Farmers are the only people who can reverse the declining quality of Otago’s Pomahaka River, farmer Lloyd McCall says.
The Pomahaka Water Care Group was formed in 2014 because the Otago Regional Council and the Landcare Trust were not going to improve the river’s water quality.
“It’s got to be by farmers,” McCall says.
“You couldn’t fix it by rules.”
The council had in 2012 identified issues with nitrate and E coli levels, especially in the river’s lower reaches, which prompted the Landcare Trust to get stakeholders together to try to address the problem.
The Pomahaka flows from the Old Man Range in the central Otago mountains into the Clutha River near Balclutha. It has a 2020 square kilometre catchment passing 304 farms.
McCall says most farmers were unaware of their impact on the river and the ecological and biodiversity values supported by the river and its tributaries.
Conservation Department staff showed him native galaxiid fish in waterways on his farm, something he never knew existed.
Concerned about the data showing the declining quality of the river McCall met five other farmers to discuss the water quality problem.
They established the group, which, at its peak, had 160 members.
The group aims for the river to have the highest quality water so future generations can enjoy it.
That means a whole-of-catchment approach because all farms can affect water quality but doesn’t preclude profitable and sustainable agriculture.
The group’s plan involved testing water samples at various points along the river’s 80km length to define the extent of the issue and the problem spots.
Four times a year the council samples water from 28 sites, which McCall says also has the benefit of showing individual farmers the impact of their activities and management.
“You haven’t got a problem until you know you have got a problem,” McCall says.
The group started raising awareness, has a regular media campaign and field days promoting farm management steps to reduce water degradation, such as preventing sediment runoff.
Schools and the wider community are also encouraged to be involved.
“It is all about taking ownership.”
He says there has been a noticeable change in culture, which he attributes to farmers’ connection to the land and a desire to fix the water quality problem themselves.
It has seen major improvements in water quality in the mid and lower sections but not in the upper reaches because of continued land development.
McCall says the group highlights excellent as well as poor farm practice while also showing interested groups such as scientists and academics what landowners are doing.
Farmers are encouraged to confront those following poor practice and the group has members prepared to approach those letting others down.
Riparian planting has been a significant tool and to ensure it has enough trees and shrubs the group has established its own native nursery with 22,000 plants ready to be planted.
Further work includes trials on crop leaching and water infiltration rates and more work on wetland traps.
McCall says improvement has not been as desired for phosphorous but monitoring of other nutrients and measures is trending positively.
Alister Body farms sheep and deer and grazes dairy cows on 380ha near Tapanui. His farm has six main discharges into the river.
The quality of some are fine, others not so.
Water testing narrowed his focus to minimising the mobilisation of sediment over his land during rainfall, which is the main source of phosphorus and E coli.
He has fenced all but 100m of his farm’s 3.5km river frontage and takes care managing areas where discharge is potentially greatest.
That means refencing his deer unit to reduce or minimise the impact of tracking and wallows and reducing runoff by careful selection of paddocks for winter cropping and the class of stock being run in steep paddocks.
Body has also changed his cultivation methods, leaving critical source areas untouched and establishing sediment traps and containment areas.
The aim of traps is to slow run-off by channeling it into traps to allow sediment to settle.
He has built a network of multiple traps or wetlands in several paddocks into which runoff, including that from tile drains, is channeled to collect sediment.
They must be cleaned out and he is soil testing the sediment to see if it has any nutrient value.
It has been rewarding addressing the source of water degradation emerging from his farm and finding those issues is quite simple.
“If you are to do one thing, do a discharge water test from your farm,” he says.
