Colma, CA Coastal Erosion Rate
What USGS measures 3 miles southwest of Colma, CA
The coast 3 miles southwest of Colma, CA has been retreating at a measured 0.48 feet a year, USGS's own long-term rate for this stretch, built from historical shoreline positions rather than a single survey. At that rate, the shoreline has lost roughly 4.8 feet over the last decade.
What this reading actually covers
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 Colma, CA. Centered near 37.65°N, 122.49°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.
25 years at this rate
If 0.48 ft/yr holds for the next 25 years, the coast 3 miles southwest of Colma, CA would retreat roughly 12 more feet, a projection, not a certainty: erosion rates shift with storms, sediment supply and any armoring built in the meantime.
Where this fits nationally
Averaging 105 separate transects produced this segment's rate, with 98% individually reading as erosion, rather than relying on any single survey line. USGS's confidence interval here is ±0.33 ft/yr. This segment ranks 304 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. For scale: Jamaica Beach, TX, 1679 miles away, ranks 256 of 1211 nationally for erosion, 0.62 ft/yr, 1.3x this stretch's rate. 3.2 miles away, Pacifica, CA is the nearest other measured stretch: slight erosion at 0.6 ft/yr.
Not this whole stretch, just Colma itself: the Coastal Change Hazards Portal is USGS's own live version of this data.