About Us

Leak RepairWestern is securing your water supply for today and tomorrow.

Providing reliable drinking water to our customers on a daily basis is fundamental to what we do. Western works to secure your water supply for the future as well as today. It takes engineering, infrastructure, responsible management and strategic governance to ensure the roughly 28 billion gallons of water we provide to our customers in western Riverside County is safe and reliable 365 days a year.

Western Municipal Water District was formed in 1954, and today provides reliable water and wastewater services to retail customers and wholesale agencies from Corona to Temecula. As a member agency of Metropolitan Water District of Southern California, the state’s largest water supplier, Western receives most of its water from the Sacramento-San Joaquin Bay-Delta and from the Colorado River. Most of the Delta water Western receives originates as snowpack in the Sierra Nevadas and travels 444 miles southerly to its final destination in Southern California homes and businesses. Slicing its way through a 200-plus mile journey, Colorado River water travels westward in the aqueduct built by Metropolitan in the 1930s.

The District has a groundwater supply in its Murrieta Division, which is combined with imported water for the region’s residents. Western also has rights to groundwater in the Bunker Hill Basin, which is transported into our Riverside Division through an agreement with the city of Riverside.

Western's is committed to transparency and accountability.

Mission Statement
Western Municipal Water District provides water supply, wastewater disposal and water resource management to the public in a safe, reliable, environmentally sensitive and financially responsible manner.

General District Information

Western supplies water on both a wholesale and a retail basis to a region stretching 527-square miles in western Riverside County with an assessed valuation of $83 billion and a population of more than 880,000 people. This regional area includes the cities of Corona, Norco and Riverside and the water agencies serving Box Springs, Eagle Valley, Lake Elsinore, Temescal Valley and Temecula.

We are governed by a Board of Directors, elected to four-year terms by registered voters in the five election divisions.

Western is staffed by approximately 140 employees who represent a variety of divisions of the District - engineering, finance, operations, water resources and administration. The District is managed by Craig Miller, who also acts as its court-appointed watermaster, and the management team.

While most of Western’s business is in wholesaling of water to water agencies and municipalities, the District directly serves approximately 25,000 residential and business customers in the following areas:

  • Riverside - home to Western’s largest grouping of direct customers. Areas served include a portion of the city of Riverside, Orangecrest, Mission Grove, El Sobrante, Eagle Valley, Woodcrest, Lake Mathews, portions of Mead Valley and Perris, and March Air Reserve Base.
  • Murrieta - with the merger of the city’s water utility agency in 2005, Western now serves a 6.5-square mile section of western Murrieta, primarily in the historic downtown area of the city.
  • Rainbow - Western’s most distant served community is an unincorporated area of southern Riverside County bordering San Diego County.
Western currently sells approximately 85,000 acre-feet of water annually. This is equal to about 28 billion gallons of water. One-quarter of Western's sales are to retail customers; three-quarters to wholesale. About two-thirds of the water Western sells is treated; the balance is untreated or raw water. About one-quarter of water sales are for agricultural uses; the balance is for domestic purposes. Nearly all water sold by the District for agricultural purposes is used to irrigate citrus and avocados planted since the 1950s.

Water Sources

About one-fifth of the water Western purchases from the the Metropolitan Water District of Southern California comes from the Colorado River Aqueduct. Most of the imported water supply comes from the State Water Project, which transports water from Northern California via the California Aqueduct. Western also imports a very small quantity of water from the San Bernardino basin. Western also has several wells for pumping groundwater in its Murrieta Division.

Santa Ana Watershed Project Authority

Western is one of five of the member agencies of the Santa Ana Watershed Project Authority (SAWPA), a regional water resources planning and project implementation organization.


As a water rights steward for the Santa Ana River Watershed, Western works to protect this important resource by carefully monitoring the quantities of water taken by all regional agencies with rights to this critical resource. Western’s general manager also serves as a court-appointed guardian or “watermaster”, as required by two 1969 court rulings or adjudications. These judgments determined the rights of the watershed users and other watershed entities.

The court designated four public agencies – including Western – to represent the interests of the upper and lower areas of the Santa Ana River and gave the agencies responsibility to oversee the watershed and fulfill court-ordered obligations.

Western is involved in four watermaster functions:

Santa Ana River – 1969 surface water rights
San Bernardino Basin Area – 1969 groundwater adjudication
Chino Groundwater Basin – 1978 groundwater adjudication
Santa Margarita River – 1964 surface and groundwater adjudication