A $100 million project to improve a San Diego North County coastal lagoon broke ground on Wednesday. The project will do more than restore the natural habitat; it will prepare the lagoon for sea level rise.
The San Elijo Lagoon is an oasis of calm between Encinitas and Solana Beach. It is home to many species of fish and birds, including some that are endangered, like the Ridgway Rail. About seven miles of public walking trails wind through 1,000 acres of habitat.
This year, the lagoon is the site of heavy construction as Caltrans rebuilds bridges to widen Interstate 5 and add a second track to the railway line. But thanks to environmental mitigation money in Caltrans' North Coast Corridor project, a major investment is now underway to improve the lagoon’s health.
The lagoon improvements are aimed at improving water flow.
“A lot of lagoons in North County have the same issue," said Doug Gibson, Executive director with the San Elijo Lagoon Conservancy. “Early transportation projects bisected these lagoons: the railroad, then Highway 101, then Interstate 5. So what that did with these lagoons is it cut off how water flows through them. That increases bacteria. So that decreasing water quality affects the fish species that can survive in the lagoon. That affects the birds and everyone else, so it’s a cascading effect.”
Caltrans new bridges will be designed to allow easier tidal flow.
Decades ago, Gibson said, sewage ran freely into the lagoons before filtering out to sea. After years of research, the plan is now to dredge the lagoon, open up the tidal flow and bury the nutrient-rich sediments.
A 40-foot-deep pit will be dug in the western end of the lagoon, and the clean sand from there will be spread on local beaches. Then lagoon sediment from further east will be moved into the pit and covered with fresh sand.
One aspect of the plan is to create contoured basins and islands, so when sea level rise hits the coast in coming decades, the marshy wetlands won't be wiped out.
“The problem is we have a lot of lagoons that are bowl shaped,” Gibson said. "So as sea level rises, that habitat becomes that small ring around the bath tub. So we know that species are going to be impacted and we’re trying to give them the best chance that we can in the future."
People who live in Encinitas will also benefit from the project — a new footbridge across the lagoon will connect them with trails on the south side that lead inland as far as Rancho Santa Fe
Many agencies gathered for the groundbreaking ceremony, which was held on the observation deck of the San Elijo Lagoon Nature Center. Caltrans District Director Laurie Berman said the work Caltrans does is no longer confined to building roads but also enhances the surrounding communities.
The work on the lagoon, and construction on the bridges across it, is projected to be complete by 2021.
