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San Dieguito wetlands restoration enters the home stretch

The inlet is opened on the San Dieguito Lagoon restoration project.

Posted on June 12, 2024

The second phase of the San Dieguito Lagoon restoration reached a significant milestone last week.

On June 6, a collection of SANDAG and Caltrans engineers and biologists gathered to witness the active release of berm at the restoration project site, opening up the saltwater marsh inlet to the tidal flow. Rather than sending an epic torrent of water into the lagoon, an excavator simply moved some dirt aside and the water slowly began to trickle in.

Kim Smith, SANDAG senior regional planner, said while it may have appeared anticlimactic, it was an incredibly exciting moment for staff to see on a project about 12 years in the making.

“The goal is to get these wetlands to look like the San Dieguito Lagoon,” said Smith on site last week, with a nod to the west to the neighboring and flourishing tidal wetlands and salt marsh habitat done by Southern California Edison 10 years ago.

Water will flow through the new inlet as the construction continues in its final months of a three and a half year process, anticipated to be complete in September. Eventually water will flow nearly all the way to El Camino Real, stopping near the SDG&E utility corridor that runs through the site.

This restoration project will not only will not only improve the overall function and health of the lagoon ecosystem, it will benefit the wildlife species that call the lagoon and river valley home. Those include birds such as the endangered light-footed Ridgway’s rail and California least tern. Smith said already the Ridgway’s rails are beginning to visit the newly restored area and they are very vocal, making their distinctive clapping sounds.

Caltrans and SANDAG began construction on the $87 million restoration project in 2021 as a mitigation of the Interstate-5 widening. The project will convert approximately 84 acres of formerly degraded land and tomato fields into the refreshed tidal wetlands.

In total, the project will create 64 acres of tidal salt marsh and 15 acres of brackish wetlands, a mixture of saltwater and freshwater. There will also be an additional five acres of restored riparian habitat.

Caltrans and SANDAG staff view the opening from a berm in the new wetlands.

The 15 acres will serve as mitigation for the El Camino Real widening and bridge replacement that is set to begin construction in 2026.

As part of the habitat rehab, each new plant is being put into the ground by hand—plants endemic to the salt marsh habitat like cattail and spiny rush, some plantings coming courtesy of the Nature Collective’s native plant nursery.

According to Smith, about 1.1 million cubic yards of soil were carved out to create the new wetlands. A raised berm was constructed between the restored salt marsh and the San Dieguito River channel, separating the new wetlands from the established wetlands.

The lagoon restoration project worked around the SDG&E utility pole corridor. As part of the project, seven poles were taken out of the lagoon and moved into an existing SDG&E utility corridor.

At the marsh inlet, the San Dieguito River comes in and attaches, flowing out to the Del Mar coast. SANDAG will help assist with the maintenance of the lagoon inlet to ensure it remains open to tidal flushing and provides sand to the beach.

The wetlands restoration looking east toward El Camino Real.

The berm through the restored area will be planted with coastal sage scrub and will be accessible to maintenance vehicles only.

While the sensitive habitat will remain protected, some public access will be provided via a new trail connection along the marsh from the northern loop of the Dust Devil Nature Trail off El Camino Real. The trail, lined with rustic split-rail fencing, will eventually connect to pedestrian lanes along the new El Camino Real Bridge across the river, providing a link to the Coast to Crest Trail.

The new trail is expected to be open in September: “It will be walkable for a mile from the Dust Devil trail to see the beautiful wetlands created,” Smith said.

Water flows through the newly opened marsh inlet in the San Dieguito Lagoon.


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