A tanker has spilled up to 15,000 litres of milk into the Mataura River in Southland this morning.
The truck crashed into a power pole at Mataura about 3am, cutting electricity to about 150 customers.
The driver was uninjured but between 12,000 and 15,000 litres of milk leaked into a drain, sending it to the river.
An Environmental Southland spokeswoman said typically that much milk into the Mataura River would be a serious concern.
However she said it was lucky the area of the river where the milk filtered to was in flood overnight, which diluted the milk immediately.