Is Upper Truckee River safe? Toxic algae status
El Dorado County, California. Harmful algal bloom (blue-green algae) reports from the California State Water Resources Control Board.
Data checked 24 October 2026. California data is updated daily.
8
bloom reports since 2020
5 of 7
years with a bloom reported (2020–2026)
2
advisories recommended: 2 Caution, 0 Warning, 0 Danger
Year by year
Each box shows bloom reports logged that year, coloured by the highest advisory recommended.
Reports at Upper Truckee River are most often logged in July, August and September.
Recent reports
| Date | Location | Result |
|---|---|---|
| 3 August 2026 | Elks Club Drive | Bloom reported |
| 29 July 2026 | below Portal drive (634UTR600) | Algal mat alert sign |
| 6 August 2025 | Upper Truckee River, above Christmas Valley (forest) (634UTR008) | Algal mat alert sign |
| 23 July 2024 | Trail of Kata Ct | Bloom reported |
| 22 July 2024 | Elks Club | Bloom reported |
| 9 August 2023 | Tahoe Keys Marina/Sailing Lagoon | Bloom reported |
| 28 September 2020 | Upper Truckee River | Caution |
| 25 September 2020 | Upper Truckee River, downstream of STPUD station | Caution |
What the results mean
Algae may be present. Stay away from scum and discoloured water, and keep pets and livestock from drinking it.
Toxins at higher levels. No swimming, and keep pets and children well away from the water.
High toxin levels. Stay out of the water and off the shoreline.
Dogs and toxic algae
Dogs face the greatest risk because they swallow water and lick algae off their fur. If a bloom has been reported, keep dogs out of the water and away from scum on the shore. If your dog swims in water that might have algae, rinse it with clean water straight away and call a vet if it seems unwell.
Common questions
Is Upper Truckee River safe to swim in?
The most recent entry in California's published data is from 3 August 2026: bloom reported (Elks Club Drive). Blooms have been recorded at Upper Truckee River in 5 different years, so treat green, scummy or discoloured water with caution. For current conditions, check the California HABs Portal map and posted signs.
When does Upper Truckee River get algae blooms?
In the state's records, reports are most often logged in July, August and September. Blooms are most likely in warm, calm weather, but they can appear at other times of year.
Source: California State Water Resources Control Board, official data. This page is independent and not affiliated with the State of California.