A Look Back in History: Mocassin Powerhouse

Board of Public Works, Moccasin Creek penstocks and vicinity; Looking east

Construction of the original Moccasin Powerhouse began in the fall of 1921. The facility began generating power on August 14, 1925. It was removed from operation February of 1969 when the new powerhouse came online.

Paul James Ost was the electrical engineer put in charge of power operations and electrical engineering phases of the Hetch Hetchy project.

“Paul assembled the Moccasin Powerhouse. He went back east to gather all the parts from multiple companies including Westinghouse and General Electric and personally directed the construction of the electrical sections of the powerhouse. The powerhouse was at one time called the ‘Ost Powerhouse’.” — Mary (Molly) Ford Ost (1950)

Board of Public Works, Hetch Hetchy, Construction of Moccasin Creek Powerhouse and penstocks, Group photograph.

Today the powerhouse is called Moccasin Powerhouse, named after its location. Moccasin is a “company town,” where the penstocks deliver water from upcountry to the hydroelectric power plant.

During the Gold Rush, Moccasin was a stage coach stop on Big Oak Flat Road. A covered bridge was built to allow crossing of Moccasin Creek during the wet season. There was a mining camp along Moccasin Creek and east of town along Priest Grade. Robberies were frequent during years when gold miners were successful in the area.

Moccasin is the furthest downstream of San Francisco’s three hydroelectric plants (Kirkwood being near the Hetch Hetchy Reservoir, and Holm near Cherry Lake). Operations at all three plants are coordinated from the control room at Moccasin in the new powerhouse.

Board of Public Works, Hetch Hetchy, Moccasin Power Plant, Interior view, Generator bearings in place.