Cal. Health & Saf. Code § 6530.1
Whenever any portion of a district has been included within a city by annexation, incorporation, or otherwise, the governing body of such city may elect, upon agreement by the district, to construct new storm water drains and storm water collection, outfall and disposal facilities within the city limits, and acquire title to and reconstruct, alter, enlarge, renew, replace, maintain and operate existing storm water drains and storm water collection, outfall and disposal facilities, lying within the city and may enter into an agreement with the board to do so.
From the date fixed in the agreement the city shall have exclusive jurisdiction to perform the functions described in the first paragraph of this section and in the agreement in that portion of the district lying within the city, and the board is not required to exercise any functions pertaining to such storm water drains and storm water collection, outfall and disposal facilities, and is relieved of all liability in connection therewith.
If the city elects to perform such functions within the city, the property within the corporate limits of the city shall not be taxed by the district for any costs necessary to construct, maintain, and keep in repair such storm drains and storm water collection, outfall and disposal facilities lying within the city which are taxed by the city for those functions, other than storm drains and storm water collection, outfall and disposal facilities within the city which continue to be owned, maintained and operated by the district pursuant to Section 6512 of this code.
Ca. Health and Saf. Code § 6530.1