As public health officials investigate what caused illness at Blue Lake Regional Park last weekend, new routine water samples taken Wednesday show a high level of E. coli in the shallow swimming area.
Blue Lake has been closed to swimming since Monday, July 14, and to boating since Tuesday, July 15, while the Multnomah County Health Department investigates an outbreak of vomiting and diarrhea.
The timing and symptoms of the illness park patrons reported suggest norovirus or a similar virus as the cause, said Dr. Jennifer Vines, Deputy Health Officer.
E. coli results from water samples around the time of the outbreak were low and it was ruled out as a cause. Health officials are still talking to people who were at the park July 11-13 and will update the public on the analysis Friday.
The most recent high E. coli results reported today were taken at a time when the lake was closed and suggests a separate incidental contamination of the lake. Such incidents are the reason for routine monitoring during the summer.
Swimming and boating will remain closed until the Health Department determines the lake is safe. Dr. Vines reminds people that even during warm weather, it is important for people to stay home when they are ill and be vigilant about hand washing to prevent the spread of illness.