Toxic runoff leaching from piles of ore discarded decades ago is seen in a detention pond in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
City councilmember Christian Luna-Leal poses for a portrait in front of a detention pond containing mine waste in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
An old mining structure is seen in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
A pile of ore discarded decades ago is seen in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
Nick Michael with CJK Milling discusses a project map at the company's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
A mobile home park downstream of a proposed project to mine gold from piles of ore discarded decades ago is seen in Leadville, Colo., on Friday, June 28, 2024. (AP Photo/Thomas Peipert)
Brice Karsh, who owns a fishing ranch downstream of a proposed project to mine gold from piles of ore discarded decades ago, speaks about his concerns at his ranch in Leadville, Colo., on Friday, June 28, 2024. (AP Photo/Thomas Peipert)
Toxic runoff from piles of ore discarded decades ago is seen in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
Ore grinding balls are seen at CJK Milling's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Margarita Perea, who lives downstream of a proposed project to mine gold from piles of ore discarded decades ago, interacts with her kids at her home in Leadville, Colo., on Friday, June 28, 2024. (AP Photo/Thomas Peipert)
Parkville Water District Manager Greg Teter is interviewed at his office in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Gary Knippa, owner of CJK Milling, stands outside of the company's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Machinery is seen at CJK Milling's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Runners pass by piles of ore discarded decades ago in Leadville, Colo., on Friday, June 28, 2024. (AP Photo/Thomas Peipert)
City councilmember Christian Luna-Leal poses for a portrait in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
Margarita Perea, who lives downstream of a proposed project to mine gold from piles of ore discarded decades ago, is interviewed at her home in Leadville, Colo., on Friday, June 28, 2024. (AP Photo/Thomas Peipert)
Toxic runofff leaching from piles of ore discarded decades ago is seen in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
Nick Michael with CJK Milling holds an example of the byproduct of a proposed project to mine gold from piles of ore in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Gary Knippa, owner of CJK Milling, walks down the stairs at the company's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Piles of ore discarded decades ago are seen with the town of Leadville, Colo., in the background on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
An old mining structure is seen in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Toxic runoff leaching from piles of ore discarded decades ago is seen in Leadville, Colo., on Wednesday, June 26, 2024. (AP Photo/Thomas Peipert)
Nick Michael with CJK Milling points to a project map at the company's mill in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Empty cyanide tanks sit outside of a welding shop in Leadville, Colo., on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)
Nick Michael with CJK Milling stands on top of discarded piles of ore in Leadville, Colo. on Thursday, June 27, 2024. (AP Photo/Thomas Peipert)