Milford-on-Sea Parish Council has warned residents that high levels of E.coli have been detected in Danes Stream, Hampshire.
E.coli are a group of bacteria which are found in the lining of the human gut, however, some E.coli bacteria can cause serious illness.
Symptoms include stomach cramps, diarrhoea, fever and nausea.
A spokesperson shared online: “We have been advised by the Environment Agency that high levels of E.Coli have been detected in the Danes Stream.
“At the recorded level there is a clear risk of illness for anyone coming into contact with the water including walkers and dogs.
“We are awaiting a further update from the Environment Agency.
“A group of councillors are meeting tomorrow at 9am to put up warning signs.”
The Environment Agency has been contacted for a comment.