Toxic Coal Ash in Wisconsin: Addressing Coal Plants’ Hazardous Legacy

For decades, utilities disposed of coal ash — the hazardous substance left after burning coal for energy — by dumping it in unlined ponds and landfills. Wisconsin has 52 coal ash dumpsites.

After years of litigation and grassroots activism, on Apr. 25, 2024, the EPA issued a new rule that will force power plants to finally clean up their toxic coal ash. The EPA extended federal monitoring and cleanup requirements to hundreds of previously excluded older coal ash landfills and ponds that have been leaking toxic pollution into groundwater.

Note: Coal ash dumpsites referenced as “unregulated” throughout this page now are likely subject to federal regulation under the final rulemaking.

Coal ash contains hazardous pollutants including arsenic, boron, cobalt, chromium, lead, lithium, mercury, molybdenum, radium, selenium, and other heavy metals, which have been linked to cancer, heart and thyroid disease, reproductive failure, and neurological harm. In 2023, the EPA acknowledged that coal ash is even more dangerous than previously thought, with levels of arsenic and radiation that pose cancer risks.

Industry’s own data indicate that across the country 91% of coal plants are currently polluting groundwater above federal health standards with toxic pollutants.

Despite EPA’s 2015 Coal Ash Rule, which created the first-ever safeguards for coal ash disposal, many coal ash dumps remained unregulated due to sweeping exemptions for legacy coal ash ponds and inactive landfills. The exempted coal ash dumps are sited disproportionately in low-income communities and communities of color. The EPA extended clean up requirements to hundreds of old coal ash dumps across the country when it issued new regulations in the spring of 2024.

The J. P. Pulliam Generating Station on Fox River in Green Bay, Wisconsin, in 2017.
The J. P. Pulliam Generating Station on Fox River in Green Bay, Wisconsin, in 2017. (James G Brey / Getty Images)

Coal ash remains one of our nation’s largest toxic industrial waste streams. U.S. coal plants continue to produce approximately 75 million tons every year.

In 2023, the EPA acknowledged widespread noncompliance with existing coal ash regulations and ramped up enforcement after designating coal ash a national enforcement priority.

Action Needed

The magnitude of harm from recklessly dumped toxic coal ash requires decisive action from federal and state regulators.

  • Utilities must be required to comply with the law and immediately clean up their pollution.
  • EPA and states must act quickly to ensure that utilities leave communities with sites that benefit rather than harm their health, environment, and economic status.
  • EPA must take action to prohibit the use of coal ash as construction fill and make polluters clean up areas where ash was used as fill.
Coal ash dump sites across the United States. Use this map to understand where coal ash might be stored near you and how a given site may be impacted by EPA's expansion of the federal Coal Ash Rule. (Caroline Weinberg / Earthjustice)

20 Regulated Coal Ash Disposal Sites in Wisconsin*

Wisconsin utilities operate 20 federally regulated coal ash ponds and landfills, containing more than 5.9 million cubic yards of toxic waste at eight coal plants.

Coal ash has caused significant groundwater contamination at nearly all the state’s regulated dumpsites according to utility data reported in 2017.

To date, however, few Wisconsin plants are even monitoring groundwater for heavy metals.

It is likely that unregulated legacy ash on the power plant sites allows Wisconsin utilities to avoid the strict monitoring and cleanup requirements of the Coal Ash Rule.

* Northern States Power Co’s Bay Front Plant, located in Ashland, WI, operates inactive coal ash ponds at the facility according to historical reporting to EPA, but the owners have not created a CCR Rule Compliance Data and Information website nor have they complied with the CCR rule’s requirements that apply to this pond, including groundwater monitoring, closure, and corrective action.

Columbia Pardeville WI Power & Light 2 unlined ponds, 3 landfills Arsenic (x2), Boron (x1), Molybdenum (x2)
Dairyland Power Alma Dairyland Power 1 landfill No contaminants exceeding federal standards
Edgewater Sheboygan WI Power & Light 4 unlined ponds, 1 landfill Arsenic (x2), Boron (x5), Cobalt (x1), Lithium (x1), Molybdenum (x55)
Nelson Dewey Cassville WI Power & Light 2 unlined ponds Boron (x2), Molybdenum (x1), Thallium (x1)
Oak Creek Caledonia We Energies 1 landfill Molybdenum (x1)
Pleasant Prairie Pleasant Prairie WI Public Service 1 landfill Molybdenum (x4)
Weston Rothschild WI Public Service 4 lined ponds, 1 landfill Cobalt (x2)

All data on groundwater contamination from coal ash derived from the utilities’ publicly accessible CCR Compliance Data and Information websites, and exceedances were calculated by Environmental Integrity Project.

For more information on regulated coal ash sites in Wisconsin, see Mapping the Coal Ash Contamination.

32 Coal Ash Legacy Ponds and Inactive Landfills in Wisconsin

March 2024 Update: The table below underestimates the legacy units that may be regulated by EPA’s upcoming CCR Legacy Pond Rule. Additional legacy units at specific plants may be found in the national map, above.

Wisconsin hosts at least 32 inactive coal ash landfills and legacy ponds that escaped federal regulation. The exact number remains unknown because utilities were not required to report these sites.

These dumps are almost certainly contaminating water and threatening health and the environment; however, monitoring data are not currently available for most unregulated sites.

As we anticipate EPA’s proposed rule on legacy ponds and unregulated landfills in May 2023, a concern remains that the agency will not address coal ash that was dumped off site or used as fill.

Alma Alma Dairyland Power 1 3 Yes – EPA damage case
Bay Front Ashland Xcel Energy/No. States Power Co- MN 0 1 No data
Ceder Sauk Landfill (Received ash from Port Washington Plant) Saukville WI Electric Power Co 0 1 Yes – EPA damage case
Edgewater Sheboygan WI Power & Light 0 1 Yes – EPA damage case
EJ Stoneman Cassville Dairyland Power 1 0 Yes – EPA damage case
Genoa Genoa Dairyland Power 2 2 No data
Highway 32 Landfill Ozaukee Co WEPCO 0 1 Yes – EPA damage case
Highway 59 (Received ash from Valley Plant) Waukesha We Energies 0 1 Yes – EPA damage case
John P Madgett / Dairyland Power Alma Dairyland Power 0 2 Yes – EPA damage case
Lemberger Landfill Whiteclaw Unknown 0 1 Yes – EPA damage case
Nelson Dewey Cassville WI Power & Light 0 1 Yes—EPA damage case
Oak Creek Caledonia We Energies 0 2 Yes – EPA damage case
Pulliam Green Bay WI Public Service 1 1 Yes – EPA damage case
Rock River Beloit WI Power & Light Co 4 0 Yes – EPA damage case
Valley Milwaukee WI Electric Power Co 0 3 No data
Weston Rothschild WI Public Service 0 2 Yes – EPA damage case
Woodfield Landfill (Received ash from Bay Front Plant) Bayfield Co. Northern States Power 0 1 Yes – EPA damage case

The retired Alma plant and the current John P Madgett (Dairyland Power) plant are directly adjacent to one another. The EPA damage case is technically for the Alma plant but is listed for John P Madgett as well given their proximity.

These data were developed by using EPA datasets relied upon in their 2007 and 2014 CCR risk assessments (Human and Ecological Risk Assessment of Coal Combustion Residuals) and comparing those datasets to the universe of regulated units.

“EPA damage case” denotes a site where US EPA has found documented groundwater contamination from coal ash.

Earthjustice fights in the courts for a long-term solution to the toxic menace of coal ash. And we act on behalf of dozens of clients and over 100 coalition partners to defeat legislative attempts to subvert federally enforceable safeguards of coal ash.

Earthjustice’s Clean Energy Program uses the power of the law and the strength of partnership to accelerate the transition to 100% clean energy.