The EPA also scrapped planned regulations on pollution from sewage plants, and proposed new guidance that reduced the number of waterways and other bodies of water protected from pollution under the Clean Water Act.
The administration has also rolled back EPA and Interior Department regulations requiring methane emitters to reduce "flares" of methane pollution on protected public and tribal lands, and give companies more leeway in repairing leaks.
In a show of deference to the coal industry, the EPA has also gutted the Stream Protection Rule, a regulation requiring coal companies to minimize pollution of nearby waterways, including sources of drinking water.
Pruitt also eliminated a previous regulation implemented by Obama requiring coal mine operators to prove they had the ability to clean up pollution, placing the burden of clean-up back on the government.
In September 2018, the EPA announced they would no longer uphold a previous ban on the use of hydro-fluorocarbons — ultra-potent greenhouse gases — in appliances like refrigerators and AC units, prompting a lawsuit from several states.
Last August, the administration also cut back Obama-era fuel efficiency standards that would have required most new cars to average 54 miles per gallon by 2025, reducing the target to 34 miles per gallon.
Trump has also signed executive orders significantly reducing the size of federally-protected national monuments including the Bears Ears National Monument in Utah, opening up much of the land for oil drilling.