Martinez Marina: toxic algae advisories
Martinez Marina, Contra Costa County. See all Contra Costa County waters.
What the state's records say
The state's latest record, from Sep 12, 2025, recommends no advisory.
Last advisory on file: Aug 21, 2025.
That reflects what the state knew on that date. It is not a finding that the water is safe now: blooms can return within days, and many are never reported.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Martinez Marina
The state's latest record, from Sep 12, 2025, recommends no advisory. For Martinez Marina, that is not the same as an all-clear for today. Look at the water before your dog goes in: keep it out of green, blue-green or scummy water and away from mats on the shore.
Reported spots
The state records each report at a spot, such as a beach or a boat ramp. Each spot's latest deciding record:
| Spot | Status |
|---|---|
| Martinez Marina Delta area | The state's latest record, from Sep 12, 2025, recommends no advisory. |
Advisory history
Every advisory record the state has published for Martinez Marina, newest first. "None" is the state's record that no advisory was recommended on that date. "NA" records do not change a status.
| Date | Spot | State's level | Notes |
|---|---|---|---|
| Sep 12, 2025 | Martinez Marina Delta area | None | Testing results below posting triggers |
| Aug 21, 2025 | Martinez Marina Delta area | Danger | Advisory based on visual and toxins |
| Aug 18, 2025 | Martinez Marina Delta area | Danger | Advisory based on visual and toxins |
| Aug 8, 2025 | Martinez Marina Delta area | Danger | Advisory based on visual and toxins |
| Aug 1, 2025 | Martinez Marina Delta area | Blank in the state's file | Visual monitoring only-present bloom |
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.