EAU CLAIRE, Wis. (WEAU) -- On sizzling hot summer days, hundreds of people can be seen flocking to a local river to cool off and soak up some sun.

But what many don’t know is that there’s a dirty little secret lurking below the surface that could be dangerous.

The Eau Claire City-County Health Department said it’s just starting to test the water in the Chippewa River again for E. coli bacteria after not testing it for about two decades.

And with so many tubers floating down the Chippewa River in Eau Claire every summer, WEAU 13 News decided to put the water quality to the test in an Assignment 13 investigation.

They may look like beaches, but popular spots for tubing the Chippewa River in Eau Claire are not designated swimming areas; which means they aren’t tested for bacteria.

WEAU took samples of the surface water at Phoenix Park, Owen Park and the Hobbs Boating Landing on May 30.

The water samples were taken to the Eau Claire City-County Health Department to be tested.

The results of the WEAU test showed E. coli levels well above the county’s standards for E. coli at Phoenix and Owen Parks.

Those tests showed more than 2,419 E. coli colonies per 100 milliliters of water.

The standard at which Eau Claire County closes beaches is if the E. coli count passes 1,000 colonies per 100 milliliters of water.

WEAU asked tubers what they thought of the results before they launched from Phoenix Park Sunday afternoon.

“That’s nasty,” said Pat Robertson of Eau Claire.

“That's pretty messed up,” said Mike Clark of Menomonie.

“I don’t know if I want to get in anymore,” said Joy Larson of Eau Claire.

Richard Thoune, the director of the health department said surface water close to the shore will usually test higher.

And in its most recent test of the water below the river’s surface, the health department found the river is safe for tubing.

But whatever the results, Thoune said any E. coli contact is still enough to get you sick, especially if you have open sores or cuts, or if the water gets in your nose or mouth.

“People can contract skin infections and they can certainly contact respiratory and gastrointestinal illnesses from that as well,” Thoune said.

He said the bacteria comes from a number of sources.

“Any other tributary that flows into the river, animal waste, ducks and geese are prime contributors, and in general, any run-off from any on point-source from anywhere along the river,” Thoune said.

E. coli can also spike after a big rainfall and as the weather heats up through the summer.

“I hope this is an important issue and that something is done,” Larson said.

But no matter how dirty water becomes, the health department said it doesn’t have the authority to shut the river down to swimmers.

“It isn't a regulated public beach, there isn't any action we can take from an enforcement authority,” Thoune said.

The Wisconsin Department of Natural Resources said it also wouldn’t try to prevent tubers from going in unless there was a bigger contamination.

Tubers WEAU talked to said they won’t let the river’s dirty little secrets spoil their summer fun.

“Probably just try not to consume any of the water,” Clark said.

“There's E. coli everywhere so just have to make sure you're making healthy choices for yourself,” said Liz Aydt of Eau Claire.

If you’re going to go into the river, the health department strongly suggests washing your hands and face or showering as quickly as possible after you get out.