Casmalia, CA Coastal Erosion Rate
Shoreline change 7.5 miles southwest of Casmalia, CA
Averaged across every transect USGS ran 7.5 miles southwest of Casmalia, CA, the shoreline has been moving inland at 0.46 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 4.6 feet over the last decade.
What this reading actually covers
Casmalia, CA is the nearest named place, 7.5 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: 34.77, -120.63. USGS's California assessment last surveyed this stretch through 1852-2016, computing the rate with its LRR method. Other US regions were surveyed in different years, sometimes decades apart, so this page states its own rather than implying one national vintage.
What 0.46 ft/yr means over time
Run 7.5 miles southwest of Casmalia, CA's 0.46 ft/yr rate forward 25 years and it implies about 12 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
12 transects feed this segment's number; 100% of them individually measured retreat. The published margin on this reading runs ±0.45 ft/yr. This segment ranks 317 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. For scale: Port Arthur, TX, 1595 miles away, ranks 60 of 1211 nationally for erosion, 4.58 ft/yr, 10.0x this stretch's rate. 0.9 miles away, Casmalia, CA is the nearest other measured stretch: also no significant trend.
Not this whole stretch, just Casmalia itself: the Coastal Change Hazards Portal is USGS's own live version of this data.