The Green Party is proposing a charge for irrigation water as part of its plan to clean up New Zealand's lakes and rivers.
The party launched the plan on Sunday as one of its three main election policies.
The policy also proposes minimum standards for water quality, water flows and intensive agricultural practice.
Co-leader Russel Norman estimates the irrigation charge would be about 10 cents per 1000 litres of water, which could generate up to $570 million a year. He says water is a public resource so there should be a price on it.
Dr Norman says some of that money would go towards fencing off and planting alongside streams.
He says if the country continues down the path it has been taking, its waterways will look like those in China, and Chinese consumers will stop buying New Zealand products if it they are not seen as clean, green and safe.
Dr Norman says cleaning up the country's waterways is a way to protect New Zealand's 100% Pure brand.
The party's other main policies are the creation of what it calls green jobs, and lifting children out of poverty.
The election takes place on 26 November.
Key says water policy unrealistic
Prime Minister John Key says the Green Party's new water policy is unrealistic and the country's waterway standards are high relative to the rest of the world.
He says the National Party is more interested in irrigation schemes that capture water, rather than penalising irrigators.
Mr Key says the Government is concerned about water issues and has increased the fines for those polluting waterways and spent a lot on the restoration of waterways.