Napa County: lake and river algae advisories

8 waters in Napa County appear in the state's harmful algal bloom records. Waters whose latest record is an advisory come first.

Waters in Napa County and what the state's latest record says
Water	Latest record
Bell Canyon Reservoir	Caution advisory, last posted Aug 10, 2026. No all-clear recorded.
Huichica Pond 8	Danger advisory, last posted Sep 2, 2022. No all-clear recorded.
Lake Berryessa	Caution advisory, last posted Aug 28, 2026. No all-clear recorded.
Lake Hennessey	Caution advisory, last posted Apr 4, 2024. No all-clear recorded.
Napa HCU Pond	Caution advisory, last posted Sep 3, 2020. No all-clear recorded.
Napa-Sonoma Marshes Wildlife Area	Danger advisory, last posted Oct 8, 2025. No all-clear recorded.
Napa River	The state's latest record, from Sep 2, 2026, recommends no advisory.
Redwood Creek	The state's latest record, from Jul 1, 2026, recommends no advisory.