Tens of thousands of defunct mines poisoning waterways around Colorado and the West present, beyond environmental harm, a multibillion-dollar financial burden.

An analysis unveiled Wednesday counting abandoned mines located just on federal public lands pegged cleanup costs at up to $21 billion, including more than $1 billion in Colorado.

That’s a burden falling primarily to taxpayers and the federal agencies that manage public lands. It represents a portion of overall cleanup costs, estimated as high as $71 billion, that include tens of thousands of mines on privately owned land.

“We need policies now that can help us address these issues,” said Jessica Goad of the Denver-based Center for Western Priorities, an advocacy group that conducted the analysis using Government Accountability Office data.

“We need our elected officials to pay attention to this problem,” Goad said. “The abandoned mines are not just an environmental time bomb but also a financial time bomb.”

The analysis draws on a GAO investigation that counted 99,737 abandoned mines on Bureau of Land Management and U.S. Forest Service federal land in western states, with 5,105 in Colorado. U.S. Rep. Doug Lamborn of Colorado Springs requested the 2011 GAO look into inactive mines located on public land. Center for Western Priorities analysts also relied on a 1993 Mineral Policy Center study that calculated cleanup costs.

Under federal superfund law, the Forest Service and BLM can be liable for disasters caused by and cleanup of those abandoned inactive mines.

Center for Western Priorities staffers said they are motivated to show that notions floated by politicians of states taking over management of federal lands likely would foist heavier burdens on state taxpayers. Federal and state government data on inactive mines has been scattered.

Center analysts gathered the best available estimates of the number of abandoned mines on BLM and Forest Service land in 13 western states. They melded these with average costs of cleaning up various contaminants to estimate low- and high-end costs of cleaning up the mines on BLM and Forest Service land in each state.

The Aug. 5 Gold King Mine disaster in southwestern Colorado, where an EPA-triggered blowout turned the Animas River mustard yellow, drew attention to a long-running problem that Congress for decades has failed to address.

Western senators including Sen. Michael Bennet this month launched legislation to reform the nation’s 1872 mining law and require companies to pay fees to create a cleanup fund for abandoned inactive mines. It aims to raise at least $100 million a year. Senate and House lawmakers also have been developing separate legislation to encourage voluntary cleanups by shielding companies and conservation groups from liability when well-intentioned mine work goes wrong.

Bruce Finley: 303-954-1700, bfinley@denverpost.com or @finleybruce