California Code
ARTICLE 3 - Conduits and Screens: Diversions Over 250 Cubic Feet per Second
Section 5990.

5990. It is unlawful for the owner of a conduit to refuse, fail, or neglect to install a screen in compliance with an order from the department or to permit the screen to be removed or taken out of place, except for repairs or cleaning while water is running in the conduit.

(Enacted by Stats. 1957, Ch. 456.)