Sand dunes planned in Cardiff to protect Highway 101

In a nod to the past, the city of Encinitas is looking to erect sand dunes in Cardiff to blunt the impact of storm surges.

Encinitas was recently awarded a $150,000 grant from the California Coastal Conservancy to develop a plan for dunes fronting Coast Highway 101, from south Cardiff State Beach to “restaurant row” to the north.

This stretch of coastline is vulnerable when there’s a combination of large surf and high tides, said Katherine Weldon, the city’s shoreline preservation manager. Such events over the years have resulted in 42 closures of Highway 101, an artery that supports 20,000 daily trips, she said.

“When you have dunes, you have significant public infrastructure protection,” Weldon said.

Powerful waves and extreme high tides have also flooded beachside restaurants and overpowered the San Elijo Lagoon, according to the staff report.

Weldon said sand dunes have proven to be effective. In the aftermath of Hurricane Sandy in 2012, New Jersey beach communities with dunes had less damage than those without.

Historical aerial photographs show sand dunes in Cardiff where there are none today. Notably, the development of the San Elijo Campgrounds in the 1950s took away large swaths of cliffs and dunes, according to Cardiff 101 Main Street’s website.

Deputy Mayor Catherine Blakespear said her mom has shared memories of the old dunes. Besides protecting infrastructure, the dunes would provide habitat for different critters, Blakespear stated.

“When you look at places (where) they have dunes, like in Coronado, there’s a whole habitat of bugs, animals and plants associated with it,” Blakespear said.

She added of the dunes: “They were once up and down the coast. Systematically, with development, they’ve been removed. And so it’s a nice connection to our history and an important ecological feature.”

Sand for dune construction would come from a planned San Elijo Lagoon excavation project.

The dune plan, which the public will eventually be invited to weigh in on, will spell out the number of dunes and their size.

What’s known so far is that the dunes would be constructed right next to Coast Highway 101 and the adjoining rock piles, but they wouldn’t be tall enough to affect views on the road, according to Weldon.

She said the city has looked into raising parts of Highway 101 in Cardiff so waves wouldn’t topple over the road. But that doesn’t appear to be in the cards.

Instead, to protect Highway 101 and surrounding infrastructure, the city relied on two regional beach nourishment projects that placed sand between restaurant row and Seaside Reef.

“Those projects were very successful as a buffer,” Weldon said.

There’s a plan to regularly replenish Encinitas beaches over 50 years, yet this would place sand farther north. Weldon said some of that sand will drift south because of shoreline currents, but there’s still a need for a buffer in the area, and different agencies agreed that sand dunes are the best alternative.

Under the $150,000 California Coastal Conservancy grant, the city will kick in $50,000 worth of staff time.

Construction on the dunes is scheduled to begin early 2017.