LAS VEGAS (KLAS) — A toxin blamed in a dog’s death two years ago has been detected again in streams at Zion National Park.

A 6-month-old husky puppy named Keanna died within 20 minutes of contact with toxic algae blooms on July 3, 2020, in the Virgin River.

The toxin is especially dangerous to children and dogs, according to the Zion National Park website.

According to an alert posted last week, “Monitoring efforts have detected cyanotoxins harmful to humans and pets in the North Fork of the Virgin River, therefore, the North Fork of the Virgin River and all connected tributaries will be elevated to a Warning Advisory.”

The Park Service warns visitors not to drink stream water anywhere in the park. There is no known recreational water filtration method effective at removing cyanotoxins. Visitors are also advised not to swim or put their head under water anywhere in the park.

La Verkin Creek and North Creek are under a Health Watch.

“Dogs are vulnerable to cyanotoxin exposure because they may bite or accidentally eat/drink material from potentially toxic algal mats,” the Park Service said.

Experts say the bacteria that produce the toxin thrive in warm water. Colonies of bacteria form “shelves” at the waterline.

Extreme heat and a lack of rain — both part of the ongoing drought in the Southwest — promote the growth of the bacteria.

Toxic algae blooms also occur at Lake Mead, and were reported last year at Cottonwood Cove and Nelson’s Landing.

Another problem — swimmer’s itch — isn’t deadly, but has been reported at Lake Mead. It’s associated with a parasite in the water.