The Golf Tunnel (or adit) is one of many mining facilities within the Chalk Creek Mining District. The district is in the upper reaches of Chalk Creek near the small historical mining town of St. Elmo, Colorado.
The watershed first came under scrutiny in 1986 after a fish kill at the CDW Chalk Cliffs Fish Rearing Unit. The kill was attributed to elevated concentrations of metals in Chalk Creek during spring runoff. Water quality sampling at that time found zinc and cadmium at levels exceeding state water quality standards. The effects were reduction of the number of brown trout and elimination of young fish for a 12-mile stretch below the mining district. Metal concentrations in Chalk Creek peaked in the vicinity of the Mary Murphy Mine and the Iron Chest tailing piles. At that time it was suspected that interaction between mine drainage, creek flows and the tailings piles contributed most of the metals in the stream. A loading analysis developed from flow and metals concentration data showed that 85 percent of the metals load exiting the main adit was attributed to one inflow from the north drift on the Mary Vein. The inflow constituted only 1.5 percent of the total discharge from the adit, but at high flow it had a total zinc concentration of 190,200 micrograms per liter. The contaminated inflow was traced back to an ore chute on a high-sulfide stope (mined-out portion of vein) on the north vein, which drained 15 gpm. This same high-concentration source also accounts for 70 percent of the zinc load discharging from the Golf adit.
