The company applied for 105 turbines however the draft consent only allows for 61. According to reports the original aim was to build a wind farm in the 300MW range.
The company said the decision would adversely impact the economics of the project, which is located near Turitea.
Mighty River general manager for development Mark Trigg said: "We now need to work through the detail of the decision and consider next steps. The next milestone is the board of inquiry’s final decision."
The project was called in by the minister for the environment Nick Smith in 2008 and referred to an independent board of inquiry.
New Zealand has three onshore projects coming forward in 2011. The biggest of these is Mighty River Power’s Kaiwera Downs, Southland, which should generate 360MW.