Hon DAVID PARKER (Minister for the Environment): Last year, the Government agreed to "reconsider the possibility of a [dissolved inorganic nitrogen] bottom line of 1 mg/l (…likely with exceptions" and, in doing so, revisit the environmental and economic implications. When making a recommendation on a dissolved inorganic nitrogen (DIN) bottom line to Cabinet, I will be considering the expected effect of current policy requirements, the marginal environmental benefit of a DIN national bottom line, the marginal economic impact of such a DIN national bottom line, and whether the science behind a national bottom line of 1 milligram per litre of DIN has become clearer since May last year, when we last considered the question. I would also note, as I have done previously, that the periphyton attribute, carried over to the current National Policy Statement on Freshwater Management, effectively provides for a DIN level below 1 for gravel-bottom rivers. The outstanding issue is muddy-bottom rivers, and I don't want a DIN of 1 to effectively become a target for gravel-bottom rivers.