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Carlsbad Desalination Plant

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Poseidon Resources (Channelside) LP owns and operates the Claude “Bud” Lewis Carlsbad Desalination Plant, which is located on the southern shore of Agua Hedionda Lagoon in the City of Carlsbad, California. The Carlsbad Desalination Plant is the nation’s largest seawater desalination plant, producing an average daily flow of 50 million gallons per day (MGD) of drinking water per day from seawater through a reverse osmosis process that results in a brine waste approximately twice the salinity of the ocean. The Carlsbad Desalination Plant is currently using cooling water from the Encina Power Station as the source water for the desalination facility and discharges the commingled brine waste to the to the Pacific Ocean through the Encina Power Station channel. Once the Encina Power Station is decommissioned, the Carlsbad Desalination Plant proposes to withdraw up to 299 MGD of seawater from the Agua Hedionda Lagoon and use flow augmentation to dilute the brine prior to discharge into the Pacific Ocean. The San Diego Water Board is currently working on the reissuance of the NPDES permit for the facility and is also working in consultation with the State Water Board on issuing a determination pursuant to Water Code section 13142.5(b) for the stand-alone desalination facility.

The current permit is Order No. R9-2006-0065, with amendments incorporated.

Permit Renewal

The current permit, Order No. R9-2006-0065, expired in 2011, but remains in effect under an administrative extension until such time as it is superseded by the reissued NPDES permit. The reissuance of the NPDES permit for the CDP is a high priority for the San Diego Water Board and the State Water Board.

Meetings with Poseidon Resources regarding NPDES permit development:

Executive Officer Reports

Reports regarding the Carlsbad Desalination Project are available in the Executive Officer's Reports for the following months:


Additional Links

Contact Information

If you have questions or need additional information please contact Mr. Ben Neill, P.E. of the Source Control Regulation Unit at (619) 521-3376.