Marlborough mayor John Leggett is concerned about the region's water assets being split in two under the Three Waters reform.
The reform will see Marlborough District Council own two shares in Entity C - which stretches from Blenheim through Wellington and up to Gisborne. But South Marlborough including Seddon and Ward, a short distance from Blenheim, will be part of Entity D.
Leggett said the convoluted design made no sense and questioned how it would deliver better quality drinking water and better environmental outcomes.
It had been suggested that Entity C should manage Entity D's assets in South Marlborough to avoid splitting Three Waters management across two entities in Marlborough.
Leggett said it was an improvement on the proposal, but was still a compromise.
He was advocating that the northern area of Entity D should be within Entity C's boundary, with the rest of Marlborough.
He said it was "regrettable" that the government did non adopt any of the alternative proposals from the 32-council strong Communities 4 Local Government group.
The council also had no clarity as to how the "cross subsidisation" of costs across the residents within each entity would be incorporated into the legislation.
"This is one of many questions that Marlborough District Council has raised with the Department of Internal Affairs and Minister of Local Government, and they remain unanswered."
Leggett said council also had concerns about the bureaucratic set up of sub-regional committees, being tasked with advising the Regional Representative Group on priorities from the contributing councils.
"I'm concerned about how Marlborough's water infrastructure needs will be given sufficient weight against other councils' needs. How is an organisation the size of Entity C going to deal with the prioritisation of projects with the governance structure that is proposed?"
Marlborough District Council has advocated for a pause in the process to further test the four entity model and consider alternative, smaller regional models.
Leggett asked that the government provide Marlborough residents and ratepayers with a better understanding of the reform proposals.