The Government needs to show how it will pay to clean up New Zealand's rivers if it will not introduce a price on water, the Labour Party says.
Labour's proposal for a tax of around 2c per 1000 litres on commercial waters users been described as "reckless" by National because it could force Treaty of Waitangi settlements to be renegotiated.
The Government said a royalty asserted ownership, and would inevitably force a counter-assertion that Maori owned the water.
Labour's environment spokesman David Parker said today this was "scaremongering" which distracted from the issue of paying for waterway restoration.
"They are trying to avoid the essential point underneath all of this. And that is if users and polluters don't pay, who does?"
"The answer is pensioners and other taxpayers. The Treaty point is subsidiary to that."
Environment Minister Nick Smith said last week that the cost of cleaning up New Zealand's rivers would be $2 billion over the next 23 years.
Those costs would fall on farmers, who had to fence off waterways, councils, which would needed to upgrade wastewater and stormwater infrastructure, and taxpayers.
The Government announced an initial $44 million towards freshwater improvement projects, as part of a new $100 million Freshwater Improvement Fund.
"The cost will be $100 million a year, so they've got a shortfall," Parker said. "And it's not coming from polluters."
Asked at the time why taxpayers should cover the costs of industry's pollution, Smith said some council projects were being held up by lack of funding and the Government wanted to "get on with the job".
Labour says it will use the revenue generated by royalties to clean up rivers, streams and lakes in partnership with councils.
Prime Minister Bill English denied today that he was putting water pricing "in the too-hard-basket".
The Government was "proud" of its progress on water quality standards, and the issue of water allocation and iwi needed to be dealt with "carefully and respectfully", he said.
National and Labour governments have previously used pan-iwi talks to resolve fishing, forestry and aquaculture rights. Securing a similar agreement for water was "much more difficult", English said.