The tunnel along with a powerhouse was built in 1902 for undercutting veins on Pendleton Mountain. Water flows from the adit of the tunnel, which ran across and down a waste-rock pile at the mouth of the tunnel, and into Leavenworth Creek. Water samples showed elevated zinc concentrations that exceeded the State's acute and chronic water quality standards. The waste-rock pile contains aluminum, copper, chromium, and zinc. The waste-rock piles were eroding due to unrestricted travel across the pile by motorized vehicles causing increased sedimentation and metal loading in the riparian wetland and Leavenworth Creek. Drainage from tunnel adit opening was diverted into a pipe through the waste-rock pile to eliminate additional metal loading. An outflow returning effluent from the settling pond to its original channel into the riparian wetland was implemented. A diversion ditch was constructed to capture clean water from an unnamed tributary which was flowing under the waste-rock pile which was also diverted into the riparian wetland. Barriers were placed to discouraged off-road vehicle use and areas of the waste-rock pile susceptible to erosion were amended to establish vegetation.