The answer isn't an opinion — it's in the federal record. Below is the USGS long-term shoreline-change rate and FEMA flood zone for each East End ocean beach, measured at 3,518 transects from Montauk Point to Breezy Point. Pick your beach.
Each rate below is the USGS DSAS long-term shoreline-change rate for that stretch of ocean shore — a decades-long linear-regression trend, not a single storm. Negative means the beach is moving landward. Open a beach for its full profile, named projects, and flood exposure.
Westhampton
Sagaponack
Ditch Plains
Fire Island
Quogue
Montauk
Which East End beach is eroding the fastest?
Westhampton is the fastest-retreating reach — its worst USGS transects lose about 1.0 m (3.4 ft) of shoreline a year — while Sagaponack has the most consistently eroding shore, with 98% of its transects losing land.
Are these ocean beaches in a FEMA flood zone?
Yes — the East End oceanfront is mapped Zone VE (coastal high-hazard, subject to breaking waves) along the beach and primary dune, stepping down to Zone AE landward, in the FEMA National Flood Hazard Layer.
Is the whole East End losing its beach?
No — 59.6% of Long Island's ocean transects are eroding and the rest are stable or gaining, so the answer is reach-by-reach, which is why each beach has its own page and its own number.
Where does Psammite's data come from?
The long-term rates are the USGS National Assessment of Shoreline Change (Open-File Reports 2010-1118 and 2010-1119), and today's waterline is read from Sentinel-2 satellite imagery.
These pages give you the rate for the reach. The $99 Psammite certificate gives you the parcel-level figure for your own address — your erosion rate, storm-surge exposure, uncertainty band, and whether a licensed site review is warranted, built from the same federal record.