MADISON, Wis. — The Wisconsin Department of Natural Resources still has a backlog of wastewater discharge permits to review more than a year after an audit found that it wasn't following its own policies aimed at preventing water pollution, the agency reported.

Findings released Wednesday show the department has a 13.6 percent backlog for municipal and industrial permits and a 21.8 percent backlog for concentrated animal feeding operation permits, Wisconsin Public Radio reported .

The report was requested by Republican state Sen. Robert Cowles, of Green Bay. He expressed frustration earlier this month over the lack of information from the agency about the backlog issue.

The report shows an improvement from a 2016 audit, which found department backlogs of 22.5 percent for municipal permits and 27.7 percent for industrial permits in 2015. The department's recent report didn't provide context for the improvement.

But the figures don't yet meet the department's policy, which says backlogs shouldn't exceed 10 percent for municipal and industrial sources and 15 percent for animal feeding operations.

Cowles said he plans to have the Legislative Audit Bureau conduct a deeper analysis comparing the recent report to the 2016 data.

"This is an ongoing analysis and it appears to be going in the right direction, but I will continue to diligently look at it to try to determine if it is indeed moving in the right direction," Cowles said.

The size of a permit backlog can be a good measure of how well a state's wastewater program is handled, the U.S. Environmental Protection Agency said.