Minersville Reservoir Algal Bloom Monitoring 2019

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Update November 12, 2019

Minersville Reservoir, October 23, 2019

The Southwest Utah Public Health Department (SUPHD) has removed the Warning Advisory for Minersville Reservoir. Toxin test results from the Utah Public Health Lab (UPHL) for samples collected by the Division of Water Quality (DWQ) on October 23, 2019, at the Midway Shore at Minersville Reservoir exceeded the recreation health-based threshold for a Warning Advisory for anatoxin-a. Microcystin levels were well below the advisory threshold.

The HABs monitoring season ended on October 31, 2019. The Utah Department of Health and local health departments have determined that the health risk from HABs from primary contact recreation drops with the onset of colder temperatures.

The close of the monitoring season and removal of advisories doesn’t mean HABs are no longer present. HABs can persist throughout the fall and winter and can pose a potential threat to humans and pets. It’s important to recognize the signs of a bloom and take appropriate precautions. Recreators are advised to stay out of the water and avoid any contact with water or scum if they suspect a harmful algal bloom. Hunters and fishers should clean waterfowl and fish well and discard all guts.

Data Summary

Midway Shore

  • Sample date: October 23, 2019
  • Sample Type: Elbow-depth integrated composite sample
  • Microcystin: <2.0 micrograms per liter (µg/L)
  • Anatoxin-a: 0.12 µg/L

Update October 28, 2019

Minersville Reservoir, October 9, 2019

Toxin test results received from the Utah Public Health Lab (UPHL) for samples collected by the Division of Water Quality (DWQ) at the midway shore of Minersville Reservoir on October 9, 2019, showed anatoxin-a and microcystin levels well below the recreation health-based threshold for a Warning Advisory. Cyanobacteria cell-count concentration results are pending from PhycoTech.

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.

Minersville Reservoir remains under a Warning Advisory.

Data Summary

  • Sample date: October 9, 2019
  • Sample type: Elbow-depth integrated composite sample
  • Microcystin: <2.0 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 µg/L

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.