A report by the Prime Minister's chief scientist, Sir Peter Gluckman, says some waterways will take more than a century to recover and even then they will never return to their original state.
Environment Minister Nick Smith describes the report as fair and robust.
Photo: RNZ / WikiCommons / Ulrich Lange
He told Morning Report he doesn't take any "negative spin" from it but says the it shows our river pollution isn't a problem that arose yesterday and will take some time to fix.