Current Cyanobacteria Advisories

The 2026 monitoring season began on May 4th. Current cyanobacteria harmful algae bloom (cyanoHAB) recreational use health advisories are listed in the table below and displayed on the Oregon Harmful Algae Bloom Advisories map. Both the table and map are updated regularly with the latest information as advisories are issued and lifted throughout the season for monitored waterbodies.

Help us improve cyanoHAB advisory notifications! We're collecting feedback to improve how we share information about water quality. Please take a few minutes to complete our short survey.

Click the buttons below to access the interactive Oregon Harmful Algae Bloom Advisories map:

Advisory Map (English) Mapa de Advertencia (Español) Advisory Map (Mobile) Mapa de Advertencia (Móvil)

Report a suspected cyanobacteria harmful algae bloom or related illness:

CyanoHAB Reporting Form Human Illness Reporting Form Animal Illness Reporting Form

Advisory Levels

permanent = Advisory in effect = Precaution in effect lifted = Advisory/precaution has been lifted

Advisory: Cyanotoxin levels have been confirmed through testing to be unsafe for swimming and boating at speeds that cause water to spray into your face, OR a combination of conditions indicate that cyanotoxin levels may be unsafe for these activities. Toxin levels are unsafe for pets.
Precaution: A bloom has been confirmed or cyanotoxins are present but at levels that are safe for human recreation. Toxins levels may still be unsafe for pets.
Advisory downgraded to precaution: An 'advisory' is downgraded to a 'precaution' when water testing shows safe levels for human recreation, but a bloom or toxins are still present. Toxin levels may still be unsafe for pets.
Precaution lifted: A 'precaution' is lifted when testing shows cyanotoxins are not present, or when the bloom is visibly gone.

Waterbody	Status	Date/Link	County	Toxin/ Measure	Details
Detroit Reservoir	Precaution	6/12/2026	Linn & Marion	Microcystin 0.78 ug/L
Lake Billy Chinook	Advisory	6/12/2026	Jefferson	Microcystin 15.5 ug/L	Visible bloom
Thief Valley Reservoir	Precaution	6/12/2026	Baker & Union	Microcystin 0.21 ug/L
Gerber Reservoir	Precaution	6/12/2026	Klamath		Visible bloom
South Tenmile Lake	Precaution	6/5/2026	Coos	Microcytin/ 0.29 ug/L
Cullaby Lake	Precaution	6/5/2026	Clatsop	Microcystin/ 0.39 ug/L
Hyatt Lake	Precaution	6/3/2026	Jackson	Anatoxin-a 0.54 ug/L	Visible bloom
Sturgeon Lake	Precaution	5/29/2026	Columbia & Multnomah		Visible bloom
Upper Klamath National Wildlife Refuge	Advisory	5/28/2026	Klamath	Microcystin/ 8.27 ug/L
Lost Creek Lake	Precaution Lifted	5/29/2026	Jackson	Microcystin/ Non-detect
Agency Lake	Precaution	5/21/2026	Klamath		Visible bloom
Upper Klamath Lake	Precaution	5/21/2026	Klamath		Visible bloom
Haystack Reservoir	Precaution	5/15/2026	Jefferson	Microcystin/ 0.63 ug/L
Ochoco Reservoir	Precaution	5/15/2026	Crook	Microcystin/ 0.16 ug/L
Willow Creek Reservoir	Precaution	5/15/2026	Morrow		Visible bloom
McKay Reservoir	Precaution	5/15/2026	Umatilla		Visible bloom
South Umpqua River and mainstream Umpqua River	Permanent Advisory	Posted Sign	Douglas

Douglas County Permanent Recreational Use Advisory: South Umpqua River and mainstem Umpqua River

The advisory covers the South Umpqua River from Canyonville downstream to the confluence with the mainstem Umpqua River, and the mainstem Umpqua River downstream past Elkton to Sawyers Rapids. Pools in the bedrock along the rivers edge are known to develop cyanobacteria blooms that can be harmful to pets and people. Signs have been posted at several access areas along the river.

Remember: Only a fraction of all waterbodies in Oregon are monitored or sampled due to limited resources. A waterbody with no recreational health advisory does not mean that a bloom is not present.

You are your own best advocate when ensuring your safety, and that of your family and pets. Be aware and "when in doubt, stay out."

Advisories in other states: This page only includes health advisories for cyanoHABs affecting waterbodies in the state of Oregon. To find advisories for bordering states, please refer to the following websites:

California: Harmful Algal Bloom Reports Map
Idaho: Harmful Algal Bloom Water Quality Testing Results
Nevada: Harmful Algal Bloom Dashboard
Washington: Harmful Algal Bloom Map