Setbacks and stock exclusion

Ngā whenua ka rāhuitia me te aukatitanga kararehe pāmu


The draft Freshwater Plan Change sets a direction for improving the health of freshwater in Te Taitokerau.

We have a good understanding of what we need to do to improve our freshwater. One of the most effective tools we have is keeping stock away from waterways, wetlands, and off highly-erodible land.

The further stock are kept from waterways, the greater the environmental benefits – especially where wider setbacks include riparian vegetation. We think we will need both wider setbacks for stock and enhanced riparian vegetation to achieve the improvements needed in freshwater health.

We also think there is a case for excluding stock from our most erodible land to limit erosion and sediment going into waterways.

The more we do, the greater the environmental benefits – but the higher the costs for landowners, many of whom are already facing tough times. This can be mitigated somewhat by allowing sufficient lead-in time, but even so the costs will be significant.

We need your input to make decisions that will work for our community as well as our waterways.

Now is your opportunity to share your thoughts and feedback. The more feedback we get, the better informed our decisions will be.

Download The Draft Freshwater Plan Change: Have Your Say on Stock Exclusion (PDF 1.37 MB)

We have looked at three setback distances for keeping stock away from all permanent and intermittently flowing rivers and streams. We don’t think rules should apply to ephemeral streams (where water flows only during and shortly after rain).

These distances are:

  • A three-metre setback
  • A five-metre setback
  • A ten-metre setback

The setback distance would likely also apply to lakes. There are also waterbodies with particularly high ecological values where larger setbacks are likely to be needed because they are very sensitive to the impacts of stock (such as outstanding waterbodies and high value dune lakes). However, we have focussed on options for rivers and streams as this is likely to affect landowners most.

To gain the most benefit, the stock exclusion areas around waterways would need to be replanted with native riparian vegetation.

The benefits and costs of these setback distances are shown in the table below. We have also included the status quo and a 30-metre stock exclusion area for comparison.

The financial impacts are presented as an average per farm per year. They include the cost of fencing, water reticulation, and lost revenue. The riparian planting cost estimates include planting and ongoing maintenance.

Stock exclusion distance from waterway Water Quality Improvement Co-benefits Financial costs (per farm per year)
Sediment reduction E. coli reduction Freshwater habitat and ecology improvement Mauri* Mitigating climate change Terrestrial biodiversity improvements
Comparator status quo** 0 0 0 0 0 0 The costs associated with existing regional and national regulations will not change with the options being considered.
Three-metre setback 3 4 1 1 1 1 Stock exclusion: $5,500 – $8,200 (non-dairy farm)
Riparian planting: $1,400 – $2,100
Five metre setback 4 6 2 2 2 2 Stock exclusion: $10,200 – $16,500
Riparian planting: $4,600 – $9,300
Ten metre setback 6 7 5 5 3 4 Stock exclusion: $12,600 – $24,500
Riparian planting: $9,200 – $18,500
Comparator thirty metres 7 7 8 8 5 8 Stock exclusion: $19,700 – $65,300
Riparian planting: $27,300 – $55,600

*Mauri is the life force given to all things through a Māori perspective. The numerical values attained and compared to the effects of stock exclusion and riparian planting have been compared against the attributes in the TWWAG Stage 2 report: Ngā Roimata o Ngā Atua (PDF 4.45 MB).  Further work is being done to assess different methodologies and confirm these values.

** ‘Status quo’ refers to the current state as of October 2023. It does not take into account national and regional rules to apply from 2025.

Scoring: 0 = no improvement (from status quo), 5 = moderate improvement, 10 = major improvement. Scoring is indicative only and is intended to show the relative difference based on the available evidence. 

Assumptions:

  • All stock are excluded from all waterways, including intermittently flowing rivers and streams.
  • There is established riparian planting in the stock exclusion areas (this will likely take many years after stock is excluded).

What does the science say?

Excluding stock reduces sediment in our waterways. Stock erode the banks and disturb the beds of waterways, which increases sediment. Keeping stock off stream banks is more effective in smaller, narrower streams with low banks than in larger, wider rivers with high banks1.

Research shows that to reduce contaminants (nitrogen, phosphorus, sediment, E. coli) in our streams and rivers, we need to target smaller streams in headwaters as well as lowland streams and rivers. A large proportion of contaminants come from smaller streams on higher slopes. About 85% of E. coli come from these small streams2.

Native freshwater species live in smaller streams in the upper parts of catchments, and the quality of their habitat is compromised by a lack of riparian vegetation. Riparian vegetation provides shade, reduces water temperature, filters contaminants, stabilises banks, and improves freshwater habitats and biodiversity. At least 10 metres of riparian vegetation is needed to noticeably improve the ecological health of freshwater3. In addition, the more riparian vegetation we have, the more effective it is at reducing the impacts of climate change, such as droughts and floods. A wider setback – for example, 30 metres – would deliver greater benefits.

Research shows that riparian vegetation can filter out sediment. A riparian vegetation buffer of five metres removes about 34% to 40% of sediment, and a 10-metre buffer removes about 60% of sediment4. Its effectiveness at filtering sediment varies depending on the width of the waterway, scale of planting, type of plants, topography and location in the river system.

The roots of riparian vegetation help to stabilise stream banks up to depths of 0.5 to 1.5 metres, especially the banks of smaller streams up to 10 metres wide. A five-metre setback is considered a minimum for stabilising banks, but 10 metres is preferable, depending on plant species.

In smaller catchments, transitioning to riparian planting can temporarily increase sedimentation because pasture grasses capture and store sediment in streambanks. As the grass dies off under increasing shade from riparian planting, these sediment sources can be remobilised until the stream reverts to the wider, shallower shape typical of forested streams5.

In summary, while riparian buffers of three to five metres provide effective filtering, vegetated riparian buffers of 10 metres or more are needed to achieve wider ecosystem health and climate change resilience benefits for waterbodies.

However, the wider the setbacks and stock exclusion rules, the higher the costs. We are concerned about the financial cost for landowners, many of whom are already facing tough times. This can be mitigated somewhat by allowing sufficient lead-in time, but even so the costs will be significant.

We need your input to make decisions that will work for our community as well as our waterways.


1 Hughes, A. (2016). Riparian management and stream bank erosion in New Zealand. New Zealand Journal of Marine and Freshwater Research. 50: 277-290; and Robson, B. (2022). Literature review to support development of Northland’s Soil Conservation Strategy: Soil erosion treatment options, relative costs, effectiveness, impact. Report prepared for Northland Regional Council.
2 McDowell, R. W., Cox, N., Snelder, T. H. (2017). Assessing the yield and load of contaminants with stream order: Would policy requiring livestock to be fenced out of high‐order streams decrease catchment contaminant loads? Journal of Environmental Quality, 46(5), 1038-1047.
3 Baillie, B. Murfitt, J. (2023). Riparian setbacks: Summary of the science. Northland Regional Council.
4 Semadeni-Davies et al. 2021; and Sweeney et al. (2014) in Semadeni-Davies, A; Haddadchi, A., Booker, D. (2020). Modelling the impacts of the Draft Stock Exclusion Section 360 Regulations on river water quality E. coli and Sediment. Prepared for Ministry for Primary Industries and Ministry for the Environment. NIWA Client Report No: 2020052AK.
5 Robson, B. (2022). Literature review to support development of Northland’s Soil Conservation Strategy: Soil erosion treatment options, relative costs, effectiveness, impact. Report prepared for Northland Regional Council.

An averaging approach could be used for stock exclusion for distances of five metres and greater to recognise the practicalities of fencing off waterways to exclude stock.

For example, under a 10-metre average exclusion rule, a landowner might choose to put the fence three metres away from the waterway in some places and 15 metres away in other places to maintain an average distance of 10 metres across the length of the waterway on the property.

Even using an averaging approach, stock exclusion would need to be a minimum of three metres away from waterways, as three metres is the standard applied in Government regulations.

Elevated levels of sediment in our streams, rivers and lakes make our estuaries muddier, our waterways less appealing to swim in, and make it harder for native plants and animals in the water to survive.

Most of the sediment in our waterways comes from two main sources – sediment coming off the land (especially the steeper highly erodible land) and stream bank erosion.

There are currently no rules in the regional plan requiring stock to be excluded from mapped areas of highly erodible land.

Highly erodible land erodes more when it is in pasture and grazed. Land erodes less if it is covered in vegetation other than pasture. It is also less vulnerable to slips.

We think changing the rules to manage stock grazing on highly erodible land would encourage permanent woody vegetation, such as regenerating bush, continuous cover forestry and/or permanent carbon forests. Over the long term, this would reduce sediment runoff into our waterways and increase our region’s resilience to slips.

Before and after: Slips caused by Cyclone Gabrielle on steep farmed land in the Kaipara Harbour catchment. While vegetation on these slopes may not have stopped all the slips, it would have helped to reduce it.

What land should be defined as highly erodible?

We think our current maps of erosion-prone land can be improved. We have developed two new draft maps of highly erodible land based on slope, which is the main driver of erosion risk:

  • Highly Erodible Land 1 shows areas with high erosion risk
  • Highly Erodible Land 2 shows areas with severe erosion risk.

We already have rules that control earthworks and land preparation on highly erodible land, but there are currently no rules for vegetation clearance or stock exclusion on this land.

Status quo
Map Area (ha) Basis for maps Summary of current rules
Erosion prone land 252,409 (18.8% of land in the region) Land defined as Land Use Capability (LUC) units 6e17, 6e19, 7e1 - 7e10, 8e1 - 8e3, and 8s1 Currently only earthworks and land preparation rules apply

We’re considering new rules limiting vegetation clearance, cultivation and earthworks in areas of high erosion risk, with tighter controls applied to these activities in areas with severe erosion risk.

We’re also considering new rules requiring stock to be excluded from both these areas.

New draft maps and rules
Map Area (ha) Basis for maps Summary of current rules
Highly Erodible Land 1 155,548 (12.25% of land in the region) Land with a slope between 25 degrees and 35 degrees

Draft rules: Moderate controls on earthworks, land preparation and vegetation clearance.

We are seeking feedback on whether stock exclusion rules should be applied on Highly Erodible Land 1 by 2040.

Highly Erodible Land 2 91,120 (7.2% of land in the region) Land with a slope greater than 35 degrees

Draft rules: Tighter controls on earthworks, land preparation and vegetation clearance.

We are seeking feedback on whether stock exclusion rules should be applied on Highly Erodible Land 2 by 2035.

We are interested in your views on the draft maps of highly erodible land and whether stock exclusion rules should apply.

The current Erosion Prone Land maps and draft Highly Erodible Land 1 and 2 maps can be viewed online.

What would it cost?

We estimate the cost of excluding stock from land with severe erosion risk (Highly Erodible Land 2) to be between $400 million and $600 million over 30 years ($13 million to $20 million per year). We estimate between 70% and 75% of the costs will be in the first five years.

The estimated cost is broken down into:

  • fencing (70% of total)
  • operating profit loss (30%).

For an average sheep and beef farm1 the extra cost would be:

  • $9,200 to $13,700 per year (over 30 years)
  • 8% to 12% of farm operating profit before tax.

We estimate the cost of excluding stock from land with high erosion risk (Highly Erodible Land 1) to be between $720 million and $1,1080 million over 30 years ($24 million to $36 million per year). For an average sheep and beef farm, the extra cost would be:

  • $16,500 to $24,700 per year (over 30 years)
  • 14% to 21% of farm operating profit before tax.

However, the cost of keeping stock off highly erodible land can be offset by planting the land in permanent forest and claiming the carbon credits. How far the carbon revenue stream can offset stock exclusion costs depends on the price of carbon. For example, if all severely erodible land were to be planted in pine, at a price of $35 tonne the returns from carbon would fully offset the estimated stock exclusion costs2.

What does the science say?

Human activities, especially clearing native forest and draining wetlands for agriculture, have worsened erosion in Northland and increased sedimentation in our rivers and estuaries. For example, sediment accumulation rates in the Bay of Islands are around 14 times higher than 150 years ago3 and about six times higher in the Kaipara harbour compared to pre-human times4.

In the Kaipara catchment, a large proportion of the land-based sediment comes from highly erodible pastureland, producing an estimated 77% of the land-based erosion. In the Bay of Islands it equates to around 60%5.

Modelling6 indicates that afforestation of highly erodible land, either into permanent forest cover or plantation forests, is an effective way to reduce sediment – estimates range from about 30% for permanent forest cover, 25% for plantation forest (space planting achieved about a 12% reduction)7

Summary

We think there is a good case for applying stock exclusion rules to our most highly erodible land and encouraging stabilisation of these areas with trees. It would be effective at reducing sediment runoff and make slips less likely and less severe.

Furthermore, some of the costs of excluding stock from this land can be recouped by planting in carbon forestry or permanent forests that are selectively logged.

 


1 We did not do an estimate for dairy because there is unlikely to be much dairy on highly erodible land.
2 On 24 July 2023 the spot price was $47.25.
3 Swales, A., Gibbs, M., Hewitt, J., Hailes, S., Griffiths, R., Olsen, G., Overden, R., Wadhwa, S. (2012). Sediment sources and accumulation rates in the Bay of Islands and implications for macro-benthic fauna, mangrove and saltmarsh habitats. Report prepared for Northland Regional Council.
4 Green, M.O. and Daigneault, A. (2018). Kaipara Harbour Sediment Mitigation Study: Summary. Report NRC1701–1 (minor revision), Streamlined Environmental, Hamilton, 64 pp.
5 Swales et al., (2012); Green & Daigneault, (2018). Op cit.
6 Semadeni-Davies, A; Whitehead, A. and Elliott, S. (2021). Water quality modelling for Northland to support NPSFM implementation, NIWA client report prepared for Northland Regional Council; and Semadeni-Davies, A. (2022). Water quality modelling to support NPS-FM implementation Further scenarios. NIWA client report prepared for Northland Regional Council.
7 These figures were estimated based on planting of the whole area of highly erodible land in Northland.

Wetlands are important habitats. They also trap sediment and other contaminants and reduce how much gets into streams and rivers. Furthermore, wetlands soak up water during floods and release water during droughts. Excluding stock from wetlands improves habitat value and their ability to trap contaminants and manage water flows.

The current rules require:

  • dairy stock and pigs to be excluded from wetlands greater than 500 square metres.
  • beef, dairy support cattle and deer to be excluded from wetlands greater than 500 square metres on low-slope land.

The current rules do not require beef, dairy support cattle and deer to be excluded from wetlands in hill country areas. However, there are important wetlands in Northland’s hill country, and wetlands higher up in catchments effectively reduce contaminants entering waterways.

We think there is a gap in the current rules for excluding non-dairy stock from hill country wetlands.

To address this, we are considering a phased approach requiring beef, dairy support cattle and deer to be excluded from hill country wetlands greater than 2000 square metres in the interim and from all wetlands larger than 500 square metres in the longer term1.

We do not see the need for setbacks from wetlands as riparian buffers are less important for wetland health and they are typically not as sensitive to sediment or nutrients compared with other waterbodies.

What would it cost?

We estimate the cost of excluding non-dairy stock from wetlands greater than 2000 square metres in hill country areas would be between $50 million and $70 million over 30 years ($1.7 million to $2.3 million per year). We estimate 65% of the costs would be in the first five years.

The estimated cost is broken down into:

  • fencing (78% of total)
  • operating profit loss (22%).

For an average sheep and beef farm the extra cost would be:

  • $1,100 to $1,600 per year (over 30 years)
  • between 1% and 1.4% of farm operating profit before tax.

The cost of excluding non-dairy stock from wetlands greater than 500 square metres but less than 2000 square metres in hill country areas is estimated at between $20 and $30 million over 30 years ($0.7 to $1 million per year). This includes fencing costs and lost production. We estimate 65% of the costs would be in the first five years.

For an average sheep and beef farm the extra cost would be:

  • $700 to $1000 per year (over 30 years)
  • between 0.4% and 0.6% of farm operating profit before tax.

What does the science say?

Excluding stock improves the quality of wetland habitats and their ability to filter contaminants – they are more effective at trapping sediment when they are not grazed. It is difficult to estimate the exact reduction in contaminants as a result of excluding stock from wetlands. However, we know hill country wetlands filter contaminants before they enter waterways and reduce downstream impacts.

As an example, modelling shows constructing new wetlands around the small tributaries in headwater catchment areas could reduce the total amount of sediment in waterways across Northland by up to 18%2.

Modelling shows constructing wetlands in headwater catchments could effectively reduce E. coli. Therefore, fencing off existing wetlands will reduce faecal contamination in waterways — particularly wetlands directly connected to waterways.

What we think

Hill country wetlands are important habitats and contaminant filters. We think there is a good case to require non-dairy stock to be excluded from hill country wetlands. We recognise this will be costly, so a phased approach would be more practical.

What do you think?


1 Examples of indicative dates could be 2030 for the interim requirements and 2035 for the longer-term requirements.
2Semadeni-Davies, A. (2022). Water quality modelling to support NPS-FM implementation Further scenarios. NIWA client report prepared for Northland Regional Council.

The current rules apply to dairy cattle, pigs, beef cattle, dairy support cattle, and deer.

However, other farmed animals can impact water quality. For example, sheep excrete high concentrations of E. coli in their faeces, so even small amounts deposited into streams will have an impact1. E. coli concentrations in Northland’s waterways are high and impact on freshwater activities such as swimming and collecting mahinga kai.

Animal access to waterways can also disturb or damage freshwater habitats, increase sediment, and reduce the effectiveness of riparian vegetation by grazing.

Given that all animals can impact water quality, increase sediment loss from highly erodible land and damage freshwater habitats, there is a case for all stock to be subject to exclusion rules.

We recognise that this is likely to mean costs will be higher. For example, fencing to exclude sheep or goats costs more than fencing to exclude cattle. This can be mitigated somewhat by allowing sufficient lead-in time, but even so the costs would be significant.


1 Moriarty, E., Gilpin, B. (draft). Sheep as a Potential Source of Faecal Pollution in Southland Waterways. Report prepared by ESR for Environment Southland; and Muirhead, R., Hudson, R., Cookson, A. (2023). A review of river microbial water quality data in the Northland region. Report for the Northland Regional Council Client Report Number: RE450/2023/029 prepared by AgResearch Ltd.

We need your feedback on when any new stock exclusion rules should apply. The longer the timeframe, the more time for people to adapt – but the longer it will take for the health of freshwater to improve.

The government requires we be ambitious but reasonable in setting timeframes for improving freshwater. The draft Freshwater Plan Change includes targets to improve water quality over time (see Appendix H.12 of the draft Freshwater Plan Change) with improvement in water quality and waterbody health by 2035.

The current rules require non-dairy stock (beef and dairy support cattle and deer) to be excluded from lowland rivers and wetlands of 500 square metres or more by 2025, and no new requirements would apply after this date. As outlined above, we do not think these rules will provide the improvement needed.

We think we need to build on existing rules by phasing in new stock exclusion requirements over the next 10 years or so. For example:

  • New requirements for stock exclusion from hill country rivers and wetlands for non-dairy stock to address the gap in current rules.
  • Extending stock exclusion rules to apply to more stock types and widen setbacks around waterways.
  • Applying stock exclusion rules to highly erodible land.

This staged approach would allow time for landowners to make the changes needed but ensure we make progress on improving our freshwater. We think this would be the best balance between giving landowners lead-in time and the need to act to improve the health of freshwater.

What do you think?