Toxic algae mats kill one dog and sicken three others in Utah’s lower Virgin River

State water quality officials have implemented a health watch and are advising people to take precautions before recreating in the water.

(Mark Eddington | The Salt Lake Tribune) The Virgin River in St. George.

St. George • Concerned about the amount of harmful algae toxin in the lower Virgin River, state water quality officials have implemented a health watch and are advising people to take precautions before recreating in the water.

Utah Division of Water Quality officials issued the advisory Friday after learning that one dog has died and three more become seriously ill over the past month due to exposure from algae mats in the Virgin River in the St. George, Bloomington and Hurricane areas.

Hannah Bonner, recreational health advisory program coordinator with the Utah Division of Water Quality, said the dog that died was exposed to harmful algae mats (or benthic cyanobacteria) near Fossil Falls Park on the Virgin River, just east of the St. George Dinosaur Discovery Site at Johnson Farm. Another dog became ill about the same time frame, and two more dogs became sick after exposure earlier this month.

“So that was kind of the canary that led to more investigation,” said Bonner, adding that health officials were unaware at the time that the toxic algae mats were much of a problem on the lower Virgin River and its tributaries. She said subsequent testing showed the problem with harmful algae toxins was pervasive and posed a significant health risk, especially to children and pets.

“The health watch is basically letting people know that these harmful algae mats are present and to be cautious when they are recreating,” Bonner said. “It’s still OK for people to enjoy or play in the water, but before getting in the river or allowing their children or pets to jump in the water, they should ensure that there are no harmful algae mats present.

Bonner said the algae mats have a mucousy texture and range in color from green, brown, yellow or blue. The toxic algae, she added, is often submerged and attached to rocks, aquatic plants and manmade structures such as concrete walls. As they grow in size, the mats can accumulate air bubbles that cause them to detach and float downstream on the surface of the water.

Exposure to the algae’s toxins most often comes when people or animals ingest harmful algae mat material or drink water in areas where the mats are present. Dogs and children, which are often most attracted to the algae and apt to put the material in their mouths, are most at risk for lethal exposure, according to Bonner.

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Common symptoms exhibited by pets exposed to toxic algae mats include excessive drooling, stumbling or muscle tremors, difficulty breathing, weakness, seizures, paralysis, and death. The symptoms typically manifest within minutes or hours after exposure.

Unlike algae blooms, which are often found in lakes and reservoirs and turn most of the water green, Bonner explained, the water in the Virgin River is clean except for the problem areas where the algae mats are present.

“These species of harmful algae occur naturally in a water body,” she said. “But we think changes in climate and the flow patterns of the Virgin River area create environments where they are able to grow in higher densities, which then leads to issues with toxin production.”

Unlike the past, Bonner said, environmental and health officials are doing a better job at linking illnesses — that previously would have been unexplained — to harmful algae. And if the toxic algae seem more problematic today than in the past, Bonner has a simple explanation.

“We’re seeing more recreation than ever before along the Virgin River,” she said. “We have more people and dogs playing in the water and so the probability of someone getting sick is much higher.”

If harmful algae are present in a body of water, state environmental officials advise people not to let their pets drink or swim in the water, eat near the water, or ingest algae or algae mats or dead animals or fish. If a pet has already entered the water, owners are advised to rinse them off immediately and prevent them from licking their fur. Owners who suspect their pets have been exposed should seek immediate help from a veterinarian.

For St. George residents Scott and Coral Nolan, who enjoy taking a Sunday stroll along the Virgin River with their silky terrier Merry on occasion, the health watch is something they take seriously. They keep their dog out of the rivers and lakes, especially during the summer when the water is more stagnant.

“It is a major concern,” Coral said. “That’s why we bring our own water [for the dog] on these walks.”

Aside from issuing a health watch on the lower Virgin River, state water quality officials have issued advisories for the north fork of the Virgin River and LaVerkin Creek in southwestern Utah. Another watch is in place for the Calf Creek Recreation Area near Escalante.

Before recreating in Utah’s rivers, reservoirs or lakes, people can consult HABs.utah.gov to check for toxins and overall water quality.