Denver has joined 29 states and cities, including Colorado, in suing the Environmental Protection Agency over a new measure that would replace the 2015 Clean Power Plan.

The replacement for the 2015 Clean Power Plan is known as the Affordable Clean Energy Rule, which would eliminate the Obama-era rules intended to reduce carbon dioxide emissions from power plants. The Clean Power Plan was never implemented because the Supreme Court granted a stay in 2016.

When ACE was unveiled in June, EPA Administrator Andrew Wheeler that it will give states the “regulatory certainty they need” to continue to reduce emissions.

“When ACE is fully implemented, we expect to see U.S. power sector CO2 emissions fall by as much as 35% below 2005 levels,” he said.

Mayor Michael Hancock and city attorney Kristin Bronson said in a Wednesday press release that the repeal would “significantly hinder” Denver’s ability to achieve its climate goals, which are to achieve 100% renewable electricity by 2040 and reduce city emissions by 80% by 2050.

“Denver believes the Trump administration is trying to prop up the dying coal industry at the expense of the global climate,” the release states.

Their main point of contention is that the new plan’s primary method of limiting emissions is equipment efficiency and heat-rate improvements, rather than fuel switching from coal to renewable sources.

“Now is not the time for the federal government to be in full retreat from safeguarding our environment from the devastating effects of climate change,” Hancock said. “Climate change is real and it’s happening right now. 

“Repealing the Clean Power Plan is the Trump administration dealing yet another blow to worldwide efforts to combat the greatest environmental threat to the security and well-being of our nation and planet.”