There is hope a government announcement today to protect the country's freshwater, will address nitrate toxicity.
A recent study shows three-quarters of the country's freshwater fish are under threat.
Victoria University of Wellington ecologist Mike Joy told Mike Yardley the nitrate toxicity level needs to be lower.
"We set the toxic level at 6.9 milligrams, which is kind of like having a drink driving limit at the level where alcohol would kill the driver."
LISTEN ABOVE AS MIKE JOY SPEAKS WITH MIKE YARDLEY