Why do we need a stormwater framework?
The proposed regional plan and central government direction both require us to do more to improve the water quality of our stormwater discharges. Our current (2008) strategy is more about managing water quantity, with a focus on flooding, sea level rise, and hydraulic neutrality (balancing the amount of water going into and out of the network).
We’ve started by working with mana whenua on an overarching framework with an agreed vision, values and outcomes for managing stormwater in the district. This will guide our local, regional and national stormwater management strategies and obligations.
Taking the ‘storm’ out of stormwater
Kāpiti has more than 200 km of stormwater pipes and more than 50 km of open stormwater watercourse, but half of them may not cope with flows from a 1-in-10-year flood. Increasing the size of the pipes or the network is not always an option due to both spatial constraints – there simply may not be room for bigger pipes – and because the upgrade costs may outweigh the benefits.
A more cost-effective alternative is storing rainfall close to where it lands, re-using it and/or slowly releasing it back into the stormwater network, and retrofitting or requiring new development to store and treat stormwater on site. Where there’s space a good option is creating ‘treatment’ facilities that imitate natural landforms and processes, like stormwater wetlands and ponds.
It’s part of our move from the traditional ‘collect, convey, discharge’ approach to ‘slow it down, spread it out, soak it in’. These new techniques help remove the more contaminated ‘first flush’ runoff from the network, even out peak flows in our pipes and drains, and provide extra water to keep your garden growing during dry weather – a win-win all round.
Stormwater responsibilities in Kāpiti
After rain, water quality can worsen due to runoff which carries contaminants from the land. Both the local and regional councils have a role in managing aspects of this, so who does what?
Greater Wellington Regional Council looks after our aquatic ecosystems and water quality by managing land use through regional policies and rules, consenting process and responding to spills or pollution. They have oversight of managing the flood risk from our larger river systems. Greater Wellington is also responsible for the whaitua process, their response to implementing the National Policy Statement for Freshwater, including the setting freshwater targets with local communities and mana whenua.
At the district council we manage flood risk in the urban area and the quality and quantity of stormwater discharged from our network of pipes. We’re currently re-building our flood hazard models to get an updated understanding of where the risks are located or increasing. We’re also working with mana whenua on a project to renew and upgrade water assets like pipes and channels and to develop the refreshed stormwater management framework.
Both councils regularly monitor water quality throughout the district to identify risks to public health and aquatic life, and to record water quality changes over time.
Learning to live with more water
We’re changing how Council manages stormwater so we can accommodate growth, respond to climate change, protect community health, and care for our environment. Council stormwater engineer Rita O’Brien explains why we’re working with iwi and the community to develop a new stormwater management framework that will help our district live with more water.
A lot has changed with water on the Kāpiti Coast since our current stormwater strategy was published in 2008 so our strategy needs to evolve too. We’re working with mana whenua to develop an overarching framework that will provide a vision, values, and desired outcomes to guide the increasingly complex and interrelated freshwater management activities in our district.
Essentially, we need to find a way to live better with more. More flooding from climate change such as increased rainfall and higher sea and groundwater levels. More development, creating more run-off by reducing natural surface areas that soak in excess water, and requiring more and bigger pipes and treatment facilities. There’s also more complex national and regional government regulation which governs the amount and quality of the water we discharge back into our natural systems. And there’s more community awareness and higher expectations around how we manage and look after our water.
The most important idea governing contemporary freshwater management is the mātauranga Māori concept: Te Mana o Te Wai. This recognises that the first priority of freshwater management is to ensure the life-supporting capacity of water. It recognises the vital importance of water to people and the environment and the interconnection between land use, the environment and the three waters we manage: waste, storm and drinking water.
Te Mana o Te Wai is central to the Government’s national direction on freshwater. This concept now governs all freshwater management decisions and activities by national, regional, and local authorities, requiring us to restore the health of freshwater, not just prevent it from getting worse.
Councils, communities and tangata whenua will determine how Te Mana o Te Wai is applied locally. This is assisted by Greater Wellington Regional Council’s whaitua (‘catchment’) committees that are responsible for setting water quality and quantity targets in order to uphold what communities value about freshwater bodies in their area. Cr Jocelyn Prvanov is our representative on the Kāpiti Coast whaitua committee.
This is important work: we need people with local knowledge and skin in the game to articulate how we balance local water uses, while implementing environmental protection and restoration in line with Te Mana o Te Wai.
Another related principle in freshwater management is Ki Uta Ki Tai (‘from the mountains to the sea’). This is not just about the water body itself, but about the integration of the entire catchment. It recognises the interconnectedness of the land, water, plants, animals, and people – past, present, and future – and aims to avoid adverse immediate or cumulative effects on the health and well-being of our freshwater environments.
An exciting local example of this in action is Waikanae Ki Uta Ki Tai, a project where mana whenua, Greater Wellington Regional Council, the Department of Conservation and Kāpiti Coast District Council, supported by community representatives, are working in partnership to improve community wellbeing by revitalising the whole of the Waikanae Awa [https://www.waikanaeawa.org.nz/
Te Mana o Te Wai and Ki Uta Ki Tai, supported by the work of the whaitua committee, have important implications for our refreshed stormwater management framework. By reviewing the framework we’ll embed these concepts and help achieve our community’s vision for managing our stormwater, adapting to our changing environment and providing better protection from flooding. A steering group of mana whenua, and local and regional council staff supported by technical experts is developing a draft stormwater management framework which will be released for consultation soon.