The Green Party wants to raise millions of dollars a year by charging for irrigation water. The proposal is part of their plan to clean up the country's waterways.
Greens co-leader Russel Norman says one of his party's election campaign priorities is "to clean up rivers and lakes so they're swimmable once again".
"Rivers and lakes are vitally important to what makes New Zealand a great place to live. It's a terrible tragedy they're so polluted at the moment, and we're committed to cleaning them up."
Dr Norman said restoring and protecting waterways also made good economic sense.
New Zealand's main economic advantage was its "clean green image".
"If we destroy that, we will undermine our economy ... If we continue down the current path then we will have rivers and lakes that look like Chinese rivers and lakes in 20 years and there is no way Chinese consumers will continue to buy our products if they are produced in a way that destroys the environment."
The Greens' plan would establish national water quality standards, impose controls on farm stock numbers and use of fertiliser and a charge for water use.
Some of the money raised would be spent on water quality measures including fencing off waterways and riparian planting.
Dr Norman said voluntary measures to improve water quality, such as Fonterra's clean streams accord, had failed.
"It's the wild west out there because there's so few regulations to protect rivers and lakes."
Dr Norman said the Greens hoped to advance their water quality plan as part of an agreement they may strike with National after the election similar to the deal under which they had driven home insulation, pest control and toxic site clean up initiatives during the present electoral term.
The Government is working through a long-running redesign of fresh water management rules, and this year adopted a national policy statement which is intended to guide decisions about water issues made by regional councils under the Resource Management Act.
But the Greens believe that statement is too weak and Dr Norman said his party's policy included a stronger version.
He said some people in the present Government understood the issues and wanted to act to better protect waterways but were being blocked by vested interests.
"National says it's a party that believes in using market signals - well, here we go, this is a market signal that would result in more efficient use of water.
If they have the political courage to do the right thing then they will talk to us."
CLEAN AND GREEN
The Green Party's clean river policy includes:
* Standards for fresh water, including limits on the amount of water taken from rivers and lakes, limits on the amount of pollution going into them, and limits on intensive agriculture.
* A charge on water taken for irrigation and other commercial use at 10c per 1000 litres, raising $370 million to $570 million a year.
* Financial support for river and lake clean up projects using $138m a year of the money raised by the water charge.