Addressing Colorado’s Toxic Legacy: The Hidden Cost of Coal Ash

As Colorado pivots toward clean energy and retires its remaining coal-fired power plants, an enormous byproduct of the state's industrial past remains scattered across the Front Range and Western Slope.

Decades of electricity generation have left over 30 million tons of legacy coal ash stored across major utility power stations—including Hayden, Pawnee, Comanche, and the retired Valmont facility. Even as annual generation declines to roughly 1.5 million tons from remaining active boilers, managing these vast, toxic mounds presents an urgent challenge.

Without proper containment or cleanup, toxic constituents like arsenic, lithium, boron, and selenium leach into vulnerable groundwater supplies and rivers. State regulators and federal oversight require utilities to implement rigorous environmental safeguards—such as full excavation or advanced synthetic capping—to guarantee our water tables remain safe for generations to come. Many power plants have on-site disposal landfills or ponds and there is concern about what will happen to the toxic components in the future as these plants are retired.

The economic and practical stakes of this transition will directly touch Colorado households and businesses. Environmental remediation and site closures carry significant capital price tags—often tens to hundreds of millions of dollars per station. As utilities petition the Public Utilities Commission to pass these compliance and excavation costs onto ratepayers, electricity rates could see upward pressure unless offset by smart waste management. This is where beneficial reuse becomes a vital economic and environmental tool.

Utilities like Xcel Energy are working to process and recycle high-grade fly ash as an additive for Portland cement in concrete. Recycling ash not only locks toxins permanently inside structural concrete and dramatically lowers the carbon footprint of the concrete, but the resulting sales revenue and avoided landfill fees also help cushion Colorado consumers from rate increases.

Environmental activists, however, caution that the reuse of coal ash needs to be very carefully managed so as not to spread the toxins.



Coal Ash Management, Xcel Energy, 

https://corporate.my.xcelenergy.com/s/energy/sources/coal/coal-ash-management?_ga=2.269239799.724929888.1786225357-1955019084.1785963218

Toxic Coal Ash in Colorado: Addressing Coal Plants’ Hazardous Legacy, Earthjustice: https://earthjustice.org/feature/coal-ash-states/colorado

Events

Dancing with Deadpool: The 27-year-long Colorado River Crisis

Thursday, October 22, 2026 7-9 pm at the Common Flame (Jefferson Universalist Church) 14350 W 32nd Ave, Golden

LIVE STREAM

Since 2000 the Colorado River has lost 20% of its annual flow, with higher temperatures and precipitation declines to blame. Up to half of this loss has been attributed to human caused warming.

Presented by Bradley H. Udall, a Senior Water and Climate Research Scientist / Scholar at Colorado State University’s Colorado Water Center.

 Co-hosted by CRES.