Intermittently over a period of five years, the operator of a Montgomery County sewage-treatment plant wasn't testing the outflow and wasn't treating it, according to law enforcement officials.

He was simply discharging raw sewage into the Perkiomen Creek, they said.

The state Attorney General's Office has filed criminal charges against the operator, Pennsburg resident Michael T. Martin, who was fired months ago from the Green Lane Marlborough Joint Authority.

He faces a maximum of 18 years in prison and $40,000 in fines for allegedly allowing untreated or partially treated sewage to flow into the stream and for fabricating sampling data that he submitted to the state Department of Environmental Protection.

DEP officials said they had no idea why Martin would have done this, or if he stood to gain from it, or whether anyone ordered him to do it. Efforts to reach Martin were not successful.

The authority's plant is in Green Lane. The Perkiomen then flows through parts of central Montgomery County and drains into the Schuylkill just north of Valley Forge National Historical Park.

The incident is an extreme case of how one man may have dealt with a growing regional problem: aging infrastructure coupled with increasing population.

Of 150 systems in the five-county area, the state DEP has rated 70 as "priority," in imminent need of attention. And about 40 are either experiencing higher flows than they can handle now, or they expect to within five years.

But this plant in particular was a portrait in failure.

Jenifer Fields, who heads the DEP's regional water management program, said Martin's actions masked growing problems at the plant.

So even when a new operating company took over in September, it had difficulty bringing it into compliance "because there were so many issues there that the previous operator never brought to the attention of the authorities.

"He made a lot of physical modifications to the plant that you couldn't actually see when the tanks were full, but that would push out a lot of solids and water [into the stream] if the flow got too high."

Now, residents of Marlborough Township and Green Lane Borough are facing large increases in their sewer bills. Green Lane and Marlborough officials did not respond to requests for comment, but reportedly rates will at least double.

"They were operating under the guise that everything was fine," Fields said. "So there was no need to look at the rate issue. Now they're faced with a huge potential bill to upgrade their system."

U.S. Rep. Allyson Y. Schwartz, whose district includes Marlborough, has requested $740,300 from the House Appropriations Committee for the project.

The plant serves 550 residences and businesses in Green Lane, the village of Sumneytown, and parts of Marlborough Township.

Just how different the reality is from the fiction that Martin supposedly put forth is difficult to determine, Fields said. "Our first problem is just getting a true characterization of what's going on, because so much was falsified," she said, adding, "We can't trust any of the data before September."

For instance, once they realized a meter measuring the flow coming into the plant was faulty, they replaced it. The plant is permitted to handle 200,000 gallons a day. But "at times, they're getting as much as five times that," Fields said.

Officials were unaware of any effects on the creek, if only because they weren't looking. Reports showing the plant was meeting permit levels gave them no reason to.

"This program requires operators to have integrity and ethics," Fields said. "When they sign the monitoring report, they swear to the accuracy of that report. For someone to step over the line so egregiously, it's very serious."

Twenty miles downstream is the water intake at Aqua America's Pickering Creek Water Treatment Plant, the company's largest in Southeastern Pennsylvania, and the next drinking-water intake is in Norristown. Officials said that any effluent would be diluted by then, and the plants routinely monitor the intake and know how to treat it.

According to the affidavit, DEP officials first became concerned in 2007, when an inspector visiting the plant found nonfunctioning equipment and illegal bypass equipment that allowed partially treated wastewater to be discharged into the creek.

At least four times, the inspector also collected effluent samples at the plant and found that the levels of fecal coliform and other contaminants exceeded permitted levels. Data submitted by Martin for the same dates indicated the levels were within permitted levels, the affidavit said.

Other investigations showed that the plant was not doing a required daily test for chlorine levels in the effluent. If the level is too low, it could mean the bacteria are not being killed. If the level is too high, fish could die.

Between March 2004 and Aug. 31, 2009, about 2,035 "chlorine reagents" should have been purchased and used for the testing, according to the affidavit. Instead, just 200 had been purchased.

Martin was arraigned Wednesday before District Judge Catherine M. Hummel Fried and released on $30,000 unsecured bail.

David Masur, director of PennEnvironment, a nonprofit that has investigated sewage treatment plant compliance, praised the DEP and the Attorney General's Office for pursuing the case. "It's bad enough that there's this outdated and crumbling municipal water treatment system, and we know they're all across the commonwealth and the country," he said. "But to have a city official falsifying federally required reports on water safety can't be tolerated."

Crystal Gilchrist, executive director of the Perkiomen Watershed Conservancy, an advocacy group for the 362-square-mile watershed, said the creek's water quality had improved greatly since regulations began decades ago.

"I just want people to be assured that most of the folks who have responsibility for keeping our water clean are doing the best job they can," she said. "These types of incidents are not the norm."

Contact staff writer Sandy Bauers at 215-854-5147 or sbauers@phillynews.com. Visit her blog at http://go.philly.com/greenspace