Edison completes river excavation, sand replenishment in Del Mar

Southern California Edison finished its excavation of the mouth of the San Dieguito River this week, moving an estimated 16,000 cubic yards of sand onto the beach in Del Mar.

The two-week job is done every year or so to maintain tidal flushing of the San Dieguito wetlands, where Edison completed a four-year, $100 million restoration of about 150 acres in 2011 along the Del Mar Fairgrounds.

Nearly all of the sand removed in the past two weeks came from deposits that had accumulated over the past year or longer in the river channel at the edge of the lagoon just east of the Camino Del Mar bridge. Heavy equipment crews dug a trench in the sand beneath the low-lying bridge so that loaded dump trucks could drive underneath to reach the beach. The final step of the project was to refill the trench.

“We dredge the same portion of the lagoon to the same (depth) every year,” Edison project manager Jenny McGee said Monday, Nov. 21.

Maintaining the open lagoon allows fish from the ocean to enter the wetlands and lay their eggs, she said. It also preserves nesting sites for birds, many of which are rare or endangered.

“It’s creating a fish nursery and a bird habitat,” McGee said.

Most of San Diego County’s lagoons are dredged routinely to prevent stagnation and restore the tidal movements that support healthy saltwater wetlands.

Edison was required to restore the San Dieguito wetlands and maintain the open river mouth as part of a mitigation agreement approved in 2003 by the California Coastal Commission. The San Dieguito restoration is one of several mitigation projects the agency required of Edison to compensate for marine life such as small fish and larvae that were killed by the seawater intakes of the San Onofre Nuclear Generating Station.

Other mitigation projects required for SONGS included the white sea bass fish hatchery in the Agua Hedionda Lagoon at Carlsbad, and an artificial reef built to anchor a kelp forest off the coast of San Clemente.

The nuclear power plant ceased operations in 2013 and is being demolished. The distinctive twin domes are expected to come down in 2026.