The incident was reported at 7:09 a.m. at 1841 Geary Road, Contra Costa County Fire Protection District spokesman Lewis Broschard said.
Seventeen firefighters responded to the one-alarm blaze and police shut down Geary Road between Buena Vista Avenue and Hall Lane, authorities said.
Broschard said firefighters had to confirm with PG&E that power to the plant was off before they could start putting water on it.
They had the fire out by 7:57 a.m.
No injuries were reported and no other structures were threatened, Broschard said.
Although the blaze was initially reported as a transformer fire, Broschard said the problem actually involved switch gear used to transfer power from PG&E to EBMUD.
The transformer at the pumping station sustained smoke damage but appears to be intact. Hardy said the pumping plant is mostly active in the summer and was not in use this morning.
The fire did not impact water service to EBMUD customers, Hardy said.