June 13, 2018
High cell counts of harmful algae found in Lane County lake
The Oregon Health Authority issued a recreational health advisory today for Dorena Reservoir, located six miles east of Cottage Grove in Lane County.
Water monitoring has confirmed the presence of harmful algae above Oregon Health Authority recreational guideline values for cell counts. Harmful algae at this level are likely to be associated with cyanotoxin concentrations that can be harmful to humans and animals.
Oregon health officials advise recreational visitors to always be alert to signs of harmful algae and avoid areas with visible scum that looks foamy, thick like paint, pea-green, blue-green or brownish-red, or where small bright-green clumps are floating in the water.
People should avoid swimming and high-speed water activities such as water skiing or power boating, in areas where blooms are identified. Although toxins are not absorbed through the skin, people who have skin sensitivities may experience a puffy red rash at the affected area.
People who draw in-home water directly from the affected area are advised to use an alternate water source because private treatment systems are not proven effective for removing algae toxins. However, public drinking water systems can reduce algae toxins through proper filtration and disinfection.
The Row River downstream of Dorena Reservoir is the source of drinking water for the City of Cottage Grove. Drinking water samples at this time show no detections of toxins. If people connected to the City of Cottage Grove public water system have questions about treatment and testing, they should contact the water supplier directly.
Exposure to toxins can produce a variety of symptoms including numbness, tingling and dizziness that can lead to difficulty breathing or heart problems and require immediate medical attention. Symptoms of skin irritation, weakness, diarrhea, nausea, cramps and fainting should also receive medical attention if they persist or worsen. Children and pets are at increased risk for exposure because of their size and level of activity. People who bring their pets to Dorena Reservoir for recreation activities should take special precautions to keep them from drinking from or swimming in the lake.
Drinking water directly from Dorena Reservoir at this time is especially dangerous. OHA Public Health Division officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters. If community members have questions about water available at nearby campgrounds, they should contact campground management.
Oregon health officials recommend that those who choose to eat fish from waters where algae blooms are present remove all fat, skin and organs before cooking, as 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 Dorena Reservoir 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.
The advisory will be lifted when the concern no longer exists.
With proper precautions to avoid activities during which water can be ingested, people are encouraged to visit Dorena Reservoir and enjoy activities such as canoeing, fishing, camping, hiking, biking, picnicking, and bird watching. Boating is safe as long as speeds do not create excessive water spray. Although inhalation risk is much lower than ingestion, it can present a risk.
For health information or to report an illness, contact OHA at 971-673-0400. For campground or lake information, call the local management agency.
OHA maintains an updated list of all health advisories on its website. To learn 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 877-290-6767.
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