A report raising doubts about the model of a farm management programme used by regulators has Hawke's Bay farmers frustrated about the possibility of further changes.
However, the Hawke's Bay Regional Council has signalled it intends to work with farmers which an environmental specialist says is an opportunity to make the programme work for farmers.
Overseer is used by councils all over New Zealand, including in Hawke's Bay, as the basis for granting consents, checking compliance and enforcement against farmers.
Concerns about the programme relate to the structure of its model, which was found to provide unreliable estimates of nitrogen loss in a range of situations.
The Government has made it clear it will redevelop Overseer until it is fit for purpose or will develop a new tool.
Either could mean years of work done by farmers to improve water quality and thousands of dollars spent on farm plans are no longer up to standard.
Tukituki farmer Bruno Chambers said it was a "bit confusing and upsetting".
A strong supporter of farm plans - "a tool to benchmark where you are" - he said it was important to have a means of measuring nutrient runoff.
"We don't want to have to do nutrient budgets and then the method gets changed further down the track and we haven't measured at the right version."
Federated Farmers Hawke's Bay president Jim Galloway agreed it was frustrating for farmers, some of whom might have to pay thousands of dollars more on creating new plans if there were significant changes.
It's one of many regulatory changes farmers have had to respond to in recent months.
"The biggest problem is [Overseer] was used for a purpose it wasn't designed for," he said.
"It was designed as a service support tool but ended up being a regulatory tool.
"Everything's based on Overseer, and if the numbers or measurements used are wrong, what does that mean after spending tens of thousands on plans and regulatory budgets."
Farmers would continue to do their bit to reduce nitrogen runoff, Galloway said. Significant price increases for nitrogen and urea also contributed to decreased usage.
"People are becoming more efficient and improving farming systems.
"We've got to work together to achieve our goals to be more efficient and reduce nutrient loss."
Environmental management specialist and director of Soter Rural Compliance Emma Buchanan was unsurprised by the findings of the review, saying "we knew those issues were there".
However, she said farmers were "actually better off" with Overseer as it allowed an output controls framework.
She said taking it away as a regulator tool would prevent regional councils being able to employ their discretion or be more flexible when working with farmers.
"We've got a really pragmatic council.
"They are able to grant consents if farmers can't manage within the timeframe."
The review was an opportunity for farmers and regulators to make Overseer work for them, she said.
Buchanan wanted to see it nationalised and "made properly", developed for New Zealand farmers specifically.
"They'll be in a better position than writing it off and sayings it's not what we want.
"We have very compliant farmers."
Brent Paterson, who created his own farm management programme, MyEnviro, said farm environment plans should be used to understand, prove and promote environmental improvements efforts.
While they "never set out to be an Overseer", he was proud the catchment group near his family's farm in Patoka had moved ahead and was using real-time data as opposed to modelled data.
He agreed with Buchanan an output model was more effective than one focused on inputs and farmers needed to work with regulators through the review process.
"I think it's really important we don't lose sight of the end goal, which is to continue improvement of the environment.
"The worst thing we can do is just stop."
Hawke's Bay Regional Council chief executive James Palmer said they were still working through the findings of the review and what it would mean for the region.
"The results of the review are particularly relevant for our assessment of Tukituki land use consent applications which will likely need to be revised, based on the future development pathway of Overseer."
Palmer said the regional council would continue to implement the Tukituki plan as required by law, and farmers could still use Overseer to collate and record farm data.
"We all know there are water-quality problems in the Tukituki catchment and farmers are making changes and working constructively with the council to address this.
"It's important this work continues."
Farmers would still need to submit Tukituki land use consent applications and updated Farm Environment Management Plans, he said.
HBRC general manager of policy and regulation Katrina Brunton acknowledged it was another change for farmers to address and factor in to their business operations.
The regional council would work with primary sector organisations and Treaty partners to look at the detail of the review findings and next steps.
"We will continue to work with our Tukituki community to improve water quality and support them through this process."
• More information about how the Tukituki farming community will be affected, the panel's review and the Government response report can be found online at hbrc.govt.nz using the searchterm #overseer.