A treatment plant operator at Mount Rainier National Park has been charged with illegally dumping 200,000 gallons of sewage into the Nisqually River.

James Barber, 52, will appear in federal court this morning to enter a plea. He has been charged with violating the Clean Water Act, a misdemeanor.

Barber was the operator in charge of the treatment plant that handles waste from the Paradise Visitor Center and the Paradise Inn.

It wasn’t clear Thursday whether he is still working at the park. Spokeswoman Patti Wold referred all questions about the matter to the U.S. Attorney’s Office.

“I think his employment status will become more clear with the plea (today),” U.S. Attorney spokeswoman Emily Langlie said Thursday. “To my knowledge, he remains employed.”

Federal prosecutors allege that during spring and summer 2011 Barber failed to properly handle the buildup of solid waste at the plant, which in August 2011 no longer was able to handle the incoming wastewater.

Because of his “gross mismanagement,” charging papers allege, filters at the treatment plant became clogged and stopped working, filling a tank with sludge.

Barber allegedly tried to cover up his error by routing the waste past the treatment unit and the tank, sending the untreated waste into a drainage ditch.

For four days, the sewage discharged through a pipe into the ditch, which flows into a waterfall that eventually leads to the Nisqually River. Testing found about 200,000 gallons of minimally treated sewage was dumped into the water.

Barber did not tell anyone what had happened, failed to sample the sewage and did not record it in the plant’s log books, court documents allege.

“Instead, he left for several days off from work, informing none of his colleagues or supervisors about the bypass of waste,” according to charging papers.

It cost about $20,000 to clean up the raw sewage that hadn’t yet made it to the river, Langlie said.

The park asked the state Department of Ecology to help diagnose what went wrong, said Greg Zentner, a supervising engineer for the department.

Routing water around the plant’s filter and into the creek that meets up with the river isn’t always a problem, Zentner said. At that stage the water should be clean, and sometimes the bypass system is used intentionally to clean the filter.

But because of how the plant had been managed for about three months, the water wasn’t fully treated and eventually clogged the filter, he said.

“He was running the plant in what he thought was an experimental mode by recycling water from farther up stream in the treatment process back to the front, so the middle part of the plant was seeing a lot more flow than it was used to seeing,” Zentner said.

“There are some plants that do that to remove nutrients like nitrogen, but if you do that, you really need to have a much larger plant.”

Barber didn’t follow the advice of his supervisor and relief operator to change his practices, and failed to test the treated water on a daily basis, Zentner said.

“In our book that’s an issue,” Zentner said. “A major issue.”

The plant’s capacity is about 100,000 gallons per day, he said. During the summer, it runs about 50,000 to 70,000 gallons daily; it drops to 5,000 gallons a day during the winter.

Because the park sees fewer visitors in the winter, operators do not treat the sewage as often as in the warmer months.

“(Summer is) when you really need to be able to be on top of the plant,” Zentner said.

The park had the plant producing clean water within days of realizing the problem last year, Zentner said.

But when it comes to clean-up, the river itself has to do most of the work in such sewage situations, he said, and it takes weeks for a stream to recover.

“There’s not much you can do,” Zentner said. “You just have to shut off the source, stop the problem and let the river naturally attenuate that.”

Drinking water in the park was another concern when evaluating the Paradise case, he said.

It takes a few days for that danger to pass, he added, during which the park used a backup supply for its drinking water system.

“You never want a source of raw sewage to be present upstream of your drinking water intake,” Zentner said. “There was sort of a real public health concern there.”