AgResearch’s Professor Rich McDowell, chief scientist for the Our Land and Water National Science Challenge, was speaking after the publication of a study looking at policies for fencing waterways on contamination loads in New Zealand waterways.
His paper was published in the American Journal of Environmental Quality.
The Ministry for the Environment’s Our Freshwater 2017 report indicates that urban waterways have the worst overall water quality in New Zealand, but much of the public focus in recent years has been on the impact of agriculture - particularly dairy farming - on waterways in rural areas.
“Fencing is very effective at reducing contaminant loads to waterways - by 10 to 90 per cent depending on the nature of the contaminants and local issues,” Prof McDowell says.
“Fencing works especially well for the likes of E. coli or phosphorus contamination that can result from animal waste or stream bank destabilisation. However, fencing all waterways in New Zealand is impractical and in some places other good management practices may be more cost-effective.”
“A combination of better awareness of the issues and the use of good management practices (including fencing) in the right place is starting to reverse degrading trends in the likes of phosphorus and sediment in the water over the last decade,” Prof McDowell says.