More than 100 Southland farms have been seriously impacted by flooding.
The Mataura river flooding around Wyndham. Photo: RNZ / Katie Todd
Dairy NZ's South Island manager said many of the farms are in a dire situation either underwater or cut off with no road access.
Dairy farms in the Oreti, Aparima and Clutha river catchments were the most severely impacted, with many areas also without power.
Tony Finch said tankers can not collect milk, so farmers are having to dispose of it.
Mr Finch said this was a challenge when the effluent management systems on many farms have also been affected by the flooding.
He said farmers and their teams were moving cows to higher ground where they can.