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Recreational use health advisory reissued for Upper Klamath Lake


August 3, 2018

High levels of cyanobacteria toxins found in some areas of Klamath County water body

The Oregon Health Authority reissued a recreational use health advisory today for Upper Klamath Lake due to water monitoring that has confirmed the presence of a cyanobacteria (harmful algae) bloom and the cyanotoxins they produce. The cyanotoxin concentrations found can be harmful to humans and animals.

Upper Klamath Lake is located off Oregon Route 140, 15 miles west of Klamath Falls in Klamath County.

OHA lifted the recreational use advisory July 31 based on the most current data available, but days later received additional data from a second source showing high levels of cyanotoxins in some areas of the lake. Due to the dynamic nature of cyanobacteria blooms, the lake-wide advisory will stay in effect until all cyanotoxins are below primary recreational values that trigger an advisory, and declining bloom conditions continue for a minimum of two weeks.

Upper Klamath Lake is a very large lake with many areas not currently affected by high cyanotoxins, officials say. Therefore, people should be mindful of the following area of concern in the lake when recreating.

  • Upper Klamath Lake at Eagle Ridge Park to include all of Shoalwater Bay.

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. Dying blooms can also release toxins that may reach into the clear water around them. Some species of cyanobacteria can anchor themselves at the bottom of a water body, live in the sediment, or grow on aquatic plants and release toxins into clear water near the surface.

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.

Drinking water directly from this area of the lake at this time is especially dangerous. OHA public health officials advise campers and other recreational visitors that toxins cannot be removed by boiling, filtering or treating water with camping-style filters.

People who draw in-home water directly from the affected area are advised to use an alternative 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. Upper Klamath Lake is not a source of drinking water for the City of Klamath Falls, but if people connected to public water systems have questions about treatment and testing, they should contact their water supplier. If community members have questions about water available at nearby campgrounds, they should contact campground management.

OHA public health officials recommend that those who choose to eat fish from waters where cyanobacteria blooms are present remove all fat, skin and organs before cooking, as cyanotoxins 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 Upper Klamath Lake 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 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 Eagle Ridge County Park and Shoalwater Bay for recreation activities should take special precautions to keep them from drinking from or swimming in the lake.

With proper precautions to avoid activities during which water can be ingested or inhaled, people are encouraged to visit Shoalwater Bay 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 the Oregon Health Authority at 971-673-0440.

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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 Media contact

Jonathan Modie

OHA External Relations


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