The Oberon Council has to pay $75,000 after releasing untreated sewage into the Fish River.
The local government says the incident did not affect the area's drinking water.
The council is required to conduct tree removal works to improve the river's health.
The mayor of a Central West NSW council has apologised to the community after untreated sewage effluent and toilet paper were released into a river over a nine-day period.
The Oberon Council has entered into an enforceable undertaking with the NSW Environment Protection Authority (EPA) after waste from a pumping station was discharged into the Fish River between September 9 and 17, 2025.
The EPA said samples of the effluent indicated high concentrations of E.coli and faecal bacteria.
Toilet paper, baby wipes and other large items were also observed in the river.
The council will be required to spend $60,000 over three years to remove willow trees along the Fish River and plant native species to improve the stream's health.
It must also pay $15,000 to cover the EPA's costs of investigating the incident.
Oberon Mayor Andrew McKibbon apologised for the incident.
"It was a fault in one of our pumps, so the discharge went out."
Chair of Central Acclimatisation Society, a volunteer group assisting with the restocking waterways with native fish, Wayne Cole said the incident was…