Council chief executive Niall Watson is concerned a more regionally based group earlier discussed and agreed on at the time of the mediation could be replaced by a recently proposed national stakeholder grouping.
This was not in keeping with the spirit of the earlier agreement, and participants in the earlier agreement should continue to be part of the stakeholder group, he said.
The more regionally based group could play an important role in achieving a successful implementation of the rural water plan change 6A in 2020, he said.
Mr Watson noted the Otago Regional Council had discussed a report by ORC chief executive Peter Bodeker at a meeting last week.
Some regional councillors had expressed misgivings about how the national group might function, with one suggesting national representatives could fight ''like ferrets in a sack''.
Mr Watson had written to the ORC outlining his concerns.
There could well be a role for some national representatives, but a key aim of the agreement was to have Otago resource users and statutory resource managers ''inside the tent on 6A implementation''.
And that would provide ''an important feedback loop'', dealing with any issues as they arose, he said.
Federated Farmers Otago provincial president Phil Hunt, of Wanaka, said farmers and other landholders ultimately had to ''take ownership'' of the scheme if it was to be successfully implemented, and he had recently spoken to ORC chairman Stephen Woodhead about the proposed group.
Federated Farmers Otago would continue to have input into 6A implementation, and people involved in the earlier mediation agreement needed to be ''involved in the implementation process'', Mr Hunt said.
Mr Woodhead said since last week's ORC meeting he had received feedback from several Otago stakeholders ''expressing concern about the national focus'' of the proposed group membership.
The ORC was listening carefully to feedback from Otago stakeholders, who would play a crucial role in 6A implementation, he said.
The feedback would be discussed internally and he wanted to clarify details of the earlier agreement about the stakeholder group.
Successful implementation of this distinctive Otago water plan ultimately required a focus on ''what's best for Otago'', he said.
Mr Watson said ''ferrets in a sack'' infighting was unlikely but he did not expect that a national group could add value to 6A implementation in the way people ''directly involved in land and water management in Otago could''.
It had been proposed Fish and Game New Zealand would be a national group member, but Otago Fish and Game had the statutory responsibility for fish and game in Otago, and the national body had a different role, he said.
