One little known engineering project from Juneau's mining era is the Mendanhal Glacier power plant. This hydropower station was built in 1911 and 1912 to supply power to the Treadwell mine 15 miles away. A wooden dam was built on Nugget Creek above one side of the glacier, and a 650 foot tunnel was bored through the ridge between the dam and the glacier valley. From the tunnel adit, water was piped through a metal-bound redwood pipeline down the hill to the hydroelectric plant near the front of the glacier. A small mine-gauge railway was built on top of the pipeline, with a steep tram section up and over the ridge to the dam site. When active, the powerplant generated 2.5 megawatts with two pelton wheels. The AJ mine purchased the plant in 1914 and probably used it until the mine closed. In 1965 the forest service built a visitor's center near the glacier, and forced the AJ owners to tear down the power plant because they felt it was a hazard to tourists. The present nature trail avoids the path of the old railway and pipeline, and the foundation of the power building is mostly hidden in bushes. The tunnel was apparently flooded at one time, and diverted much of Nugget Creek into a small waterfall, but the entire dam has now clogged with silt and the upper end of the tunnel is mostly plugged. The lower end is still open, and there are a lot of ruins and artifacts left in the woods around the area.