Newcastle Reservoir Algal Bloom Monitoring 2019

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If you believe you or your pet have been exposed to a harmful algal bloom, call (800) 222-1222.

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Update November 12, 2019

Newcastle Reservoir, October 23, 2019

The Southwest Utah Public Health Department (SUPHD) has removed the Warning Advisory for Newcastle 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 Boat Ramp at Newcastle Reservoir exceeded the recreation health-based threshold for a Warning Advisory for anatoxin-a. Microcystin levels were 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

Boat Ramp

  • 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 29, 2019

Newcastle Reservoir, October 19, 2019

Toxin test results received from the Utah Public Health Lab (UPHL) for samples collected by the Division of Water Quality (DWQ) at the boat ramp at Newcastle Reservoir on October 9, 2019, showed anatoxin-a and microcystin levels 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.

Newcastle Reservoir remains under a Warning Advisory.

Data Summary

  • Sample date: October 9, 2019
  • Sample type: Elbow-depth integrated composite sample
  • Microcystin: 3.0 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 mg/L

Update October 3, 2019

Due to levels of microcystin found at Newcastle reservoir that exceed the recreation health-based Danger threshold, Southwest Utah Public Health Department has posted signs at the Newcastle Reservoir boat ramp warning recreators of dangerous levels of cyanotoxins, but has not closed the area. The reservoir remains open to fishing and boating but it is recommended to avoid areas of algae scum when boating, keep animals away, and clean fish well and discard guts.

The Warning Advisory remains in place on Newcastle Reservoir.

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


Update September 27, 2019

Microscopic view of dolichospermum, Newcastle Reservoir, September 24, 2019

The Southwest Utah Public Health Department (SUPHD) issued a Warning Advisory for Newcastle Reservoir after a report of a bloom on the reservoir was confirmed by microscopic identification and visual observation. Toxin test results received on September 27, 2019, confirmed high toxin levels in the reservoir. Signs have been posted to notify the public of the advisory.

Microcystin levels from the surface sample collected by the Division of Water Quality (DWQ) at the boat ramp on September 24, 2019, exceeded the recreation health-based threshold for a Danger Advisory. Microcystin levels from the water column sample exceeded the threshold for a Warning Advisory. Anatoxin-a levels in the surface sample also exceeded the recreation health-based threshold for a Warning Advisory.

A Danger Advisory indicates a high relative probability of acute health risk, cell-count density of >10 million cells per milliliter (cells/mL), microcystin levels >2,000 micrograms per liter (µg/L), or anatoxin-a levels >90 µg/L. 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.

Newcastle Reservoir is currently under a Warning Advisory.

Data Summary

Boat Ramp

  • Sample type: Surface sample
  • Microcystin: 2300 micrograms per liter (µg/L)
  • Anatoxin-a: 0.17 µg/L

Boat Ramp

  • Sample type: Elbow-depth composite sample
  • Microcystin: 56 micrograms per liter (µg/L)
  • Anatoxin-a: <0.10 µg/L