Little Truckee River algae bloom history
California's Water Boards hold 7 bloom reports for Little Truckee River going back to 2022. Reports came in every year since then, with the busiest year being 2024 (3 reports).
State staff recommended an advisory 1 time: 1 Caution. Caution is the lowest level and means people and pets should stay away from scum and discoloured water.
Blooms have been recorded every year for the last 3 years in the data.
- 2022 2 reports
- 2023 2 reports
- 2024 3 reports
When do algae blooms happen at Little Truckee River?
At Little Truckee River, reports are most often logged in June, July and August.
About 100% of reports fall between May and September, when warm, calm, sunny weather lets blue-green algae multiply.
Blooms can appear, move with the wind and fade within hours or days, so the time of year is only a guide.
Recent Little Truckee River algae reports
Recent reports came from 5 different locations around Little Truckee River, including Upper Little Truckee Campground, ~ 1 Mile Down Jackson Meadow Road and Little Truckee River ~2.4mi below Worn Mill Cyn.. A bloom in one cove or beach doesn't mean the whole lake is affected, and conditions can differ a short distance away.
| Date | Location | Result |
|---|---|---|
| 6 August 2024 | Little Truckee River ~0.8mi below Stampede Res. (636PS0086) | Bloom reported |
| 19 June 2024 | Upper Little Truckee Campground | Algal mat alert sign |
| 19 June 2024 | ~ 1 Mile Down Jackson Meadow Road | Algal mat alert sign |
| 14 September 2023 | Little Truckee River ~2.4mi below Worn Mill Cyn. | Bloom reported |
| 30 August 2023 | Below Hwy 89 (636PS0246) | Algal mat alert sign |
| 28 July 2022 | Boyington Mill Campground | Caution |
| 24 July 2022 | Little Truckee River about 1-2 miles north of Boyingtom Mill Campground | Bloom reported |
What the California results mean
California recommends one of three advisory levels when a bloom is checked, matched to the signs posted at the shore.
- Caution
- Toxins may be present. Stay away from scum and keep pets and livestock from drinking the water.
- Warning
- Toxins are at higher levels. No swimming, and keep children and pets away from the water.
- Danger
- High toxin levels. Stay out of the water and off the shore until further notice.
- Bloom reported
- A bloom was reported, often by a member of the public, without a formal advisory level.
Is Little Truckee 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 3 different years here, take particular care at Little Truckee River in June, July and August.
- 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.
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
- Stampede Reservoir2 km away, 2 reports, last in 2023
- Boca Reservoir6 km away, 2 reports, last in 2023
- Prosser Reservoir11 km away, 4 reports, last in 2026
- Prosser Creek14 km away, 3 reports, last in 2023
- Martis Creek Reservoir16 km away, 3 reports, last in 2026
Questions about Little Truckee River
Is there algae in Little Truckee River right now?
There are no bloom reports for Little Truckee River in the last 30 days of California's data. The most recent was a bloom report on 6 August 2024. California's data is checked every day, so for today's conditions check the California HABs Portal map and the signs at the shore.
When was the last algae bloom at Little Truckee River?
The most recent entry in California's data is from 6 August 2024: a bloom report.
Has Little Truckee River had toxic algae before?
Yes. Blooms are recorded every year from 2022 to 2024, most often in June, July and August.
Can dogs swim in Little Truckee 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 Little Truckee 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 California State Water Resources Control Board, which updated daily. Reports are grouped by waterbody, and Little Truckee River combines reports from Nevada County and Sierra County. 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 California, and isn't health advice. View the source data.