Here is what the regs say. I say the aquaduct is a tributary of the sacramento river. I may be wrong but I have never been ticketed for it

2.40. Chumming.
Chumming is permitted only in:
(a) The Colorado River District, but only the approved bait fishes for this District
may be used as chum (see Section 4.15) except in the Salton Sea where corn
may also be used.
(b) Carquinez Strait and Suisun Bay and their tributaries and saltwater tributaries.
(c) Sacramento River and tidewater of tributaries downstream from Interstate 80
bridge.
(d) San Joaquin River and tidewater of tributaries downstream from Interstate 5 bridge.