Manchester, CA Coastal Erosion Rate
Is the coast eroding 1.8 miles north of Manchester, CA?
1.8 miles north of Manchester, CA: USGS's transects didn't pick up a trend here that beats the survey's own uncertainty. That's the majority case nationally, and for this stretch specifically it means the coast is holding, not that the data failed to find anything.
What "Manchester" means on this page
This is a roughly 3.5-mile stretch of coast, not one address or parcel - USGS's own transects run every few hundred feet, but that's finer than any one property needs, so this page reports the stretch nearest Manchester, CA. Centered near 39.00°N, 123.70°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.
What backs this reading up
Averaging 116 separate transects produced this segment's rate, with 28% individually reading as erosion, rather than relying on any single survey line. Uncertainty on this specific number: 0.22 ft/yr either side. Taken at face value, this segment's raw 0.08 ft/yr reading would land it 838 of 1211 nationally - a number worth ignoring, since it's statistical noise rather than a real trend. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. For scale: Seal Beach, CA, 478 miles away, ranks 1072 of 1211 nationally for growth, 0.73 ft/yr. 2.4 miles up the coast, Manchester, CA shows the same lack of a significant trend.
Not this whole stretch, just Manchester itself: the Coastal Change Hazards Portal is USGS's own live version of this data.