Edgartown, MA Coastal Erosion Rate
What USGS measures 7.3 miles west of Edgartown, MA
USGS's shoreline-change data puts this stretch, 7.3 miles west of Edgartown, MA, at 1.85 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 18.5 feet over the last decade.
What this reading actually covers
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 Edgartown, MA, rather than showing one arbitrary line. Segment center: 41.35, -70.65. The survey behind it runs to 2007-2009, in USGS's New England / Mid-Atlantic 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.
What 1.85 ft/yr means over time
Run 7.3 miles west of Edgartown, MA's 1.85 ft/yr rate forward 25 years and it implies about 46 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
How solid is this number
Averaging 84 separate transects produced this segment's rate, with 100% individually reading as erosion, rather than relying on any single survey line. Uncertainty on this specific number: 0.39 ft/yr either side. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 140. Source: USGS Open-File Report 2010-1119. For scale: Seaside Park, NJ, 207 miles away, ranks 248 of 1211 nationally for erosion, 0.66 ft/yr, 0.4x this stretch's rate. 2.6 miles away, Edgartown, MA is the nearest other measured stretch: moderate erosion at 2.13 ft/yr.
One address near Edgartown: the Coastal Change Hazards Portal zooms past this stretch to the underlying map.