Lake Oroville: toxic algae advisories
Lake Oroville, Butte County. See all Butte County waters.
What the state's records say
Caution advisory, last posted Sep 14, 2026. No all-clear recorded.
2 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 Lake Oroville
The state has an advisory on file for Lake Oroville (Caution advisory), last posted Sep 14, 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.
Satellite estimate (not an advisory)
No satellite reading on file for Lake Oroville in recent weeks. Clouds, ice, or a lake shape the satellite's estimate near its center misses can cause this. It is a gap in the data, not a reading.
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 |
|---|---|
| middle fork upstream of Bean Creek | The state's latest record, from Oct 14, 2026, recommends no advisory. |
| near dam | The state's latest record, from Oct 14, 2026, recommends no advisory. |
| Loafer Creek Swim Beach | The state's latest record, from Oct 14, 2026, recommends no advisory. |
| Loafer Creek Campground — Site 65 (coordinates : 39.6152051,-121.4810537) near boat dock and waterfall | Caution advisory, last posted Sep 14, 2026. No all-clear recorded. |
| North Fork | Caution advisory, last posted Sep 30, 2025. No all-clear recorded. |
| Feathers falls /middle fork | The state's latest record, from Aug 1, 2025, recommends no advisory. |
| near dam | The state's latest record, from Jul 1, 2021, recommends no advisory. |
| Lake Oroville, West Branch | The state's latest record, from Nov 13, 2020, recommends no advisory. |
| Lake Oroville, North Fork | The state's latest record, from Nov 13, 2020, recommends no advisory. |
| Lake Oroville, near dam | The state's latest record, from Nov 13, 2020, recommends no advisory. |
| Lake Oroville North Fork | The state's latest record, from Dec 10, 2019, recommends no advisory. |
| Lake Oroville - South Fork | The state's latest record, from Sep 7, 2018, recommends no advisory. |
| Lake Oroville - Middle Fork | The state's latest record, from Sep 7, 2018, recommends no advisory. |
| North Fork of Lake Oroville | The state's latest record, from Sep 7, 2018, recommends no advisory. |
| Lake Oroville | The state's latest record, from Sep 9, 2016, recommends no advisory. |
Advisory history
Every advisory record the state has published for Lake Oroville, 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 14, 2026 | middle fork upstream of Bean Creek | None | Updates from routine monitoring program-organization |
| Oct 14, 2026 | near dam | None | Updates from routine monitoring program-organization |
| Oct 14, 2026 | middle fork upstream of Bean Creek | None | Updates from routine monitoring program-organization |
| Oct 14, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Oct 13, 2026 | Loafer Creek Campground — Site 65 (coordinates : 39.6152051,-121.4810537) near boat dock and waterfall | NA - refer to Report Details | Suspected illness report closed |
| Oct 2, 2026 | near dam | Caution | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Sep 24, 2026 | middle fork upstream of Bean Creek | Caution | Updates from routine monitoring program-organization |
| Sep 22, 2026 | middle fork upstream of Bean Creek | Caution | visual monitoring based advisory |
| Sep 22, 2026 | Loafer Creek Swim Beach | Caution | Updates from routine monitoring program-organization |
| Sep 14, 2026 | Loafer Creek Campground — Site 65 (coordinates : 39.6152051,-121.4810537) near boat dock and waterfall | Caution | Suspected illness reported |
| Sep 10, 2026 | middle fork upstream of Bean Creek | Caution | visual monitoring based advisory |
| Sep 4, 2026 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 28, 2026 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 17, 2026 | Loafer Creek Swim Beach | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jul 15, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 3, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 30, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 30, 2026 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 12, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 8, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 29, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 22, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 22, 2026 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 22, 2026 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 1, 2026 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Sep 30, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Sep 30, 2025 | North Fork | Caution | Updates from routine monitoring program-organization; visual monitoring based advisory |
| Sep 3, 2025 | North Fork | Caution | Updates from routine monitoring program-organization; visual monitoring based advisory |
| Sep 3, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 29, 2025 | North Fork | Caution | Updates from routine monitoring program-organization; Visual monitoring only-present bloom |
| Aug 1, 2025 | Feathers falls /middle fork | None | End date recorded: Aug 1, 2025. Visual monitoring only-absent bloom |
| Jul 25, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 25, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 18, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 14, 2025 | Feathers falls /middle fork | Caution | visual monitoring based advisory |
| Jul 14, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 3, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 3, 2025 | Feathers falls /middle fork | Caution | visual monitoring based advisory |
| Jul 1, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 1, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 1, 2025 | Feathers falls /middle fork | Visual observation | Suspected bloom, investigation ongoing |
| Jun 20, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 11, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 9, 2025 | near dam | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| May 30, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 30, 2025 | near dam | None | Updates from routine monitoring program-organization |
| May 29, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| May 23, 2025 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 1, 2025 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Oct 28, 2024 | near dam | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Sep 26, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 30, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 30, 2024 | near dam | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Aug 12, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 29, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 29, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 19, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 12, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 3, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 27, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 27, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jun 20, 2024 | Loafer Creek Swim Beach | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 14, 2024 | Loafer Creek Swim Beach | None | Testing results below posting triggers; Updates from routine monitoring program-organization |
| Jun 6, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 30, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 23, 2024 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| May 23, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Apr 25, 2024 | near dam | None | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Oct 27, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Sep 29, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Aug 31, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Aug 28, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Aug 28, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Aug 10, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Aug 8, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Aug 8, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Jul 28, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Jul 28, 2023 | Loafer Creek Swim Beach | NA - refer to Report Details | Updates from routine monitoring program-organization; Visual monitoring only-absent bloom |
| Jul 19, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Jun 30, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Jun 26, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Jun 26, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Jun 15, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| Jun 7, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| May 25, 2023 | Loafer Creek Swim Beach | None | Updates from routine monitoring program-organization |
| May 25, 2023 | near dam | None | Updates from routine monitoring program-organization |
| May 2, 2023 | near dam | None | Updates from routine monitoring program-organization |
| Oct 28, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Sep 30, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Sep 6, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Aug 1, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Jun 27, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Jun 1, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Apr 29, 2022 | near dam | None | Updates from routine monitoring program-organization |
| Jul 1, 2021 | near dam | None | Testing results below posting triggers |
| Nov 13, 2020 | Lake Oroville, West Branch | None | |
| Nov 13, 2020 | Lake Oroville, North Fork | None | |
| Nov 13, 2020 | Lake Oroville, near dam | None | |
| Dec 10, 2019 | Lake Oroville North Fork | None | |
| Sep 7, 2018 | Lake Oroville - South Fork | None | |
| Sep 7, 2018 | Lake Oroville - Middle Fork | None | |
| Sep 7, 2018 | North Fork of Lake Oroville | None | |
| Sep 9, 2016 | Lake Oroville | 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.