The head of Forest and Bird says the Mt Messenger Bypass project on State Highway 3 in Taranaki is yet another example of nature being sacrificed in favour of human convenience.
The $200 million project is inching closer to a start date after a High Court appeal against re-routing the highway through the Mangapēpeke Valley was lost earlier in December.
Forest and Bird chief executive Kevin Hague said he was not a party to this appeal, but had opposed the bypass from the beginning.
"We are sad about the outcome but the outcome does seem to be settled now. We don't think we can change it," Hague said.
"For us, it is another example of nature once again giving way to kind of human endeavour and we've just lost so much we actually can't afford to keep sacrificing nature for human convenience, which is exactly what the bypass is about."
The project would damage some vulnerable areas, Hague said.
The prime minister had spoken about finding a balance between the competing demands of nature and human development, he said.
"The problem with that metaphor is that the point of balance was reached - I don't know - 100 years ago. We are long, long beyond that point of balance.
"We have two thirds of our ecosystem that is highly damaged, more than 4000 species at risk or threatened with extinction, 12 out of the 13 native habitat types that Manaaki Whenua [Landcare Research] monitors continuing to be destroyed over the past 10 years.
"So what we need to do to achieve a point of balance is restore nature not destroy more of it."
The planned 5.2km bypass, which has been supported by the transport lobby and Taranaki local government authorities, is shorter than the existing SH3 route over Mt Messenger, and the New Zealand Transport Agency Waka Kotahi believed it would save between four and six and half minutes.
It includes a 120m-long bridge over wetland and a 230m long tunnel.
Waka Kotahi had to satisfy the Environment Court it was able to mitigate the ecological and environmental effects of the project before consents were granted.
Previously, the Transport Agency said the route was the least ecologically destructive and would deliver road safety and resilience improvements.
Ngāti Tama approved a Transport Agency deal swapping 20 hectares of its land needed for the bypass for a 120-hectare parcel that will give it better access to a block of Treaty settlement land.
The deal also includes a $7.7 million mitigation and compensation payment, and an ongoing pest management scheme.
The Department of Conservation, which initially submitted against the route, was now also onboard for the project.
Chief planning advisor David Spiers previously said its position was based on conservation outcomes relating to the least possible impact on the natural environment.
"We acknowledged there will be a loss of flora and fauna in the immediate vicinity of the road. The purpose of the off-set and mitigation package is to address this loss and, over time, significantly enhance the biodiversity of other nearby and similar areas."
Spiers said the predator control programme would be key to improving the ecology of the area long-term, including habitat for taonga species such as kōkako, long-tailed bats and kiwi.