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Toxic Algae Bloom Around Zion’s National Park

Producers Near Warned to Prevent Animal Exposure to Toxic Algae Bloom Around Zion’s National Park

A Harmful Algae Bloom (HAB) was recently detected in the North Fork of the Virgin River in Zion National Park. The Utah Department of Agriculture and Food is issuing a warning to all producers with livestock along the 15 mile stretch of river from Zion National Park (ZNP), down to Virgin City, to use other sources of water, if available.

Preliminary research is showing that water taken from the Virgin River and distributed in stock tanks is safe. However, having animals drink directly from the river may expose them to the harmful algae. The algae found in the Virgin River seems to not pollute the water so long as it is not disturbed by movement such as animal crossings or recreational traffic. However, because producers cannot predict what is happening upriver from them, it is advised that they use
alternate water sources where available.

Animals that ingest cyanotoxins or cyanobacteria cells may show symptoms such as vomiting, lethargy, diarrhea, convulsions, difficulty breathing and general weakness. Consumption of cyanotoxins can result in livestock deaths.

For producers that irrigate, there is currently limited information on plant update of toxins. The main concern is protecting irrigators from these toxins. Individuals are encouraged to practice good hygiene, especially in the areas where they come in contact with irrigation water.

Microcoleus a benthic algae found in the North Fork of the Virgin River can produce high levels of anatoxin-a, a nervous system cyanotoxin and harmful cyanobacteria. Benthic Samples taken from the river have shown anatoxin-a concentration greater than 55 micrograms per liter in some samples. The Department of Water Quality (DWQ) and Utah Department of Health’s threshold for primary recreation is 15 micrograms per liter. Testing is currently on going from the area above where the river enters ZNP, down to Virgin City. Currently, water column samples taken from the river have not detected cyanotoxins.

UDAF is currently monitoring the situation with other agencies such as the Utah Department of Environmental Quality, Zion National Park, and the Department of Health, and the cities of Springdale, Rockville and Virgin, Utah.

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