Notorious lagoon in line for $2.8M upgrade, fixes
Six decades after harbor construction caused sands to shift, project aims to reduce flooding, fish habitat loss, drownings
SANTA CRUZ » For more than a century, the mouth of the San Lorenzo River had been a place for locals to swim, fish and relax before two jetties forever changed the river.
Since the jetties were built in the early ’60s during construction of the Santa Cruz Small Craft Harbor, however, sand has accumulated at the river mouth and created a lagoon on Santa Cruz’s iconic Main Beach near the Beach Boardwalk. When the water gets too high, the boardwalk’s basement floods and the lagoon breaches, purging fish and creating unsafe currents for swimmers and other beachgoers.
After decades of Band-Aid solutions and debating what to do about the problem, the city of Santa Cruz will begin work later this year on a $2.8 million project to stabilize the water level of the lagoon by creating a low-flow outlet when the water begins to rise.
“The project is a flood control project, public safety project and habitat protection project all rolled up into one, said Scott Ruble, principal analyst with the city’s Public Works Department.
The undertaking is aimed at managing the shifting sands that once drifted down-shore but now get trapped by the west jetty, causing sand to widen Seabright Beach and accumulate near the Boardwalk.
“The upside was we have these big, beautiful broad beaches that we all enjoy and that are part of our tourist draw,” Ruble said. “But the downside is it changed natural conditions.”
Up and down the California coast, beaches near harbors have suffered similar ills stemming from construction of jetties designed to protect harbors from Pacific waves. So Santa Cruz’s first-of-its-kind project could eventually serve as an environmental model for other California cities and towns.
In many ways, the San Lorenzo River and San Lorenzo Lagoon are inseparable. The river ends in the lagoon during the dry season when there isn’t enough water to prevent a sandbar from forming. And flood control levees along the river determine the course of water through the city center.
“The river is at the heart of the city,” said project consultant Gary Griggs, a professor of earth and planetary sciences at UC Santa Cruz. “And it’s been a big factor for well over a century as far as how the city is built, why it’s been flooded, how it’s rebuilt.”
During the dry summer months, the river is cut off from the ocean by a sandbar that connects Seabright and Main beaches, causing the lagoon to form. A mix of river and ocean water, the lagoon becomes brackish, provid
ing an ideal hangout for federally threatened steelhead trout and endangered tidewater gobies, a tiny fish that constructs burrows in the sand.
But when the fall and winter rains come, the lagoon’s water level rises, backs up the river and drenches the Boardwalk basement, used to store equipment.
Kris Reyes, longtime spokesman for the Santa Cruz Seaside Co., the Boardwalk’s owner, said the company has spent upward of $250,000 on pumps and waterproofing during the last decade to battle the floodwaters. And the city spends roughly $1,000 every time it needs to dig a trench to release lagoon water into the ocean — which becomes necessary as often as a dozen times each year.
Reyes said he’s excited to see the city moving forward with a long-term solution.
“For many years, it wasn’t really managed at all,” Reyes said. “It was completely hands-off. And that was not a sustainable approach.”
And it created a hazardous situation.
Parents and their young children and other inexperienced swimmers often spend time in the lagoon because the water is relatively shallow, without any crashing waves. But the stagnant waters and high bacteria levels cause staph and hepatitis A infections.
The most significant threat, however, comes when lagoon waters break through to the ocean.
The breaches happen under two circumstances: One is a natural breach in which the water in the lagoon overtops the sandbar protecting the lagoon from the ocean. The second is an unnatural breach caused by people, either purposely or inadvertently.
Griggs said both residents and tourists often think swimming or wading in the lagoon is safe and that the currents won’t be strong. But that’s often not the case.
“What starts out as a little trickle can become a river at full force,” he said.
The lagoon has been breached by children digging tiny channels through the sandbar, which ultimately causes water to burst through the sandbar, requiring lifeguards to evacuate beachgoers, said Capt. Dara Herrick of the Santa Cruz Fire Department’s marine safety division.
Surfers occasionally breach the lagoon illegally to create better surf conditions temporarily. But according to the Public Works Department’s Ruble, the most common breach occurs when local residents who live upstream dig through the sandbar to release water into the ocean to try to prevent flooding upstream.
In May, a San Jose man and his two children were pulled from the ocean 200 yards off Main Beach after an unauthorized breach of unknown cause swept the family out to sea.
Hai Pham, 50, was found unconscious and later died in the hospital. One of the Santa Cruz Fire Department’s rescue swimmers was also hospitalized to recover from hypothermia and extreme exhaustion.
Whether the breach is natural or not, Herrick said, the release of the lagoon water is dangerous. “The conditions that you see now may not be the conditions that you see in five minutes, 10 minutes or half an hour,” she said.
The city also regularly cuts through the sandbar, but the water is released as public works employees and lifeguards are deployed to protect swimmers and other beachgoers.
Construction on a new culvert pipe is set to begin next summer or fall and take about three months to complete, Ruble said.
The pipe will rest underneath the water’s surface to create an outlet into the ocean so that the water level doesn’t go higher than 5 feet. The pipe will passively drain the lagoon, capturing the high salinity water so that dissolved oxygen increases and the temperature decreases — perfect conditions for the protected trout and gobies. Crews will also install two water intakes, both with fish screens.
Ruble and Griggs say they hope the project will show other cities how to create long-term solutions to the flooding, fish habitat loss and occasional drownings caused by jetties and other coastal construction.
“This,” Griggs said, “seems like a win-win for all three.”