Construction on the original Moccasin Powerhouse, which was built as a component of the Hetch Hetchy Project system, started in fall 1921. The facility was completed and began generating power on August 14, 1925. The Moccasin Dam was completed in 1930 as a regulating reservoir for the outlet of the turbines for the Moccasin Powerhouse.
Moccasin is the furthest downstream of San Francisco’s three hydroelectric plants (the others are Kirkwood, near Hetch Hetchy Reservoir and Holm near Cherry Lake). Operations at all three plants are coordinated from the control room at Moccasin.
The original powerhouse was replaced by the new powerhouse in the 1960s. It was removed from operation on February 7, 1969. There have been times when revival of the old adobe structure was considered, not as a powerhouse but for some different purpose.
The drawing above appears to have been executed at one of those times. It has no date but is titled “Rehabilitation Study.” The structure, of course, still stands over water, so rehabilitation would be a major undertaking. But wouldn’t a museum or deep archive be a wonderful tribute to this graceful old structure that was an up-country cap to our water and power system?