On March 22, the council granted land use consent to NZSki Ltd to extend its learners slope at the Remarkables skifield.
The project involved extending the learners slope, including the construction of two surface escalators, as well as track access to Shadow Basin.
It would destroy a 100sqm wetland listed as "regionally significant'' in the council's water plan.
The Department of Conservation gave permission for the consent, despite many concerns outlined in an internal science report.
University of Otago emeritus professor Sir Alan Mark said he supported Forest and Bird, which was contemplating legal action regarding the consent.
Sir Alan has extensive knowledge of the mountain range's ecology through involvement in studies of the area starting in the 1970s. He was also involved in a task force in the 1980s assessing wetlands nationally, which is partly responsible for the legal protection they get now.
He had "serious concerns'' about the consent and was disappointed Doc granted permission, he said.
Doc has defended granting permission, saying it was comfortable the effects could be mitigated by NZSki.
New Zealand's wetlands had unique flora and fauna and an important role in regulating water yield, Sir Alan said.
"There are some threatened wetland species in the area and they should be recognised in having national significance.''
The Shadow Basin was important in terms of ecological values, he said.
"In terms of water regulation maybe less so. It's the ecological value there. It forms a natural setting in the basin.''
In his work in a wetlands task force it discovered humans had destroyed 90% of New Zealand's wetlands.
"Almost all of them can be considered nationally significant.''
