Some of the aqueducts that deliver some of the water to LA do rely on pumping. But, the Los Angeles Aqueduct, which is the subject of this post, does not. The LA Aqueduct is entirely gravity driven, and under normal circumstances it is sufficient to supply LA's water needs.

Another nitpick is that California's various aqueducts are net producers of electricity (i.e., after accounting for pumping), so, while some of them do rely on electricity, they do not require an external source of power to operate.