There are fears a snail habitat would be wiped out, and numbers of a critical native plant species would be cut by a quarter if a proposed dam project gets approval.

Forest & Bird is fighting against the proposal by Waimea Community Dam Ltd to construct a dam at the Lee River in the Tasman District.

Nelson regional conservation and volunteer manager Debs Martin says so-far, their concerns have fallen on deaf ears.

"I mean what we're talking about here is kind-of rubbing out New Zealand's biodiversity for the sake of development without even really giving the environment a cursory nod or appreciation."