Waikato Regional Council expects it will take several weeks to dispose of a large pond of buttermilk on a farm in the Atiamuri area of the central North Island.
The butter milk, a by-product of butter making, has been trucked to the farm from Fonterra processing plants in Waikato and Bay of Plenty and is being stored for dispersal on farmland.
Fonterra has been unable to cope with the record spring flush of milk production on North Island farms and has been forced to dump some surplus low value milk by-products from its processing plants.
They are being buried or spread on farm land, and in Taranaki, discharged through sewerage systems.
Waikato Regional Council's compliance division manager Rob Dragten, says it's investigating the buttermilk lake at Atiamuri to make sure it poses no environmental threat and complies with resource consents.
He says it's the first time he's aware of that milk by-products have had to be stored in that way before they're spread.