Published: Aug 12, 2011 3:47 AM EDT

LEE COUNTY, Fla. -- Tests confirm four southwest Florida beaches now have high levels of bacteria.  Water advisories are in effect at the Port Charlotte Beach Complex in Charlotte County, Bonita Park Beach, Bowditch Beach and Lynn Hall Memorial Park in Lee County.  Yellow advisory signs are up at all four beaches warning swimmers to stay out of the water.  But the reason for the warning is possibly none other than Mother Nature.

Enrique Ramos and his friends are visiting Fort Myers Beach from Indiana.

"We've been here for a whole week, its been raining the whole time and we finally got some good weather and this is the first time I'm hearing about this," said Ramos.

Health officials said Thursday that torrential rain is behind the high levels of bacteria in the water.

"Often times its runoff but it could come from any other sources too.  It might be natural from animal sources and it could be unnatural from fertilizers or different things like that," said Diane Holm, Lee County Health Department.

The Lee County Health Department doesn't test where the bacteria comes from so they can't stop it from happening.  Going into the water could make swimmers sick.

"Gastro-intestinal symptoms are primarily what the bacteria will cause so it will be like diarrhea and cramping," said Holm.

Jeremy Hosch was visiting Fort Myers Beach from Phoenix and despite the warning, he refused to stay out of the water.

"I'm on vacation, its not bothering me.  We're out here getting wet, having fun.  There is bacteria everywhere.  Its not going to make me sick," said Hosch.

Tourists like Steve Cooper were heeding the warning and staying on the sand.

"I'm definitely putting all the antibiotics and stuff on my kids cuts and whatever else I can do to prevent that but it doesn't look like its slowed too many people down," said Cooper.

Some have slowed down.  As for Ramos, he said he'll just have to go for a dip somewhere else.

"I'll come to the beach, I wont swim.  I'll just come get some sunshine, thats all," said Ramos.

The Lee County Health Department will do another round of testing on Monday.  Results are expected to be back on Tuesday afternoon.  Until then the yellow advisory signs will remain up, warning swimmers to stay out of the water.