Workers at a steel mill and a power plant were the first to notice something strange about the Monongahela River in summer 2008.

The water that U.S. Steel and Allegheny Energy used to power their plants contained so much salty sediment that it was corroding their machinery. Nearby residents saw something odd, too. Dishwashers were malfunctioning, and plates were coming out with spots that couldn't easily be rinsed off.

Pennsylvania's Department of Environmental Protection soon identified the likely cause. The Monongahela, a drinking-water source for 350,000 people, had apparently been contaminated by chemically tainted wastewater from the state's growing natural- gas industry.

The DEP reduced the amount of drilling wastewater that was being discharged into the river and unlocked dams upstream to dilute the contamination.

But questions raised by the incident haven't gone away. And the state budget, signed into law last Friday by Gov. Rendell, allows gas drillers to expand their drilling on state land.

Yesterday, the DEP announced that contamination levels in the Monongahela have spiked again. And the DEP is still investigating whether drilling wastewater contributed to the recent death of 10,000 fish on a 33-mile stretch of Dunkard Creek, which winds through West Virginia and feeds the Monongahela.

A spate of other water-contamination problems have also been linked to gas drilling in Pennsylvania, including methane leaks that have affected drinking water in at least seven counties.

A flood of wastewater

Pennsylvania is at the forefront of the nation's gas-drilling boom, with at least 4,000 new oil and gas wells drilled here last year alone, more than in any other state except Texas. This rapid expansion has forced state regulators to confront a problem that has been largely overlooked during the drilling boom: How will the industry dispose of the enormous amount of wastewater it produces?

Oil and gas wells disgorge about 9 million gallons of wastewater a day in Pennsylvania, according to industry estimates used by the DEP. By 2011 that figure is expected to rise to at least 19 million gallons. That's more than all the state's waterways, combined, can safely absorb, DEP officials say.

"I don't know that even our [water] program people had any idea about the volumes of water that would be used," said Dana Aunkst, who heads the DEP's water program.

Much of the wastewater is the by-product of a drilling process called hydraulic fracturing, or fracking, which pumps at least a million gallons of water per well deep into the earth to break layers of rock and release gas. When the water is sucked back out, it contains natural toxins dredged up during drilling, including cadmium and benzene, which both carry cancer risks. It can also contain small amounts of chemicals added to enhance drilling.

But DEP officials say that one of the most worrisome contaminants in the wastewater is a gritty substance called total dissolved solids, or TDS, a mixture of salt and other minerals that lie deep underground. Drilling wastewater contains so much TDS that it can be five times as salty as seawater.

Large quantities of TDS can clog machinery and affect the color, taste and odor of drinking water - precisely the problems reported along the Monongahela.

Gas-drilling companies dispose of their wastewater in Pennsylvania's municipal sewage plants, which then discharge it into rivers and streams.

The U.S. Environmental Protection Agency warns against this form of treatment, because the plants aren't equipped to remove TDS or any of the chemicals the water may contain. Of even more concern, TDS can disrupt the plants' treatment of ordinary sewage, including human waste.

A lack of capacity

When U.S. Steel and Allegheny Energy complained about the Monongahela's water in 2008, the DEP found almost twice as much TDS as considered safe. What apparently tipped the balance was the drilling wastewater that nine sewage plants were discharging into the river.

Steve Rhoads, president of the Pennsylvania Oil and Gas Association, an industry trade group, argues that most of the TDS had come from abandoned mines, not from drilling wastewater. A study prepared for a different trade group made the same conclusion.

Rhoads also says that Pennsylvania's waterways "are not anywhere near" their capacity to handle TDS and that the DEP's estimate of how much wastewater the industry produces is "completely exaggerated."

DEP chief John Hanger is confident his agency can control the wastewater problem. In April drilling companies began temporarily trucking their wastewater to other states or to sewage-treatment plants in other parts of Pennsylvania: The idea is to dilute it by spreading it among more rivers.

Hanger said a more permanent solution will begin on Jan. 1, 2011, when, he has promised, new regulations will be in place requiring that the wastewater be treated by plants capable of removing TDS.

But an examination of public records, visits to sewage-treatment plants and interviews with state officials by ProPublica reveal flaws in the DEP's plans. ProPublica is a nonprofit firm that does investigative journalism for the public interest.

Currently, no plant in Pennsylvania has the technology to remove TDS, and it's unlikely that plants capable of doing so can be built by 2011. The company whose bid is furthest along in the permitting process says its plant won't be ready until at least 2013. And at its peak that plant would be able to treat only 400,000 gallons of wastewater a day. The DEP would need 50 plants that size to process all the wastewater expected by 2011.

In the meantime, the DEP is allowing municipal sewage plants to continue taking the wastewater, even though none of them can remove TDS.

Caught off guard

Hanger says Pennsylvania's extensive experience with oil drilling - the country's first oil well was drilled in the state in 1859 - has prepared it to deal quickly with gas-drilling problems.

But ProPublica found that the DEP was caught off guard by the amount of wastewater the industry would produce when drilling began in the Marcellus Shale, a deeply buried layer of rock that some analysts say holds enough gas to meet the nation's natural- gas needs for more than 20 years.

When energy prices spiked in 2008, drillers flocked to Pennsylvania, bringing sorely needed revenue and jobs. A recent Penn State study touted the benefits that drilling brought last year: 29,000 jobs and $240 million in state and local taxes.

Plant operators say the DEP didn't initially offer them much guidance about processing the water, a complaint the DEP doesn't dispute.

Ed Golanka, who manages a sewage plant in Charleroi, said that when he checked with the DEP nobody told him that state and federal laws required his plant to get an amendment to its permit before accepting industrial wastewater. The amendment would require expensive modifications that Charleroi couldn't afford, he said.

"At the time, it was a new subject for all of us," Golanka said. "There was a limited amount of conversation [with the DEP] until the issue with TDS last summer."

Aunkst, the DEP's director of water standards, says he didn't know the plants along the Monongahela were accepting the water until spring 2008, when people complained about long lines of trucks idling at sewage-treatment plants. But the agency was so short-staffed that it didn't respond to the complaints immediately.

Aunkst said many DEP regulators had left for more lucrative jobs with drilling companies.

"As the industry was ramping up, we were ramping down," he said. "In order for us to really catch these people, we have to almost have an inspector coincidentally there on the day that these trucks pull up, because we have so many facilities and so few staff."

The DEP is supposed to inspect the plants once a year, but ProPublica found that most inspections are triggered by pollution violations or equipment failures.

A review of inspection records at the DEP's Pittsburgh office showed that only three of the nine plants along the Monongahela were inspected in the year before Allegheny Energy and U.S. Steel complained.

Inspections occur even less frequently at sites where wells are drilled. According to minutes taken at an October 2008 meeting of DEP officials, the agency has so few inspectors that they visit gas wells only once every 10 years.

After Aunkst heard about the trucks, he wrote a letter to all the state's sewage plants, reminding them that they couldn't take the wastewater without a special permit.

But before he sent it, TDS levels in the Monongahela skyrocketed, causing U.S. Steel and Allegheny Energy to complain. The chain of events made Aunkst remember two other peculiar incidents: Two creeks had been sucked dry, and DEP inspectors suspected that drilling companies had withdrawn the water to fracture nearby wells.

"We were trying to scramble, to put it bluntly, to get our act together to figure out how we were going to address these withdrawals as well as the disposal issues," Aunkst said.

Today, drilling wastewater is still being processed in Pennsylvania's municipal sewage-treatment plants, albeit in limited amounts.

Federal guidelines specifically recommend against this practice because TDS can damage the plants and taint drinking-water supplies. But the EPA approved Pennsylvania's plan, because the DEP promised to have more aggressive regulations in place by 2011.

To keep the water safe until then, the DEP has added more TDS monitors along the Monongahela. And before the DEP allows a sewage plant to accept drilling wastewater, the agency will assess the TDS level in the stream where the water will be discharged, to make sure it can handle the additional load.

To read more about the problem of wastewater contamination from natural-gas drilling in Pennsylvania, go to www.propublica. org/feature/wastewater-from-gas-drilling-boom-may-threaten-monongahela-river.