News Release

Water Advisory for Lake Powell

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News Release Date: July 2, 2025

Glen Canyon National Recreation Area, Utah, Ariz. – The National Park Service has detected the presence of cyanotoxins in the mouth of Antelope Canyon in Lake Powell in concentrations that are at the high end of safe exposure levels. Cyanotoxins are produced by certain types of algae blooms and can be harmful to humans and animals.

The National Park Service recommends boaters to use caution and avoid unnecessary exposure to reservoir water if fishing, boating, or recreating in this area of Lake Powell. Other areas of Lake Powell may also contain these toxins, please use caution. Recreation on the lake remains open throughout Glen Canyon National Recreation Area.

Algal blooms can occur for a variety of reasons. Warm, still water is the perfect breeding ground for cyanobacteria and the addition of nutrients like nitrogen and phosphorus that enter the lake from outside sources, encourage the growth of algae and bacteria. Harmful algae, also known as blue-green algae, is common and natural to our waters and found throughout Arizona and Utah. The algae can multiply rapidly to form blooms and scums, particularly in areas of shallow, warm water. Some algae may be harmless, but please follow the following guidelines on how to stay safe during Harmful Algal Blooms (HABs.)

• Don’t swim in water that has an algal bloom.
• Don’t boat, water ski, or jet-ski on scummy water. These activities can cause toxins to become airborne, increasing the likelihood you will inhale them.
• Clean harvested fish in treated water. As always, remember to clean, drain, and dry all boats and fishing gear.
• Keep children away from scum in the water or along the shore.
• Keep pets or livestock from swimming or drinking from scummy waters.
• Always take a shower after coming into contact with any surface water whether or not an algal bloom appears to be present. Rinse/wash animals immediately if they swim in scummy water and don’t let them lick their fur.

Contact medical care (doctor or veterinarian) if, after exposure to the water, individuals or pets exhibit nausea, vomiting, digestive distress, breathing problems, seizure, or unexplained illness. Water quality staff are sampling and monitoring the situation. Watch our website or follow on our social media sites.

Additional information on Harmful Algal Blooms (HABs) can be found at on Glen Canyon's Lake Powell Water Advisory page and this National Park Service Harmful Algal Blooms article.