Desal plant operator assumes maintenance of Carlsbad lagoon

Poseidon Water takes over dredging, plans new intakes and pump station
​SAN DIGO UNION TRIBUNE  -  By PHIL DIEHL
MAY 13, 2019 - CARLSBAD — The company that built and operates the Carlsbad seawater desalination plant took over stewardship of the Agua Hedionda Lagoon this week, the only San Diego County lagoon that allows power boats, kayaks, paddleboards and other recreational and commercial activities.Poseidon Water will be responsible for dredging Agua Hedionda to keep it open and deep enough for public and private uses including a YMCA Aquatic Park, the Hubbs-SeaWorld Fish Hatchery, the Carlsbad Aquafarm shellfish operation and the lagoon foundation’s nature center.

Sand dredged from the lagoon is used to replenish the nearby beach, as a byproduct of the maintenance.
“Our location along the shore of the Agua Hedionda Lagoon makes it a critical part of the Carlsbad desalination plant’s operations, which enables us to provide San Diego County with more than 50 million gallons of high-quality drinking water every day,” Poseidon CEO Carlos Riva said in a news release.
“We look forward to taking an even more active role in the protection and preservation of the lagoon so that we can all enjoy its recreational and marine resources now and for generations to come,” Riva said.
In the past, NRG Energy and the previous owners of the Encina Power Station have dredged the lagoon every year or two to keep the waterway open and to maintain access to the seawater used to cool the natural gas-fired power plant. The old power station, built in the 1950s, was retired in December after a new, more efficient power plant built nearby on the same property went into service. The new plant does not use seawater for cooling.
Officials also announced this week that Poseidon will build a new pumping station and seawater intakes. The facility began production using seawater drawn from the power plant’s cooling system, and added a temporary intake system when the power plant closed.
The new, stand-alone intakes will have smaller screens to reduce the number of fish drawn into the system and provide greater protection for other marine life, according to a news release from the San Diego Regional Water Quality Control Board.

​Another advantage expected from the improved system will be to increase the production of drinking water to 60 million gallons daily.
Also this week, the water quality board renewed the permit issued to Poseidon that allows the plant to discharge its brine, mixed with seawater, into the ocean. The updated permit establishes more stringent guidelines to minimize the toxic effects of the brine on bottom-dwelling marine life.
Construction of the new facilities is expected to begin in mid-2020 and be completed in 2023. Until then, the desalination plant will continue to use the intakes.
The seawater, purified by reverse osmosis, is combined with water imported by aqueducts from the Colorado River and Northern California and pumped throughout the county under contracts with the San Diego County Water Authority and other local agencies. Desalination provides about 10 percent of the county’s drinking water.
“Desalinated water, as regulated by the permit for Poseidon, is an important component of our overall water supply portfolio,” said regional water board Chairman Henry Abarbanel.
The plant began production in 2015 and is the largest seawater desalination facility in the Western Hemisphere. Poseidon is building a similar plant in Huntington Beach that could be finished by the end of this year.
“The Carlsbad Desalination Plant is an invaluable asset for the state and region that helps us adapt to the changing climate and sustain a $231 billion regional economy,” said Jim Madaffer, chairman of the San Diego County Water Authority’s board of directors, in a news release Wednesday.
“It is the most environmentally sensitive and technologically advanced plant of its kind in the nation – part of our commitment to collaborative projects and integrated water solutions for San Diego and the Southwest.”