Restoring Huichica Creek
A North Bay Creek thrives after Caltrans restores natural habitat during Bridge Replacement Project
By: Pedro Quintana
A North Bay creek ecosystem is thriving after Caltrans completed the State Route 121 Bridge Replacement project in 2022, making it easier for fish to navigate the creek and safer for motorists traveling on the Carneros Highway in Napa County.
The $13.9 million two-year project demolished the old Huichica Creek Bridge and built a new and improved bridge with no culverts, which would help create an easier channel for fish to access the creek.
Huichica Creek flows from the southern Mayacamas Mountains to Napa Slough, which empties into the Napa River.
The creek is known to be a spawning ground for Chinook Salmon and other species.
This was the most extensive fish passage restoration project in recent years for District 4, said Lauren Ross, environmental scientist for Caltrans District 4
Ross and a group of environmentalists were only permitted to work inside the creek bed from June through October. The creek restoration and bridge replacement project was a two-year project involving the relocation of species such as Chinook Salmon, California Red-Legged Frogs, Pond Turtles, and California Fresh Water Shrimp.
Ross’s team relocated more than a dozen Fresh Water Shrimp to another location.
Most of the species found in the creek are considered endangered by Federal and State agencies.
“It was really exciting because you don’t usually catch that many, and you usually don’t find that many, so it proved that this is a really important site for the shrimp,” Ross said.
After the species were relocated, crews got to work building habitats that would help protect the species and improve the ecological system in the North Bay.
The project created weirs, engineered stream bed material along with cobblestones to create creek bed with a two-and-a-half percent slope that allows fish to pass with minimal effort and enabling them to spawn.
Ross and her team installed California Freshwater Shrimp habitat elements such as re-wire logs and willow roots in the creek bank at specific elevations to provide refuge for freshwater shrimp during high flows.
“They can cling onto the logs or the roots of the willows that we planted on each side of the logs,” Ross said. “The habitat improvements will benefit all of those future-generation shrimp.”
The creek restoration included installing plants, woody materials, and redwood root wads, which were installed along the stretch of the project.
“It provides habitat for the fish during the higher flows where they can hide under it, use it as a refuge, and find a nook or cranny to rest when they’re moving upstream,” Ross said.
The bulk of the work that took the longest during the bridge replacement project was the work inside the creek bed.
Ross said this was one of the largest restoration projects, which was substantial for the many species who call Huichica Creek home.
“I was really excited to be a part of this project because this was rare for Caltrans because this project was primarily focused on improving habitat for listed species,” she said.
