It will be weeks before a judge issues a ruling in North Carolina’s lawsuit over smokestack emissions from coal-fired power plants operated by the Tennessee Valley Authority, a newspaper reported Thursday.

U.S. District Court Judge Lacy Thornburg, who heard the case without a jury, told lawyers to file their final documents by Sept. 15, the Asheville Citizen-Times reported. A decision would come after that date.

During a 12-day trial that ended Wednesday, North Carolina asked that the TVA be required to cap sulfur dioxide and other pollutants that cross into the state from its coal-burning plants in Tennessee, Alabama and Georgia. The utility also serves Kentucky, Mississippi and Virginia.

“Clean air is critical to our health and economy, and I believe we have presented an excellent case that shows why and how TVA can cut the pollution coming into North Carolina,” said North Carolina Attorney General Roy Cooper.

TVA witnesses testified the utility works hard to abide by regulations and that emissions from its plants don’t cause health problems.

The lawsuit said North Carolina’s economy and health have been affected.

North Carolina witnesses said TVA emissions drift across the state lines and cause health and economic problems.

James Gulick, senior deputy attorney general, said in his closing argument that history shows the utility invests in emissions control technology only when forced by government rules or court orders.

TVA lawyer Frank Lancaster asked Thornburg to dismiss the lawsuit, saying the state hadn’t provided evidence to support it.

Pollution scrubbers are being built at two of the plants and plans are in the works for a third, the lawyer said, at a cost of $1.5 billion.

“TVA is doing everything it can to make those among the cleanest-burning plants in the country,” Lancaster said.