Site information:

Mt. Baldy Rd, ~7 N of the 210, Claremont

Site was in the canyon below the plaque site, but nothing remains of the site, as far as I know.

34.211866,-117.676017

Plaque information:

State plaque has gone missing

Plaque text:

The first hydroelectric installation in California for long-distance transmission of alternating current at high voltage was built in 1892 on San Antonio Creek below this spot by the San Antonio Light and Power Company organized by Dr. Cyrus Grandison Baldwin, President of Pomona College. The first high-voltage transformers built by George Westinghouse for this installation provided for transmission of 10,000 volts from this plant to Pomona.

Marked by the California State Park Commission in cooperation with The Historic Society of Pomona Valley.   May 7, 1955

Registered 11/25/1953