Swampscott, MA Coastal Erosion Rate
What USGS measures 0.6 miles west of Swampscott, MA
0.6 miles west of Swampscott, MA: 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 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 Swampscott, MA. Centered near 42.47°N, 70.90°W. USGS's New England / Mid-Atlantic assessment last surveyed this stretch through 2007-2009, 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 backs this reading up
This reading comes from 22 individual transects averaged together, 27% of which measured erosion rather than growth. USGS's confidence interval here is ±0.12 ft/yr. Taken at face value, this segment's raw 0.05 ft/yr reading would land it 818 of 1211 nationally - a number worth ignoring, since it's statistical noise rather than a real trend. Source: USGS Open-File Report 2010-1119. Santa Monica, CA sits at national rank 932 for growth (0.21 ft/yr), one reference point among the 1211 scored segments, 2614 miles from here. 0.7 miles up the coast, Swampscott, MA shows the same lack of a significant trend.
Swampscott, MA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.