And Matthews wants to know whether rates could be exempted from areas set aside for environmental reasons.
The society's area of interest spans the coastal streams from the Omapu near Whanganui across to the Mowhanau, Kai Iwi, Okehu and Ototoka. Matthews proposes to divide them into three catchments.
The Omapu and Mowhanau would form one, the Kai Iwi has the biggest catchment of the five and would be on its own, and the third would be the Okehu and Ototoka.
All of the streams are in a very poor state. The E. coli levels in the Mowhanau Stream are in the worst 25 per cent of sites, according to the Land, Air, Water Aotearoa (LAWA) website.
"Our forefathers came to New Zealand, developed the land and just assumed the waterways would look after themselves," Matthews said.
"Our generation [has] to refocus and review activities around waterways, including wetlands and subterranean water."
The group has about three big meetings a year. Its executive has met more frequently, sometimes by Zoom. It has been approaching local people to gauge their interest.
"We have had no rejection of the concept from anyone we have approached," Matthews said.
Having farmers talking to one another is better than "a bureaucrat preaching the gospel according to the Horizons One Plan", he said.
"We are farmer-led and farmer-driven, with community and local support. That's our vision."