Government Code § 38751
ARTICLE 5.5. Transfer of City Waterworks Systems
If the legislative body of the city determines that it is for the best interests of the city to sell, lease, or otherwise transfer the control or management of its waterworks system, or portion thereof, to such a municipal water district, by a four-fifths vote of all its members, it shall pass an ordinance, authorizing the sale, lease, or other transfer.