Search all of DEQ Main Menu Utah Department of Environmental Quality
Secondary Navigation

Deer Creek Reservoir Algal Bloom 2017

Update September 15, 2017

September 11, 2017

Division of Water Quality (DWQ) monitoring crews encountered a shoreline-localized cyanobacteria bloom on Deer Creek reservoir during routine E. coli monitoring on Monday September 11. The bloom was observed along the shoreline at Island Park Marina, but did not appear to be located in the open water, Rainbow Bay, or the main boat launch.

The monitoring crew collected two samples: a surface sample and a depth-integrated sample. Toxin strip tests on the surface sample tested >10 micrograms per liter (µg/L) for microcystins; the integrated sample had a result of 2.5 µg/L. According to UDOH-UDEQ health guidance, microcystin levels >4 µg/L trigger a recreational warning advisory. Concentrations for cylindrospermopsin and anatoxin-a were non-detect.

DWQ sent the samples to the Utah Public Health Lab on September 12, 2017, for Enzyme-Linked Immunosorbent Assay (ELISA) for further microcystins testing.

Deer Creek Algal Bloom

Algal Bloom observed along shoreline in Island Park Area

September 12

Lab testing from 9/11 samples resulted in microcystins of >100 µg/L. Central Utah Water Conservancy District collected phytoplankton samples at several locations in the reservoir. We are still waiting on those cell counts. They reported that the algal mat has almost dispersed.

Deer Creek Algal Bloom

September 13

Toxin test trips were taken along both the shore and by the dock. Shore results > 10 µg/L and the dock was 0 µg/L. Wasatch County Health Department posted warnings signs at Island Park. They will continue to monitor the site and remove signs when appropriate.

Red dots show the warning signs locations

Red dots show the warning signs locations.

Deer Creek Algal Bloom

Thursday, Sept 14

Toxin tests strips were all non-detects. Wasatch County Health Department will sample again or Monday (9/18).

Deer Creek Reservoir Continuous BGA (blue-green algae) results from 9/9 to 9/15

Continuous BGA (blue-green algae) results from 9/9 to 9/15

Update September 13, 2017

Division of Water Quality (DWQ) monitoring crews encountered a shoreline-localized cyanobacteria bloom on Deer Creek reservoir during routine E. coli monitoring on September 11, 2017. The bloom was observed along the shoreline at Island Park Marina, but did not appear to be located in the open water, Rainbow Bay, or the main boat launch.

The monitoring crew collected two samples: a surface sample and a depth-integrated sample. Toxin strip tests on the surface sample tested >10 micrograms per liter (µ/L) for microcystins; the integrated sample had a result of 2.5 µ/L. According to UDOH-UDEQ health guidance, microcystin levels >4 µ/L trigger a recreational warning advisory. Concentrations for cylindrospermopsin and anatoxin-a were non-detect.

DWQ sent the samples to the Utah Public Health Lab on September 12, 2017, for Enzyme-Linked Immunosorbent Assay (ELISA) for further microcystins testing.

Warning Advisory for Deer Creek Reservoir

A Warning Advisory indicates a moderate relative probability of acute health risk, cell count density of 20,000 -10 million, 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