A Lisburn councillor is calling for agencies to investigate why raw sewage was flowing into the River Lagan on Saturday.
Jenny Palmer, who was contacted by concerned residents, described the state of the towpath as “disgraceful”.
She said: “This is the jewel in the crown for our residents within the Lagan Valley.
“The towpath at Huguenot and Hilden is home to some beautiful birds and natural heritage and yet only a few feet from these birds was an absolutely disgraceful breach of raw sewage.
“It not only endangered the habitat, but the users in the Lagan Valley Regional Park.”
A spokesperson for NI Water said an investigation into what they called a “minor” spillage was underway.
“NI Water is aware of a minor sewage spillage, resulting from a blocked sewer in the Millbrook/Huguenot Drive area of Lisburn.,” the spokesperon said
“The sewer was unblocked and a clean-up effected on Tuesday, March 25.
“The exact cause of this spillage is under investigation.
“NI Water would like to encourage our customers to be aware of the damage they can unwittingly cause to the sewerage system by disposing inappropriate items down the toilet.”