The mines drained by the Argo Tunnel are no longer active .
The water draining out the tunnel was a source of pollution in Clear Creek until the U.S. Environmental Protection Agency ( EPA ) began treating the water .
The mines drained by the Argo Tunnel are no longer active , and the water draining out the tunnel was a source of pollution in Clear Creek until the U.S. Environmental Protection Agency ( EPA ) began treating the water .