— Duke Energy is asking a federal judge to make the sworn statements of a state environmental toxicologist off-limits to the public amid an ongoing lawsuit between environmentalists and the energy company over coal ash.

In a motion filed in U.S. District Court Tuesday, Duke argued the deposition of Dr. Kenneth Rudo is "largely hearsay" and that releasing it publicly would affect the firm's right to a fair and impartial trial. Company lawyers point to the heavy media attention surrounding coal ash cleanup and contamination, which has drawn the concern of nearby well owners who have received mixed safety advice from the state about their water.

"Through this coverage, Plaintiffs have sought to manipulate the media and the public, igniting fear and consternation in order to garner support for the extreme remedy Plaintiffs seek in these cases: excavation of all of Duke Energy’s coal ash basins," a Duke brief supporting the motion reads.

After state lawmakers in 2014 required testing of drinking water wells neighboring the unlined Duke coal ash dumps, the state's health and environmental agencies have wavered on recommendations that residents avoid using the water for drinking and cooking. Just last month, a handful of well owners with high levels of the cancer-causing hexavalent chromium were told their water was unsafe after assurances earlier in the year that it was drinkable.

Rudo, along with several of his colleagues in the epidemiology branch of the state Department of Health and Human Services, was deposed as part of several lawsuits against Duke by environmental groups. That includes the Southern Environmental Law Center, which has released transcripts of those state employees' statements over the last few months showing disagreements among state scientists about the advice residents should receive.

Democratic state lawmakers cited the transcripts in calls for an investigation into the matter, although they were unable to articulate how to proceed with it.

The motion Duke filed Tuesday was specific to a suit filed in 2014 by the nonprofit Waterkeeper Alliance and the Yadkin Riverkeeper over unlawful discharges from the coal ash pits at the Buck Steam Station in Salisbury, where some of the highest levels of hexavalent chromium were detected.

"Dr. Rudo traveled to communities across the state to explain the science behind the letters telling residents not to drink their water," Yadkin Riverkeeper Will Scott said in a statement. "Duke Energy is now trying to block his sworn testimony from being made public. The public deserves to know what was happening in DHHS when they were making important public health decisions that affected hundreds of coal ash pit neighbors across the state."

Duke has long maintained that its coal basins have not contaminated nearby well water. The company continues to provide bottled water to many residents near its facilities. Just last week, state lawmakers and the governor gave final approval to a measure that will allow the company to use less expensive options to close the pits if they supply well owners with water lines.

When reached Tuesday, Rudo declined to comment on the motion.

​In a written statement, Southern Environmental Law Center attorney Frank Holleman called the energy company's move to block the testimony an "extraordinary action."

"The state has told well users not to drink their water, to drink their water and not to drink their water. These citizens deserve complete information about how the issue of their water has been handled, as do all citizens of North Carolina," Holleman said. "Duke Energy should not be trying to keep this important information from the public and the press."

But in their brief to the court, Duke lawyers said many of Rudo's statements would be inadmissible in court and that their public release would prejudice any jury in the case.

Calling much of the deposition "speculation and hearsay," company spokeswoman Paige Sheehan said the SELC's intent to release the transcript was "an abuse of the thoughtful legal process, and another example of SELC’s cynical pattern of playing public opinion, forcing us to ask the court to step in."

"With hours of questions still to be asked, lawyers are just beginning to challenge Dr. Rudo’s motives, his claims and his credibility. SELC knows that," Sheehan said. "No wonder they want the transcript released now."