Two places I would think of checking:
UCSB Our own David Seubert
Cal State Fullerton's Center for Oral and Public History (COPH) When
did Mulholland die? COPH's archives only go to the 1950s, I believe.

At 12:26 PM 8/22/2005, Jeanette Berard wrote:
>I have a researcher who is helping to organize a museum for the Los
>Angeles Dept. of Water and Power.  He is hoping to discover if there
>is any audio recording of William Mulholland out there.
>

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