Lake Powell Recreational Water Advisory

Take care of basic hygienic practices at high-visitation beaches like at Wahweap.

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Water Recreation Advisory

Lake Powell is one of the largest man-made reservoirs in the U.S.A. With 96 side canyons, nearly 2,000 miles of shoreline, high summer temperatures, and fluctuating reservoir levels, its waters experience a wide range of water quality conditions.
A number of conditions can cause potential water quality issues, including elevated Escherichia coli (E. coli) counts, on Lake Powell, at Lees Ferry, and on Colorado River tributaries. These include:

• High visitation at beaches, at popular houseboat sites, and at other frequently visited areas.

• Rising reservoir waters that come in contact with previously deposited human waste, pet waste, and livestock manure.

• Headwaters of the many canyons along the lake (that are experiencing snow melt, rainwater runoff, or intense monsoonal storms coming from the plateaus and mountains) can pick up E. coli from livestock and wildlife waste and transport it to the reservoir.

• Frequently visited areas (Antelope Canyon, areas near Lone Rock, popular house boat and accessible shoreline beaches, etc.) where visitors fail to use portable toilets, wag bags or other approved waste disposal methods.

• Illegal dumping of septic tanks from private houseboats and larger recreational boats with bathrooms. All rental houseboats are now outfitted to not allow illegal dumping.

• Sandy areas and water frequently used by wildlife such as geese, gulls, ducks, ravens, herons, coyotes, rabbits, and desert bighorn sheep can harbor E.coli.

• Slot canyons, water pockets, and beach areas with warm pools of water cut off from flowing water or the reservoir can be hotspots for E.coli from wildlife, visitors, or other sources. These are often areas where children prefer to play – help steer them away from these areas and ensure their hands are washed before they eat.

Anytime that you do recreational activities (swimming, water skiing, making sand castles, etc.) on the beaches or in the waters of Lake Powell you are strongly encouraged to follow basic hygiene practices:

1. Do not ingest the water

2. Wash your hands before eating and touching your eyes or mouth

3. Shower with soap after participating in any water activities

4. Wash your hands after handling fish, gathering up your water gear and toys, changing out of your swimming suit, etc.

5. Do not enter the water if you have open sores or cuts or if you are currently sick with diarrhea as one of your symptoms

 

Cyanobacteria in a harmful algae bloom on Lake Powell, 2025

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Be On The Watch For Signs of Harmful Algal Blooms

With warm summer water temperatures and plentiful nutrients from monsoonal storms there is a possibility that conditions leading to Harmful Algal Blooms (HABs) may develop. HABs occur when normally occurring cyanobacteria in the water multiply quickly to form visible colonies or blooms. These blooms sometimes produce potent cyanotoxins that pose serious health risks to humans and animals. Stay out of the water and avoid any contact with water or scums if you see pale-green or pea-green scum on or in the water and suspect a waterbody is experiencing a harmful algal bloom.

Report potential harmful algal blooms by emailing [e-mail] with photos and gps coordinates.

How to stay safe during 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.

• Don’t let children play with scum in the water or along the shore.

• Don’t let pets or livestock swim in or drink 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.

 

July 2025 HAB questions and answers

What and where are the algal blooms? Is this common? How did they get there?

Harmful Algal Blooms (HABs) can form from blue-green algae that occurs naturally in waters across Arizona and Utah. At low levels, the algae is normally not a threat to human health. However, the algae can sometimes multiply rapidly to form blooms and scums on or below the water surface. Water that is warm, calm, and shallow is perfect for rapid algae growth into blooms.  These blooms can concentrate cyanobacteria which produce toxins that affect human health.  Nutrients which enter the park and lake from outside sources, such as nitrogen and phosphorus, encourage growth of algae and bacteria.

Can this be prevented?

It is difficult to prevent HABs when warm, calm, shallow water conditions occur in nature. Prevention can come in the form of reducing or controlling outside sources of nutrients, such as from stormwater runoff, agricultural runoff, stock yards, or water treatment discharges. At Lake Powell, prevention comes with the assistance of nature.  Summer monsoons in the area provide thunderstorms and canyon water flows which help to mix lake water and flush canyons, dispersing harmful algae and bacteria into lower levels, often helping to prevent HABs.   

Will Glen Canyon NRA issue any restrictions related to this HAB advisory?

No additional restrictions are currently in effect.

What can people do to still safely enjoy nature in these areas?

Glen Canyon National Recreation Area remains fully open for recreation, including for water activities on Lake Powell.  Activities involving boats, kayaks, and other approved water devices are still ok.  Other activities, such as fishing and swimming, are also ok across Lake Powell and its canyons, with an added caution to look at the water’s surface before you decide to swim, fish or allow your dog in the water. If you see a thin light green film or scum on the water’s surface, or just below the surface, it is best to choose a different water location on the lake to enjoy.  This simple practice helps ensure you can enjoy the nature and grandeur of Lake Powell while remaining healthy.  For those who wish to hike or ride and explore the land areas of the park, there is plenty of open space to enjoy scenery and wildlife.

Safe practices will ensure good travels and good health.  Watch the water and shoreline to make sure children are not playing in thin layers of light green algae or scum.  If such layers are present in the water, choose to swim or boat or jet ski or kayak elsewhere on the lake in better waters. Clean, drain and dry your water equipment and fishing gear as you leave the lake.  Use treated water to clean the fish you catch. 

What are the concerns based on the levels of cyanotoxins discovered in Antelope Canyon?

Our water quality monitoring methods include collecting water samples from algal blooms and using test strips to measure the level of cyanotoxins present. This approach confirmed the toxin microcystin is present in water samples taken from the algal bloom on the water's surface in Antelope Canyon. Drawing a water sample directly from an algal mass floating on the water surface showed a result of >10 ppb (i.e., the measure limit built into the test strips).  Using the same water sample, but mixing before testing, the test result was ~7.5 ppb. In regard to swimming, the US EPA recommends a threshold of 8ppb in regard to a determination of concerns to human health.  Since our data shows the level of the toxin microsystin is near or above the recommended threshold, Glen Canyon National Recreation Area advises visitors to use caution when recreating at locations in Lake Powell where Harmful Algal Blooms (HABs) occur. See the latest US EPA information.

 

Recreational Water Illnesses

Swimming pools, spas, lakes, reservoirs, rivers, slot canyon pools, and sandstone tanks full of water are all potential sources of recreational water illnesses. Recreational water illnesses typically affect a person's stomach and intestines, skin, or respiratory system. If you think you have a recreational water illness that needs medical attention, contact your health care provider.

Stomach and Intestinal Illness

Gastrointestinal illnesses affect a person's stomach and intestines, and can cause diarrhea, nausea, or vomiting. The following gastrointestinal illnesses have been associated with recreational water activities.

Cryptosporidium (Crypto)

Crypto is one of the most common causes of water recreation diarrhea illness in the United States. The germ is found in people's stool. It's highly resistant to chlorine disinfection and can survive in a pool for as long as ten days. Swallowing contaminated water is how people are often infected. To help stop the spread of Crypto, people with diarrhea shouldn't go swimming.

Giardia

Giardia is another common cause of diarrhea found in infected people's stool and beaver are a common carrier. It can take about 45 minutes for this germ to be killed by chlorine disinfection in pools. You shouldn't swim if you have diarrhea and you should always avoid swallowing water while swimming.

Shigella

Shigella causes severe diarrhea, which is often bloody. It can be spread if an infected person with diarrhea swims or plays in areas such as beaches or inadequately disinfected pools. Having hand washing stations with soap near swimming areas helps keep the water from becoming contaminated.

E. coli

People can get an E. coli infection by swallowing lake water while swimming. Symptoms are similar to Shigella and include severe diarrhea and bloody stool. This infection can be life-threatening and cause permanent damage to the kidneys. Swimming at contaminated beaches are potential sources of infection.

Norovirus

Noroviruses are very contagious and can spread through an infected person's stool or vomit. The illness often begins suddenly and usually includes nausea, vomiting, diarrhea, and stomach cramps. Chlorine disinfection helps kill this virus in pools, but lakes and beaches can be contaminated. Avoid swallowing water while swimming to help prevent infection.

Skin Irritations

Skin rashes, boils, allergic reactions to chemicals, and skin damage from the sun can occur when enjoying water recreation activities.

Hot Tub Rash - Pseudomonas dermatitis / Folliculitis

Hot Tub Rash or dermatitis is an infection that causes an itchy bumpy rash on the skin. The rash usually occurs within days of swimming in poorly maintained hot tubs or spas, but can also be spread by swimming in a contaminated pool or lake. Properly maintaining hot tubs and pools helps eliminate the germ that causes this rash.

Swimmer's Itch - Cercarial dermatitis

Swimmer's itch is a rash caused by an allergic reaction to parasites that typically infect some birds and mammals. The parasites come from infected snails which live in lakes, ponds, and oceans. People are not suitable hosts for the parasite's life cycle, so after burrowing into a swimmer's skin, the parasite soon dies. Reduce your risk by not swimming in area's known to have a swimmer's itch problem or where snails are commonly found, and showering or towel drying immediately after leaving the water.

Swimmer's Ear - Otitis externa

Swimmer's ear is an infection of the outer ear canal and can affect anyone, but is most common in children. Symptoms usually start a few days after swimming and include ear pain, itchiness, redness, swelling, and pus draining from the infected ear. It can be treated with antibiotic ear drops. Swimmer's ear is caused when water stays in the ear canal for long periods of time, allowing germs to grow and infect the skin. When swimming, try to keep ears dry.

Cyanobacteria – Harmful Algal Blooms

Cyanobacteria, or blue-green algae, are found in lakes, rivers, ponds, and seawater. Sometimes cyanobacteria is toxic and people can experience skin, eye, or ear irritation with contact. If toxic cyanobacteria is swallowed, it can cause stomach cramps, vomiting, diarrhea, sore throat, fever, headache, muscle and joint pain, or nerve and liver damage. Avoid swimming in or having contact with algal blooms. Don't let pets drink or swim in waters with algal blooms.

Chemical Sensitivity

Some people can experience allergic reactions, such as skin redness and itching, to chemicals used in pools. The reactions commonly occur within an hour or two of being in the water. It's also possible that improper use of chemicals or a chemical release at a pool could expose people to skin or respiratory irritants.

Respiratory Illness

Some water recreation illnesses can affect a person's breathing causing cold or flu-like symptoms, shortness of breath, cough, or a serious infection in the windpipe or lungs.

Legionellosis

Legionnaire disease is a serious infection that creates life threatening pneumonia. Another less serious form of the infection is Pontiac fever, which has the same early symptoms of Legionnaire disease (body pain and weakness, headache, fever, chills, and cough) but isn't associated with pneumonia or death. The germ that causes the disease can be found in streams, ponds or in man-made structures such as fountains or spas. People are typically infected by breathing in contaminated water vapor or steam. Proper maintenance of pools and spas helps eliminate this germ.

Source: Washington Department of Health Website
More information on each illness can be found on the Center for Disease Control website

 

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