Pressure on water quality

The conclusion comes in her latest report, Water quality in New Zealand: Land use and nutrient pollution, which examines how New Zealanders are changing the way they use land and the pressure this puts on water quality.

"The report is focused on the two nutrient pollutants – nitrogen and phosphorus. On land they are valuable nutrients, helping plants to grow. But when there is too much of them in water, they become pollutants, and can lead to excessive growth of weeds, slime and algae.

"Over recent years, hundreds of thousands of hectares used for sheep and beef farming have been converted to dairy farming on the one hand, and forestry on the other.

"Conversion to dairying increases nutrient loads on water; conversion to forestry does the opposite."

Dr Wright added: "I applaud the effort that is being put into environmental mitigation on dairy farms. Unfortunately, it is particularly difficult to control nitrogen. Nitrogen – in the form of nitrate – is so soluble that I think of it as the 'elusive' pollutant.

"I am pleased that fresh water policy is very much on the Government's agenda with the recent release of a discussion paper on setting 'bottom lines' for water quality. I hope that this report will better inform both the general public and those who make decisions on their behalf."

See full report at http://www.pce.parliament.nz/publications