Olivenhain Municipal Water District (OMWD) is a public agency providing water, wastewater services, recycled water, hydroelectricity, and the operation of the Elfin Forest Recreational Reserve.

OMWD was organized in 1959 and has been serving water to its customers since 1961. The District currently includes over 48 square miles, and serves a population of approximately 68,000 residents.

OMWD includes portions of the cities of Encinitas, Carlsbad, San Diego, Solana Beach, and San Marcos as well as the communities of Olivenhain, Leucadia, Elfin Forest, Rancho Santa Fe, Fairbanks Ranch, Santa Fe Valley and 4S Ranch.