The Nature Conservation Council (NCC) said changes to state planning laws could put at risk protected wetlands, forests and coastal areas on the Coffs Coast.
The proposed changes are expected to the be tabled in State Parliament within weeks.
The NCC is worried they give developers more power and remove environmental protections.
The Council's Pepe Clarke said areas like the Coffs Coast have the most to lose.
"These protections, which are contained in State Environmental Planning Policies (SEPPs), will be repealed and replaced under the new planning system," he said.
"There's no guarantee that they'll be replaced by equivalent or stronger environmental protections.
"So we believe that for a place like the Coffs Coast, that has such important natural values, this planning system is something that people really need to be aware of."
The NCC aid the mid north coast is also vulnerable to coal seam gas exploration despite new protections.
The State Government has put in place a 2 kilometre 'buffer zone' around 95 percent of properties in NSW.
Mr Clarke said it is welcome news but much of the region's valuable agricultural land and native bushland is still unprotected.
"Beyond the residential exclusion zones, the fact is the mid north coast and north coast remain open for coal seam gas activity.
"The industry seems to be responding to some of the Federal Government's promotion of coal seam gas," she said.