The Department of Conservation (DOC) is calling for environment commissioners to overturn Meridian Energy's resource consent for a $300 million dam project on the Mokihinui River, north of Wesport.
DOC chief executive Al Morrison appealed to the Environment Court today, against the erection of the of 80 metre-high 300m-wide dam, which the state-owned enterprise wants to build 3km upstream of the Seddonville settlement, creating a 14km-long lake.
The DOC opposed the proposal during consent hearings. arguing the dam, the associated transmission line and other infrastructure would have significant environmental effects on the river and native wildlife.
Mr Morrison today outlined these as continuing objections to the proposed 337ha reservoir, dam and electricity pylons 40km north of Westport.
Two of three commissioners who heard Meridian's application to the West Coast regional council and the Buller District Council agreed to grant resource consents, but a third said such consents could not be sustainably managed.
Mr Morrison said many of the consent conditions laid down by the panel of commissioners were unworkable or unenforceable, or would require his permission: much of the new lake will be on land managed by DOC.
Other conditions incorrectly applied principles of adaptive management or unlawfully delegated decisions on matters that ought to have been determined in the consents.
The decision failed to sustain the potential of the Mokihinui River gorge, safeguard the river catchment, or to avoid damage to the gorge and the route for transmission lines across the Denniston plateau and the Stockton plateau.
The catchment had high natural values and the river was largely unmodified, with significant indigenous vegetation around it.
Damming of the river - holding back sediments - would worsen the effects of climate change on coastal erosion.
Mr Morrison said the river was of significant cultural importance to Maori.
But he did not mention Te Runanga o Ngati Waewae, a sub-tribe of Ngai Tahu which originally strenuously opposed the dam, later came out in support of the scheme.
The sub-tribe explained that Meridian had agreed to set up a cultural fund, and would pay the iwi to monitor the dam and its impact.
Forest and Bird South Island manager Chris Todd this month described the proposed lake as "the biggest inundation of conservation land ever in New Zealand".
"If we are now damming pristine rivers, then nothing is safe... it's a huge backward step for conservation," he said.
Meridian chief executive Tim Lusk has said the hydro project had the "overwhelming support" of locals, and Mokihinui would allow the region to use its own natural resources to provide a source of clean, renewable power.
Meridian has previously said the scheme would produce between 310 and 360 gigawatt hours of electricity per year, powering about 45,000 homes on the West Coast.
If it goes ahead, construction is expected to take three years and employ more than 300 workers, dropping to just six jobs running the power plant once the hydro scheme is running.
