August 7, 2018
Testing confirms no cyanotoxins in algal bloom
The Oregon Health Authority (OHA) has lifted the recreational use health advisory issued Aug. 3 for the Willamette River's Ross Island Lagoon, located about a mile south of downtown Portland in Multnomah County.
Water monitoring has confirmed that the bloom in Ross Island Lagoon is not producing toxins at this time, prompting OHA to lift the recreational use advisory. Since the bloom is still present in the lagoon, future cyanotoxin testing will be scheduled to ensure levels remain below advisory values. The advisory will be re-issued if levels are elevated.
Although the advisory has been lifted, conditions can change due to the dynamics of the Willamette River, which can cause the water level within the lagoon to rise and recede. People should always be aware that blooms can develop on any water body under the right environmental conditions, and can grow and disappear throughout the season. The Willamette River is large, and blooms can develop in areas of low flow and slow water movement, officials say.
Recreational visitors to the Willamette are advised to always be alert to signs of cyanobacterial (harmful algae) blooms as you are your own best advocate when it comes to keeping you and your family safe while recreating.
People, and especially small children, and pets should avoid recreating in areas where the water is foamy, scummy, thick like paint, pea-green, blue-green or brownish red in color, if a thick mat of blue-green algae is visible in the water, or bright green cells are suspended in the water column. If you observe these signs in the water you are encouraged to avoid activities that cause you to swallow water or inhale droplets, such as swimming or high-speed water activities.
It's possible cyanotoxins can still exist in clear water. Sometimes, cyanobacteria can move into another area, making water that once looked foamy, scummy or discolored now look clear. However, when a bloom dies elsewhere in the water body, it can release toxins that may reach into the clear water. There also are species of cyanobacteria that anchor themselves at the bottom of a water body, live in the sediment, or can grow on aquatic plants and release toxins into clear water near the surface.
For recreational health information, to report human or pet illnesses due to blooms or cyanotoxins in recreational waters, contact the Oregon Health Authority at 971-673-0440.
For information about recreational advisories issued or lifted for the season, contact the Oregon Public Health toll-free information line at 1-877-290-6767 or visit the Harmful Algae Blooms website and select "Algae Bloom Advisories."
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