South Bay Irrigation District was formed as an independent California Special District in 1951 to represent local residents. Voter approval assured the move toward access to imported water from the San Diego County Water Authority (SDCWA), the County's water wholesaler. At that time, local water resources were inadequate to serve the needs of those living and working in the growing Sweetwater Valley.
In 1977, as a result of another public initiative, SBID and National City formed a joint powers public water agency, named Sweetwater Authority. Sweetwater Authority manages and operates the water system, providing water to National City, western portions of Chula Vista and Bonita, California.
Sweetwater Authority's governing board is composed of 7 members. Five directors are elected by division by the citizens of the SBID. Two directors are appointed by the Mayor of National City, subject to City Council confirmation.