TL;DR: Do not swim in, swallow, or drink bloom-affected water at the Powder Arm of Brownlee Reservoir after Oregon officials raised the July precaution to a full advisory on Sept. 21, 2026.
What changed on Sept. 21
Oregon Health Authority issued a recreational use health advisory for the Powder Arm of Brownlee Reservoir on Sept. 21, 2026, according to the Oregon Health Authority : Recreational use advisory issued for Powder Arm of Brownlee Reservoir Sept. 21 : External Relations Division : State of Oregon.
The action applied to the Powder Arm because sampling found cyanotoxins above Recreational Use Values, the state thresholds used for recreation decisions.
A health precaution had covered that arm since July 14 because cyanotoxins were present.
The waterbody is in Baker County.
The Sept. 21 notice was released from Portland.
Media contact for the notice was Erica Heartquist.
For wilderness travelers, the practical meaning is simple: treat visible-bloom areas as no-contact water for mouth, nose, and lungs.
Swimmers, paddlers, hunters, anglers, and families camping nearby should plan alternate water and adjust routes before arrival.
Where the advisory applies
The advisory covers the Powder Arm of Brownlee Reservoir in Baker County.
That arm reaches west from the main reservoir for several miles, according to the State issues health advisory for Powder River Arm of Brownlee Reservoir due to algae | Baker City Herald.
The Herald placed the affected arm near Richland.
The Herald reported that an earlier Brownlee Reservoir advisory dated July 20 had not included the Powder River Arm.
That arm had remained under a precautionary notice until the Sept. 21 upgrade.
A file photograph with the Herald report showed the boat dock at Hewitt Park on the Powder River Arm.
The Herald report was published at 10:55 a.m. Monday, Sept. 21, 2026.
Backcountry users should not assume that clear-looking areas elsewhere on the reservoir system are covered by the same notice.
Use the named location — Powder Arm — when checking campground boards, ranger updates, and health-department postings.
What to avoid in bloom areas
People should avoid swimming where blooms are present.
People should also avoid other water activities with a high chance of swallowing water.
Activities with a high chance of breathing spray or droplets should also be avoided in bloom areas.
Ingestion is the exposure route of concern.
Inhalation of water droplets is also an exposure route of concern.
Toxins are not absorbed through the skin.
People with sensitive skin may develop a puffy red rash after contact.
Oregon Health Authority said its Recreational Use Values are intended to protect the most vulnerable.
Children are specifically included because they are more active and more likely to swallow water during play.
For trip planning, that means adults should keep children out of scummy shorelines, foam lines, floating mats, and discolored coves.
Splash fights, dunking, water toys, and unsupervised wading do not belong in a bloom zone.
What remains open for low-spray recreation
Oregon Health Authority encouraged people to continue visiting the Powder Arm area.
Camping was listed as an activity with lower risk when water is not swallowed or inhaled.
Hiking was listed in the same lower-risk group.
Biking was listed in the same lower-risk group.
Picnicking was listed in the same lower-risk group.
Bird watching was listed in the same lower-risk group.
Motorized boating with a low chance of swallowing spray was listed as acceptable.
Non-motorized boating with a low chance of swallowing spray was also listed as acceptable.
The Herald added that boating is safe as long as speeds do not create excessive spray.
In readiness terms, choose propulsion and speed for dry travel.
Keep bow spray down, avoid sharp turns that throw mist, and sit away from spray.
Rinse hands with clean water before eating.
Change out of wet clothing after accidental splash exposure.
Drinking-water rules for camps and cabins
Drinking water directly from bloom-affected parts of the lake is especially dangerous.
Toxins cannot be removed by boiling.
Toxins cannot be removed by filtering.
Toxins cannot be removed by treating water with camping-style filters.
Contact campground management with questions about water available at nearby campgrounds.
Contact the local health department with questions about water available at day-use areas.
Not all private treatment systems remove cyanotoxins effectively.
People who do not use a well should pay close attention.
People who do not use a public water system should pay close attention.
People who draw household water directly from an affected area should use another source for drinking.
Those same households should use another source for cooking.
For wilderness readiness, carry enough potable water for the full stay.
Do not plan to make lake water safe with a backpack filter, chemical drops, or a rolling boil.
Confirm potable spigots, pump stations, and campground supplies before dark.
How exposure can affect people
Children face increased risk because of their size.
Children face increased risk because of their activity level.
Children face increased risk because they are more likely to swallow water.
Pets face increased risk for the same three reasons.
In people, cyanotoxin exposure can be serious.
Symptoms may resemble food poisoning.
Reported stomach-related symptoms include stomach cramps.
Reported stomach-related symptoms include diarrhea.
Reported stomach-related symptoms include nausea.
Reported stomach-related symptoms include vomiting.
More serious symptoms can include numbness.
More serious symptoms can include tingling.
More serious symptoms can include dizziness.
More serious symptoms can include shortness of breath.
Those symptoms may require medical attention.
For health information or to report an illness, contact OHA at 971-673-0482.
OHA also directed the public to its Cyanobacteria Harmful Algae Blooms website.
Save that phone number in a waterproof trip card.
Seek care promptly for breathing difficulty or neurologic changes after possible exposure.
How to protect dogs on shore and afloat
Dogs can become extremely ill after cyanotoxin exposure.
Dogs can die within minutes to hours after heavy exposure.
Risk routes include drinking the water.
Risk routes include licking wet fur.
Risk routes include eating toxins from floating mats.
Risk routes include eating dried crusts along the shore.
The danger exists regardless of whether a recreational-use advisory is in place.
Symptoms in dogs can include difficulty walking.
Symptoms in dogs can include seizures.
Symptoms in dogs can include lethargy.
Symptoms in dogs can include loss of appetite.
Other symptoms are also possible.
If a dog shows symptoms, seek veterinary treatment as quickly as possible.
OHA recommended keeping dogs on leashes near affected water.
OHA also recommended keeping dogs away from mat material on shore.
For field practice, leash dogs well back from the waterline.
Do not throw sticks or toys into bloom water.
Carry clean dog water and a bowl, plus extra rinse water for coats and paws.
Fish handling when blooms are present
Fish caught where cyanobacteria blooms are present may pose unknown health risks.
OHA recommended not eating fish from those areas.
People who choose to eat such fish should first remove fat.
People who choose to eat such fish should first remove skin.
People who choose to eat such fish should first remove organs.
Toxins are more likely to build up in those tissues.
Removal should occur before cooking.
Removal should occur before freezing.
Fillets should also be rinsed with clean water.
In a survival context, this is not a reliable wild-food source during a bloom.
Prioritize packed food and clean-water meals instead.
If fishing continues for recreation, practice careful release away from mats and scum.