ITV News Meridian's Kara Digby spoke to environmentalists at the River Test
Environmental campaigners are "horrified" that sewage could be pumped into the River Test in Hampshire which is famed for its diverse wildlife and fishing. A temporary pump has been placed at Chilbolton Common near Andover ready to release diluted sewage into the river as part of an emergency plan to prevent flooding.
James Murray, Actor and Activist Angler, said: "It drives me mad. I'm representing 30 river keepers whose livelihoods depend on the health of this river.
"You get local people whose raw sewage is going to bypass the treatment centre and be pumped straight into a chalk stream, jewel of England, river."
Southern Water says the plan is a "last resort" and it would only happen if groundwater overloads the sewage system.
The company says the pipe network is under severe pressure, with groundwater making its way into sewers, clogging up the system.
At the moment, Southern Water is using tankers to take the excess groundwater away, but if the situation gets worse, the company says it will have no choice but to release the overflow into the river.
If Southern Water had to resort to over-pumping, there are plans in place to also release it into the river at Longparish, five miles away.
The River Test is one of around 200 chalk streams in the world and has been labelled a site of Special Scientific Interest.
Sir David Attenborough described chalk streams as one of the rarest habitats on earth.
Howard Taylor, Estate Manager, Freelands Estate: "Season-wise it's just after the salmon and trout have spawned in the river so they have live eggs in nests in the gravel.
"I'm horrified that none of this has been taken into account."
Geoff Cooper, Liberal Democrat prospective candidate, said: "The reason that the pipes are flooding with groundwater is because the pipes are cracking, it's overwhelming the system. They need to invest in the infrastructure."
In a statement Southern Water said: "As part of an emergency plan to prevent flooding, we are preparing overland pipes to remove groundwater and prevent it causing internal flooding of homes, schools and businesses.
"The plan will only be implemented if exceptionally high levels of groundwater overload the sewage system, causing water and sewage to enter people’s homes.
"The geology of the Chilbolton area is highly vulnerable. The plan, drawn up with co-operation from the Environment Agency, may see us pump ground water out of the sewer and drainage network and into nearby watercourses as a last resort.
"An impact assessment is currently being carried out and samples from the network and from the area where releases may be made, are being collected for analysis."
Alex Saunders, Head of Wastewater Networks, said: "We are not using the pipes set up to pump into the Test. At the moment tankers are taking excess flows away for normal treatment.
"This plan will only be implemented as an absolute last resort to prevent flooding within homes, schools and businesses because groundwater levels are exceptionally high and overloading the system.
"It was last used during floods about three years ago and will operate for as short a period as possible.
"Releasing highly diluted waste water into a watercourse like this is something we do everything in our power to avoid, but the alternative would mean homes suffering internal flooding."
The Environment Agency said it takes over-pumping extremely seriously, and if Southern Water do resort to this, then any impacts on local watercourses would be closely monitored.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...