The latest storms have done a number on our beaches, washing precious sand out to sea and, in some cases, leaving nothing but a bed of rocks behind. This is typical for winter months, with some sand returning during the summer. However, keeping enough sand on local beaches is an ongoing challenge due to coastal erosion, heavy storms, sea level rise and other factors.

Source: Littoral Cells, Sand Budgets, and Beaches: Understanding California’s Shoreline

Sand projects have been in the news lately, with the City of Oceanside holding a design competition to come up with new solutions for its shoreline and, just this week, news of a sand replenishment project put on hold in San Clemente mid-stream due to concerns about sand quality.

With the beach being such a big part of what makes Carlsbad special – and a large driver of our tourism economy (an estimated $2.4 billion in total economic impact and 22,000 jobs) – the city has a Beach Preservation Commission that investigates, researches, and makes recommendations to the City Council and the City Manager on coastal topics, studies and programs, including sand replenishment. The public is invited to attend their monthly meetings and provide input, and you can watch online live or after the fact.

At a glance

Carlsbad beaches get sand from three main sources:

1. Regional effort: Sand doesn’t respect jurisdictional boundaries, which is why the San Diego County Association of Governments coordinates with local cities on a regional effort to dredge sand off shore and deposit it on local beaches. Next deposit scheduled for 2027
2. Lagoon dredging: Agreements are also in place that allow the Agua Hedionda and Batiquitos lagoons to be dredged regularly, which helps lagoon health and returns sand to our shores. Next dredging scheduled for fall 2024 and/or spring 2025.
3. Oceanside dredging: The City of Oceanside dredges its harbor periodically, which deposits sand on nearby beaches. Some of this sand eventually makes its way down to Carlsbad. Next dredge is planned for this spring.

Long version

Where does sand come from?
Sand is created over time mostly from the weathering of rocks and shells. Some originates in the ocean, and some is transported to the coast by rivers and wind. Once the sand arrives, it settles in a self-contained area off the coast called a littoral cell.

The California coast is made up of several of these cells, where currents, waves, rivers, underwater canyons and other conditions transport sand, depending on the time of year and storm activity, to the beach and off shore within the cell, but not usually beyond the cell. For this reason, these cells are sometimes called “containers” of sand. So, when sand disappears from the beach, it isn’t all gone for good, it’s just moved into a different part of the cell, including on the ocean floor.

Carlsbad is within the Oceanside littoral cell, which starts in Dana Point and extends to La Jolla. Oceanside’s littoral cell is artificially divided by the north jetty at the Oceanside harbor. This jetty limits sand from north of the harbor from traveling south. The conclusion from some historical studies is that most sand in California moves from north to south due to the direction of waves.

Carlsbad beaches
The State of California manages most of the beaches in Carlsbad, except for a ¾ mile stretch at the north end of town. The city coordinates closely with California State Parks on issues related to local beaches, including sand replenishment. However, the state has ultimate say over projects to deposit sand on its beaches.

Regional efforts
Since 2001, a regional effort led by SANDAG has placed approximately 3.6 million cubic yards of beach quality sand onto our region’s beaches. That’s enough sand to fill 1,100 Olympic-size swimming pools. The first project in 2001 cost $18 million. The second in 2012 cost $36 million, not adjusting for inflation.

Carlsbad has been an active participant in the two previous SANDAG-led projects, including providing funding. Planning for the next sand replenishment from this regional project is already underway. The City of Carlsbad has contributed funding to getting the initial planning and studies conducted.

The next sand deposit from this regional effort, the third since it started, is tentatively scheduled for 2027.

Agua Hedionda Lagoon dredging
Since the 1950s, SDG&E dredged the lagoon regularly to maintain its seawater intake and outfall system, which was used to cool the power plant. This sand was placed on nearby beaches. NRG took this over when it bought the power plant. When NRG built the new power plant, which does not use ocean water for cooling, Poseidon Water assumed responsibility for dredging the lagoon. The desalination plant operated by Poseidon Water utilizes the same seawater intake and outfall pipes previously used by the old power plant.

The last time the lagoon was maintenance dredged was 2021, and the next time is scheduled to start in late fall of this year and conclude by early spring of 2025, depending on conditions.

Batiquitos Lagoon dredging
About 30 years ago, a $55 million state project was completed to restore ocean-water flow in and out of the Batiquitos Lagoon. This lagoon is owned and operated by the California Department of Fish and Wildlife.

The restoration project was completed in 1997. Sand from the lagoon was pumped onto the beach and around nesting sites and the railroad berm in south Carlsbad. Approximately 50,000 cubic yards of sand are washed back into the lagoon naturally through tides and storms each year. The California Department of Fish & Wildlife has maintenance dredged the lagoon twice since then and is planning to start another dredging operation again this fall.

Oceanside Harbor dredging
The City of Oceanside dredges its harbor regularly, and that sand is deposited on Oceanside beaches. Some of this sand is transported south, although a recent study showed the amount is less than what previous studies had shown. The next maintenance dredging operation is scheduled for this spring.

This regular maintenance dredging is different from Oceanside’s ReBEACH project, which is focused on developing innovative sand retention pilot projects for the City of Oceanside. The Oceanside City Council is planning to discuss the recommended approach from the design competition on Jan. 31. The City of Carlsbad is monitoring this project, which is still in the very early conceptual stages.

Challenges
Sand projects are very expensive and require lengthy review and approval processes. Most use specialized dredging equipment, which is sort of like a giant sand vacuum, and great care must be taken to protect marine life. Dredging projects also must avoid nesting seasons for certain shore birds and other sensitive environmental conditions.

All of this makes planning and executing these projects challenging. Agencies typically work for years before any dredging work can start, and then need to begin the planning and studies process all over again to be ready in time for the next project. However, this work remains a priority, with the City of Carlsbad working on several fronts to help plan, fund and coordinate sand replenishment on an ongoing basis.

More information
SANDAG sand management web page
Batiquitos Lagoon dredging
Agua Hedionda Lagoon dredging
Oceanside Harbor dredging