After three years of construction, the San Diego County Water Authority and Poseidon Water dedicated the Claude “Bud” Lewis Carlsbad Desalination Plant on Dec. 14, 2015. The plant is producing approximately 50 million gallons per day of locally controlled water for San Diego County, helping to minimize the region’s vulnerability to statewide drought conditions. It is part of a $1 billion project that includes the nation’s largest and most technologically advanced and energy-efficient treatment plant, a 10-mile large-diameter pipeline and improvements to Water Authority facilities for distributing desalinated seawater throughout San Diego County. The plant meets about seven to 10 percent of the region’s water demand – about one third of all the water generated in the county.

California Special District asked San Diego County Water Authority to discuss how the plant came to be and how it meets the needs of the local community.

Mark Weston, Board Chair

Mark Weston, Board Chair

What is the Carlsbad Desalination Plant?

The Claude “Bud” Lewis Carlsbad Desalination Plant produces approximately 50 million gallons of drinking water from the Pacific Ocean each day – enough for approximately 400,000 people – reducing the San Diego region’s vulnerability to drought and interruptions of imported water supplies due to an earthquake or other unexpected event. The plant, the largest seawater desalination plant in the nation, relies on reverse osmosis technology to generate about 10 percent of the region’s water supply. Water from the facility is pumped about 10 miles east through a newly constructed large-diameter pipeline to the Water Authority’s treatment plant, where it is blended with treated water from other sources for regional distribution. The Carlsbad plant is the result of an innovative public-private partnership between the Water Authority and Poseidon Water, the owner/developer of the facility.

In March 2016, water from the Carlsbad plant was certified by the State Water Resources Control Board as “drought-resilient,” reducing the regional impacts of emergency water-use mandates the state imposed in June 2015.  In April, the facility was honored with a Global Water Award as the Desalination Plant of the Year for 2016 by Global Water Intelligence, publisher of periodicals for the international water industry. And in June, the public-private partnership between the Water Authority and Poseidon, the owner/operator of the Plant was awarded the highest honor by the San Diego County Taxpayers Association for “stretching taxpayer dollars through cooperation between the public and private sectors.”

Explain the need for the plant. What challenges does it solve for the local community?

From the earliest recorded history in San Diego County, securing a safe and reliable water supply has been a central challenge due to the region’s semi-arid climate and limited natural water supplies. The region has few major aquifers and just 10 inches of rain fall in the average year at the official weather station at Lindbergh Field. In fact, 1946 was the last year local water supplies were sufficient to meet local water needs.

bg_heroAn additional challenge is that San Diego County is at the end of the imported water supply network, which delivers water from the Colorado River and the Sacramento-San Joaquin Bay-Delta. In 1991, the San Diego region relied on the Metropolitan Water District of Southern California for 95 percent of its supplies. However, severe drought conditions that year led MWD to reduce San Diego County’s water supplies by 31 percent. Stung by the drought and over-reliance on a single supplier, the Water Authority’s Board of Directors laid out a vision for a diversified water supply portfolio that would help the San Diego region thrive even in dry years.

Of course, water conservation was the first step, and per capita potable water use in the region has dropped nearly 40 percent between 1990 and 2015. The Water Authority is a leader in sponsoring conservation legislation (including the landmark bill that required ultra low-flush toilets statewide) and developing innovative, hands-on programs to promote WaterSmart landscapes as the new normal.

As the agency promoted conservation, it started negotiations with Imperial Irrigation District to transfer water conserved in the Imperial Valley to the San Diego region. These negotiations became critical components of the historic 2003 Colorado River Quantification Settlement Agreement, which included the largest ag-to-urban conservation-and-transfer program in the country and helped to reduce California’s over-reliance on the Colorado River. With these new, highly reliable and independent supplies secured, the Water Authority began looking to the vast Pacific Ocean for another major piece of its water supply portfolio.

How long was the process to construct the plant, from the idea’s inception to completion?

The idea for a commercial-scale seawater desalination plant on the San Diego County coastline emerged in the early 1990s as a result of advances in desalination technology, but it took decades of study, planning and project development for a specific project to gain the necessary traction. After several concepts failed to materialize, the Water Authority and a private developer, Poseidon Water, began negotiations to develop the Carlsbad Desalination Plant that resulted in a Water Purchase Agreement in 2012. The agreement protects ratepayers by shifting appropriate construction and operational risks to Poseidon, and it provided Poseidon with the certainty that it needed to attract investors. Financing was secured in late 2012, and commercial operations began three years later.


What are the environmentally-responsible aspects of the plant?

The Carlsbad plant meets some of the strictest environmental regulations in the world, designed by the California Coastal Commission and other agencies to protect sea life, water quality, and other resources. And, the plant uses energy-recovery devices that reduce overall energy consumption of the reverse osmosis process by 46 percent and carbon emissions by 42,000 metric tons annually.

Poseidon’s Climate Action Plan calls for the plant to be net carbon neutral over 30 years through the purchase of carbon offsets and energy recovery technology. Poseidon also is restoring 66 acres of wetlands in San Diego Bay. That project involves excavating and grading a former salt production pond to create a mosaic of coastal habitats beneficial for a variety of fish and bird species. In addition, Poseidon is preserving the 400-acre Agua Hedionda Lagoon by assuming responsibility for the continued stewardship of the lagoon and restoration of 37 acres of wetland habitat.

What were the biggest challenges you faced with making the plant a reality? How did you solve those challenges?

Poseidon and the Water Authority faced several challenges in making the plant a reality:

  1. Regulatory: Poseidon, the Water Authority and stakeholders worked for six years to secure permits for the plant from the California Coastal Commission, the San Diego Regional Water Quality Control Board, the state’s Department of Health Services, the State Water Resources Control Board, and the City of Carlsbad.
  2. Legal: Environmental groups filed 14 lawsuits against the plant, and none of them were successful. Poseidon successfully defended the project each time.
  3. Community: The 10-mile conveyance pipeline that delivers water from the plant to the Water Authority’s aqueduct system traverses business parks and neighborhoods. Construction posed significant challenges to businesses and residents in Carlsbad, Vista and San Marcos. Prior to construction, Poseidon and the Water Authority began talking with neighbors about the impacts. During construction, Poseidon held informational meetings in neighborhoods, kept local elected officials apprised of progress and worked with staff from each of the cities to reduce traffic and other impacts. Another potential community challenge was the cost of the desalinated water, which is about twice the cost of treated imported water from MWD. The Water Authority worked with Poseidon to educate the public about the need for a more reliable water supply, showing that it would cost typical homeowners just $5 a month and over the long-term would be less expensive than imported water.

San Diego Mayor Kevin Faulconer refers to the desalination plant as a “game-changer” for the region. What makes it so?

The desalination plant changed the game by tapping the ocean on a scale never done before in the Americas. While desalination may not be the right strategy for every community, it’s now clear that it is a viable option for coastal communities in need of improved water supply sufficiency.

What can attendees of the plant’s pre-conference tour look forward to experiencing?

Tour stops include secondary pretreatment facility, the reverse osmosis building, and the product water tank. Attendees also can sample desalinated seawater.

Are there any other innovative projects on the horizon for the Water Authority?

Yes! Innovation is at the heart of how the Water Authority operates, builds and maintains the region’s water supply system. For instance, the Water Authority’s Aqueduct Protection Program uses state-of-the-art technology such as magnetic flux leakage detection to identify necessary repairs. When sections of pipe need repair, the Water Authority installs new steel liners through small portals instead of digging out old sections of pipe and replacing them. This approach reduces costs and impacts to neighbors and the environment, while extending the useful life of the pipeline by 75 years or more.

The Water Authority also supports the development of potable water reuse efforts across the region as the next major increment of local supply. For instance, the agency sponsored state Senate Bill 322, signed by Gov. Jerry Brown in October 2013, to expedite a transparent and rigorous scientific assessment of potable reuse as a potential water source. In addition, the Water Authority supported a successful application from the WateReuse Research Foundation for $2.1 million from Proposition 84 to fund a potable reuse study at the City of San Diego’s demonstration facility.

The Water Authority is also active on the energy front. For instance, we are also partnering with the City of San Diego to study the feasibility of building a new pumped storage project to generate up to 500 megawatts of clean, hydroelectric energy. We also are preparing to install floating solar panels on a reservoir (to generate electricity while reducing evaporation) and install large batteries at two facilities to store energy during peak solar production for later use – all part of our commitment to innovation.