Conservation groups have called on city council leaders to allow them to display warning notices about the polluted condition of a Southampton river.

Friends of Itchen Estuary and the Junior Conservationists made the appeal following their efforts to highlight the need to clean up the waterway.

Making the case at this month’s court leet ceremony, Gavin Miller from Friends of Itchen Estuary said rivers were frequently treated like “open sewers”.

He said the volunteer group had carried out more than 150 water quality tests, with more than 100 found to have e.coli levels between two and 10 times the level regarded as safe for swimming by the Environment Agency.

Mr Miller said: “We have heard many first-hand accounts of gastrointestinal and skin infections after swimming, rowing and canoeing.

“Southern Water has a copy of our extensive May Itchen e.coli report.

“It is said that there is no likelihood of Portswood sewage works having the tertiary sewage treatment processes which have been installed at Woolston and Millbrook to sterilise the continuously flowing sewage effluent.”

Mr Miller referenced the events of this year’s Boat Race between Oxford and Cambridge, which saw three members of the Oxford crew suffer from gastrointestinal infections.

The rowers had been advised not to enter the water in the river Thames and cover any wounds due to very high e.coli levels.

“Friends of the Itchen Estuary has reported e.coli levels at Cobden Bridge over three times higher than those reported for the river Thames in March,” Mr Miller said.

Members of the Junior Conservationists addressed the court leet jury, putting forward the request to place warning notices at various positions around the river Itchen.

They said: “We hope Southampton City Council will agree there is a moral responsibility to make people aware of the public health risk posed by dangerously high faecal pathogen levels in river Itchen and will agree to our request.”

The court leet presentment was accepted by the jury of civic dignitaries. It will be considered by the council, with a response or update due to be given at a future cabinet meeting.