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The City of Portland, Oregon

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Phone: 503-823-7740

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OHA issued health advisory for Willamette River's Ross Island Lagoon


Media contact: Oregon Health Authority, Jonathan Modie, 971-246-9139,



Media contact: Oregon Health Authority, Tony Andersen, 971-239-6483,

Health advisory issued August 19 for Willamette River’s Ross Island Lagoon

A health advisory is being issued today for the Ross Island Lagoon and the mouth of the lagoon as it connects to the Holgate Channel. Ross Island Lagoon is located about one river mile south of downtown Portland in Multnomah County.

The advisory is being issued due to visual confirmation of a blue-green algae bloom in the lagoon. Water monitoring has been completed to confirm the type of blue-green algae present, and the level of any potential toxins that may be produced; however, shipping and analysis of the sample will take time. It is expected that data from the analysis of the bloom sample will be available by the middle of next week. At that time, depending upon the level of toxins found in the sample, Oregon Public Health officials will determine if the advisory can be lifted, or if it will continue in place until the bloom is gone.

Because sample analysis is needed to determine if a bloom is producing toxins, and because of the extreme heat predicted over the weekend and through next week, Oregon Public Health officials believe in order to protect the public health, that an advisory based on visual observation and extent of the bloom is warranted until data is available. This is because if toxins are being produced by the bloom, they can be potentially harmful to people, and even at low levels can be very harmful to pets.

Although the advisory is confined at this time to the Ross Island Lagoon and its mouth, the lagoon is influenced by the dynamics of the river which can cause bloom creep as the water in the lagoon rises and recedes. Always be aware that blooms can develop on any waterbody under the right environmental conditions. The Willamette is a big river and blooms can develop in areas along its course where low flow and slow moving water can be found.

If you see areas where the water is foamy, scummy, thick like paint, pea-green, blue-green or brownish-red, follow the motto “When in doubt, stay out.”

Oregon Public Health officials advise people to avoid swallowing or inhaling water droplets as a result of swimming or high-speed water activities, such as water skiing and power boating in areas where blooms are identified.

Drinking water directly from the river where a bloom is identified is especially dangerous since any toxins produced cannot be removed by boiling, filtering or treating the water with camping-style filters. People who may draw water directly out of this area for drinking or cooking are advised to use an alternative water source. No public drinking or potable water systems are affected.

Oregon health officials recommend that people who choose to eat fish from waters where algae blooms are present remove all fat, skin and organs before cooking, because toxins are more likely to collect in these tissues. Fillets should also be rinsed with clean water. Public health officials also advise people to not eat freshwater clams or mussels from any freshwater source affected by a bloom and that Oregon Department of Fish and Wildlife regulations do not allow the harvest of these shellfish from freshwater sources. Crayfish muscle can be eaten, but internal organs and liquid fat should be discarded.

Exposure to toxins in some cases can produce symptoms very similar to food poisoning such as weakness, cramps, diarrhea, nausea, vomiting and fainting. If these symptoms persist or worsen you should seek medical attention. Other toxins can produce numbness, tingling and dizziness that can lead to difficulty breathing or heart problems, and require immediate medical attention for you or your pet. There is no antidote for these toxins but supportive care can treat symptoms and other concerns.

Contact with cells from a bloom can cause skin irritation and a red, puffy rash in individuals with skin sensitivities or those who develop rashes easily.
Children and pets are at increased risk for exposure because of their size and level of activity. People who bring their pets to areas where blooms are identified should take special precautions to keep them from drinking from or swimming in the water.

People may still visit the lagoon and enjoy activities allowed in the area such as bird watching and boating at low speeds. However, in all areas where a bloom has been identified or an advisory is in place, people should avoid any activities that might expose them to ingestion and inhalation.
For more information, or to report a human or pet illness, contact the Oregon Health Authority at 971-673-0400.

OHA maintains an updated list of all health advisories on its website. To find out if an advisory has been issued or lifted for a specific water body, visit the Harmful Algae Blooms website and select “algae bloom advisories,” or call the Oregon Public Health Division toll-free information line at 1-877-290-6767.

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