Half Moon Bay, CA Coastal Erosion Rate
Is the coast eroding 5.3 miles south of Half Moon Bay, CA?
5.3 miles south of Half Moon Bay, 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 "Half Moon Bay" 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 Half Moon Bay, CA. Centered near 37.39°N, 122.42°W. 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.
Where this fits nationally
This reading comes from 30 individual transects averaged together, 45% of which measured erosion rather than growth. USGS's confidence interval here is ±0.18 ft/yr. Taken at face value, this segment's raw 0.1 ft/yr reading would land it 854 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: Fort Myers Beach, FL, 2470 miles away, ranks 990 of 1211 nationally for growth, 0.39 ft/yr. 1.7 miles away, Half Moon Bay, CA is the nearest other measured stretch: slight erosion at 0.36 ft/yr.
One address near Half Moon Bay: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.