New measures to improve the quality and management of freshwater are being proposed by the government.
The 23 initiatives include making all dairy and pig farmers fence their stock from waterways as soon as July next year, with a gradual roll out to all beef and deer farms by 2030.
Those who did not comply could be instantly fined.
Environment Minister Nick Smith said it was unrealistic to make all farmers comply with the proposed regime sooner, because of the large costs involved.
