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Historically, the Raymond Basin has provided water for many beneficial uses. Until the population boom of the 1920’s, the Basin primarily served agriculture. During the 1800’s there was an adequate supply to meet the area’s agricultural water needs until shortages occurred at the turn of the 20th century when many areas of Southern California experienced severe water shortages.

Water supply and demand continued to be an increasing problem and by the 1930’s, it was evident that the available water supply was inadequate to serve all of the needs of a growing population. Not only did the immediate communities within the Raymond Basin rely on this supply, but other communities south of the area as well.

To ensure that all of these communities received a portion of the water, legal actions beginning in 1937 established the Raymond Basin as the first adjudicated groundwater basin in the state. Under the adjudication, a court of law determined who had a right to extract water and the maximum annual amount of water allowed to be pumped by each producer.

This “safe yield” concept allows an annual fixed amount of water to be used by the 16 water producers served by the Basin. The Raymond Judgment set a standard for careful management and protection of all groundwater basins throughout California.

Prior to 1984, the administration of the Basin was under the authority of the State Department of Water Resource (DWR) serving as Watermaster. During that time, the Raymond Basin Advisory Board acted solely in an advisory capacity. In 1984, the Raymond Basin Judgment was amended to form the Management Board which now serves as Watermaster. The Management Board oversees the implementation of the adjudication provisions of the Judgment and approves plans for storage of local and imported water in the Basin.


























The Raymond Basin covers approximately 40 square miles. It is bounded on the north by the San Gabriel Mountains, on the south and east by the San Gabriel Valley and on the west by the San Rafael Hills. Because of its natural formations and barriers, the Raymond Basin is replenished by surface water flows from the San Gabriel Mountains, including the Arroyo Seco, Eaton Wash and Santa Anita Wash.

The Basin supplies over half of the overlying area’s total annual water needs and is one of the most valuable local resources. At least 250,000 acre feet of water can be collected in this underground water table. Water is pumped by 16 different water purveyors to serve customers’ daily needs throughout the area.


Download the Raymond Basin Judgment

Download the Raymond Basin 2012 Rules and Regulations

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