Manchester, CA Coastal Erosion Rate
Shoreline change 8.1 miles north of Manchester, CA
0.17 feet a year: that is the measured retreat rate USGS's transects show for the coast 8.1 miles north of Manchester, CA, averaged across the full historical record surveyed here. At that rate, the shoreline has lost roughly 1.7 feet over the last decade.
The grain of this number
Nothing here is parcel-level. USGS's raw transects run every few hundred feet along the shore; this page averages the ones nearest Manchester, CA into one ~3.5-mile reading rather than picking a single arbitrary line to represent the area. Centered near 39.09°N, 123.71°W. Survey years: 1852-2016, method LRR, from USGS's California shoreline-change assessment. That's how current the data is here, real, but not a live feed, since a shoreline survey is a major undertaking, not an annual check-in.
25 years at this rate
If 0.17 ft/yr holds for the next 25 years, the coast 8.1 miles north of Manchester, CA would retreat roughly 4 more feet, a projection, not a certainty: erosion rates shift with storms, sediment supply and any armoring built in the meantime.
How solid is this number
37 transects feed this segment's number; 56% of them individually measured retreat. USGS's confidence interval here is ±0.14 ft/yr. Among the 1211 US coastal segments with a measurable trend, this one ranks 542 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. South Padre Island, TX sits at national rank 91 for erosion (3.17 ft/yr), one reference point among the 1211 scored segments, 1763 miles from here. 2.8 miles up the coast, Manchester, CA shows the same lack of a significant trend.
Manchester, CA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.