Westhaven State Park, Half Moon Bay is a saltwater beach in Grays Harbor County, Washington. Across 220 bacteria samples collected between 2021 and 2025 at nearby monitoring stations, it earns a Beach Safety Grade of A — Excellent.
About 0.0% of samples at Westhaven State Park, Half Moon Bay exceeded the EPA Beach Action Value of 104 CFU/100 mL for Enterococcus — the threshold at which water managers typically post a swimming advisory. In practice that means the safe-swimming limit was almost never crossed here over the monitored period. Bacteria samples almost never exceed the safe-swimming threshold.
The evidence behind this grade is deep for a beach page: 220 results from 3 monitoring stations, spanning 2021 to 2025. Enough sampling, from enough places, over enough seasons that one bad week can't drive the letter.
Westhaven State Park, Half Moon Bay was not under a swimming advisory in the most recent EPA snapshot. Conditions can change quickly after heavy rain or high runoff, so it's still worth checking the current advisory the day you go.