Cal. Water Code § 8160

Any city within the limits of which any drainage improvement has been constructed, and which drainage improvement also lies within the territorial limits of a flood control district, may, by four-fifths vote of the legislative body of the city, transfer and convey to the flood control district any drainage improvement; and, if drainage improvements have been conveyed to and accepted by a flood control district under the provisions of Article 2 of this chapter, such flood control district shall accept any drainage improvements conveyed to it by any city under this article.