Keeping Carpinteria Salt Marsh connected to the tides

Carpinteria Prop. 84
Carpinteria Salt Marsh is one of the largest tidal wetlands remaining along the Central Coast. To reach the eastern portion of the marsh (to the right in this image), water must travel through culverts beneath the access road. Image: courtesy Andy Brooks

By Kathleen Wong, UC Natural Reserve System

Carpinteria Salt Marsh is a world defined by mud, floods, and salt. Ocean brine inundates its twisting channels twice a day, fostering plants that can tolerate salty leaves and perpetually wet feet. The long-legged birds that nest and forage here dine on snails and fishes living within its twisting channels.

Seawater is the lifeblood of this UC Natural Reserve, one of the largest remaining estuarine wetlands on the Central Coast. Much the way the heart pumps blood through the body, the ebb and flow of the tides circulates water through marsh waterway. Without regular inundation by saltwater, Carpinteria Salt Marsh Reserve “would dry out, become choked with weeds, and no longer would function as a tidal wetland,” says Andy Brooks, reserve director and a UC Santa Barbara marine biologist.

The marsh has faced more than its fair share of survival challenges over the past seventy years. A history of petroleum production, then a raging wildfire and a deadly mudslide, nearly managed to disconnect a third of the 230-acre wetland from the ocean. Today, however, seawater flows through the marsh more vigorously than it has in decades. This achievement is thanks to both the dedication of its managers and the generosity of the people of California.

Carpinteria Prop. 84
Multiple culverts along the march access road wore out over time and needed to be replaced to ensure seawater reached the eastern portion (Basin II) of Carpinteria Salt Marsh Reserve. Prop. 84 bond funds were instrumental in funding the replacement of the culverts. Image: courtesy Andy Brooks

Impacts from oil exploration

Carpinteria Salt Marsh’s circulation problems stem from a road built into the tidal wetland in 1945, more than 30 years before the reserve was established. An oil company had drilled an exploratory well into the wetland, and used the road to service the derrick. While the well never went into long-term production and the derrick was removed, the road remained. Resembling a dirt levee ten feet high, 40 feet wide, and a third of a mile long, the road divides the western basin of the wetland, which includes the channel linking the salt marsh to the ocean, from the eastern basin. A series of metal pipes along the length of the road allows water to flow between the basins.

The last 70 years, however, have taken a toll on these ersatz culverts. “The pipes were rusted out, and the tops were collapsing. We were worried a complete collapse would restrict water from moving into the eastern basin, and take out the road, which serves as our main access route for classes and researchers,” Brooks says.

The culverts have needed replacing at least since 1997, when they were listed as a repair priority in the reserve’s management plan. But the cost to replace the humble structures was well beyond the reserve’s modest annual operating budget. “It would have taken us 30 years to save enough money,” Brooks says.

Carpinteria Prop. 84
Essentially metal pipes, the marsh culverts were in dire shape after 75 years of use. Views from the side (left) and overhead (right) show the top of one culvert pipe had rusted through and and threatened to collapse under the weight of the dirt piled above it to form the access road. Images: Andy Brooks

The portion of the marsh in the reserve also suffered from inadequate fencing. Years of erosion and digging animals had left gaps of up to a foot between the bottom of the boundary fences and the ground. Feral cats, skunks, raccoons, and foxes slinking beneath the fence eventually decimated the local population of endangered Ridgway’s rails.

Marine shell mountains

It took two strokes of luck more than a decade apart to bring these critical repairs within reach. The first was a drama playing out just a few miles south of the marsh, in the oil fields of the Santa Barbara Channel.

In the 1990s, the Chevron oil company began decommissioning the drilling platforms it owned in the channel. Its leases required complete removal of the rigs. However, decades of drilling activity and maintenance involving scraping off the oysters and mussels that had settled on the underwater beams and columns had produced a problem: “a mountain of drilling debris and shells up to 25 feet high around the entire perimeter of the oil platform,” Brooks says. To make matters worse, the shell piles were cemented together by other marine organisms. Removing them would require using explosives that could release toxic drilling byproducts entombed with the shells into the ecosystem.

Carpinteria Prop. 84
This culvert by the head of the marsh access road was not only collapsing from above but was also partially blocked by fallen concrete debris. Image: Andy Brooks

Funding secured from offshore battles

Several environmental NGOs took Chevron to court in an attempt to force the removal of the shell mounds. In the meantime, Chevron seized on the possibility of funding restoration at Carpinteria Salt Marsh as mitigation for leaving the mounds in place. The project would involve removing sand from the mouth of the marsh to restore deepwater habitat—work already indicated as a priority in the reserve’s management plan. The dredging would increase nursery habitat for halibut. Dredging the sand would be apt mitigation for leaving the shell mounds in place since the formations would disrupt commercial bottom trawling for halibut.

The fact that the dredging had already secured government agency approvals to proceed “meant that the reserve had a permitted, shovel-ready mitigation project that just needed funding. Chevron offered to provide that funding should the shell mounds be allowed to remain on the sea floor.”

To guard against the possibility of the NRS finding another source of funding for the dredging, the company contributed $100,000 to Carpinteria Salt Marsh Reserve restore the culverts in exchange for ten years of the right of first refusal for the restoration project.

Carpinteria Prop. 84
Piled in a heap after removal, the old culverts were rusted through and quite fragile. Image: Andy Brooks

At about this same time, the marsh experienced its second stroke of luck. In 2006, California voters made up to $20 million in bond funding available for NRS land acquisition and facilities improvements as part of Proposition 84. The Chevron donation was enough for the reserve to meet the required 1:1 match for all requested bond funds, giving the reserve the $200,000 needed to repair the culverts.

Debris flow disaster

Brooks and colleagues at UC Santa Barbara were poised to start the project in January of 2018. But days before the construction bids came in, disaster struck. Heavy rains on the night of January 8 saturated the Santa Ynez Mountains. Soils denuded of vegetation by the Thomas Fire the previous autumn thundered downhill, burying the town of Montecito in mud. The two creeks that drain into the marsh delivered tons more debris into the channels that feed into the Carpinteria Salt Marsh, clogging them with 30-foot-long trees, boulders, trash, and mud.

“The contractors we were hoping would bid on the project all said, we’ve gotta go. Everyone is now digging out Montecito,” Brooks says. At that point, their disappearance was almost moot since the culverts were unreachable beneath several feet of mud and debris.

Carpinteria Prop. 84
New plastic culvert pipe being installed across the marsh access road. Image: Andy Brooks

The Santa Barbara County launched an all-out effort to clear the main channels. To reduce the risk of creek flooding in the town of Carpinteria, they needed to restore the ability of water from Franklin and Santa Monica creeks to flow through the marsh and into the Pacific. The scale of the task was jaw-dropping.

“Dump trucks were coming out of there every three to five minutes, seven days a week, for three to four weeks,” Brooks says. He calculates that the amount of debris extracted from the marsh alone would have filled a line of dumpsters stretching from downtown Santa Barbara all the way to Ventura, a distance of about 30 miles.

Work to clear the main channels—which happily included dredging much of the sand reserve staff had wanted removed from the ocean outlet of the marsh—lasted through spring. But environmental protections meant work on the culvert project couldn’t commence until the next fall. “Because we have listed bird species nesting here in summer, we could only do project work between September and March.” Brooks says.

Carpinteria Prop. 84
The new culverts permit can accommodate more water, and have enabled increased tidal flows to the eastern basin of Carpinteria Salt Marsh Reserve. Image: Andy Brooks

As the smaller tidal channels alongside the access road began opening up, it became clear that the mudflow had destroyed yet another, previously sound culvert. The Wildlife Conservation Board, which administers Prop. 84 grant funds, approved more money to repair this sixth culvert.

Reopening marsh arteries

Work on the project finally commenced February 2019. The contractor dug out the soil above the rusted old culverts, replaced old pipes with new plastic versions two feet in diameter, and re-surfaced the roadway. The construction portion of the project took a total of four days to complete. Native plants grown from cuttings collected in the marsh are being used to revegetate the tiny amount of habitat disturbed.

“The culverts have improved the habitat,” Brooks says. “Now we’re getting more water into the basin, so the water reaches tidal heights not seen in past.”

Carpinteria Prop. 84
Fence repairs done as match for culvert improvements funded by Prop. 84 are a major step toward returning endangered Ridgway’s rails to Carpinteria Salt Marsh Reserve. Image: Joanna Gilkeson/USFS

As additional match for the bond money, UC Santa Barbara paid to extend the reserve fence to the ground. Subsequent efforts to remove predators, plus the installation of floating nesting platforms, and the restoration of the birds’ preferred bulrush habitat, has laid the groundwork to return Ridgway’s rails to the marsh.

The last component of the project will add picnic tables to a flat area at the end of the road. “Students in classes can sit, take notes, and see the mouth of the marsh and the main channel” from those tables, Brooks says.

Brooks says having the project completed feels great and has been a shot in the arm for the health of the marsh. “It’s too bad that it took 23 years to finish, but sometimes you just need to go with the flow and take things one day—or tide—at a time.”

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