Upper District is a special district formed by the regions voters on December 8, 1959, to help sustain adequate water supplies in the rapidly-developing San Gabriel Valley.

The District was incorporated shortly thereafter on January 7, 1960.On March 12, 1963, residents within Upper Districts service area voted to annex to the Metropolitan Water District of Southern California (MWD)

Through MWDs facilities, supplemental water is brought into the San Gabriel Valley;first from the Colorado River, and also from the State Water Project.

Today, Upper District also provides recycled water and facilitates efforts in water stewardship, including conservation and stormwater capture.