Peter Wiessing, the council's Kaitaia area manager, told Newshub the dumping was not only illegal but dangerous to public health.

"This is a very popular swimming lake and it's quite disrespectful and offensive that someone would throw material there, given that these things, if they're left there for any length of time, can degrade and cause human health issues."

However, he says the lake - commonly known as 'Coca Cola Lake' for its distinctive colour - is now safe to swim in again because the carcasses were not left in the water for long.

"The carcasses that were dumped in the lake were fairly fresh. There's no evidence of any contamination because they were taken out so quickly."