Carquinez Strait: toxic algae advisories

Carquinez Strait, Contra Costa County. See all Contra Costa County waters.

What the state's records say

Danger advisory, last posted Jul 8, 2026. No all-clear recorded.

Reporting is voluntary, so the state may not have recorded an end even if conditions changed. Check posted signs and the official map.

What this level asks: Toxins may be at levels that can seriously harm people and animals. Stay out of the water and keep children and pets away from the water and the shore.

Before you go, check the state's official algae page and any signs posted at the water.

Dogs at Carquinez Strait

The state has an advisory on file for Carquinez Strait (Danger advisory), last posted Jul 8, 2026, and no all-clear recorded. Keep your dog out of the water and away from scum on the shore until the state records an end.

Reported spots

The state records each report at a spot, such as a beach or a boat ramp. Each spot's latest deciding record:

Each reported spot at Carquinez Strait and its latest status
Spot	Status
Martinez Marina at Radke Martinez Regional Shoreline	Danger advisory, last posted Jul 8, 2026. No all-clear recorded.
Martinez Marina	Reports on file, with no advisory level the state has classified.

Advisory history

Every advisory record the state has published for Carquinez Strait, newest first. "None" is the state's record that no advisory was recommended on that date. "NA" records do not change a status.

Advisory records for Carquinez Strait, newest first
Date	Spot	State's level	Notes
Jul 8, 2026	Martinez Marina at Radke Martinez Regional Shoreline	Danger	Advisory based on visual and toxins
Jul 8, 2026	Martinez Marina at Radke Martinez Regional Shoreline	Caution	Advisory based on visual and toxins
Jun 19, 2020	Martinez Marina	NA - refer to Report Details

Source

Advisory data: California State Water Resources Control Board, Freshwater Harmful Algal Bloom Program, via data.ca.gov (public domain). Advisories are recommendations; reporting is voluntary and incomplete. The state's data. An advisory ends only when the state records a later "None" (no advisory recommended) at the same spot, or an end date. A blank end date is unknown.