Public health officials have issued a warning about high algae levels in the South Umpqua River near Myrtle Creek.

Public health officials have issued a warning about high algae levels in the South Umpqua River near Myrtle Creek.

The water was tested after a dog died and people saw a scum of algae there, officials said in a news release.

Oregon Health Authority's Public Health Division and Douglas County Health Department officials put out the warning this afternoon after tests confirmed the presence of blue-green algae that can produce toxins harmful to humans and animals.

These algae levels are likely to be associated with dangerous toxin concentrations in the water, according to World Health Organization guidelines. Public health officials advise that swallowing or inhaling water droplets should be avoided, as should skin contact with water.

Drinking water from South Umpqua River near Myrtle Creek is especially dangerous as toxins cannot be removed by boiling, filtering or treating the water with camping-style filters.

Exposure to toxins can produce symptoms of 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 particularly susceptible. Dogs have died each of the past two summers after ingesting water from Umpqua River backwaters.

The public will be advised when the algae and its toxins clear.