Sediment in the Ōpāwaho Heathcote River is a problem. The CCC is responding to this continuing issue by producing a Port Hills Plan. What should it contain?
Recently, Environment Canterbury produced the two images below that explain the issue that sediment causes for life in our rivers and streams. Quite simply, sediment smothers the habitat of organisms that are vital members of the food chains within the river, reduces light penetration and promotes weed growth.
Click the image to see an enlargement.
Sediment in the Ōpāwaho Heathcote River largely comes from erosion of loess soils in the Cashmere Valley although there are contributions from just about every other tributary as well. Streams such as the Bowenvale Stream and Victoria Drain as well as the many stormwater outlets all bring their varying contribution of water-borne silt. However, nothing matches the level of sediment leaving the Cashmere Valley.
When ŌHRN submitted on the Christchurch City Council 2023 Annual Plan in March, we asked, along with several other interested parties, that urgent priority be given to increase the planting of erosion-prone gullies of the Port Hills to reduce erosion at source and to reduce the sediment loading of the Ōpāwaho Heathcote River.
The Port Hills Plan: The CCC has responded to these requests by instructing staff, led by the Regional Parks and Parks Planning teams, to produce a Port Hills Plan. ŌHRN wants to be a supportive advocate in the development of the Port Hills Plan. To do this, we need to:
- Engage with the Council staff at an early stage
- Understand their intended approach
- Communicate our priorities for the plan
Who should be involved in creating the plan? Many groups will need to contribute to the plan the most important of which are Te Hapū o Ngāti Wheke and Ngāi Tūāhuriri. Consultation must also include Environment Canterbury, Department of Conservation, Christchurch West Melton Water Zone Committee, the Summit Road Protection Authority, the Summit Road Advisory Committee, the relevant Community Boards, Christchurch Adventure Park, Christchurch Gondola, local forestry owners and farmers, as well as developers. Trusts and societies that operate in the Port Hills should also play a significant role in providing a community voice: the Port Hills Trust, Summit Road Society, and the Ōpāwaho Heathcote River Network.
Key Issues: The key issues to be addressed by the plan will need to include:
- Climate change with more extreme rain and drought events
- Susceptibility to erosion of loess soils
- Impact of erosion on the sediment loads in the tributaries and mainstem of the Ōpāwaho/Heathcote River
- Increase awareness and community support for biodiversity and habitat restoration, planting, and weed and animal pest control
- Changes in farming practices – forestry, carbon farming, grazing
- Fire risk management given the Port Hills fire in February 2017
- Urban encroachment and subdivisions in and adjacent to the Port Hills with accelerated construction activity and residential development on the Port Hills following the 2011 earthquakes
- Recognition of environmental, geological, landscape and scenic values
- Significant increase in recreational use, both in numbers and in the range of activities of which the Christchurch Adventure Park which opened in December 2016 is a significant item
Guiding documents: It is not as if the Port Hills Plan will be breaking new ground. It will come into existence sitting comfortably underneath higher-level legislation and plans. For instance, the purpose of the Natural and Built Environments Act 2023 is to enable Te Oranga o te Taiao to be upheld, by protecting and enhancing the natural environment. From the National Policy Statement for Freshwater 2020, Te Mana o te Wai ensures that the health and well-being of the water is protected and human health needs are prioritised before enabling other uses of water. The following will also have an impact:
- National Policy Statement for Indigenous Biodiversity 2023
- Mahaanui Iwi Management Plan 2013 – Wai Māori, Papatūānuku and Tāne Mahuta
- Environment Canterbury Regional Policy Statement
- Environment Canterbury Land and Water Plan
- Christchurch District Plan 2017 – The Port Hills have significant natural features, landscape, ecological and Ngāi Tahu values that are protected
- Summit Road (Canterbury) Protection Act 2001
Click to view a 1-page summary of what ŌHRN believes should guide the Port Hills Plan.
Purpose of the Plan: From the ŌHRN point of view, the two related purposes of the Port Hills Plan should be to:
- Provide an overarching and long-term vision for the integration of freshwater management and land use on the Port Hills to achieve Te Mana o Te Wai of the Ōpāwaho/Heathcote River and other freshwater resources.
- Drive action to achieve the desired outcomes of the Plan
Outcomes of the Plan: From the ŌHRN point of view, the overall outcome of the Port Hills Plan is that the integrated management of the Port Hills land and the Ōpāwaho/ Heathcote River and its tributaries is restoring Te Mana o te Wai. Other outcomes would include:
- The headwaters and tributaries of the Ōpāwaho/Heathcote River are protected and the health of the freshwater resources is improving
- The stability and resilience of the Port Hills has been strengthened to protect the Port Hills from erosion and fire
- Biodiversity and natural values are being preserved and enhanced (Remnant ecosystems are protected; there is active revegetation/regeneration; weeds and pests are managed.)
- The Port Hills are valued for low-impact recreation (un-motorised recreation)
- Landscape and heritage values are being protected and enriched
- Land uses in the Port Hills are appropriate and sustainable, and within the capability of the land
- Vegetation is concentrated in the tributaries/gullies and lower slopes, and the tussock is maintained on the upper slopes
We have produced a 1-page summary of our suggestions for the Port Hills Plan. You can read that here.