Bringing more life to rural drains in the Ararira/LII catchment
March 31, 2021
New Zealand’s agricultural waterways will support biodiversity and cultural values and be effective drains. That’s the goal of an ambitious project taking shape in the spring fed Ararira / LII River catchment of Te Waihora / Lake Ellesmere in the Selwyn District of Canterbury.
The outcomes could be game-changing says Sarah Yarrow, National Manager of the Living Water partnership set up in 2013 by Fonterra and the Department of Conservation (DOC).
“For over 100 years, drainage in Canterbury and across much of New Zealand’s lowlands, has focused on draining land to enable agricultural development and urban settlements. However, this has resulted in the loss of freshwater habitats in the process”, says Yarrow. “From trials conducted in this catchment, we now know that streams with gently sloped and planted banks, pools and natural rapids, support freshwater species and effectively remove excess water as well as straight, steep-sided and mechanically cleared drains. They can also reduce the contaminants flowing downstream into Te Waihora / Lake Ellesmere.”
Living Water has learnt a lot from trials within the Selwyn District’s Ararira/LII River catchment in spring-fed permanently flowing drains – working with iwi, local farmers, and the LII Drainage Committee. The University of Canterbury has completed significant work over a decade to understand how waterways function on the Plains and how to bring back some of the natural qualities to these important habitats. Armed with this information, Living Water, approached the Selwyn District Council (SDC) and Te Taumutu Rūnanga with a proposed Memorandum of Understanding (MoU) to work together on redesigning the LII/Ararira Drainage District.
The goal is to combine small-scale trials with other mitigations, such as strategic land use change, retention ponds, wetland enhancement and other ideas from around the world to create a plan that supports ecological, cultural and drainage values across the whole catchment. The MoU was signed in October 2020, and officials from DOC, Fonterra, Taumutu, SDC, Environment Canterbury and the LII Drainage Committee began work in January 2021.
The MoU is the culmination of several years’ work by the Living Water partnership that has been trialling methods to improve freshwater ecosystem health in the Ararira/LII River catchment and on Fonterra dairy farms. The Living Water partnership has worked closely with both the SDC and Te Taumutu Rūnanga on projects within the drains and streams that flow into Te Waihora / Lake Ellesmere. Trials of small-scale interventions including sediment traps, shading to reduce weed growth, bank reshaping, two-stage channels and enhancing in-stream habitat, have shown the potential for taking a catchment wide approach to transforming drains into healthy waterways.
There are about 76kms of council drains and a similar length of private drains in the Ararira/LII catchment. These drains were constructed from the mid 1800’s to drain the extensive wetlands that surrounded Te Waihora to enable farming and land settlement.
Although these drains are mostly straight with steep banks and may appear to have little ecological value, they are some of the only remaining habitats for indigenous freshwater biodiversity in Canterbury. Traditionally excessive sediment and aquatic weeds were removed with mechanical diggers. This practice contributes to the loss of habitat for native fish and invertebrates. Small-scale interventions provide proof that alternatives are possible.
All the signatories to the MoU recognise the value of improving freshwater ecosystem health. SDC want to sustainably manage the waterway network to ensure effective drainage and enhanced biodiversity. Fonterra can see how this approach will contribute to sustainable farming. DOC sees value in enhancing degraded habitats for freshwater species. For Te Taumutu this new way of managing waterways will align with Ngāi Tahu tribal whakatauki: ki uta ki tai – from the mountains to the sea - by recognising the interconnectedness of the surrounding environment and people’s interaction with the waterways.
A project team has been formed with representatives from SDC, Te Taumutu Rūnanga, Fonterra, DOC, Environment Canterbury and the LII Drainage Committee, to develop a shared vision for the Ararira/LII catchment and support the development of an integrated catchment plan. Advice will be sought from local stakeholders and professionals.
The ideal outcome will be a fit for purpose approach that with community input SDC could implement in the Ararira/LII catchment and other similar catchments under their management. Sarah Yarrow says if successful, there is an opportunity for other councils to use a similar approach in catchments across New Zealand.
“We’re creating partnerships like this because no single organisation or sector has all the skills, knowledge and influence to improve freshwater health and we know it requires more than just on-farm action’, says Yarrow. “By partnering we are making it easier for farmers, iwi and communities to improve freshwater which is a goal we all share.”