Just past the Minnesota Point Lighthouse ruins near the end of Minnesota Point stands the concrete remains of the U.S. Lighthouse Service Depot. The station was not built to serve the Minnesota Point Light. Rather, it was used to store buoys and acetylene used to power the North Pier Lighthouse, South Pier Lighthouse, and Inner Harbor Light along the Duluth Ship Canal.
The depot likely held calcium carbide, not acetylene, which was more stable. The acetylene was made by dripping water into calcium carbide at the lighthouses, releasing the gas. .
The Corps of Engineers did not want to store the raw material for a dangerous gas too close to Canal Park and the Aerial Lift Bridge. So the vessels Amaronth and Marigold loaded and unloaded calcium carbide and other supplies at the building from 1905 until World War II, when the lights were electrfied. Today the buildings walls are covered with graffiti and there is evidence it has been used as a party location for many years.