Jordanelle Reservoir Algal Bloom 2017

Report a Bloom

24-Hour DEQ Environment Incidents Line: (801) 536-4123

Call Utah Poison Control Center

Call the Poison Control Center

If you believe you or your pet have been exposed to a harmful algal bloom, call (800) 222-1222.


Update November 15, 2017

The Wasatch County Health Department saw a decrease in cyanobacteria levels at Jordanelle Reservoir over the last few weeks. The health department collected a sample at Rock Cliff on November 14, 2017. The sampler reported no visual evidence of current cyanobacteria blooms, and toxin strip test results on the samples were non-detect for both microcystin and anatoxin-a.

Given the lack of visual evidence of continued algal blooms, the test strip results, and the significant decline in potential human exposure due to a decrease in visitors to the area, Wasatch County Health has decided to remove all warning signs and lift the warning advisory.

Update October 17, 2017

Officials have posted warning signs at the Rock Cliff Boat Ramp at Jordanelle Reservoir after a bloom was observed early in the week of October 8, 2017.

The Wasatch County Health Department (WCHD) collected a sample next to the boat ramp at the Rock Cliff recreation area on October 10, 2017. Cyanobacteria cell-count concentrations in the sample were greater than 17 million cells per milliliter (cells/ml). These cell-count densities exceed the 20,000 cells/ml threshold for a warning advisory under UDOH-UDEQ health-based guidance.

Toxin strip tests on the October 10, 2017, sample were non-detect for microcystin and 0.4 micrograms per liter (µ/L) for anatoxin-a. ELISA testing by the Utah Public Health Lab showed 0.28 µ/L for microcystin (ELISA provides a more quantitative analysis than a toxin strip test). A subsequent toxin strip test conducted by WCHD on October 13, 2017, at the boat ramp also showed 0.4 µ/L for anatoxin-a.The health department scientist observed algae at the ramp, but no evidence of algae elsewhere in the reservoir along the accessible shoreline. WCHD collected another sample on October 16, 2017. Toxin strip-tests on this latest sample were also non-detect for microcystin and 0.4 µ/L for anatoxin-a.

Any test results for anatoxin-a above non-detect trigger a warning advisory under UDOH-UDEQ health-based guidance.

The cyanobacteria genus in the sample, Dolichospermum, has the potential to produce high levels of microcystin and anatoxin-a. Although the toxin strip-test results were non-detect for microcystin and relatively low for anatoxin-a, a high potential exists for very high toxin concentrations with these elevated cell counts.

Warning Advisory for Jordanelle Reservoir, Rock Cliff Boat Ramp

A Warning Advisory indicates a moderate relative probability of acute health risk, cell-count density of 20,000 -10 million cells per milliliter (cells/ml), microcystin levels of 4-2,000 micrograms per liter (µg/L), or anatoxin-a levels above non-detect. Advisory actions:

  • Do not swim or water ski
  • Do not drink the water
  • Keep pets and livestock away
  • Clean fish well and discard guts
  • Avoid areas of scum when boating