Lake Sherwood, CA Coastal Erosion Rate
Is the coast eroding 6.3 miles south of Lake Sherwood, CA?
USGS's shoreline-change data puts this stretch, 6.3 miles south of Lake Sherwood, CA, at 0.18 feet of erosion a year on average, a long-term rate for this specific ~3.5-mile section, not one storm's damage. At that rate, the shoreline has lost roughly 1.8 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 Lake Sherwood, CA, rather than showing one arbitrary line. Segment center: 34.04, -118.90. 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.
What 0.18 ft/yr means over time
Run 6.3 miles south of Lake Sherwood, CA's 0.18 ft/yr rate forward 25 years and it implies about 5 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
Where this fits nationally
This reading comes from 88 individual transects averaged together, 100% of which measured erosion rather than growth. USGS's confidence interval here is ±0.09 ft/yr. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 533. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. For scale: Colma, CA, 320 miles away, ranks 304 of 1211 nationally for erosion, 0.48 ft/yr, 2.7x this stretch's rate. 2.6 miles up the coast, Malibu, CA shows the same lack of a significant trend.
One address near Lake Sherwood: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.