The clearest lake doesn't mean it's the cleanest. A lake's cleanliness level is based on the most commonly measured characteristics, including dissolved oxygen, ammonia, lead, phosphorus, sulfate, total dissolved solids, turbidity and pH. Based on these measurements America's cleanest lake is Lake Louise, Florida. Lake Louise's pH level is 6.98, which promotes life and can even improve human skin health. Where else can you find America's cleanest lakes? Learn more: https://science.howstuffworks.