The Green Party says a decision to allow damming of the Mokihinui River on the West Coast is a mistake.
Commissioners on Tuesday approved Meridian Energy's 100 megawatt dam, 40km north of Westport.
The 85-metre-high dam will create a 14km lake and cost $300 million. The dam will flood 280 hectares of native bush.
Buller District Mayor Pat McManus says the decision will put the West Coast on an even keel with the rest of New Zealand.
He says the region has always had to rely on an unreliable power supply from the other side of the Southern Alps.
However, the Green Party says the dam will devastate the valley. Spokesman Kevin Hague says the party supports the Stockton Plateau hydro scheme, also in the Buller District, which is more environmentally friendly.
United Future Leader Peter Dunne says the granting of resource consent for a hydro dam on the West Coast is a strike against New Zealand as a whole.
Mr Dunne told Morning Report the significance of the Mokihinui River outweighs any potential economic benefits such as the creation of jobs and described the decision as narrow-minded and backward.
Meridian says it expects opponents to take the project to the Environment Court.
