Port St. Joe, FL Coastal Erosion Rate
What USGS measures 10.3 miles south of Port St. Joe, FL
USGS's shoreline-change data puts this stretch, 10.3 miles south of Port St. Joe, FL, at 7.6 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 76 feet over the last decade.
The grain of this number
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 Port St. Joe, FL, rather than showing one arbitrary line. Segment center: 29.67, -85.35. 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.
What 7.6 ft/yr means over time
Run 10.3 miles south of Port St. Joe, FL's 7.6 ft/yr rate forward 25 years and it implies about 190 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
Averaging 15 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: 3.89 ft/yr either side. This segment ranks 33 of 1211 measured US coastal segments, ordered from fastest erosion to fastest growth. Source: USGS Open-File Report 2004-1089. For scale: Taholah, WA, 2398 miles away, ranks 262 of 1211 nationally for erosion, 0.61 ft/yr, a small fraction of this stretch's own rate. 1.9 miles away, Port St. Joe, FL is the nearest other measured stretch: moderate erosion at 1.72 ft/yr.
Not this whole stretch, just Port St. Joe itself: the Coastal Change Hazards Portal is USGS's own live version of this data.