United Seamen's Service Beach (Uso Beach) is a saltwater beach in Guam County, Guam. Across 525 bacteria samples collected between 2021 and 2026 at nearby monitoring stations, it earns a Beach Safety Grade of B — Good.

About 4% of samples at United Seamen's Service Beach (Uso Beach) 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 rarely crossed here over the monitored period. Bacteria samples rarely exceed the safe-swimming threshold.

In the most recent full reporting year, United Seamen's Service Beach (Uso Beach) was under a swimming advisory for about 12% of its monitored beach days — a useful gauge of how often problems recur here beyond any single sample.