Action for Healthy Waterways aims for a noticeable improvement in river and lake water quality within five years and to restore waterways in a generation.
It said nitrogen contamination is the most significant impact of agriculture and horticulture on freshwater health, with livestock effluent the primary source, followed by fertiliser use.
The existing National Policy Statement on Freshwater Management says every regional council must have a plan to reduce contaminant losses, including nitrate-nitrogen leaching, by 2025.
Now the Government wants to rapidly reduce leaching and wants feedback on the options.
The first option will set a cap in catchments with high nitrate-nitrogen levels, with farms having to reduce losses to get below the cap.
It will limit allowed nitrogen leaching in sub-catchments with similar soil types and rainfall.
It will apply where nitrate-nitrogen levels are in the highest 10% of monitoring sites and regional rules implementing the national freshwater policy standards are not already in place.
The threshold will be based on Overseer figures across the catchment.
To illustrate how this will work the document gives the example of a sub-catchment with 100 dairy farms, with farms ranked from lowest to highest on their Overseer nitrogen losses.
If the threshold was set at the figure for the 75th farm in the ranking then the 25 farms with Overseer figures higher than that farm will have to change their practices to get below it. It is a similar approach to Waikato Regional Council’s proposed Plan Change 1. Feedback sought includes where the threshold should be set.
The second option is to set a national nitrogen fertiliser cap.
Total nitrogen applied in fertiliser per hectare per year will be capped, based on research findings and good management practice.
Caps will be applied nationally, with a higher threshold for higher nitrogen-demanding crops and land uses.
All farms and horticultural producers will have to use less than the threshold amount or get resource consent to exceed the threshold.
The final option will require farmers in catchments with nitrogen levels to show in a farm plan how they will rapidly reduce leaching and trace their progress through independent auditors.
It will apply in catchments where nitrogen levels are in the highest 10% of monitoring sites and regional rules implementing the National Policy Statement on Freshwater Management are not already in place.
High nitrate catchments where regional council plans or proposed plans have already set a path for reducing leaching and so are not targeted by the first and third options are in Canterbury, Otago, Central Hawke’s Bay, Manawatu and Waikato/Waipa.
Plans in those catchments are expected to deliver reductions in nitrogen leaching.
For example, in the Hinds catchment in Canterbury, properties with a nitrogen baseline exceeding 20kg/ha/year must reduce nitrogen losses by 15% by 2025, 25% by 2030 and 36% by 2035.
Submissions to the Ministry for the Environment on the proposed changes close at 5pm on October 17.
Other proposals include:
All farmers and growers must have a farm plan to manage risks to fresh water by 2025.
Tight restrictions on further intensification of land use, including no new irrigation or dairy conversions from June 2020 unless there is evidence they will not increase pollution.
More fencing and wider setbacks to keep stock out of waterways to reduce erosion and capture contaminants before they reach the water.
National winter grazing standards, including restrictions on the area used, the distance it is set back from waterways and the depth of pugging.
Commercial vegetable growers wanting to increase the area of land they use will need resource consent.
