With the passing of winter storm surges, it’s time for spring-cleaning at the mouth of San Elijo Lagoon. Earthmovers will be at the Cardiff State Beach lagoon inlet to dredge and disperse accumulated sand from Monday, June 2 through Friday, June 6. This annual inlet excavation reconnects San Elijo Lagoon to the Pacific Ocean. Construction equipment begins to arrive May 29. San Elijo Lagoon Conservancy (SELC) is the organization overseeing the process.
“The lagoon’s inlet and channel appears open but is 80 percent blocked,” said Doug Gibson, executive director and principal scientist at SELC. “At present, tidal circulation is significantly muted as a result of sand buildup in three of four bays under the coast highway bridge and in the main channel.”
The small opening, just south of San Elijo State Beach Campground, is the lagoon's only access to the Pacific Ocean. Left unattended, it could remain closed much of the year from buildup of sand transported by high incoming tides and surf. The cooler winter and spring weather helps keep oxygen levels in the lagoon in the safe zone, but as temperatures rise in late spring and the demand for oxygen increases, an inlet operation is conducted. The inlet excavation is also scheduled so as not to interfere with grunion spawning.
Efforts over the past decade have improved tidal circulation and water quality, with significant ecological and recreational benefits. This delicate process is designed to prevent stagnation of the shallow-body ecosystem, which improves habitat for all plants and animals that reside in the lagoon. Several fish populations depend on the lagoon as a nursery. Without a constant connection to the ocean, future generations will not thrive. Stagnant water also can trigger a rise in mosquito populations, which is why County of San Diego’s Vector Control Program covers part of the project’s costs.
Inlet excavation involves the task of relocating approximately 25,000 cubic yards of sand out of the lagoon inlet, and back on to the beach. Sand removed from the tidal channel is deposited south onto Cardiff State Beach.
It has been decades since San Elijo Lagoon was naturally connected to the Pacific Ocean. The first bridge and berm crossing the lagoon was constructed in 1887 for Santa Fe Railroad, followed by Pacific Coast Highway in 1891, and the completion of Interstate 5 in 1965, which divided the wetland in half. This "partitioning" of the lagoon alters flows for both fresh and saltwater, leading to accelerated sediment deposition, reduced water quality, and a reduction in native estuarine habitats due to increased runoff from development upstream.
Dredging is a visual event, like watching giant “beach toys” sculpt the opening of the lagoon. The inlet excavation costs approximately $100,000 and is conducted through the support of California Coastal Conservancy, U.S. Fish & Wildlife Service, and County of San Diego Vector Control Program.
—San Elijo Lagoon Ecological Reserve