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Otter 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 Otter 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 4, 2020

On September 02, 2020, the DWQ HABs monitoring team visited Otter Creek Reservoir. The monitoring team observed a harmful algal bloom at the midway shore. Cyanotoxin and toxigenic cyanobacteria cell count densities samples were taken and results are pending.

Results delivered from Phycotech for samples taken on August 18, 2020, and August 27, 2020, show the presence of high toxigenic cell count densities above the DWQ/DOH Recreational Health Threshold for an advisory.

Results delivered from the UDAF lab show for samples taken on August 18, 2020, and August 27, 2020, show the presence of the liver toxin, microcystin, but below the DWQ/DOH Recreational Health Threshold for an advisory.

Otter Creek shoreline

Otter Creek, September 2, 2020


Update August 19, 2020

Otter Creek Reservoir was sampled on August 11. A surface sample consisted of >1.5M cells/ml of toxigenic cyanobacteria. A depth-integrated composite sample consisted of 355K cells/ml of toxigenic cyanobacteria. Both samples exceed the recommended recreational threshold for toxin-producing cyanobacteria concentration (100K cells/ml). The cyanobacteria bloom is dominated by Gloeotrichia, a known toxin-producer. Cyanotoxin results are pending.

Otter Creek Reservoir remains under a Warning Advisory.


Update July 9, 2020

Otter Creek Reservoir is currently under a Health Watch after Utah State Park personnel observed surface and water-column cyanobacteria on July 1, 2020, at the beach near the cabins at the south end of the reservoir. A Health Watch is not a formal advisory level but rather an indicator that a bloom may exist or become more severe based on available information from the DEQ Division of Water Quality (DWQ) and Department of Health. Indicators can include visual reports. The Central Utah Public Health Department and Utah State Parks have been notified.

DWQ plans to sample Otter Creek Reservoir within the next seven days.