He feared the plan would add new regulation, and farmers would have to pay consultants to make the plans needed.
Some farmers did need to improve their winter grazing and feedlot practice, he said, but in general farmers were keen to keep rivers swimmable.
Rangitīkei/Manawatū Federated Farmers president Richard Morrison said farming morale was very low, despite good prices and good seasons.
Farmers who have been moving in the right direction on water quality feel under attack at the imposition of rules.
Morrison said the plan will be tough for Horizons, which had been "farmer-friendly".
"They are probably quite tired and disgruntled themselves," he said.
But Ken Mair, the chairman of the Māori Freshwater Fisheries Trust, welcomed the plan's change toward holistic health and wellbeing standards.
He told RNZ it stopped short of addressing water rights, which have been an issue for Māori for decades. He would have also liked a moratorium on land intensification and further water takes.
Fish & Game chief executive Martin Taylor blamed regional councils for the state of New Zealand's fresh water.
Horizons' Whanganui councillor David Cotton preferred a catchment-by-catchment approach to water quality, rather than blanket rules, because different rivers had different problems.
More than $80 million has already been spent on the Sustainable Land Use Initiative and change can only happen at a certain pace, he said.
His colleague Nicola Patrick said the action plan was "overdue" and good farmers would welcome it.
Horizons chief executive Michael McCartney said the plan supported his council's objectives, and the council will take a lead role in implementing it.
Councillors have yet to understand the full scope of it, and will need to find a way to bring the community along with any action.
The proposal should align with Horizons' catchment-by-catchment approach to water management, and the council will have to make sure no effort is wasted between the two.
In the meantime, McCartney urged people from the region to go along to the Ministry for the Environment's roadshow about the plan, in Palmerston North, and give their views.
It's on September 11, from 5.30 to 7.30pm, at 175 Cuba St.