A right to discharge used factory water into a Bay of Plenty river is to go to the Environment Court.
In November, the Bay of Plenty Regional Council granted Tasman Pulp and Paper Mill the right to continue discharging waste water into the Tarawera River for a further 25 years.
The Kawerau-based mill had previously poured used water into the river and sought a longer renewal for 35 years.
The council ruled that, though discharge did cause discolouration of the river water, it produced no significant harm.
But 2500 people from Ngati Rangitihi, a sub-tribe of Te Arawa, claim the discharge harms development opportunities at its home in Matata, near the river mouth and has filed an appeal in the Environment Court.
Mill owners Norske Skog and Carter Holt Harvey could not be reached for comment.