Dumped animal carcasses have been hauled out of a culvert near Maketu.
The animals, which included cows, pigs, deer guts and carcasses had been in the water for a long time before being reported to the Bay of Plenty Regional Council. Staff had to remove them so the carcasses did not block the culvert or jam open the flood gate.
Regional Council pollution prevention team leader Annabelle Ellis said the outlet flowed into the Maketu estuary.
"This follows illegal dumping of sheep guts, skins and heads in the Wairoa River in western Bay in August this year. This sort of criminal behaviour pollutes the water and then the estuary the water flows into. In this case, if the flood gate was jammed open, tidal waters would flow through or flood waters could back up the drain, flooding low lying land.
"But the worst part is disposing of the mess, which is a very serious health and safety risk to staff, and this happens regularly. We really need someone to step up and identify the culprits," she said.
"If these animals have been stolen, which is likely, they represent a big loss for farmers.
The people who do this have no regard for animal welfare, people's property or the environment."
She urged people to report any dumping they saw, and record details of vehicles, people's clothing and time of day so that a prosecution could be taken.
"People need to speak up, and communities need to stand together to stop this happening in their neighbourhoods, especially in remote areas. The high cost of cleaning up is coming out of their rates," she said.
Any suspicious activity or illegal dumping should be reported to police or Bay of Plenty Regional Council's Pollution Hotline on 0800 884 883.