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San Elijo Lagoon Project Helps Habitat And Benefits The Beach

San Elijo lagoon, March 6th 2018

Photo by Alison St John

Above: San Elijo lagoon, March 6th 2018

A $100 million project to restore the San Elijo Lagoon in Encinitas is underway, and the first phase benefits not only the health of the lagoon but also the beach.

The lagoon is a nearly 1,000-acre ecological reserve that stretches from the coast in Encinitas, inland to Rancho Santa Fe. It's a coastal wetland and home to hundreds of species of plants and animals — many of them endangered.

Caltrans has major projects underway to widen both Interstate Five and the railway line that cut across the endangered wetlands of the lagoon. To compensate for the disruption caused by the construction, money from the half-cent sales tax paying for the improvement has been earmarked for an unusual environmental restoration project.

The first thing a passerby on Cardiff state beach notices is the pipe pumping sand slurry — a mixture of sand and water — from the lagoon into the ocean.

Doug Gibson, executive director of the San Elijo Lagoon Conservancy, said this clean sand will help the beach.

“As we move though spring, that sand will start migrating back on shore,” he said, “so during the summertime, we’ll have more sand along the beaches. “

Cardiff State Beach benefited from another sand replenishment project in 2012, and Gibson said you can tell the difference between that sand brought from offshore and the new sand, which is slightly lighter and finer.

“This being lighter and more like our native sand, it will move a lot quicker than our last beach nourishment project,” he said, picking up two handfuls and rubbing the grains between his fingers. “That thicker grain tended to stay around a lot longer.”

The finer sand is likely to be washed south to Solana Beach by tidal currents faster than the coarse sand. That may not seem like a good thing for those who want it to stay on the Cardiff beach, but Gibson said it is because the finer sand won’t block the mouth of other lagoons down the coast, which has been an issue.

Birds such as snowy egrets and ducks feed in the shallow water of the lagoon, just yards from where heavy equipment is excavating material. Some of the sediment in the lagoon is contaminated from sewage flows years ago, and the plan is to bury the contaminated material in a pit created by dredging the clean sand.

"What we’re doing there, is we’re removing this historic sediment build up — this fine silt and clays which are nitrified," Gibson said, “which is bad for water quality and the lagoon. We can’t put those in the beach. That isn’t toxic, but it’s toxic to aquatic species in the sense that it creates algae blooms.”

Once the more contaminated material is buried in the pit, it will be covered with another layer of clean sand.

The San Elijo Lagoon Conservancy bought the land in 2012, and now is benefiting from the transit improvements that are funding this experiment in lagoon restoration. Heavy equipment will likely be working in the lagoon for several years, but by 2021, the goal is to have a newly contoured wetland for wildlife, and a new pedestrian bridge leading to new nature trails for hikers.

"It’s really a unique way to restore lagoons and get rid of sediment," said Gibson. "We’ll have a higher productive wetland system."

A $100 million project to restore the San Elijo Lagoon in Encinitas is underway, and the first phase benefits not only the health of the lagoon but also the beach.

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