Cal. Wat. Code § 35410
The board of a district whose corporate area, in whole or in part, is included within a metropolitan water district may in any fiscal year declare its intention to pay out of its district funds the whole or a stated percentage of the amount of taxes to be derived from the area of such metropolitan water district within the district as such amount of taxes shall be fixed in the next succeeding fiscal year by resolution of the board of directors of such metropolitan water district. District receipts from any source, including assessments, acreage assessments and standby charges, may be used to pay said metropolitan tax. A district may provide for the levy, collection and enforcement of any district or improvement district assessment, acreage assessment or standby charge for the payment of said metropolitan water district tax in the same manner as other district or improvement district assessments and standby charges.
Ca. Water Code § 35410