Point Arena, CA Coastal Erosion Rate
What USGS measures 2.8 miles southeast of Point Arena, CA
Good news, and an honest one: USGS's data can't distinguish this stretch, 2.8 miles southeast of Point Arena, CA, from a flat trend. Whatever small movement it measured here is statistical noise, not a reliable direction, so none is claimed.
The grain of this number
USGS surveys the coast in transects spaced a few hundred feet apart; this page groups the nearest ones into a single ~3.5-mile reading for the stretch closest to Point Arena, CA, rather than showing one arbitrary line. Segment center: 38.88, -123.67. 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
19 transects feed this segment's number; 100% of them individually measured retreat. USGS's confidence interval here is ±0.25 ft/yr. The unadjusted figure here, -0.25 ft/yr, would place it 444 of 1211 if ranked directly - but an unreliable rank isn't a useful one, which is exactly why "no significant trend" is the headline instead. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. Rank 994 nationally for growth belongs to Dover Beaches South, NJ, 2613 miles from this stretch, measured at 0.4 ft/yr. Point Arena, CA, 1 miles off, is the adjacent measured stretch, reading slight erosion at 0.19 ft/yr.
Not this whole stretch, just Point Arena itself: the Coastal Change Hazards Portal is USGS's own live version of this data.