DENVER (AP) — A mining company is formally challenging an Environmental Protection Agency order to pay for an investigation of underground water flows at a Colorado Superfund site.

Sunnyside Gold Corp. said Wednesday it asked for a conference at which the company can ask EPA to modify or revoke the order. No date has been set.

Gold King Mine (credit: CBS)

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EPA wants Sunnyside to study part of the Bonita Peak Mining District, which includes the Gold King Mine. EPA-led contractors inadvertently triggered a spill of potentially toxic wastewater there in 2015, polluting rivers in Colorado, New Mexico and Utah.

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Sunnyside doesn’t own the Gold King but has other property in the Superfund site. EPA says previous work at a Sunnyside’s mine may have redirected wastewater that found its way into rivers.

Sunnyside says it didn’t cause the problems.

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