States, led by Indiana, granted more autonomy under Trump's administration, holding potential to set their own regulations for coal ash disposal methods.

In a move that could have significant implications for coal ash regulation, coal and energy companies in Indiana have requested the government to expedite state control over the issue. This request comes as several other states, including West Virginia, Wyoming, Alabama, and North Dakota, have also sought primacy, raising concerns among environmentalists and consumer groups.

Indiana, known for its lenient approach to pollution and its friendly stance towards the coal industry, could potentially follow the path of North Dakota in regulating coal ash. North Dakota has earned preliminary approval from the U.S. Environmental Protection Agency (EPA) to regulate coal ash at the state level instead of the federal level, a decision that is considered precedent-setting.

However, the distinction between federal and state regulation could lock in weaker enforcement even if a future administration wants to take a tougher stance on coal ash contamination. This is because once a state is given primacy, it takes responsibility for issuing coal ash permits and enforcing regulations, which may not always meet federal standards.

The U.S. EPA allows states to adopt their own coal ash rules that are at least as protective as federal standards. However, the possibility of primacy being granted in Indiana is a concern due to the large amount of coal burned and coal ash mismanaged in the state.

In May 2022, the Biden administration denied Alabama's request for primacy, and state officials said they would appeal. Similarly, North Carolina, the US state given primary responsibility for regulating coal ash by the federal environmental agency in January 2019, has faced criticism for its handling of the issue.

EPA Administrator Lee Zeldin has encouraged states to adopt their own coal ash rules, citing the administration's commitment to "clean beautiful coal." However, the Trump administration, during its first presidency, did not enforce federal coal ash regulations, and states like Georgia have issued permits allowing utility companies to leave large amounts of coal ash in pits submerged partially in groundwater, a move that environmental groups say violates federal rules.

Texas and Oklahoma also have primacy programs. The North Dakota decision is a contentious issue, with the state's attorney general sending the EPA a notice of the state's intent to sue over its coal ash primacy application.

Indiana lawmakers have been supportive of the coal industry, passing multiple measures in its favour. Environmentalists fear that if Indiana is given primacy, it could lead to weaker enforcement and increased coal ash contamination, posing a risk to the health and safety of Indiana's residents.