Canterbury dairy conversions surge amid soaring milk prices and looser rules
Tuesday, 22 July 2025
A wave of dairy conversions is rolling through Canterbury, with more than 15,000 additional cows approved in just six months — a notable change after a period of slowdown.
It comes as farmers respond to record-high milk prices and the roll back of national environmental rules. But while farmers embrace new opportunities, critics warn the trend could deepen Canterbury’s struggles with freshwater pollution.
New data from Environment Canterbury (ECan) shows seven consents involving new dairy conversions were granted since January, with another 11 being processed. Ten more dairy farms have received, or are seeking, approval to increase their herd sizes.
Together, these applications would allow for about 16,000 additional cows — a higher figure than previously thought. In May, The Press reported about 15 farms were considering conversions, involving about 10,000 cows. With increasing global demand for dairy products, more applications are likely.
Most of the proposed conversions are part of irrigation schemes that operate under collective nitrogen limits — caps that, in theory, are meant to prevent any overall increase in pollution, even if land use intensifies.
Nearly half of the new cows would be located in the Selwyn District, especially around Darfield and Sheffield. If pending applications are approved, Selwyn’s dairy herd could surpass 180,000, its highest level on record. Other planned conversions are concentrated in the Ashburton and Waimate districts.
It follows a Government decision to allow temporary freshwater protections introduced in 2020 to lapse. Those protections meant nearly all dairy conversions required resource consent, a barrier that dropped the number of conversions in Canterbury to near zero.
Because conversions no longer require specific land-use consent, the figures now reflect applications to discharge effluent from dairy sheds.
When deciding on these consents, ECan can only consider the local effects of the effluent disposal, and not the broader environmental impact of increasing cow numbers on the wider catchment.
“What consent applicants are seeking for dairy conversions is consent to discharge animal effluent from their dairy shed,” ECan director of operations Dr Tim Davie said.
“The consent planner must decide whether the effect of this effluent dispersal will be more than minor on the local environment. They cannot consider the wider effect of an increase in the dairy herd on the catchment, as that is already managed under a different consent (frequently an irrigation scheme global consent).”
Nutrient modelling suggests some farms may reduce their pollution by converting to dairy, especially if they are moving away from intensive winter grazing, which can leach large amounts of nitrogen into soils during wet months.
Still, the increase in conversions has drawn concern in areas already struggling with nitrate-contaminated water. Local rūnanga have formally objected to several applications, warning of threats to environmental and cultural values.
“Te Taumutu Rūnanga and Te Ngāi Tūāhuriri Rūnanga are opposed to conversions of land for the purpose of dairy farming within high nitrate locations and the detrimental effects, both known and unknown, that this may have on land and water,” the rūnanga submitted in response to one application near Darfield.
The rūnanga said the proposal failed to protect mana whenua values or the environment for future generations, a view an ECan planner disagreed with, noting the concerns were out of scope.
Tom Kay, of the advocacy group Choose Clean Water, said the increase in cow numbers reflected the Government’s weakening of environmental protections.
'More cows means more nitrate-rich cow urine leaching down into groundwater, and more faeces running off into rivers,“ he said.
“Sixteen thousand cows is a lot of cows, so that’s a lot of urine and faeces.”
He found it hard to believe that nitrogen pollution would not increase as a result of the conversions.
“There’s a massive question as to whether the limits that these farms will supposedly be operating within are even accurate or appropriate in the first place,” he said.
“Even if we could believe that nitrate leaching won't increase, the current level of leaching is way too high. We should not be allowing more dairy cows on the Canterbury plains. This is going to be incredibly hard to undo. We will all pay.”
Federated Farmers North Canterbury president Karl Dean previously said he knew of about 15 farmers interested in converting to dairy, though most conversions would take time due to the costs and infrastructure needed.
Fonterra has also said it was working with farmers planning to convert and supply the co-operative with milk.