The Waitaki Irrigators Collective (WIC) believes Labour's water policy could lead to a growing rural-urban divide and the loss of millions of dollars from the Waitaki and Waimate districts.
Waitaki Mayor Gary Kircher has also let rip at the policy, claiming Waitaki irrigators could lose $25 million to $40 million if there is a change of government on September 23.
David Parker, Labour's water spokesman, will speak at a public meeting in Oamaru tonight.
WIC policy officer Elizabeth Soal said the collective was keeping a close eye on Labour's plans to charge irrigators a levy of 1c-2c per 1000 litres of irrigation water, and was "very concerned" about the implications of the proposed water royalty.
"This is not just in terms of the economic effects on farmers and the wider community, but also the potential unintended consequences, issues around implementation and administration, what the charge will mean for specific catchment outcomes, and that the framing of the public debate will see a growth in the urban-rural divide."
The WIC was concerned about the potential economic impact of any levy and where money collected would be spent, Ms Soal said.