O'Neill Forebay: toxic algae advisories
O'Neill Forebay, Merced County. See all Merced County waters.
What the state's records say
Caution advisory, last posted Dec 19, 2022. 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 O'Neill Forebay
The state has an advisory on file for O'Neill Forebay (Caution advisory), last posted Dec 19, 2022, 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.
Satellite estimate (not an advisory)
Week ending Feb 14, 2026: about 21,000 cells/mL of cyanobacteria near the center of O'Neill Forebay.
A satellite estimate from EPA CyAN for a 9.1 km² lake. It does not measure toxins and does not change the advisory status.
| Week ending | Estimate |
|---|---|
| Feb 14, 2026 | about 21,000 cells/mL |
| Apr 1, 2023 | about 6,900 cells/mL |
| Mar 4, 2023 | about 14,000 cells/mL |
| Feb 25, 2023 | about 150,000 cells/mL |
| Feb 18, 2023 | about 19,000 cells/mL |
| Sep 17, 2022 | about 31,000 cells/mL |
| Sep 3, 2022 | about 820,000 cells/mL |
| Aug 27, 2022 | about 140,000 cells/mL |
This is a satellite estimate from the U.S. EPA's Cyanobacteria Assessment Network, not an advisory. It estimates how much cyanobacteria is in the water near the lake's center, not whether toxins are present: a high number does not mean toxins, and a low one does not mean there are none. It covers lakes of about 1 square kilometer and larger, so small ponds, dog parks and most rivers are not covered, and clouds can hide a lake for weeks. It never changes the advisory status above.
Satellite estimates: U.S. EPA Cyanobacteria Assessment Network (CyAN), from Copernicus Sentinel-3 data. Provisional, research-level estimates; EPA does not endorse this site. Checked Oct 22, 2026.
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 |
|---|---|
| Boat Launch | The state's latest record, from Oct 2, 2026, recommends no advisory. |
| swim beach | Reports on file, with no advisory level the state has classified. |
| Outlet/Check 13 | The state's latest record, from May 25, 2023, recommends no advisory. |
| Gianelli Pumping Plant | The state's latest record, from May 25, 2023, recommends no advisory. |
| Boat Launch | Caution advisory, last posted Dec 19, 2022. No all-clear recorded. |
| Gianelli Pumping Plant | The state's latest record, from Dec 19, 2022, recommends no advisory. |
| Outlet/Check 13 | The state's latest record, from Dec 19, 2022, recommends no advisory. |
| boat launch | The state's latest record, from Jul 16, 2021, recommends no advisory. |
| Outlet/Check 13 | The state's latest record, from Jul 16, 2021, recommends no advisory. |
| O'Neill Forebay, Gianelli Pumping Plant | The state's latest record, from Dec 3, 2020, recommends no advisory. |
| O'Neill Forebay, boat launch | The state's latest record, from Dec 3, 2020, recommends no advisory. |
| O'Neill Forebay, Outlet/Check 13 | The state's latest record, from Dec 3, 2020, recommends no advisory. |
| O'Neill Forebay at the Boat Launch and North Swim Beach Area | The state's latest record, from Sep 12, 2019, recommends no advisory. |
| O'Neill Forebay Boat Launch | The state's latest record, from Oct 25, 2018, recommends no advisory. |
| O'Neill Forebay Outlet (Check 13) | The state's latest record, from Oct 25, 2018, recommends no advisory. |
| O'Neill Forebay | The state's latest record, from Sep 20, 2016, recommends no advisory. |
Advisory history
Every advisory record the state has published for O'Neill Forebay, 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 |
|---|---|---|---|
| Oct 2, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Sep 10, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 24, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 7, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 31, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 29, 2026 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 16, 2026 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 16, 2026 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 10, 2026 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 3, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 30, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 29, 2026 | swim beach | NA - refer to Report Details | Under investigation |
| Jun 24, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 12, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 8, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 5, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 22, 2026 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Sep 2, 2025 | Boat Launch | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 22, 2025 | Boat Launch | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 18, 2025 | Boat Launch | Caution | Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 11, 2025 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 1, 2025 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 25, 2025 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Jul 21, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 14, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 7, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 1, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 23, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 12, 2025 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 6, 2025 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 2, 2025 | Boat Launch | None | Lake-wide advisory; Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 28, 2025 | Boat Launch | None | Lake-wide advisory; Testing results below posting triggers; Updates from routine monitoring program-organization |
| Sep 20, 2024 | Boat Launch | None | Lake-wide advisory; Testing results below posting triggers; Updates from routine monitoring program-organization |
| Sep 20, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 11, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 30, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 23, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 20, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 13, 2024 | Boat Launch | Caution | Advisory based on visual and toxins; Updates from routine monitoring program-organization |
| Aug 2, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 19, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 12, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 9, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 28, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 21, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 14, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 7, 2024 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 30, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 23, 2024 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 31, 2023 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 31, 2023 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 18, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Aug 17, 2023 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Aug 8, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jul 28, 2023 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 14, 2023 | Boat Launch | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 7, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 29, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 23, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 15, 2023 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 7, 2023 | Boat Launch | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 25, 2023 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| May 25, 2023 | Boat Launch | Caution | Updates from routine monitoring program-organization |
| May 25, 2023 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| May 2, 2023 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jan 1, 2023 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jan 1, 2023 | Boat Launch | Caution | Updates from routine monitoring program-organization |
| Jan 1, 2023 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Dec 19, 2022 | Boat Launch | Caution | Updates from routine monitoring program-organization |
| Dec 19, 2022 | Gianelli Pumping Plant | None | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 19, 2022 | Outlet/Check 13 | None | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 14, 2022 | Gianelli Pumping Plant | None | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 14, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 14, 2022 | Outlet/Check 13 | None | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 2, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 2, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Dec 2, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 28, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 28, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 28, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 18, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 18, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 18, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 18, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 15, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 15, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 15, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 4, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 4, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 4, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 1, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 1, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Nov 1, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 21, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 21, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 21, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 17, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 17, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 17, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 7, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 7, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Oct 7, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 30, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 30, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 30, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 26, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 26, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 26, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 16, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 16, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 16, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 13, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 13, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 13, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 8, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 8, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Sep 8, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 30, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 30, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 30, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 22, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 22, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 22, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 18, 2022 | Boat Launch | Caution | Advisory based on visual and toxins; Floating/planktonic bloom observed; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 18, 2022 | Gianelli Pumping Plant | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 12, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Aug 9, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Aug 1, 2022 | Outlet/Check 13 | Caution | Advisory based on visual and toxins; Lake-wide advisory; Updates from routine monitoring program-organization |
| Aug 1, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Aug 1, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Aug 1, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Jul 25, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jul 15, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jul 15, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Jul 15, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jul 13, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jul 11, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jul 1, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jun 27, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 27, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jun 20, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 14, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Jun 14, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 14, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jun 14, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Jun 3, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 1, 2022 | Boat Launch | None | Updates from routine monitoring program-organization |
| Jun 1, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Jun 1, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Apr 28, 2022 | Outlet/Check 13 | None | Updates from routine monitoring program-organization |
| Apr 28, 2022 | Gianelli Pumping Plant | None | Updates from routine monitoring program-organization |
| Jul 16, 2021 | boat launch | None | Testing results below posting triggers |
| Jul 16, 2021 | Outlet/Check 13 | None | Testing results below posting triggers |
| Dec 3, 2020 | O'Neill Forebay, Gianelli Pumping Plant | None | De-posting advisory. |
| Dec 3, 2020 | O'Neill Forebay, boat launch | None | De-posting advisory. |
| Dec 3, 2020 | O'Neill Forebay, Outlet/Check 13 | None | De-posting advisory. |
| Sep 12, 2019 | O'Neill Forebay at the Boat Launch and North Swim Beach Area | None | |
| Oct 25, 2018 | O'Neill Forebay Boat Launch | None | |
| Oct 25, 2018 | O'Neill Forebay Outlet (Check 13) | None | |
| Sep 20, 2016 | O'Neill Forebay | None |
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.