An Environment Court appeal is under way in Oamaru regarding resource consents granted to Meridian Energy for a $900 million North Bank Tunnel power scheme.
The Lower Waitaki River Management Society is appealing against the four water-only consents granted by Canterbury Regional Council in December, largely on environmental grounds.
The scheme involves building a 34km tunnel on the north bank of Waitaki River.
Water diverted through the tunnel would be used to generate enough electricity to power up to 170,000 homes in the South Island.
If Meridian's water consents are approved by the court, the company will apply for consents for land use and construction.
The hearing is expected to take two weeks.