The U.S. Environmental Protection Agency has proposed approving Wisconsin's application to run its own coal ash landfill oversight program, moving enforcement of the federal coal combustion residuals rule from Washington to state regulators in Madison.

The proposal, if finalized, would make Wisconsin's Department of Natural Resources the primary permitting and enforcement authority for coal ash landfills in the state, substituting state-administered requirements for the federal CCR program that EPA has direct-enforced since the 2015 rule took effect.

What does the change mean for the material stream?

Coal combustion residuals — fly ash, bottom ash, boiler slag and flue gas desulfurization gypsum — remain one of the largest industrial waste streams in the United States, disposed in landfills and surface impoundments at and around coal-fired power plants. Under the federal framework Congress set in the 2016 Water Infrastructure Improvements for the Nation Act, states can apply to EPA for program approval, and EPA must either approve a qualifying application or keep direct federal enforcement in place.

Wisconsin filed for that substitution, and EPA has now issued a proposed approval. The agency's finding behind the proposal holds that the state's program is at least as protective as the federal CCR criteria, the statutory test Congress wrote into the WIIN Act.

For operators of coal ash landfills in Wisconsin, the shift would change where they file compliance documents, who inspects their facilities and which regulator answers enforcement questions. The material itself does not change: the ash disposed in Wisconsin landfills stays subject to liner, groundwater monitoring, closure and post-closure requirements, now written into a state-run permit structure rather than a federally self-implemented one.

Built rules versus proposed ones

Readers should keep the distinction sharp. EPA's action is a proposal, not a final approval. Until the agency signs a final rule approving the state program, the federal CCR requirements continue to govern Wisconsin's coal ash units, and EPA retains direct enforcement authority.

Wisconsin is not the first state down this path. Congress opened the door to state CCR program approval in 2016, and EPA has approved a small number of state applications since, while rejecting or declining others — most notably denying Oklahoma part of its program on grounds tied to enforcement authorities. Each approval EPA issues narrows the universe of coal ash units the agency directly polices and widens the patchwork of state regimes that utilities, landfill operators and environmental groups must track.

What happens next

The proposal now heads to public comment. EPA will take input on whether Wisconsin's program meets the statutory adequacy standard before deciding whether to finalize the approval. Once finalized, the state assumes permitting and enforcement for coal ash landfills, and EPA's direct role recedes to oversight of the state program itself.

The milestone to watch is the close of the comment period and the date EPA signs a final determination. That decision, not the proposal, decides who regulates Wisconsin's coal ash landfills — and how quickly the state's DNR begins issuing the permits that govern how the ash stream is contained, monitored and closed.

By Grace Kim