COLUMBIA, SC — Santee Cooper has failed to stop a pollution lawsuit that says the state-owned utility should clean up a legacy of toxic coal ash pollution along an eastern South Carolina river.

A circuit judge ruled this week that the suit can proceed, meaning the power company must provide information in court about its disposal practices and cleanup plans. Environmental groups want the company to clean out its coal waste ponds at the Grainger power station on the Waccamaw River at Conway.

Santee Cooper had sought to have the suit dismissed. Company spokeswoman Mollie Gore said her agency has not decided whether to clean out the ponds. The company will close the Grainger power plant for good at the end of this month.

“We have not ruled out anything at this point,” she said.

Coal ash, like that at Santee Cooper’s Grainger power station station, contains toxins, such as arsenic. Pollution from coal waste ponds is a major issue nationally and has prompted discussion of tighter federal regulation.

State records show Santee Cooper’s ponds have polluted groundwater. Environmentalists allege the tainted groundwater has seeped into the Waccamaw River, but Santee Cooper denies that.

The SC Coastal Conservation League, the Waccamaw Riverkeeper and the Southern Alliance for Clean Energy want the coal ash to be put in a landfill.

“We are committed to ensuring that Santee Cooper meets its responsibility to remove its toxic coal ash from Conway and safely dispose of it,” said Dana Beach, director of the Coastal Conservation League.

Santee Cooper’s legal fight isn’t the first in South Carolina over coal ash cleanup plans. Environmentalists sued SCE&G in January. Unlike Santee Cooper, SCE&G settled the suit and agreed to remove more than two million tons of coal sludge from ponds along the Wateree River in lower Richland County. Santee Cooper has less than 1 million tons to clean up.

In the Santee Cooper case, a key legal question is whether the lawsuit was filed before the Legislature outlawed so-called “citizens suits” last spring. But in his ruling Monday, Circuit Judge Larry Hyman said the pollution allegedly occurred before the 2012 law passed, so the case could continue.