The Safety Committee sampled Dunlap Lake water on May 6 to measure fecal coliform levels prior to Memorial Day. Fecal coliform presence indicates contamination from animal or human waste. Such waste may contain pathogens, like some strains of E. coli, which can infect swimmers. Fecal coliform was detected at low levels and E. coli was present all three samples this month. Results are measured as the number of colony forming units (cfu) in 100 ml of water. Near the dam fecal coliform concentration was lowest at 10 cfu/100ml. The middle lake sample measured 50 cfu/100ml and the upper lake sample was highest at 70 cfu/100ml. To put this in perspective the Illinois Department of Public Health will close a public beach to swimmers when the fecal coliform levels exceed 500 cfu/100ml or E. coli is present at 235 cfu/ml. Fecal coliform in Dunlap Lake water samples are well below a level considered hazardous to swimmers. Dunlap Lake water will be sampled again prior to the 4th of July and Labor Day holidays.
Another water quality concern to swimmers is so-called blue green algae or cyanobacteria. Blooms are indicated by scum on the water surface. A chemical produced by cyanobacteria can be toxic, especially to children and pets. Not all surface scum contains toxins but it is best to avoid contact with water that is suspect.