Dillon Beach, CA Coastal Erosion Rate
Is the coast eroding 6.6 miles south of Dillon Beach, CA?
Unusual good news for this stretch: the shoreline 6.6 miles south of Dillon Beach, CA has grown by a measured 0.53 feet a year on average, per USGS's long-term transect data for this section. At that rate, the shoreline has gained roughly 5.3 feet over the last decade.
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 Dillon Beach, CA, rather than showing one arbitrary line. Segment center: 38.15, -122.95. 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.
What 0.53 ft/yr means over time
Holding the 0.53 ft/yr accretion rate 6.6 miles south of Dillon Beach, CA for 25 years would add roughly 13 feet of shoreline, again assuming nothing about the local sediment supply changes.
How solid is this number
This reading comes from 104 individual transects averaged together, 7% of which measured erosion rather than growth. Uncertainty on this specific number: 0.31 ft/yr either side. This segment ranks 1029 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. Rank 1184 nationally for growth belongs to Quinby, VA, 2553 miles from this stretch, measured at 3.29 ft/yr, 6.2x this stretch's rate. 3.1 miles away, Dillon Beach, CA is the nearest other measured stretch: also no significant trend.
Dillon Beach, CA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.