Determining whether excluding livestock from large streams in flat catchments would substantially decrease the contaminant load
Project Details Ngā taipitopito
The New Zealand dairy industry’s Water Accord requires farmers to exclude livestock from all large fourth-order streams – “wider than a stride and deeper than a Red Band gumboot” – by committing to a riparian planting plan (due by 31 May 2020, with 50% of planting complete). Government is considering implementing this as national policy.
Our research looked at whether excluding livestock from large streams (over 1 metre wide, over 30cm deep) would substantially decrease the load of contaminants (nitrogen, phosphorus, sediment and E.coli) entering waterways.
The researchers found that loads from large streams in flat catchments dominated by pasture accounted for, on average, 23% of the national load of all contaminants. This research suggests additional mitigations should be implemented to reduce the 77% of contaminants that enter waterways from smaller streams in rolling to steep land.
Further Our Land and Water research is now developing a simple tool for farmers to identify mitigations that are more cost-effective than fencing.