News Item

South County and North County: Apples and Oranges When It Comes to Desalination

Desalination would provide an eco-friendly, local, drought-proof water supply to South County

Reverse Osmosis
Desalination uses reverse osmosis technology to transform ocean water into high-quality drinking water. 

Recently, two opinion pieces were posted regarding proposed desalination at the Poseidon Huntington Beach facility. The first by Orange County Water District President Denis Bilodeau defended the need for desalination. The second by Irvine Ranch Water District General Manager Paul Cook stated that “Seawater desalination is not a solution that fits our problem; groundwater storage is the correct solution.”

Often, South Orange County is lumped into a discussion of North County water needs by use of the description “Orange County.” It is critical when discussing water that the correct geographic areas must be used and defined. North and Central Orange County’s water supply is drastically different from Sorth Orange County.

“Northern Orange County is blessed with a large and well-maintained aquifer. Like a savings account, an aquifer is a great place to save up for a day when you might run a bit short.” – IRWD General Manager Paul Cook.

The difference between North and South

South Orange County is not as fortunate as the north in two very critical ways. First, South Orange County has little to virtually no aquifers. We obtain 85 to 100 percent of our water from the Colorado River or Northern California. North Orange County gets 75 percent or more of their water from groundwater aquifers.

Second, in North and Central Orange County, sewage travels to one central location for treatment. It is the job of the Orange County Sanitation District (OCSD) to recycle the sewer water. After treating the sewage, OCSD then sends 100 million gallons per day of recycled water to the Orange County Water District. There, the water receives advanced treatment. OCSD then injects the recycled water into large aquifers. The water is further filtered through the aquifer and later used for drinking water. The purified water provides enough water for 850,000 residents each year. Our wastewater treatment plants are located throughout South Orange County. This makes it difficult for us to model North Orange County’s sewer water recycling. Replicating their system could be cost prohibitive.

South Orange County’s Water Reliability

Here at South Coast Water District (SCWD), we have projects to help us reduce our reliance on imported water. More than four decades ago, South Orange County led the way by using recycled water for irrigation. “Purple pipes” sprouted up throughout the county, and now make up 15 percent of SCWD’s water supply. We continue to expand our programs to use as much recycled water as possible.

During the past 20 years, new technology made conserving water easier. Many homeowners installed ultra low-flow toilets, water sense products, weather-based irrigation controllers, and other tools to cut water use. Others installed artificial turf and drought-tolerant gardens. These savings add up to nearly a billion gallons of water each year.

The San Juan Basin Authority, a group made up of South County water agencies—including SCWD, also plans to decrease reliance on imported water. The goal is to make more groundwater available to our region by capturing more of the runoff from the north. SCWD is a 20 percent partner in this effort.

All water agencies are actively seeking ways to lessen our dependence on imported water. All new projects are needed to meet Orange County’s water demand.

South Coast Water District’s Goals

South Coast Water District’s goal is to diversify our water portfolio for three critical reasons. First, we want to be ready for the “Big One” that will come. Second, we want to create a high quality, drought-proof, and locally controlled water supply. We don’t want to be severely limited or cut off from water supplies. And the last reason is a financial concern: We must insulate the District from significant price hikes of imported water due to water to vulnerabilities in the Bay-Delta and Colorado River shortages, or extreme water conservation.


South Coast Water District is considering a project to build an ocean water desalination facility in Dana Point. The facility would have an initial capacity of up to five million gallons per day (MGD) with potential for future expansions up to 15 MGD.

The project would create a critical community benefit: a reliable, local and drought-proof water supply that does not rely on expensive imported water and is environmentally friendly. In addition to providing a local, reliable and secure water supply for the District, the desalination facility would also provide emergency backup water supplies, should delivery of imported water be disrupted.

Using environmental friendly slant well technology, located beneath the ocean floor, the proposed project would draw water from beneath the ocean floor to the desalination facility site. The project conforms to the State Water Board’s California Ocean Plan. It specifies the type of location and technology proposed for new desalination plants. The State even awarded the project a $10 million grant this year. The grant, which is contingent upon receiving regulatory permits, was the only one awarded to an ocean desalination project; the other seven would all draw on brackish water inland from the ocean.

It’s human nature to lump similar things in with each other. However, in this case, it is crucial to realize that South County and North County have different topographies resulting in a different infrastructure. South Orange County lacks an aquifer to hold our water. “Northern Orange Couty is blessed with a large and well-maintained aquifer.”

To learn more about water conservation, water supply, new water sources and desalination visit us at And sign up to receive regular notices from us updating you on what you can do to help.

See an earthquake simulation of what would happen if a major earthquake hit the Bay Delta region.

Watch a short 2-minute video on the difference between Northern and Southern Orange County.