Chris Lewis, a Feds national board member and spokesman on immigration and labour issues for the past two years, will leave at its annual meeting in Auckland early July.
Vice-president Karen Williams says all is not well with important pieces of the legislation.
"But before we replace the RMA, let's make sure the new legislation will drive better outcomes."
The Government is proposing a drastic overhaul of New Zealand's resource management framework with its Natural and Built Environments Bill.
"But from what we can see in the skeleton of the Bill available so far, things will be much worse, communities will be robbed of their ability to have their say on matters that affect them, there will be disruption to society and the economy, and the environment will be no better off," Williams claims.
"A big problem is not just with what we have seen to date but what is yet to come.
"We've only seen the bare bones of the proposed Natural and Built Environments Act (NBA) and nothing ot the other two pivotal Acts that are proposed to replace the RMA - the Strategic Planning Act and the Climate Change Adaption Act.
"We are effectively running blind at the moment due to a lack of detail," Williams adds.
She says, at this stage, there is no guarantee at all that the Bill will generate more benefits than costs and there is a significant risk of the reverse.
"We mus not under-estimate the costs of delay and the risk of drawn-out litigation that could stem from the lack of clarity. Large chunks of the economy are underpinned by consents and related resource management processes."
Feds' subission included suggested changes to Part 2 of the Bull (the purpose and related provisions), to turn it back to the terminology and concepts in the RMA.
"Any replacement legislation needs to keep local democracy, community stewardship and local identity. They belong at the heart of resource management."