Friday to discuss growing concerns about the industry. Among the topics discussed was whether monitoring at wastewater treatment plants was good enough to determine whether drilling is contaminating rivers.
It represents an escalation of EPA's involvement in gas drilling issues in Pennsylvania since 2008, when the riches of the Marcellus Shale began attracting a gas rush of hundreds of companies drilling thousands of wells. Regulation of the industry has been largely left to the state DEP, as under federal rules, the state -- not the EPA -- is primarily responsible for enforcing federal laws like the Clean Water Act.
Records kept by the state show that in the last six months of 2010, at least 2.77 million barrels, or around 116 million gallons, of wastewater from the drilling industry was sent for processing at plants that discharge into the state's rivers and streams.
The great majority of that waste went to just seven plants that discharge into the Allegheny River, the Mahoning River, the Conemaugh River, the Blacklick Creek, the Monongahela River, the Susquehanna River and the South ForkTenmile Creek.
Energy companies have argued that those treatment plants have adequate systems in place to remove radium and other pollutants found in drilling waste, like barium and strontium.
Public water suppliers don't always test frequently for those substances, however, to see if the industry's claims are correct. Water suppliers currently test only occasionally for radium. It has been years since the utilities drawing from rivers in the affected drilling region have done those tests.
"To ensure public safety, additional sampling is needed," Garvin said, adding that he hoped sampling could begin within 30 days.
On Monday, the state DEP announced it has for several months tested water downriver from treatment plants that handle gas drilling wastewater -- and has found no cause for concern. The initial DEP tests showed levels of radionuclides -- radioactive contaminants in water -- to be at or below the naturally occurring background levels of radioactivity.
Radium, swallowed or inhaled, can accumulate in human bones, EPA says, and long-term exposure can increase the risk of such diseases as lymphoma and bone cancer.
Garvin acknowledged the initial DEP tests but suggested the testing is not sufficient to account for such variables as the volume of wastewater and the concentrations of its radioactivity.
The wastewater plants do not remove the salty dissolved solids that could potentially make the waste stream environmentally damaging, so the Department of Environmental Protection strengthened rules last year that will make it difficult for any new treatment plants to be built unless they have expensive distilling equipment.
The rules, however, rely partly on tight controls of which plants are discharging the waste, and Pennsylvania has not always been able to track where all of the water is going. An Associated Press review, published in Jaunary, found that a good portion of the wastewater was unaccounted for, and some was going to at least one plant that hadn't received the proper permissions from regulatory bodies.
In the meantime, the industry has been working to reduce the amount of waste sent to rivers.
Drilling for gas in deep underground shale deposits requires injecting huge volumes of water underground to help shatter the rock -- a process called hydraulic fracturing. Some of that water then returns to the surface.
Lately, drillers have been reusing that water in new wells, rather than simply discarding it. These recycling efforts now account for at least 65 percent of all wastewater generated by the industry, according to state records.
The percentage of wastewater being recycled has grown tremendously, up from nearly nothing 18 months ago, but it has been offset to a degree by an overall increase in drilling activity.
The EPA is currently planning a nationwide study on the environmental consequences, particularly the impact on the quality and quantity of water.
Associated Press writers Dina Cappiello in Washington and Marc Levy in Harrisburg, Pa., contributed to this report.