The Public Utilities Commission has been considering ways to reduce pollution along the Front Range that’s associated with coal-fired power plants, as a new state law requires. As the Denver Business Journal reports, the Minneapolis-based utility has drafted nine alternatives to meet the new Clean Air-Clean Jobs law, which seeks to cut nitrogen-oxide pollution by as much as 80 percent. In a big step on Monday, the PUC voted to shut down six aging plants between 2011 and 2017 and to allow Xcel, which serves 1.4 million people in Colorado, to replace them with new, allegedly cleaner, $530 million natural-gas-fired plants.

Two other coal plants outside the Front Range will be allowed to add pollution controls for $340 million, according to The Denver Post. “None of these scenarios are cheap,” says PUC staffer Ron Davis. “Rates are going to rise.” Still up in the air is the fate of Cherokee 4, the “largest source of air pollution in the Denver area,” says John Nielson, with the environmental-policy group Western Resource Advocates. He says Cherokee should be shut down, but Xcel argues it needs the plant to ensure reliable delivery of electricity in the region.

Environmentalists gathered Sunday at the Denver Pavilions Mall in a Santa demonstration, delivering the Mining Association a lump of coal, writes Denver Daily News. “The key question is whether these aging coal plants will be fully replaced by cleaner resources or if at least one major unit will be put on life support and kept operating,” says Dana Hoffman of Environment Colorado, referring to the Cherokee 4 plant. “And hanging in the balance is the air quality and quality of life for three million Coloradans for decades to come.”