Sea-level rise could wipe out precious habitat at Huntington Beach’s Bolsa Chica wetlands and eventually flood neighborhoods just east of the ecological reserve, according to a new study three years in the making.

But ongoing estuary maintenance and continued improvements — including new levees and elevating some existing wetlands — would preserve and improve existing wildlife ecosystems. Such work also would bolster the buffer that the wetlands provide for adjacent homes against rising seas, the study found.

Because portions of the 1,400-acre wetlands have subsided as a result of decades of oil drilling, there is growing urgency to take action — and the opportunity to provide a model for the state’s other remaining wetlands.

Adaptation efforts at Bolsa Chica “have broad ramifications in that the site provides early insight into issues other coastal wetland systems will face in coming decades,” according to the 462-page study, paid for with $282,000 of Proposition 1 water bond money.

Southern California has lost 62% of its wetlands since the 19th century, with the Orange-Los Angeles county region losing more than 90% — mostly to development and urbanization.

That’s resulted in the loss of habitat crucial to many species that are now threatened, endangered and of special concern — 23 of which reside or make migratory stops at Bolsa Chica. In addition to providing wildlife habitat and a buffer to homes, wetlands also absorb carbon dioxide from the atmosphere.

But wildlife is the main reason $151 million was spent on the Bolsa Chica restoration completed in 2006. The project created a new ocean inlet at the south end of the wetlands that has proved a boon to both the variety and total population of wildlife in the reserve.

Much of that habitat will be lost without ongoing improvements, the report said. And while the focus of the report’s recommendations is on wildlife, humans living nearby also would benefit from the reduced risk of flooding.

“Bolsa Chica acts as a giant sponge,” said Kim Kolpin, executive director of the Bolsa Chica Land Trust. “How good a job we do will determine its resiliency. A healthy wetlands means a healthy barrier from sea-level rise.”

The land trust wrote the grant application that resulted in the Prop. 1 funding, and commissioned the study in coordination with government agencies involved with the wetlands. The Bolsa Chica Steering Committee, composed of two state and three federal agencies, will determine the next steps in maintenance and improvements.

“It’s in everyone’s best interest to have Bolsa Chica thriving, so it can best absorb the impact of climate change and sea-level rise,” Kolpin said.

Cinderella story

Without human intervention, coastal wetlands can be dynamic and unpredictable. The location of river mouths and ocean inlets as well as lagoons and tidal basins can shift from season to season, depending on how the storms affect associated rivers and ocean fronts.

But such year-to-year changes often don’t bode well for man’s plans for ports, roads and buildings.  As a result, urbanization has meant filling in or otherwise constricting many of the state’s wetlands.

Probably the first significant human impact on the Bolsa Chica wetlands came with the establishment of the Bolsa Chica Gun Club in 1899, which included a two-story building and damming of a portion of the wetlands to facilitate duck hunting.

Subsequent decades saw the construction of Pacific Coast Highway and a coastal trolley line, as well as extensive oil drilling and construction of a stormwater channel, each of which reduced the dynamic shifting of the wetlands and impinged wildlife.

In the 1970s, developers proposed turning the wetlands into a marina surrounded by 5,000 homes. That marked a turning point, as environmentalists and residents rallied against the development in order to preserve the natural wetlands.

In 2000, a state Coastal Commission determination led to just 379 homes being built in an elevated corner of the broader wetlands area.

“Throughout most of recorded world history, wetlands were regarded as wastelands and problem areas to be drained and filled,” said the 2018 report “Wetlands on the Edge,” commissioned by a coalition of federal and state environmental agencies.

“(But) a shift in the understanding and appreciation for these habitats has occurred, and wetlands are now valued worldwide for the many benefits they provide.”

Bolsa Chica, a state-owned ecological reserve, is a prime example. The 2006 ocean inlet construction and associated improvements — then the largest wetlands project on the West Coast — are testament to how such estuaries have become an asset to improve upon.

Bolsa Chica now hosts more than 300 feathered resident and migratory species, many of which lay their eggs in the wetlands. All told, there are an estimated 900 different species in the wetlands, including turtles, rays and octopi.

Kolpin said the wetlands is the healthiest it’s been since the 1940s, when oil drilling peaked. However, she added that the coming effects of sea-level rise are already being seen, as king tides have encroached on  the wetlands’ two nesting islands.

Those sandy islands — vital for the endangered least tern — and wetlands areas popular with other shorebirds are among Bolsa Chica habitat in most immediate jeopardy from sea-level rise.

The islands are just part of ongoing challenges. The wetlands has become a manmade reconstruction of wildlife, lacking some historical natural features that allowed it to be self sustaining and now requiring continued maintenance.

“The wetlands at Bolsa Chica never looked the way they do today,” Kolpin said. “The pieces never fit the way they do now.”

The biggest current maintenance issue is dredging of the ocean inlet, necessary to maintain the intertidal flow. The trust fund set up for that $1 million annual expense has been exhausted, requiring new budget approvals each cycle and no guarantee the money will be available from year to year.

The new study looked at alternatives to dredging and found none that were feasible.

Hope for future

What is known as Bolsa Chica’s full tidal basin — the intertidal lagoon created by the inlet — has exceeded expectations in terms of preserving wildlife habitat. But other aspects of the wetlands, particularly the muted tidal basin that fronts the homes to the east, have been less successful.

The new study, completed by the environmental engineering firm Anchor QEA, examines current and future challenges — and viable solutions — for the reserve.

In addition to ongoing dredging, pumping water out of the muted tidal basin will need to be continued because tidal action flushes water into the basin but without human help and, once there, that water remains stagnant.

Levees and ground elevation are part of the hydrological recommendations to both improve habitat in the muted tidal basin and adapt to sea-level rise.

The proposals also address the groundwater table beneath the nearby homes which, without changes to the wetlands’ hydrology, is expected to come closer to the surface as sea-level rise obstructs its westward migration.

That’s in addition to the ocean’s elevated levels washing directly over the wetlands and into that neighborhood.

“By the turn of the century, the entire (wetlands) site and surrounding residential neighborhood will likely become inundated without some type of intervention,” the study concluded.

Study recommendations are broken into short-, mid- and long-term strategies. Not addressed is funding, although Kolpin expressed optimism and pointed to the Gov. Gavin Newsom’s “30×30” executive order as one reason for hope.

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Oil wells in Bolsa Chica reserve could jeopardize wetlands

The order calls for the state to conserve 30% of its land and coastal waters by 2030, with wetlands restoration a highlighted priority.

“It’s a large state with a lot of challenges to natural resources,” she said. “Wildfires and drought are huge. You’re going to have a lot of money poured into that, but habitats are important too.”

Kolpin, who’s been fighting for the preservation and restoration of the wetlands for more than 20 years, is hardly new to such challenges.

“Bolsa Chica,” she said, “has never been cheap or easy.”