Costa Mesa, CA Coastal Erosion Rate
What USGS measures 3.7 miles south of Costa Mesa, CA
Unusual good news for this stretch: the shoreline 3.7 miles south of Costa Mesa, CA has grown by a measured 0.48 feet a year on average, per USGS's long-term transect data for this section. At that rate, the shoreline has gained roughly 4.8 feet over the last decade.
What this reading actually covers
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 Costa Mesa, CA, rather than showing one arbitrary line. Segment center: 33.62, -117.94. USGS's California assessment last surveyed this stretch through 1852-2016, 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 0.48 ft/yr means over time
Holding the 0.48 ft/yr accretion rate 3.7 miles south of Costa Mesa, CA for 25 years would add roughly 12 feet of shoreline, again assuming nothing about the local sediment supply changes.
How solid is this number
61 transects feed this segment's number; 0% of them individually measured retreat. The published margin on this reading runs ±0.24 ft/yr. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 1021. Source: USGS National Shoreline Change data release (ScienceBase, DOI 10.5066/P94J0K7Z), Kratzmann 2024 / Data Report 1187. Rank 1112 nationally for growth belongs to Qui-nai-elt Village, WA, 997 miles from this stretch, measured at 1.04 ft/yr, 2.2x this stretch's rate. 1.9 miles away, Costa Mesa, CA is the nearest other measured stretch: accretion (beach growing) at 1.48 ft/yr.
Not this whole stretch, just Costa Mesa itself: the Coastal Change Hazards Portal is USGS's own live version of this data.