JOIN THE SAN DIEGO COUNTY WATER AUTHORITY! The San Diego County Water Authority is an independent public agency that serves as San Diego County's regional water wholesaler. The mission of the Water Authority is to provide a safe and reliable water supply to its 24 member agencies serving the region's $220 billion economy and 3.3 million residents. The Water Authority is executing a long-term strategy to diversify the region's supplies, make major investments in the region's water delivery and storage system, and improve water use efficiency. Through dynamic leadership, thoughtful planning, and prudent fiscal policies, the Water Authority is cost effectively managing the region's water portfolio, while continuing to diversify supplies to enhance current and future reliability.