Staying safe from toxic algae in freshwater: A kayaker's guide

It’s important that recreational kayakers in the Pacific Northwest (and beyond) learn how to recognize and stay safe from toxic algae blooms while kayaking our fresh waters. In this article, we’ll give you the toxic algae 101 and resources for the latest news.

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We love paddling through the serene waters of the Willamette River and Sauvie Island, where kayakers can have an unparalleled connection to nature on pleasant calmer water. But last Friday, the Oregon Health Authority issued an algae warning, and they have been sharing and updating maps of no-swim zones, like this one from their X (formerly Twitter) feed below.

It's crucial for every kayaker, beginner or intermediate, to understand the threat of toxic algae blooms and navigate with knowledge and caution (and know how to find the most up-to-date information on which paddling, swimming, and kayaking routes to avoid).

Toxic algae is also reported at Willamette Cove. pic.twitter.com/noKcLmOvWo

— Multnomah County, OR (@multco) August 12, 2023

What is toxic algae in freshwater and why kayakers should care

Toxic algae, also known as cyanobacteria or blue-green algae, are microscopic organisms found in fresh and marine waters. These organisms thrive in warm, stagnant water with high nutrient levels. While they naturally occur, certain conditions can cause cyanobacteria to proliferate rapidly, leading to what are sometimes called "blooms."

“Algae and cyanobacteria can rapidly grow out of control, or ‘bloom,’ when water is warm, slow-moving, and full of nutrients.”

— Center for Disease Control (CDC)

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Some of these blooms produce toxins harmful to humans and wildlife when they decay. According to the World Health Organization, these toxins can cause a range of symptoms, from mild irritations to severe gastrointestinal illnesses, depending on the level of exposure.

For kayakers, coming into direct contact with or accidentally ingesting waters affected by toxic algae can significantly impact their health and overall kayaking experience. However, dogs and children are actually at the greatest risk of getting severely ill due to their greater likelihood of swallowing river water. Learn more from the CDC and download a free informational PDF to share with your network.

“Multnomah County said not to swim or play in areas where cyanobacteria blooms have been reported. It said not to drink the water because it causes serious illness. OHA said children and pets are at increased risk.”

— KPTV News, Portland, Oregon

Recognizing toxic algae in the Willamette River and Sauvie Island in Portland

As stated by Multnomah County health officials, toxic algae often appear as spilled green paint or look like pea soup in consistency. Blooms can resemble paint or foam on the surface of the river. And according to the CDC, these blooms don’t always create green water – they can change the water to colors of blue, brown, and even red.

The presence of a foamy, scummy layer, particularly at the shoreline, is another indicator. If these signs are visible, the best measure is to be cautious and avoid contact.

The risks associated with freshwater toxic algae exposure

If you’re exposed to toxic algae, you can experience skin rashes, eye irritations, respiratory issues, stomach cramps, and diarrhea. Severe cases, though rare, can lead to liver and nerve damage and even death.

“You cannot tell if a bloom is harmful by looking at it, so it is best to use caution and stay away.”

— CDC

According to Mulnomah County expert sources, children and pets should absolutely stay out of the infeced water anywhere near where toxic algae has been identified.

“Dogs and children run the highest risk of getting severely ill from green algae.”

— Willamette Week

Dogs can get gravely ill, and even die within minutes to hours from exposure to the toxins by drinking the water, licking their fur, or eating the toxins from floating mats or dried crust along the shore.

Call Poison Control at 1-800-222-1222 if you have questions about cyanobacterial toxin poisoning.

Call the ASPCA Animal Poison Control Centerexternal icon at 1-888-426-4435 or the Pet Poison Helpline at 1-855-764-7661 if you have questions about your pet or livestock. (FYI: There’s a fee for these calls.)

Report cyanobacterial blooms or illnesses to your health department online or by phone.

Key locations in Portland, Oregon to monitor for freshwater algae blooms

Hotspots in Portland, Oregon for potential algae blooms include areas like Sellwood Riverfront Park, Willamette Park, and Cathedral Park. But the dynamic nature of water currents means that blooms can shift locations rapidly (they’re most likely to appear in summer and fall, but they can occur anytime). Always ensure you're updated on the current condition of your chosen paddling spot.

On social media, it’s a good idea for paddlers to follow Multnomah County news online for the latest credible updates on algae blooms and no-swim zones. Oregon Department of Health advisories are also a great place to follow for the most up-to-date news in the state of Oregon (and look for this source in your state as well – here are the quick links to other Pacific Northwest States, including Washington State Department of Health and Idaho State Department of Health).

Safety precautions for kayakers in algae-prone waters

Avoid water contact in suspected areas. If you come into contact, immediately wash the exposed skin and equipment with clean water. And remember, never drink or use the river water for cooking, even if boiled, as boiling doesn't neutralize the toxins. The most common route of toxic algae exposure is ingestion of water.

Staying informed and responsible on the water

Consistently check for advisories and updates in your area. If you come across a suspected new algae bloom location while you’re out paddling on the river, report it immediately to authorities (and be sure to avoid the area and wash down your boat thoroughly with a hose when you get home). A collective effort can help ensure the safety of the kayaking community and the general public.

*It’s important to note that saltwater can also have algae blooms, but for this article we are focused on freshwater algae identification and action.

Summary

Being in the know is key! Equip yourself and your kayaking party with information about potential hazards like toxic freshwater algae, taking the right precautions, and looking out for one another, your kayaking adventures can remain both safe and memorable.