Sheep and beef farmer Andrew Paterson, who lives near Omakau, said he recently had his driest 12 months in 70 years.
"The effect on myself personally was extreme stress during this period."
The proposed minimum flow levels for the area would lead to farmers suffering serious mental health issues, he said
It would also result in a "large swing" to dairying in the valley, he said.
He favoured incremental increases in minimum flows.
The new plan change was meant to hasten the process, as the council battles with the historic 100-year-old water-take rights in these catchments which expire in 2021.
It would not speed up the process as it would end in legal intervention, Mr Paterson said.
Former regional councillor Gary Kelliher, who farms near Alexandra, said the Manuherikia River was heavily used for recreation and the community was its own watchdog for water quality.
He agreed it would force the area's farmers into dairy. High intensity dairy farming would be the only way to be viable.
Council chairman Stephen Woodhead said he understood the angst in the community, but changes had "been coming for years".
Debate about the flows themselves were better suited to later in the process, he said.
It was up to irrigators to work together, collect information and use it to inform the process, he said.
Council chief executive Sarah Gardner said she understood it was a "difficult conversation".
The proposed minimum flows were not finalised, she said.
Cr Bryan Scott said there was always going to be some angst from irrigators.
"No process is perfect. We tasked the CE [chief executive] with progressing these minimum flows as quickly as possible prior to 2021. We're doing our job."
The council resolved to notify the public of the plan change once hydrology and cultural assessments were completed.
