Carmen, I don't know where you live but if you are swimming in a low level lake there are a few issues that are concerning. A form of meningitis, goes into the body through the nose, mostly, attaches to the membrane between sinuses and brain, causes much damage. Mortality is very high, if caught in early stages it can be treated. If the water temp is above 85 degrees I don't let my children swim in the shallows, usually not found in the deep part of the lake. I am aware of several (3) seperate cases of children dying from this. It's one of my BUTTONS. I was a aquatic scientist for over 20 years. Just be aware, and safe.