Conservationists and the opposition say government's changes to clean water standards are a "shambles" and "trickery", after an official report found the new rules may weaken some regulations.
The National Institute of Water and Atmospheric Research (Niwa) this week released its report into the government's proposed changes to freshwater management policy.
It found although the new standards were tougher than the 2014 standards for boating and wading quality, they lowered the standard for the "minimum acceptable state" for swimming.
However, the report did note the 2014 swimability standard was "very high" - equivalent to an "excellent" grade under European Union standards.
Minister for the Environment Nick Smith on Tuesday said the government would be reopening submissions on the proposal to the public and extending the deadline for scientific reports on the details of the grading outlined by Niwa.