A damning report on the state of Ōtūwharekai/Ashburton Lakes shows the area is at an ecological tipping point.
And it could have flow-on effects for high country farmers, with concerns increasing regulations might drive farmers off the land altogether.
But while the problems are known, Ashburton Water Zone Committee chairperson Bill Thomas says more investigation is needed to come up with solutions.
“The only thing that will solve it is science,” he said.
“If we don’t use science to find out what the problem is and what we can do to fix it, it will never be fixed.”
The Ministry for the Environment has just released the new Ōtūwharekai/Ashburton Lakes lessons-learnt report. It’s a case study that could have national ramifications.
The lessons-learnt report outlines the ongoing deterioration of the area has reached a point where it is at risk of flipping – a scientific term to describe the transition of lakes from clear weed-dominated water to turbid algae-dominated water – with detrimental impacts on lake ecosystems.
The report was “not about the actions or intentions of the people who operate within the system” however, it highlighted a direct cause of the decline is too many nutrients entering the lakes from the surrounding land.
It states “90% or more” is due to leaching and run-off from land use practices on the adjacent pastoral farms.
There was no disputing farming has had an impact, Thomas said.
But it was a varied and complex system with more testing required to steer the solutions.
“The last thing we want to do is kick all the farmers off the land and find the problem is still there,” Thomas said.
There was a risk the historic stations’ days could be numbered, he said, with stricter regulations changing the way they can farm, or whether they could farm at all.
The farmers in question – Castleridge Station, Hakatere Station, Lake Heron Station and Mount Arrowsmith – issued a joint response to the report acknowledging the “serious and concerning situation, and the role some farming practices have played in this degradation”.
“There has been significant investment by individual farms in the basin, this action has been under way for many decades, in line with our long-term stewardship of this land we love.
“Much of this change and investment has been above and beyond what the regulations have required.
“The report makes it very clear that actions need to encompass a wide range of agencies, individuals and other stakeholders and good science is imperative.”
Fish & Game chief executive Corina Jordan said the report highlighted intensive agriculture should never have been allowed in the sensitive ecosystems.
“The alarming state of these outstanding ecosystems is despite the rural community going above and beyond to meet regulations, working to implement farm environment plans and voluntarily adopting good management practices,” Jordan said.
“Farm environment plans and good management practices were never going to be enough.”
What’s needed to protect the area is “ultimately to return to extensive sheep-based farming systems”, Jordan said.
Given the magnitude of the contaminant reductions required, the report states land use change, such as livestock reductions in parts of the catchment, may be needed.
But, it noted, aside from existing measures which were all being complied with, ECan had no other provisions allowing it to require changes to current land management.
“ECan is therefore reliant on the voluntary actions of the catchment farmers, supported by the Ōtūwharekai Working Group.”
A separate, parallel ministry report focusing on the science and what difference mitigation options might make to water quality is due to be released soon.

• By Jonathan Leask