Minersville 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 September 26, 2019

Minersville Reservoir, September 10, 2019

Toxin test results and cyanobacteria cell-count concentrations for samples collected by the Division of Water Quality (DWQ) at the midway shore of Minersville Reservoir on September 10, 2019, were below the recreation heath-based threshold for a Warning Advisory. The primary taxon in the samples was Aphanizomenon.

The DWQ monitoring crew observed visible cyanobacteria that resembled grass clippings throughout the water column. The cyanobacteria were also clumped together in some places.

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.

The Warning Advisory remains in place for Minersville Reservoir.

Data Summary

  •  Date: September 10, 2019
  • Sample type: Elbow-depth integrated composite sample
  • Microcystin: 2.4 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 µg/L
  • Cell count concentrations: 12,363 cells per milliliter (cells/mL)

Update September 5, 2019

The Southwest Utah Public Health Department (SWUPHD) has issued a Warning Advisory for Minersville Reservoir after cyanobacteria cell-count results from samples collected by the Division of Water Quality (DWQ) on August 28, 2019, exceeded the recreation health-based threshold for a Warning Advisory. Signs are being placed at the two access points: the pay station and a dirt road on the BLM-owned portion of the lake.

Cyanobacteria cell count results received by DWQ on August 30, 2019, from PhycoTech showed 32,540 cells per milliliter (cells/mL) in the water column. The majority of cells were Dolichospermum, and most of the remaining cyanobacteria were Aphanizomenon.

While both species, particularly Dolichospermum, are known to produce potent cyanotoxins, toxin-test results from the Utah Public Health Lab (UPHL) were well below recreation health-based thresholds for both anatoxin-a and microcystin.

The DWQ monitoring crew observed a large number of visible cyanobacteria in the water column during their August 28, 2019, visit. These cyanobacteria resembled grass clippings and formed isolated clumps. The water was a green hue. The monitoring crew will return to the reservoir next week to collect additional samples.

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

  • Sample Date: August 28, 2019
  • Sample type: Elbow-depth integrated composite sample
  • Microcystin: <2.0 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 µg/L
  • Cell count concentrations: 32,540 cells per milliliter (cells/mL)

Update September 3, 2019

Cyanobacterial cell-count results received by the Division of Water Quality (DWQ) for samples collected on Minersville Reservoir on August 28, 2019, exceeded the recreation health-based threshold for a Warning Advisory. The primary cyanobacteria taxa found in the samples was Dolichospermum, a species that can produce microcystin and anatoxin-a. Toxin test results received from the Utah Public Health Lab (UPHL), however, were well below the advisory threshold.

The DWQ monitoring crew observed a large amount of visible cyanobacteria in the water column. These cyanobacteria resembled grass clippings and formed isolated clumps. The water was a green hue.

A Warning Advisory indicates a moderate relative probability of acute health risk, a 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

  • Sample Type: Elbow-depth integrated composite sample
  • Sample Date: August 28, 2019
  • Microcystin: <2.0 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10µg/L
  • Cell Counts: 32,540 cells per milliliter (cells/mL)

Update August 30, 2019

Minersville Reservoir, August 28, 2019

On August 28, 2019, the Division of Water Quality (DWQ) observed a cyanobacteria bloom at Minersville Reservoir and collected samples. Toxin-screen strip tests were nondetect for microcystin and anatoxin-a. DWQ delivered the samples to the lab for toxin analysis and cell identification and concentration. Results are expected sometime next week.

Minersville Reservoir remains open for recreation. It’s recommended that recreationists not swim or water ski in areas of scum, avoid boating in areas of scum, not ingest untreated water, and keep animals away from the water. Visitors are cautioned to be mindful of water conditions, as blooms may move or disperse depending on temperature, wind, and weather.