Lenain Water Treatment Plant


Anaheim Public Utilities is rehabilitating the Lenain Water Treatment Plant. This plant treats water that is imported from the Colorado River and stored in Anaheim’s Walnut Canyon Reservoir. The treated water from the plant serves the residences and businesses throughout Anaheim, providing water supply and meeting maximum day water demands. The plant includes the water treatment facilities, an operation and control center and a water quality lab. The plant was last upgraded in 1996 and improvements are needed to replace aging infrastructure and improve safety and security. 

This project will replace outdated equipment such as valves, electrical controls and pumps in the treatment plant as well as valves in Walnut Canyon Reservoir, retrofit facility structures to meet current seismic codes, install a back-up power generator, improve the access road, install surveillance cameras, construct new pipelines and replace the pavement on the boat ramp. The project will also include construction of a new storage building adjacent to Walnut Canyon Reservoir to house the controls for valves and chemical feed systems.

As part of the project, several valves in Walnut Canyon Reservoir will need to be replaced. In order to have safe access to replace these valves, the reservoir level will need to be lowered. The process of gradually lowering the reservoir level has started. The level will slowly be lowered over the next several months and remain at that level until Spring 2019, while work is conducted prior to refilling the reservoir.

During construction, water level in Walnut Canyon Reservoir will be dropped to about 30 million gallons of water, which is more than sufficient to support firefighting helicopters that take between 500 and 1,500 gallons per trip, and the reservoir can be refilled with water to maintain that volume.

The appropriate fire authorities have been informed of the water level, and they are still able to use the reservoir for firefighting.

Project construction is scheduled to begin on September 13, 2018.

Project Updates:

Upcoming work within the plant site:

  • Construction of new pipeline and access road.
  • Rehabilitation work on the treatment facilities. 

Upcoming work at and near Walnut Canyon Reservoir: 

  • Replacement of valves in Walnut Canyon Reservoir.
  • Pavement rehabilitation of the boat ramp.
  • Construction of the new building near Walnut Canyon Reservoir. 

Completion date: March 2020

If you have questions or comments regarding the Lenain Water Treatment Plant rehabilitation project, please contact Robert Hoang, Project Manager and Community Liaison, at 714.765.4229 or e-mail rhoang@anaheim.net.

lenain map