The EPA wants to let states and coal-powered electric utilities decide whether substances leaking from coal ash ponds and landfills are unsafe for the public and the environment.

The Environmental Protection Agency announced March 1 it is proposing to allow states to establish “alternative” risk-based groundwater protection standards for substances such as metals and other contaminants that may be present in coal ash landfills and ponds but are not federally regulated in drinking water.

Coal combustion residuals—or coal ash—are the...