Ilwaco, WA Coastal Erosion Rate
Is the coast eroding 3.4 miles southwest of Ilwaco, WA?
Averaged across every transect USGS ran 3.4 miles southwest of Ilwaco, WA, the shoreline has been moving inland at 6.42 feet a year, a real measured rate, not a regional estimate applied to this stretch. At that rate, the shoreline has lost roughly 64.2 feet over the last decade.
What this reading actually covers
Ilwaco, WA is the nearest named place, 3.4 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: 46.28, -124.08. USGS's Pacific Northwest assessment last surveyed this stretch through 2002-2011, computing the rate with its LRR method. Other US regions were surveyed in different years, sometimes decades apart, so this page states its own rather than implying one national vintage.
What 6.42 ft/yr means over time
Run 3.4 miles southwest of Ilwaco, WA's 6.42 ft/yr rate forward 25 years and it implies about 161 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 4 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: 5.5 ft/yr either side. This segment ranks 39 of 1211 measured US coastal segments, ordered from fastest erosion to fastest growth. Source: USGS Open-File Report 2012-1008. Cheriton, VA sits at national rank 48 for erosion (5.55 ft/yr), one reference point among the 1211 scored segments, 2524 miles from here. 0.4 miles up the coast, Ilwaco, WA shows 10.32 ft/yr of eroding.
Not this whole stretch, just Ilwaco itself: the Coastal Change Hazards Portal is USGS's own live version of this data.