A legal challenge to stop the $23 million move of Environment Bay of Plenty headquarters from Whakatane to Tauranga is being prepared.
The regional council has agreed to a scaled-back shift which will see 100 staff transfer to a new office.
Under the original plan 130 staff weregoing to shift but chief executive Bill Bayfield said the lower number would minimise negative economic and social effects of the proposal on Whakatane and the eastern Bay.
The council argues the move to Tauranga - the region's fastest growing centre - is necessary for it to perform its leadership functions under the Local Government Act and respond to growth in the western Bay.
The council will meet again on June 21 to vote on whether to adopt the relocation as part of its 10-year plan.
But opponents of the plan are working with lawyers to gather information for a judicial review.
Jacqui Hughes, chairwoman of a regional focus group opposing the move, said the council's decision was disappointing and unreasonable.
"We don't believe they listened to the voice of concerned submitters," she said.
A total of 742 groups and individuals made submissions on the move, 556 in opposition.
She said the lawyers already had evidence that the council had failed to follow due process under the Local Government Act when formulating the plan.
Community relations group manager Bruce Fraser said the council needed to focus more on western Bay issues than it had in the past.
"Because a big proportion of the Bay of Plenty people are increasingly living in the western Bay, we believe we need to be there to service those people."
But opponents say the plan would have a devastating effect on the eastern Bay economy, taking skilled workers and their families out of the area. They say the money the move will cost could be better spent on environmental projects.
The move is estimated to cost $23 million, $15.4 million of which would be spent on building a new head office in Tauranga.
