Landowners are being asked to come forward and clean up their part of the River Nene in Northampton after it dropped to worrying levels.
The stretch of an arm running between Bedford Road and Rushmere Road is overgrown with aquatic plants and clogged with fallen trees.
The flow of the water, residents say, has almost stopped and the level is much lower than usual.
Sally Brannan, who lives in nearby Tanfield Lane, Abington, said: “We used to go fishing near the house all the time, but fish are now non-existent.
“There’s thick layer of algae on top and it barely flows. There’s a bouguet of flowers floating in the middle of the river that just sits there.”
Residents and walkers have complained to the Environmemt Agency, which is responsible for the main river.
But because the stretch was designated a mere arm of the Nene in the 1970’s, its powers do not extend that far.
The exception is if there was danger of flooding.
Instead, landowners with plots adjoining the river are responsible for the section in line with their land.
It is understood that some of the land belongs to either Northampton Borough Council or Northamptonshire County Council along with a mix of other organisations, who have all let the river degenerate.
An Environment Agency spokeswoman said it did not have the resources to intervene.
She said: “This is a riparian watercourse, which means maintenance of the bank and the river out to the middle of the water is the responsibility of the landowner.
“We have received no reports of dead or distressed fish in this area, but should you see fish in distress, please report it to our 24-hour incident hotline on 0800 80 70 60.”