Tides raise concerns over proposed Poseidon desalination plant

An official with the environmental nonprofit Orange County Coastkeeper said recently that the high tides over Christmas weekend spelled potential trouble for a proposed desalination plant in Huntington Beach.

Ray Hiemstra, associate director of Coastkeeper, said the string of king tides was a possible preview of what tides near the AES natural-gas power plant, where Poseidon Water looks to build its desalination facility, would look like should the sea level rise several feet.

“The tides that we saw last weekend are an example of what we’re going to be looking at in the future,” Hiemstra said on Dec. 30. “When we see something like we saw last week, that’s going to be a normal day in 50 to 100 years. Throw in big waves or a storm on top of that, we’re going to have some real interesting situations.”

During that weekend, tides were about 6.8 feet tall but produced no flooding in the area, Huntington Beach Marine Safety Lt. Claude Panis said.

In 2009, the nonprofit Pacific Institute published a comprehensive study on sea-level rise for the state and concluded that several power plants along the coast, including AES’s facility, would be vulnerable to a 100-year flood, which could increase the sea level about five feet.

A 100-year flood is a term used to describe a flood that has a 1% likelihood of occurring in any year, according to the United States Geological Survey.

Heather Cooley, water program director for the Pacific Institute, said she believes the increased sea level would prompt Poseidon to build additional structures to protect its desalination facility from any flooding. She added that it could also negatively affect how the plant’s intake system works.

“You not only have rising seas, but you have changes in the dynamics,” she said. “So there could be changes in erosion patterns and [they could] create problems for existing infrastructure, especially if it’s not designed to accommodate these changes.”

Hiemstra said that billion-dollar projects like Poseidon’s should not be built in an area that is already prone to flooding. He suggested that the project be moved to another location, possibly Doheny State Beach.

However, an official for Poseidon said the 12-acre plot will be unaffected by sea-level rise during the desalination plant’s 50-year operation cycle. Vice President Scott Maloni wrote in an email that sea-level rise does not pose a risk to the facility.

“The [California] Coastal Commission has adopted a sea-level rise guide document,” Maloni wrote. “Using this guidance document, we have applied the [Coastal Commission] staff’s worst-case sea-level rise estimates to our analysis. The worst-case sea-level rise projection in the year 2070 is 3.5 feet [mean sea level]. The desalination project current sits at 9 to 14 feet [mean sea level], so 3.5 feet of sea level rise doesn’t pose a risk at this time.”

Maloni said during a phone interview Dec. 30 that the company in 2013 submitted a plan to the Coastal Commission stating that it would design the facility to withstand the forces of a tsunami and elevate the height of the land around the building.

Maloni wrote that the California Energy Commission approved AES’s renovation project in 2014. According to the commission’s final decision, the project is “not susceptible to flooding, even if sea-level rise were to occur.”

“The Coastal Act specifically states that new development must minimize hazard risks to life and property and assure structural stability,” he wrote. “Worst-case sea-level rise and other hazards do not pose a risk to life and property or the plant’s structural stability.”