BEACH EROSION IS CAUSED BY LACK OF SAND
Our coastline has a deficit of two million cubic yards of sand
Our beaches represent a delicate balance between the amount of sand supplied to the coast and the degree of wave energy sweeping it away. The decreasing supply of sand along the California Coast has emerged as a critical factor contributing to widespread coastal erosion. Human activities have significantly reduced the amount of sand reaching the coast. As a result, many beaches are experiencing accelerated erosion, putting coastal communities, infrastructure, and ecosystems at risk. However, this is a human-made problem which has a human-made solution: bring back the sand. How much do we need? The primary source of sand to San Clemente's beaches is San Juan Creek, which historically yielded about 40,000 cubic yards per year (CY/yr) on average. This discharge has an enormous variability, from 2,000 CY/yr to 1,000,000 CY/yr depending on the amount of precipitation. Our coast may also receive some sand from San Mateo Creek, which historically discharges an average of about 11,000 CY/yr. Smaller intermittent streams (such as Prima Desecha and Segunda Desecha) may have contributed up to 2,000 CY/yr under natural conditions. Due to human activities such as damming, upstream development, sand mining, siltation basins and flood control, and stormwater management programs, these sources have been significantly reduced. The protracted drought over the last 20 years has essentially meant that virtually no sand has been delivered to our coast -- between 2005 and 2023 there was virtually no sediment discharge from San Juan Creek.A tertiary source of sediment is directly from the bluffs, by runoff erosion and landslides bringing sediment to the surf zone. With the construction of the railroad in front of the bluffs in the 1890s, this source of sediment has been completely blocked by the presence of the tracks (and landslides are remediated). A study by Coastal Environments (2014) provided an assessment of the sediment budget for the coast between Dana Point and San Mateo Point (Dana Point Sub-cell). They estimated that the sediment budget for the Dana Point Sub-cell has been in a 56,000 cy per year deficit (erosion) in dry years, and in a 3,000 cy per year surplus (accretion) in wet years, over the last four decades. This deficit which must be offset by artificial sand replenishment
Within the Dana Point sub-cell there has only been one large sand replenishment project. Construction of the Dana Point Harbor resulted in the placement of 2,353,000 CY of sand on Doheny State Beach between 1964 and 1972. Movement of this sand downcast supported our beaches for the next few decades. Since then, sand dredged from the harbor has been placed nearshore at Capo Beach on a semi-annual basis, but this sand is too fine-grained to be at equilibrium on the beach, and it is transported further offshore. The City of San Clemente has carried out two opportunistic sand replenishment programs at North Beach, replenishing 5,000 CY in 2005 and 12,000 CY in 2016. Neither project lasted more than a few years. In 2023, Orange County trucked in around 30,000 CY of sand at Capo Beach; how long that will last remains to be seen. The current sand replenishment project is not enough sand and not the right places
San Clemente has just begun its first major sand replenishment program, which will put 250,000 CY of sand over the 3/4-mile stretch of beach between Linda Lane and T-Street. The project is intended to be repeated every six years for the next 50 years. These beaches are the widest and most stable beaches in San Clemente (see the "State of the Beaches" page for details). As detailed in the “Waves” section, longshore drift is not expected to move much of this sand into the most critically eroded public beaches — North Beach and State Beach. None of the sand will impact the Capo Shores or Cyprus Shores beaches. We need at least 2,000,000 CY of sand placed on San Clemente’s threatened beaches
Please forward to our GAMEPLAN pages for our answers on how to bring back our sand.