Holmes Creek Reservoir Algal Bloom Monitoring 2019

Warning Advisory

  • Do not swim or water ski in this area.
  • Avoid areas of algae scum when boating.
  • Keep animals away.
  • Do not ingest the water.
  • Clean fish well and discard guts.

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.

Get BloomWatch App

Help us track cyanobacteria blooms with your smartphone. Go to cyanos.org for more info.

Update October 2, 2019

The Davis County Health Department (DCHD) issued a Warning Advisory on Holmes Creek Reservoir on October 1, 2019. Toxin test results and cyanobacteria cell-count concentrations from samples collected by the Division of Water Quality (DWQ) on September 26, 2019, exceeded the recreation health-based threshold for a Warning Advisory. DCHD has posted signs at all three entry points to the reservoir.

DCHD will collect follow-up samples this week from the reservoir as well as irrigation water from this source.

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.

Data Summary

Shoreline

  • Sample type: Surface sample
  • Microcystin: <2.0 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 µg/L
  • Cyanobacteria cell counts: 33,557 cells per milliliter (cells/mL)

Shoreline

  • Sample type: Elbow-depth integrated composite sample
  • Microcystin: <.2.0 micrograms per liter (µg/L)
  • Anatoxin-a: 0.14 µg/L
  • Cyanobacteria cell counts: 34,141 cells per milliliter (cells/mL)

Update September 27, 2019

September 27, 2019, Holmes Creek Reservoir

On September 26, 2019, the Division of Water Quality (DWQ) received a report from the member of the public of a suspected algal bloom at Holmes Creek Reservoir. Monitors from Davis County Health Department followed up the same day and observed a cyanobacteria bloom both along the shoreline and within the water column. Monitors sampled for cyanotoxins and cyanobacteria cell-counts.

DWQ delivered the samples to UPHL for toxin analysis and to PhycoTech for cell identification and concentration. Cell count results are expected sometime next week.

Toxin results were delivered on September 27, 2019, and showed anatoxin-a levels of 0.14 micrograms per liter (µg/) from the elbow-depth sample. These levels are above the recreation health-based threshold for a Warning Advisory.

This reservoir is not yet on an official advisory but visitors are cautioned to be mindful of water conditions, as blooms may move or disperse depending on temperature, wind, and weather.

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.