There would be 40 per cent decrease in profit for Tararua dairy farmers if the revised One Plan - the result of a successful appeal by Wellington Fish and Game and the Environmental Defence Society to the Environment Court - is implemented.
"We are an incredibly resilient district but the impact of the Manawatu Gorge closure, the impact of the One Plan on farmers and pressure on our health services means we're taking a hammering," Mrs Collis said.
Tararua has 254 dairy farms requiring consents and Mrs Collis said the challenge for Tararua District Council will be if farmers have a huge drop in profit and land values drop.
"I'm not saying we don't need to take care of our environment, we do. So I'm strongly encouraging farmers to continue with their environment work because we are working towards improvements in our waterways," she said.
Horizons Chairman Bruce Gordon said the Manawatu River is already showing signs of water quality improvement.
"Of the 16 monitored in the catchment from 2006-2015, 31 per cent had improved bacteria levels, 50 per cent had improved in turbidity and phosphorus, and 75 per cent had improved nitrogen levels. None are in decline," he said.
Mrs Collis said the challenge for her includes how the Plan as it stands will affect people purchasing or selling a dairy farm in the district.
"This just adds to farmers' stress," she said. "We have to find a way forward and while everyone is talking about dairying, the effect on horticulture is just as severe.
Horticulture has as big a challenge as dairying and in Horowhenua it's extremely doubtful they will get a consent to farm as the One Plan stands at the moment. It will be virtually impossible."
The report presented to Horizons strategy and policy committee stated: "Our understanding is that a significant number of existing farms are likely to be unable to meet the One Plan's nitrogen-reduction requirements while remaining economically viable. No practicable consenting pathways exists for these activities." Mrs Collis said advice on likely social and macro-economic impacts would be sought.
"The policy and strategy committee don't have a mandate to bring down decisions, but there will be a full Horizons council meeting in two weeks and Horizons officers have been instructed to investigate Plan change options," she said.
"It was a unanimous decision to find a way for a One Plan change which satisfies everyone."
Dannevirke dairy farmer and member of the Tararua Economic Impact Group, Russell Phillips said working collaboratively towards a Plan change is the beginning of a roadmap we can all be involvedwith.
And Mrs Collis said it's about talking with all parties.
"Horizons are being extremely optimistic in saying they can have a Plan change in 12 months. Realistically, I think it will be three to four years to get a Plan that works."
Mrs Collis said one telling comment at last Tuesday's meeting was, 'there's been a seismic shift in what applicants (farmers) are required to produce to gain a consent'.
"This is going to be incredibly challenging.
"We have 254 dairy farmers in the Tararua District and there has been a lot of discussion on how difficult and expensive it will be for farmers to obtain consents.
Pahiatua beef and sheep farmer Andrew Day said he believed farmers will be justifiably frustrated they've illegally been granted resource consents.
"Quite how much financial liability the regional council have taken on by this action is uncertain at the moment," he said.
"To be clear, Horizons have illegally been rewarding farmers for more pollution rather than less via long-term consents.
"The most common consent individual farmers signed up to required no reduction in pollution at any point in time. The regional council has been implementing an illegal resource grab.
"From the outside it's difficult to explain how the implementation of the plan became so corrupted. Sir Geoffrey Palmer is quoted as marvelling at the 'stunning illegality' that bordered on the wrongful use of power."
Sir Geoffrey, the architect of the Resource Management Act, delivered his blistering attack on Horizons handling of intensive agriculture consenting after they were defeated in the Environment Court earlier this year.
"It will be interesting to see if much the same group of people who have brought about this illegality are able to move to legality on their own. I doubt it," Mr Day said.