A dairy farming company and an earthworks company have each been convicted and fined for carrying out illegal earthworks in the Mangakaeo Stream near Otorohanga.
The earthworks were over a kilometre in length and caused significant environmental damage to the stream in breach of the Resource Management Act.
The prosecution was brought by Waikato Regional Council following a site inspection in June 2017.
In passing sentence from the Hamilton District Court last week, Judge Melanie Harland fined Okawa Limited and Greener Earthmoving Limited $31,550 and $24,150 respectively.
Judge Harland stated that "a further warning to the farming and earthmoving industry should be signalled" and the "need for caution when excavating waterbodies has still not been fully appreciated".