The Urban Water Management Planning Act became part of the California Water Code with the passage of Assembly Bill 797 during the 1983–1984 regular session of the California legislature. Subsequently, state and assembly bills have periodically amended the Act. Several new requirements for 2020 UWMPs were added based on State Assembly Bill 1668 and Senate Bill 606. The Act is described in California Water Code (CWC) Division 6, Part 2.6, Sections 10610 through 10657.
The Act requires every urban water supplier providing water for municipal purposes to more than 3,000 customers or supplying more than 3,000 acre-feet (ac-ft) of water annually to adopt and submit an UWMP every five years to the California Department of Water Resources (DWR). The Act describes the contents of the UWMP as well as how urban water suppliers should adopt and implement the UWMP.