DEAD fish have been found in the River Chess, leading to walkers being warned to stay clear of the water and not to let their pets in.
Volunteers from the River Chess Association have found sewage from Chesham's treatment works leaking into the water downstream of the Blackwell Hall Lane outflow pipe.
Thames Water, which owns the treatment plant, says the works are running at maximum capacity due to higher than usual levels of groundwater flowing into it.
But environmental groups are concerned at the impact this is having on wildlife, after dead fish were found in the water.
The River Chess Association said this week planned educational events with schools have had to be cancelled due to pollution concerns and members have warned it is best to keep pets from entering the river while further tests are carried out.
Thames Water say they have increased the plant's storage by 160 per cent in recent years and are working with the Environment Agency "in the hope that a robust investment plan can be agreed that deals with the problems of capacity and groundwater ingress at the Chesham Sewage Treatment Works".
Pollution incidents should be first reported to the Environment Agency on 0800 807060 and sewer leaks can be reported to Thames Water on 0845 9200 800.
River Chess Association members have asked people who see any dead fish in the river to contact them on firstname.lastname@example.org, sending photos if possible.