The regulations would require a 30 percent cut in carbon dioxide emissions from U.S. electricity generation, compared to 2005 emissions, by 2030. Wyoming, under the rules, would need to reduce emissions by 19 percent from 2012 levels.
That could hit Wyoming harder than most other states. Coal-fired power plants produce a huge share of the gas blamed for global climate change and Wyoming produces far more coal than any other state, close to 40 percent of the U.S. total.
The coal industry provides nearly $1 billion in revenue to the state government every year.
The rules are coming down even though carbon-capture techniques have shown promise and utilities have proved they can drastically reduce other types of pollution from coal-fired power, said Jonathan Downing, executive director of the Wyoming Mining Association.
"I think it's still a viable alternative as far as a clean energy source, and an affordable one at that," Downing said.
Wyoming is not only the top-coal-producing state but emits more carbon per person than any other state. That's largely because Wyoming is a net exporter of electricity, 85 percent of which comes from coal-fired power.
Mead said his office was reviewing the rules but would fight for the coal industry if necessary. As it is, Wyoming has been pursuing or participating in litigation against the EPA in a dozen cases involving air emissions.
"Coal, clean air, water, and a robust economy are all parts of our future, as they are parts of our present. Wyoming is proof that this balance is achievable," Mead said.
Yet, the proposed rules take into account that Wyoming is a coal-producing state and holds the state to a more flexible standard, said Shannon Anderson with the Powder River Basin Resource Council landowners' group.
"The standards specifically acknowledge that Wyoming will be burning coal well into the future. It doesn't stop that any time soon. It does, I think provide some flexibility and recognizes the state's unique situation," Anderson said.
Even so, Barrasso described the 650 pages of rules as "extreme," while Lummis said they're "stifling" and harmful to the economy.
"The costs are real, the benefits are theoretical," Barrasso said.
Obama administration officials said the rules won't hurt the economy.