Deer Creek Reservoir Algal Bloom Monitoring 2020

Harmful algal bloom monitoring has ended for the season. Regular sampling updates to the Utah Recreational Water Monitoring Map will resume in spring 2021.

Report a Bloom

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

Call Utah Poison Control Center

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

Update November 2, 2020

The Warning Advisory for Deer Creek Reservoir has been removed as a result of the end of the sampling and monitoring recreation season.

The Utah Division of Water Quality’s water recreation season runs from May 1 through October 31. At this time, no further monitoring or sampling for harmful algal blooms or waterborne pathogens at priority water bodies will be conducted until May 2021.

This does not mean that the potential for harmful algal blooms or waterborne pathogens has ceased. Please remain aware while recreating in or near water bodies and for information on how to keep yourself, your family, and your pets safe, please visit:


Update September 21, 2020

Wasatch County Health Department has issued a Warning Advisory for Deer Creek Reservoir at all public access points.

On September 16, 2020, the DWQ HABs monitoring team visited Deer Creek Reservoir. The monitoring team observed a harmful algal bloom at Rainbow Bay and Island Park Marina. Cyanotoxin and toxigenic cell density samples were collected.

Results delivered from UDAF Lab on September 19, 2020 show the liver toxin, microcystin, concentrations greater than 50 ug/L which is at least 6 times greater than the DWQ/DOH Recreational Health Threshold for an advisory.

Rainbow Bay Closeup

Rainbow Bay Closeup

Deer Creek Rainbow Bay

Rainbow Bay


Update September 2, 2020

Wasatch County Health Department has issued a Health Watch for Deer Creek Reservoir.

On September 2, 2020, the DWQ HABs monitoring team visited Deer Creek Reservoir. The monitoring team observed a harmful algal bloom at Rainbow Bay, Charleston Day Use Area, Island Park Marina, and the shoreline at the State Park. Cyanotoxin and cell density samples were collected and results are pending.


Update July 15, 2020

DWQ HAB monitoring of Deer Creek Reservoir was conducted on July 15, 2020. A low-density HAB was observed at Rainbow Bay, Charleston Day Use Area, Island Park Marina, and the shoreline at the State Park. The dominant HAB material consisted of isolated clumps within the water column. Samples were collected at this location but results from the EPA Lab show cyanotoxins as non-detect.