San Gorgonio Pass Water Supply Sources

Local Geography

The San Gorgonio Pass is an elevated, relatively narrow land mass between the San Bernardino mountains on the north and the San Jacinto mountains on the south, connecting the San Bernardino Valley on the west to the Coachella Valley on the east.  The region straddles two large watersheds.

The western half of the region is drained primarily by Little San Gorgonio Creek and Noble Creek, which are tributary to the Whitewater River and is part of the Colorado River Basin.  A small portion of the region drains to the San Jacinto River which drains to Lake Elsinore.

Sources of Water Supply

StreamThe main sources of water supply within the region are:

Groundwater – begins as precipitation in the form of rain along with snow in the local mountains that percolates into underground aquifers.  The mean annual precipitation in the region is 17.5 inches.

Imported Water – State Water Project water is conveyed through the California Aqueduct and is treated to drinking water standards for direct deliveries or is placed into percolation basins, stored in underground aquifers and extracted via groundwater production wells for residential, institutional, industrial purposes or agricultural purposes .   The San Gorgonio Pass Water Agency, one of 29 State Water Project contractors, has an allocation of 17,300 acre feet of water that originates in northern California.  It sells this water supply to water purveyors in its service area.

The State Water Project is the nation’s largest state-built water and power development and delivery system.  Stretching from Northern California through the Bay Area, the Central Valley and into Southern California, it is a multi-faceted system that includes reservoirs, lakes, storage tanks, canals, tunnels, pipelines and pumping and power plants.  Together, these elements enable the state to capture, store, and convey water to 27 public water agencies. Through the State Water Project, State Water Contractors member agencies deliver water to more than 26 million residents, businesses and farms up and down California.  For more information, access or

Recycled Water – treated waste water used for irrigation of large landscapes and industrial uses or percolated in groundwater basins. Several Pass Area agencies are in various stages of implementing or planning recycled water systems.

Local Runoff of Surface Water– accounts for a small portion of local water resources, primarily in Edgar and Banning Canyons that is recharged into local groundwater basins where it becomes part of the groundwater.

Storm Water Capture – a potential new source of water to the region during large storm flow events.  Large areas of land to construct percolation ponds are required.

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