Delta Coves: toxic algae advisories
Delta Coves, Contra Costa County. See all Contra Costa County waters.
What the state's records say
Caution advisory, last posted Jul 27, 2026. No all-clear recorded.
7 reported spots here have an advisory with 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: Algae that can make toxins may be present. Keep people, children and pets away from algae and scum, and do not let pets drink the water.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at Delta Coves
The state has an advisory on file for Delta Coves (Caution advisory), last posted Jul 27, 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:
| Spot | Status |
|---|---|
| North | Caution advisory, last posted Jul 27, 2026. No all-clear recorded. |
| Entire cove near Bethel Island | Caution advisory, last posted Aug 14, 2025. No all-clear recorded. |
| Isle Place | Caution advisory, last posted Aug 6, 2025. No all-clear recorded. |
| Corner of Point Place/Delta Coves Drive | Caution advisory, last posted Aug 4, 2025. No all-clear recorded. |
| near Sea Gate Pl and across entire cove | Caution advisory, last posted Jul 28, 2025. No all-clear recorded. |
| Beacon at Delta Coves, near island | Reports on file, with no advisory level the state has classified. |
| Bethel Island | Reports on file, with no advisory level the state has classified. |
| Navigators Place Cove | Visual observation, last posted Jul 17, 2023. No all-clear recorded. |
| Delta coves | Caution advisory, last posted Jun 27, 2023. No all-clear recorded. |
| marina, near Bethel Island | The state's latest record, from Jun 30, 2021, recommends no advisory. |
Advisory history
Every advisory record the state has published for Delta Coves, 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 |
|---|---|---|---|
| Jul 27, 2026 | North | Caution | visual monitoring based advisory |
| Aug 14, 2025 | Entire cove near Bethel Island | Caution | Lake-wide advisory |
| Aug 11, 2025 | Isle Place | NA - refer to Report Details | Under investigation |
| Aug 6, 2025 | Isle Place | Caution | Suspected illness reported |
| Aug 4, 2025 | Corner of Point Place/Delta Coves Drive | Caution | Suspected illness reported |
| Jul 28, 2025 | near Sea Gate Pl and across entire cove | Caution | Lake-wide advisory; Suspected illness reported; Visual monitoring only-present bloom |
| Jul 28, 2025 | near Sea Gate Pl and across entire cove | Caution | Suspected illness reported |
| Jun 7, 2024 | Beacon at Delta Coves, near island | NA - refer to Report Details | Suspected bloom, investigation ongoing |
| Jun 7, 2024 | Beacon at Delta Coves, near island | NA - refer to Report Details | Suspected bloom, investigation ongoing |
| Jun 7, 2024 | Bethel Island | NA - refer to Report Details | Suspected bloom, investigation ongoing |
| Jul 17, 2023 | Navigators Place Cove | Visual observation | Under investigation |
| Jun 27, 2023 | Delta coves | Caution | Floating/planktonic bloom observed |
| Jun 30, 2021 | marina, near Bethel Island | None | Testing results below posting triggers |
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.