The Metropolitan Water District of Southern California was formed to import water from the Colorado River. During the 1930s, MWD built the Colorado River Aqueduct to convey this water. The first deliveries were made to Metropolitan member agencies in 1941. The aqueduct is more than 240 miles long, beginning at Lake Havasu on the Arizona/California border and ending at Lake Mathews in Riverside County. The aqueduct has capacity to deliver up to 1.3 million acre-feet of water each year.
Colorado River salinity levels are much higher than supplies from the State Water Project, so water is blended at Lake Skinner before it is delivered to the member agencies.
The California agencies that use Colorado River water are working to reduce their reliance on the river. The primary vehicle for this effort is California's Colorado Water Use Plan, which is designed to reduce California's demand on the river to its 4.4-million-acre-foot apportionment when surplus water or other states' apportionment is not available.