San Clemente, CA Coastal Erosion Rate
Is the coast eroding 9.7 miles southeast of San Clemente, CA?
The coast 9.7 miles southeast of San Clemente, CA is actually gaining ground, not losing it: USGS's transects measure 0.34 feet of accretion a year here, sediment building up rather than washing away. At that rate, the shoreline has gained roughly 3.4 feet over the last decade.
What "San Clemente" means on this page
Nothing here is parcel-level. USGS's raw transects run every few hundred feet along the shore; this page averages the ones nearest San Clemente, CA into one ~3.5-mile reading rather than picking a single arbitrary line to represent the area. Centered near 33.34°N, 117.51°W. The survey behind it runs to 1852-2016, in USGS's California assessment, using the LRR method. Shoreline surveys aren't repeated every year, so this is the most recent long-term measurement USGS has published for this coast, not a live reading.
25 years at this rate
Holding the 0.34 ft/yr accretion rate 9.7 miles southeast of San Clemente, CA for 25 years would add roughly 9 feet of shoreline, again assuming nothing about the local sediment supply changes.
What backs this reading up
This reading comes from 73 individual transects averaged together, 18% of which measured erosion rather than growth. Uncertainty on this specific number: 0.14 ft/yr either side. Among the 1211 US coastal segments with a measurable trend, this one ranks 980 for erosion, 1 being the fastest-retreating coast in the dataset. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. For scale: Fort Myers Beach, FL, 2172 miles away, ranks 990 of 1211 nationally for growth, 0.39 ft/yr, 1.1x this stretch's rate. 2.2 miles away, Camp Pendleton South, CA is the nearest other measured stretch: slight accretion (beach growing) at 0.44 ft/yr.
San Clemente, CA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.