"I've walked up here several times in the last few days, and I go home and say why? Why does this keep on happening to our environment? It's just not fair," Mr Johnson said.

Goulburn-Murray Water (GMW) notified irrigators about the herbicide treatment and told them not to use water from the channels for 72 hours afterwards.
Water full of dead fish is meant to be safe

But three days later, Mr Johnson is still removing dead fish from the water.

"This channel is meant to be safe to use today," he said.

But he's concerned that the dead fish and plants in the water may cause botulism in cattle.

GMW assistant manager Tim Nitschke said the water was safe for use.

"I'm extremely confident that it is safe," he said.

"There have been many, many studies done on this product. We've also done multiple and extensive water quality testing programs to demonstrate that," he said.

Mr Nitschke said fish kills were to be expected during the herbicide treatment, but there was no alternative.