Virgin River Watershed Recreational Water Quality Monitoring - Utah Department of Environmental Quality

This webpage is updated monthly with information provided by Zion National Park. The Utah Division of Water Quality does not routinely conduct HAB sampling within the Virgin River Watershed. If you have additional questions, please contact Zion National Park by calling (435) 772-3256.

Babylon Road Area

Confluence Park

George Baker

Learn More About Harmful Algal Blooms

(opens in a new tab)

Report a Bloom • (801) 536-4123

Utah Poison Control • (800) 222-1222

This webpage is updated with information provided by Zion National Park.

View the Map Full Screen

(opens in a new tab)

Updates

Babylon Road Area:
Check for mats

Check for algae mats: do not touch them, keep dogs and babies away, and wading is ok.

June 29, 2026: Harmful algae mats monitoring update

CHECK FIRST: Our monitoring team observed a small number of harmful algae mats at Babylon Trail and Babylon Area. Direct contact with or ingestion of mats can make humans and animals sick. Avoid mats while you recreate.

Do not touch or eat any algae mats
Keep children away from any algae mats
Keep animals away from any algae mats
Wading, fishing, and paddling are OK
Know how to recognize a harmful algae mats

June 5, 2026: Harmful algae mats monitoring update

BE CAREFUL: Harmful algae mats are present at the Babylon Road Area. Direct contact with or ingestion of mats can make humans sick and may be lethal for dogs.

If you visit the watershed:

Keep dogs and young children away from the water
Do not touch or eat any algae mats
Don't filter drinking water here
Wading, paddling, and fishing are OK
Know how to recognize a harmful algae mats

May 14, 2026: Harmful algae mats monitoring update

Warning: Local officials have confirmed the presence of harmful algae mats at the Babylon Road area.

We recommend:
Harmful algae mats are present. Touching or eating mats can make humans sick and may be deadly for dogs.

Do not filter drinking water here
Do not touch or eat algae mats
Keep dogs and young children away
Wading, fishing and paddling are OK

Select the “Learn More” tab at the top of this page for information on how to enjoy the water safely.

Confluence Park:
Check for mats

June 5, 2026: Harmful algae mats monitoring update

WARNING: Harmful algae mats are present at Confluence Park. Multiple lines of evidence suggest that a dog died on the week of May 11-13 after consuming algae mats at this location. Although field inspections have not occurred, harmful algae mats are likely present. Touching or eating mats can make humans sick and may be deadly for dogs.

If you visit the watershed:

Keep dogs and young children away from the water
Do not touch or eat any algae mats
Don't filter drinking water here
Wading, paddling, and fishing are OK
Know how to recognize a harmful algae mats

May 13, 2026: Harmful algae mats monitoring update

WARNING: Multiple lines of evidence suggest that a dog died this week after consuming algae mats at this location. Although field inspections have not occurred, harmful algae mats are likely present. Touching or eating mats can make humans sick and may be deadly for dogs.

Do not touch or eat any algae mats
Keep children away from any algae mats
Keep animals away from any algae mats
Wading, fishing, and paddling are OK
Know how to recognize a harmful algae mats

George Baker:
Check for mats

July 17, 2026: Harmful algae mats monitoring update

BE CAREFUL: Harmful algae mats are present at George Barker. Direct contact with or ingestion of mats can make humans sick and may be lethal for dogs.

If you visit the river:

Keep dogs and young children away from the water
Do not touch or eat any algae mats
Don't filter drinking water here
Wading, paddling, and fishing are OK
Know how to recognize a harmful algae mats

Since July 2020, the National Park Service (NPS) in Zion National Park has been monitoring harmful algal bloom (HAB) toxin production on a monthly basis at several water bodies inside the park.

Cyanobacteria and HABs in the Virgin River are different from what is commonly seen in Utah’s lakes and reservoirs. This cyanobacteria grows in mats on the bottom of the riverbed, often attached to rocks or plants. It may be brown, black, tan, or green and comes in a variety of textures.

Harmful Algal Bloom Example: "Benthic Mats"

How can I stay safe while recreating in Zion National Park?

Check water body conditions before visiting.
Know what to look for so you can avoid coming into contact with cyanobacterial mats.
Do not swim or put your head under water. Children are especially vulnerable to accidental exposure.
Keep dogs on a leash and out of water. Dogs are vulnerable to toxin exposure as they may bite or accidentally eat/drink material from cyanobacterial mats.
Shower after coming into contact with recreational water.
Wash hands with clean water before eating or preparing food.
Do not drink any water from streams or rivers in Zion National Park. There is no known recreational filtration method that can remove these toxins. If you must filter water, get it directly from a spring.

Why are habs in zion national park dangerous?

Cyanobacteria living in the Virgin River (including “The Narrows” and other locations in Zion Canyon) may produce dangerous toxins. These toxins target the liver and nervous system and are dangerous for people and animals.

Toxins can be absorbed through eyes, nose, or mouth by swimming in contaminated water – very small or even invisible pieces of the cyanobacterial growth may contain enough toxin to cause harm.

What are the symptoms of HAB exposure?

Symptoms of toxin exposure include:

Skin rash
Salivation
Drowsiness
Tingling or numbness,
Incoherent speech
Muscle contractions or twitching
Vomiting and/or diarrhea

If you think you have been exposed, immediately contact the Utah Poison Control Center at (800) 222-1222.

How does Zion National Park determine exposure risk?

The NPS, DWQ, and Utah Department of Health and Human Services have worked to characterize exposure risk from HABs in the Virgin River in order to better compare toxin results to the current DWQ/DHHS HAB Guidance and Recreational Thresholds.

Zion National Park staff rely on three lines of evidence for issuing recreational advisories:

The presence or absence of known toxin-producing cyanobacteria species.
The presence or absence of toxins in the water body using SPATT bags.
‘Benthic disturbance sampling’ – a process where a water quality scientist walks along a cyanobacterial mat (imitating recreation) and then measures the concentration of toxins produced.

Virgin River Watershed Recreational Monitoring

Current Conditions