From the CDPHE website, calling the decision to proceed on developing implementation despite the stay issued by the U.S. Supreme Court on the Clean Power Plan, while litigation is proceeding, as a “prudent” move:

Statement on U.S. Supreme Court Decision Regarding the Clean Power Plan

Yesterday, the United States Supreme Court stayed the U.S. Environmental Protection Agency’s (EPA) Clean Power Plan, a rule designed to reduce nationwide emissions of carbon dioxide from power plants by about one-third. The stay is a temporary measure while the federal courts review the merits of the rule.

The Colorado Department of Public Health and Environment has been working since last summer to develop a state plan to achieve the Clean Power Plan’s carbon reduction targets for Colorado. The department will continue to coordinate with stakeholders to develop this state plan during the litigation. The Court of Appeals for the District of Columbia Circuit will hear oral arguments on the rule in June.

It is prudent for Colorado to move forward during the litigation to ensure that the state is not left at a disadvantage if the courts uphold all or part of the Clean Power Plan. Because the Supreme Court did not say whether the stay would change the rule’s compliance deadlines, Colorado could lose valuable time if it delays its work on the state plan and the rule is ultimately upheld.

Colorado’s utilities, local governments, nongovernmental organizations, and other stakeholders have provided valuable input on the development of the state plan. The department will evaluate the decision and coordinate with stakeholders to assess how the stay might impact the timing and substance of the state plan.

Climate change remains both a critical environmental and public health and welfare issue. Colorado has and will continue to develop cost-effective strategies to diversify our energy mix, strengthen our economy and lower our greenhouse gas emissions. Through the Colorado Climate Plan, state agencies also will develop and implement innovative strategies to mitigate the impacts of climate change.

Governor John Hickenlooper attempted to challenge Attorney General Cynthia Coffman’s ability to join the multi-state lawsuit against the EPA and the Clean Power Plan, but failed when the Colorado Supreme Court decided not to review the petition.