Big Lagoon, CA Coastal Erosion Rate
Shoreline change 3.2 miles north of Big Lagoon, CA
Averaged across every transect USGS ran 3.2 miles north of Big Lagoon, CA, the shoreline has been moving inland at 0.68 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 6.8 feet over the last decade.
The grain of this number
Big Lagoon, CA is the nearest named place, 3.2 miles away, to a ~3.5-mile stretch of coast USGS has surveyed - the reading below covers that whole stretch, not a single property in it. Segment center: 41.20, -124.12. 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.
What 0.68 ft/yr means over time
Run 3.2 miles north of Big Lagoon, CA's 0.68 ft/yr rate forward 25 years and it implies about 17 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
How solid is this number
93 transects feed this segment's number; 91% of them individually measured retreat. The published margin on this reading runs ±0.4 ft/yr. This segment ranks 246 of 1211 measured US coastal segments, ordered from fastest erosion to fastest growth. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. Carmel-by-the-Sea, CA sits at national rank 239 for erosion (0.72 ft/yr), one reference point among the 1211 scored segments, 344 miles from here. Big Lagoon, CA, 1.8 miles off, is the adjacent measured stretch, itself no significant trend.
Not this whole stretch, just Big Lagoon itself: the Coastal Change Hazards Portal is USGS's own live version of this data.