The Metropolitan Water District of Southern California was established by the California Legislature in 1928 through the Metropolitan Water District Act. The primary purpose of the Act was to construct and operate the 242-mile Colorado River Aqueduct (CRA).

Concurrent with the enactment of the Metropolitan Act, the U.S. Congress passed the Boulder Canyon Project Act, authorizing construction of Hoover Dam, which provided power to pump water to Southern California. 

Metropolitan was one of the first wholesale water agencies in the United States, and currently is the largest. (excerpt from MWD Act & Code).