Grand Isle, LA Coastal Erosion Rate
Shoreline change 12.3 miles northeast of Grand Isle, LA
The coast 12.3 miles northeast of Grand Isle, LA has been retreating at a measured 8.55 feet a year, USGS's own long-term rate for this stretch, built from historical shoreline positions rather than a single survey. At that rate, the shoreline has lost roughly 85.5 feet over the last decade.
The grain of this number
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 Grand Isle, LA. Centered near 29.32°N, 89.87°W. Survey years: 2001, method LRR, from USGS's Gulf of Mexico shoreline-change assessment. That's how current the data is here, real, but not a live feed, since a shoreline survey is a major undertaking, not an annual check-in.
25 years at this rate
If 8.55 ft/yr holds for the next 25 years, the coast 12.3 miles northeast of Grand Isle, LA would retreat roughly 214 more feet, a projection, not a certainty: erosion rates shift with storms, sediment supply and any armoring built in the meantime.
What backs this reading up
This reading comes from 11 individual transects averaged together, 100% of which measured erosion rather than growth. USGS's confidence interval here is ±4.85 ft/yr. Among the 1211 US coastal segments with a measurable trend, this one ranks 28 for erosion, 1 being the fastest-retreating coast in the dataset. Source: USGS Open-File Report 2004-1089. Virginia Beach, VA sits at national rank 111 for erosion (2.4 ft/yr), one reference point among the 1211 scored segments, 953 miles from here. 1.6 miles up the coast, Grand Isle, LA shows 15.54 ft/yr of eroding.
Grand Isle, LA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.