O.C. Wetlands Restoration May Have a Downside

The recent restoration of the Bolsa Chica wetlands may be killing off a grove of eucalyptus trees that appears to be under attack by seawater that has been allowed to flow back into a far corner of the marshlands.

The stand of trees is in the northern lowlands of Bolsa Chica, where ocean water from nearby Huntington Harbour has been permitted to pour back in but isn’t properly flowing back out with the tide.

The seepage of seawater is apparently unrelated to -- and physically separated from -- the inlet recently cut from the ocean to the wetlands that replenished a huge portion of the marshlands with salt water for the first time in more than 100 years.

Dozens of eucalyptus, which were healthy several months ago, are now dead or dying in and near the Bolsa Pocket, a 42-acre area in the northeast corner of the wetlands.

Environmental activist Mark Bixby said he first noted the problem in early summer after restoration officials let ocean water back into the Pocket.

“It was supposed to be a ‘muted tidal area,’ ” Bixby said. “But now it’s a stagnant pond. There’s water in there all the time.”

He said he hoped federal restoration officials would install an underground barrier for the Pocket to protect other trees. Such an effort was undertaken to protect other areas near the Wintersburg Channel, which runs alongside the wetlands.

Biologists hired by Hearthside Homes, which is building more than 350 bluff-top homes on the mesa above Bolsa Chica, agree that seawater intrusion is probably the cause of the tree deaths, said Ed Mountford, a Hearthside vice president.

“This doesn’t affect us because it’s not on our property,” Mountford said. “It’s state property below ours, and when we were made aware of the situation, we wanted to make sure that the seawater doesn’t migrate underground too far.”

Federal officials don’t deny that more water than expected has filled the Pocket. But they add that there is no “solid evidence” that points to the restoration work as the cause of the dead and dying trees.

In the affected area, the soggy soil has caused trees to lean over and die as their roots are exposed. Their leaves are brown instead of their natural green hue, Bixby said.

“There is some accuracy with [the assertion of] the Pocket not performing as expected,” said Robert Hoffman, a National Marine Fisheries Service biologist who is on the restoration project’s steering committee. “But there were dead trees in that area before the restoration. We would have to look at photographs, before and after,” to make an assessment. “Those trees were stressed before our project started.”

The groundwater level in the wetlands is high to begin with, Hoffman said.

Homes that back up to the main wetlands have had backyards flooded during winter storms, which prompted federal restoration officials to install a protective water barrier 30 feet deep in some areas, Hoffman said.

“Our charge was not to worsen the groundwater situation,” he said. “There’s water moving out from inland and water moving in from the ocean in that area. There was, during preparation, a legitimate concern about this.”

Hoffman said he had not visited the eucalyptus grove. But he said restoration officials intended to assess the area and “fix it up,” which means digging and removing sediment that is blocking the water from flowing back out of the Pocket.

In addition, they can adjust the flow of ocean water with tide gates near Warner Avenue, Hoffman said. “It’s tough to get things to work exactly right the first time,” he said. “Things don’t always work exactly to plan.”

Bixby says that may not be enough. He said the eucalyptus stand also serves as habitat for birds such as the white-tailed kites and the endangered California gnatcatcher.

“I wonder what environmental agencies and others would think when they hear that a decision made by federal officials may have destroyed the habitat for sensitive species,” he said.

The recent restoration efforts capped a three-year, $147-million state project to reclaim a portion of the 880-acre wetlands that, for years, had been used for oil drilling.

Once slated to be developed into an oceanfront housing tract, the wetlands were spared by environmentalists who lobbied for both money and political support to restore the marshland. Although fresh water -- mostly urban runoff carried in flood channels -- has long drained into the marshland, ocean water had, until Aug. 24, been blocked from reaching the area.

It was the most significant and visible step in the long, ambitious effort to revive the degraded wetlands.

The flow of ocean water -- cut off by members of a duck hunting club in 1899 -- is expected to help transform the saltwater marshes into a major wildlife sanctuary.

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david.reyes@latimes.com