REGION — The largest water desalination plant in the western hemisphere is set to open this fall and will supply 7 percent of the San Diego region’s water supply.
The $1 billion Carlsbad Desalination Plant developed by Poseidon Resources is the largest and newest to open, and will be the last project to have been approved on a regional case-by-case basis, after new state regulations were passed, laying the groundwork for more desalination plants.
On May 5, the State Water Resources Control Board approved an amendment to the state’s Water Quality Control Plan to address effects from the construction and operation of desalination plants.
The amendment provides uniform regulations for regional water boards looking to permit water desalination plants.
The amendment process started in 2007, and state water board staff have been meeting with the public, stakeholders and experts on desalination.
State water officials see water desalination plants as a tool to provide a secure and drought proof water source.
“Desalination is one of several tools communities can use in appropriate circumstances to gain greater water security,” said State Water Board Chair Felicia Marcus. “This amendment will provide a consistent framework for communities and industry as they consider desalination, while protecting the coastal marine environment.”
Members from local and state environmental watchdog groups as San Diego Coastkeeper, a part of the California Coastkeeper Alliance, view the desalination plants as costly, energy intensive and devastating to marine life.
“The Desalination Policy adopted creates a framework for local entities to consider and mitigate facility impacts to the ocean, but aside from environmental impacts, desalination is almost always the most costly and energy-intensive source of water,” said California Coastkeeper Alliance’s Executive Director Sara Aminzadeh.
For every two gallons of ocean water a desalination plant takes in, it creates one gallon of drinkable water and one gallon of water with twice the amount of salt through reverse osmosis.
The reverse osmosis pushes water through tiny filters, using pressure to remove the salt and other minerals.
Microscopic marine life, like larvae and plankton can be harmed in the process.
Larger marine life can also get trapped and killed in the intake pipes.
One method, subsurface intake, prevents the death of fish, by installing pipes under the seafloor.
The Carlsbad desalination plant will not use subsurface intake pipes because it will take over the Encina Power Station’s existing pipe system.
In its early years of operation, the plant will use the Encina Power Station’s discharged water, which is used to cool the 60-year-old power station
The pipes receive and dispel water through the Agua Hedionda Lagoon.
Once the Encina Power Station goes offline in 2017 Poseidon will purchase the intake and outtake pipes and retrofit them with screens for filtration.
Poseidon is required to restore 66 acres of wetlands elsewhere, to replace the habitat lost from the intake of larvae.
Vice President of Project Development at Poseidon Scott Maloni said they’ve chosen a location in south San Diego Bay and are going through the permitting process now.
He said nothing would change at the Agua Hedionda lagoon, because the Encina Power Station has been the steward of the lagoon since the ‘50s, in order to keep a constant flow of water.
“If it wasn’t for the power plant’s maintenance of the lagoon, it would all
shrivel up and go to its natural historic state,” said Maloni. “We’ll become the stewards of the lagoon and keep it functioning as it is today.”
Another issue raised by environmental groups includes the production of residual brine, or leftover salt.
When it is not properly diluted, it can settle on the ocean floor and create an oxygen deficiency.
Methods to combat the residual brine include mixing it with municipal wastewater or disposing it through diffusers that rapidly mix and dilute the brine.
The Carlsbad plant will mix the brine with additional seawater for dilution.
The state amendment that was approved regulates that new or expanded seawater desalination plants must use the best available design, technology and mitigation measures possible for the site.
Poseidon is also developing a desalination plant in Huntington Beach that mirrors the Carlsbad Plant in linking up with an existing power station.
Several other desalination plants are also being considered for the California coastline, including along Camp Pendleton, Dana Point, El Segundo, Oceano, Cambria, Monterey Bay, Santa Cruz, and Moss Landing.