San Diego Bay Shelter Is is a saltwater beach in San Diego County, California. Across 300 bacteria samples collected between 2021 and 2025 at nearby monitoring stations, it earns a Beach Safety Grade of F — Failing.
About 26% of samples at San Diego Bay Shelter Is 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 frequently crossed here over the monitored period. Bacteria samples exceed the safe-swimming threshold a large share of the time — this beach flags advisories often.
The evidence behind this grade is deep for a beach page: 300 results from 2 monitoring stations, spanning 2021 to 2025. Enough sampling, from enough places, over enough seasons that one bad week can't drive the letter.
San Diego Bay Shelter Is is currently listed as inactive in the EPA beach-monitoring program, so it may no longer be routinely sampled. Its grade reflects the water-quality results collected while it was active — useful history, but confirm the beach's current status and any local advisory before you visit.