Flood-affected Coromandel roads are proving stressful for Waikato dairy farmers, with tankers unable to get through to collect their milk.
Waikato Regional Council says farmers are running out of storage room and is urging them to be considerate about disposing of waste.
The council's farming services leader Stuart Stone says there's a strong possibility of further road closures.
"There is heavy rain going to come back in tonight. There are some roads which are still operating, but down to one lane. These roads could close again, so it just depends whether the milk tankers can get in and get the milk out before they do close again."
Milk can be hugely destructive for aquatic life if it gets into the water.
"We do not want milk entering any waterways," says Mr Stone. "Any discharge of milk into the waterways has the effect of depletion of oxygen, which is going to kill all river and stream life."
Farmers should contact supply companies or the council for consultation about dumping options.
"We're available to talk to any farmers. But in the first instance we suggest that farmers talk to their suppliers, and if they have any concerns around potential environmental effects, they get in touch with us."