A group of Massachusetts citizens is planning to use the Clean Water Act to sue the Entergy Corporation over what they see as environmental violations at the Pilgrim Nuclear Power Station.

The group, through attorney Meg Sheehan, says the company should pay nearly a billion dollars in penalties. They say the plant has polluted Cape Cod Bay, massively killed local fish populations, and the operators kept inadequate environmental records. Citizens have the right to sue when the government fails to enforce the Clean Water Act so if the EPA does not step in within 60 days, this plaintiff group can proceed.

Sheehan, who represents a group known as EcoLaw, says Entergy has violated the Clean Water Act more than 30,000 times.

"They’re failing to adequately monitor and report some of the discharges that they’re dumping out into the bay," she said, as well. "Since about 2000 when Entergy took over Pilgrim from Boston Edison, Entergy has failed to obtain EPA’s approval for their marine monitoring plan. To us that’s a really egregious violation because when Pilgrim was built in the ’70s, there was great concern in the scientific community among the fishermen and the fisheries experts that there would be this terrible impact."

Unsurprisingly, Entergy officials say they take their environmental responsibilities seriously.

"We will respond to the notice of intent after we have had a chance to thoroughly review the specific allegations. We note that EcoLaw unsuccessfully raised a number of these allegations in the NRC license renewal proceeding for Pilgrim Station," the company said in a statement.

Sheehan argues that the company is, in addition to polluting, is also killing a number of fish. It sucks in millions of gallons of water from Cape Cod, for example.

"Back in the 1990s, the state Marine Fisheries Department stated that Pilgrim’s operation had killed off up to 40 percent of the winter flounder population," she said.

Sheehan said using the citizen-initiated lawsuit under the Clean Water Act was the group's only option to try and halt what they consider to be environmental damage. She said the group had been talking to state and federal regulators since the beginning of the year and urging them to take action.

The power plant's emissions permit expired 16 years ago, she said.

"This plant is going to be operating for another 20 years from what we understand, so we just felt this was our only option," Sheehan added.

It's unrealistic, Sheehan said, to expect the power plant will be shutdown, so the eco group is doing what it can to make it more environmentally responsible.

"Continu(ing) to operate with this kind of environmental destruction, is unacceptable, these kinds of violations are unacceptable, and the EPA really does have to take a solid look at this," she argued.

Patrick Parenteau, a professor of law at Vermont Law School, said citizen lawsuits against nuclear power plants, on environmental grounds, are extremely rare.

"This case does represent sort of taking it to a whole other level in terms of using the Clean Water Act against a nuclear power plant," he said.

And even if the plaintiffs do succeed, Parenteau said its practically impossible they'll get the amount of damages they're seeking. Courts just don't hand out judgments that large.

While Parenteau said the plaintiffs might win, he said the more likely outcome is a settlement with the utility. In another, somewhat similar, case, a judge was appointed to mediate the suit, ultimately producing a settlement.

"These mediation judges have tremendous power to kind of force the parties into a settlement agreement, basically saying neither one of you can be sure who is going to win, and you both have a lot to lose, so I am going to meet with you and require that you’d make a serious effort to try to settle your differences," Parenteau explained.