South Umpqua River algae bloom history
The Oregon Health Authority has issued 10 advisories and precautions for South Umpqua River since 2010, covering 10 of the 16 years from 2010 to 2025.
10 were recreational use health advisories, issued when toxins or cyanobacteria are above Oregon's guideline values for people.
Blooms have been recorded every year for the last 8 years in the data.
That puts South Umpqua River 3rd of the 30 Oregon lakes on this site for the number of years with blooms.
- 2010 1 advisory
- 2011 1 advisory
- 2012 None
- 2013 None
- 2014 None
- 2015 None
- 2016 None
- 2017 None
- 2018 1 advisory
- 2019 1 advisory
- 2020 1 advisory
- 2021 1 advisory
- 2022 1 advisory
- 2023 1 advisory
- 2024 1 advisory
- 2025 1 advisory
Recent South Umpqua River algae reports
| Date | Details | Result |
|---|---|---|
| 1 July 2025 | South Umpqua River and mainstream Umpqua River | Permanent advisory |
| 1 July 2024 | South Umpqua River and mainstream Umpqua River | Permanent advisory |
| 1 July 2023 | South Umpqua River and mainstem Umpqua River | Permanent advisory |
| 1 July 2022 | South Umpqua River and mainstem Umpqua River | Permanent advisory |
| 1 July 2021 | South Umpqua River and mainstem Umpqua River | Permanent advisory |
| 1 July 2020 | South Umpqua River and Lawson Bar | Permanent advisory |
| 1 July 2019 | South Umpqua River and Lawson Bar | Permanent advisory |
| 1 July 2018 | Anatoxin-a | Permanent advisory |
| 29 July 2011 to 9 January 2012 | S. Umpqua River, near Myrtle Creek; Microcystis | Health advisory |
| 24 August 2010 to 8 December 2010 | South Umpqua River Lawson Bar area | Health advisory |
What the Oregon results mean
The Oregon Health Authority issues two kinds of notice for waterbodies it monitors.
- Health advisory
- Toxins or cyanobacteria are above Oregon's recreational guideline values for people. Avoid swimming and water activities that could make you swallow water, and keep pets and children out.
- Precaution
- Toxins are below the guidelines for people but still above Oregon's guideline values for dogs. Keep pets away from blooms and avoid foamy, scummy or paint-like water.
Is South Umpqua River safe for dogs?
Dogs are at the greatest risk from toxic algae. They swallow water while swimming, eat scum on the shore and lick algae off their fur afterwards, and a small amount can kill a dog within hours. With blooms recorded in 10 different years here, take particular care at South Umpqua River.
- Keep your dog on a lead near water that looks green, scummy, foamy or discoloured, and away from algae washed up on the shore.
- If your dog gets in, rinse it straight away with clean water and don't let it lick its coat.
- Call a vet immediately if your dog vomits, drools, has diarrhoea, staggers, shakes or seems weak after being near the water.
Read the full guide to toxic algae and dogs: symptoms, what to do in the first minutes and how vets treat it.
Health effects of toxic algae
Blue-green algae (cyanobacteria) can produce toxins that affect the liver, nervous system and skin. Swallowing water during a bloom can cause stomach pain, vomiting and diarrhoea. Skin contact can cause rashes, and breathing spray from the water can irritate the eyes, nose and throat. Children are at higher risk because they are smaller and more likely to swallow water.
How to spot a bloom
Toxic blooms can look like pea soup, spilled paint or green streaks on the surface, and they can also be blue, brown, white or red. Scum often collects along the shore downwind. If you can't see your feet in knee-deep water, or you aren't sure, stay out.
Don't drink untreated lake water, and don't boil it to make it safe: boiling doesn't destroy algal toxins. If you feel unwell after contact with the water, contact a doctor or Poison Control on 1-800-222-1222.
Nearby lakes with algae reports
- Sru Lake60 km away, 2 reports, last in 2011
Questions about South Umpqua River
Is there algae in South Umpqua River right now?
Oregon issued a permanent advisory for South Umpqua River in 2025, listed on 1 July 2025. Oregon publishes its data once a year, so for today's conditions check the OHA current advisories page and the signs at the shore.
When was the last algae bloom at South Umpqua River?
The most recent entry in Oregon's data is from 1 July 2025 at South Umpqua River and mainstream Umpqua River: a permanent advisory.
Has South Umpqua River had toxic algae before?
Yes. Blooms are recorded in 10 of the 16 years from 2010 to 2025.
Can dogs swim in South Umpqua River?
Keep dogs out of the water whenever a bloom is reported or the water looks green, scummy or discoloured. Dogs are the animals most often killed by algal toxins because they swallow water and lick their fur. If your dog swims in water that might have algae, rinse it with clean water and call a vet if it vomits, drools, staggers or seems weak.
Can you eat fish caught in South Umpqua River during a bloom?
If you keep fish caught during a bloom, health agencies advise removing the guts and liver and rinsing the fillets in clean water before cooking, because toxins collect most in the organs. Some agencies advise not eating fish from an active bloom at all, so follow local guidance.
About this data
This page uses official records from the Oregon Health Authority (OHA), which published as a yearly advisory archive; this season's advisories are on the OHA advisories page. Reports are grouped by waterbody. The site was last rebuilt on 24 October 2026.
States only test some lakes, some of the time, so a lake without a recent report hasn't necessarily been checked. This page is independent, isn't affiliated with the State of Oregon, and isn't health advice. View the source data.