Walnut Canyon Reservoir

Aerial of Lenain and WCR

Walnut Canyon Reservoir is a 920-million-gallon reservoir that supplies water to Anaheim homes and businesses.

The reservoir receives deliveries of imported, untreated Colorado River water from the Metropolitan Water District (MWD) of Southern California. Water from the reservoir is then treated at the August F. Lenain Treatment Plant prior to delivery to Anaheim Public Utilities' customers. The reservoir is capable of storing 920 million gallons of imported water, enough to supply the area for 30-45 days in the event of an interruption to imported supplies from MWD.


Walnut Canyon Reservoir provides operational flexibility to minimize imported water peaking charges during summer periods, which results in fluctuations of water levels. Additionally, when groundwater wells that serve the majority of Anaheim are offline for upgrades, the reservoir is relied upon to serve customers that may cause lower water levels.

Quick Facts

  • Constructed in 1968, Walnut Canyon Reservoir has served the community for over to 50 years.
  • A working water storage reservoir, it serves as a primary source of water to the Anaheim hill-and-canyon areas; which allows the City to manage short-term, emergency, and seasonal water supply needs.
  • This reservoir provides water for helicopter-based firefighting. Water levels are constantly monitored and coordinated with Anaheim Fire and Rescue Department to ensure sufficient availability of water.
  • The Walnut Canyon Reservoir is also historically significant. While the construction crew was restoring the concrete “A” monument, contractors found a handwritten letter inside, which was signed by the original City crew. This letter serves as a testament to the pride that City staff have long had in their work.
Wide view of Walnut Canyon Reservoir with houses in the distance
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