SANTA CRUZ — After the San Lorenzo River naturally breached Friday, the city of Santa Cruz is urging beachgoers to recreate safely near the ever-shifting and potentially dangerous river lagoon.
“There’s been two natural breaches,” said Ryan Haley, assistant engineer with Santa Cruz Public Works. “We had a couple of wave events that shoaled it up for maybe about eight hours, so it didn’t build up so high. Then it started to trickle over the top and that’s how the natural breaching happens and that happened twice.”
According to a statement from the city, the Fire Department’s Marine Safety Division monitored the natural breach of the river mouth Friday. Wednesday morning, a contractor used a bulldozer to relocate the river mouth closer to San Lorenzo Point and build a sand berm to prevent the river from meandering northward.
“This will keep the river here, which will do a couple of things,” said Haley. “It will protect Main Beach from future meandering and it will help with the culvert repair when we pick that back up next month.”
While the sand is getting pushed around, the city asks that everyone stay away from the river mouth and surrounding area. Beachgoers should respect all posted signage and guidance from city workers because the conditions during a breach can create strong currents and hazardous situations that can result in injury or death.
At the river mouth Wednesday morning, Haley, who serves as the project manager for the San Lorenzo River lagoon culvert project, told the Sentinel that the crews are preparing to fix the culvert, which is meant to minimize the number of mechanical river breaches in the summer months, but was damaged during the intense January 2023 storms.
“During the storm, a piece of wood got in there and broke the valve and the flow was being restricted in the wrong direction,” said Haley. “Sand then built up inside the pipe and there is a plug of sand in there.”
The culvert consists of two intakes and an outflow pipe, and is intended to keep water levels at the river mouth around 5 feet, which is the level agreed upon by the environmental agencies working with the city. One intake pipe is at the 5 foot threshold and the other is placed below the surface of the lagoon. The culvert then removes the saline-heavy water back into the ocean, which is a boon for the wildlife as the brackish water increases the lagoon’s temperature and degrades the habitat.
Haley mentioned that the culvert repair has been delayed since last year because it takes a perfect storm of river and ocean conditions to allow for crews to clear the clogged pipe and make the fix. He said work should start in August.
“We are very hopeful that the whole system will be functional by mid to late August,” said Haley. “It could take a few more weeks because everything is so unpredictable. We’re fighting three different things. We’re fighting waves, river flow and the tides. Between those three things, we don’t have many opportunities to work on it.”
Haley said the culvert was engineered to take some abuse but not the barrage of bomb cyclones and intense wave action that occurred last year. With the potential for extreme weather events in mind, city workers will replace the current outflow valve with a different design that is intended not to cause a sand plug like its predecessor.
“It’s all been a learning process,” said Haley. “We ask that people bear with us. We are dealing with the same storms that destroyed the Aptos pier and the Capitola Wharf is still not open.”
According to Haley, the sand plug inside the culvert pipe is about 20 feet long and he and others at Public Works are still deciding on the best way to flush it out, whether with a fire hose or pump. Haley hopes that after the sand clog is cleared and the valve is replaced, the culvert should be operational into the future.
“The long-term maintenance will consist of digging out and opening valves, jetting this thing with a fire hose, if needed, and replacing valves if they’re broken in extreme weather,” said Haley. “Then, at the end of the summer, we’ll do one big breach and that’s how we expect things to go. And if it doesn’t and we have to adjust, we’ll keep adjusting. That’s what we do.”
For information about the culvert, visit cityofsantacruz.com.