Montauk, NY Coastal Erosion Rate
Shoreline change 2.6 miles east of Montauk, NY
Averaged across every transect USGS ran 2.6 miles east of Montauk, NY, the shoreline has been moving inland at 0.28 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 2.8 feet over the last decade.
The grain of this number
Montauk, NY is the nearest named place, 2.6 miles away, to a ~3.5-mile stretch of coast USGS has surveyed - the reading below covers that whole stretch, not a single property in it. Segment center: 41.05, -71.90. 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 0.28 ft/yr means over time
Run 2.6 miles east of Montauk, NY's 0.28 ft/yr rate forward 25 years and it implies about 7 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
What backs this reading up
96 transects feed this segment's number; 100% of them individually measured retreat. Uncertainty on this specific number: 0.16 ft/yr either side. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 415. Source: USGS Open-File Report 2010-1119. Rank 28 nationally for erosion belongs to Grand Isle, LA, 1294 miles from this stretch, measured at 8.55 ft/yr, many times over this stretch's own rate. 1.9 miles up the coast, Montauk, NY shows 0.18 ft/yr of eroding.
Not this whole stretch, just Montauk itself: the Coastal Change Hazards Portal is USGS's own live version of this data.