The Otakairangi Swamp is a remnant of what would have been a much more common vegetation type in the Upper Wairua catchment floodplain before being cleared for farming.
While only 2.6 km2, it is a very significant remnant of a now rare type of wetland.
It is under threat from the impacts of drainage and elevated nutrients from nearby farms.
Living Water has funded a number of baseline information projects to determine the need for and methods of mitigating these impacts. We established and maintained strong stakeholder communication with land owners and tangata whenua throughout this work.
The first project commissioned in early 2015, sought to better understand the importance of the Otakairangi Swamp. The subsequent report, Living Water - Opportunities for restoration: Hikurangi Floodplain by Bev Clarkson, Scott Bartlam, Robbie Price - Landcare Research[RC1] , recommended that Otakiarangi Swamp be restored and a restoration plan be developed. Specifically the report wanted to see previously destroyed populations of native rushes (Sporadanthus ferrugineus) and invertebrates (Houdinia flexilissima) re-established and peat-forming processes restored to demonstrate to the public what could be achieved.
Further reports were needed to determine the best ways of achieving these recommendations and included extensive mapping of the swamp, and understanding the hydrological functioning and resilience of the swamp.
Mapping: In early 2016 a drone was used to systematically photograph and map the contours of the swamp. During this work invasive weed species were identified and later controlled. An aerial pig hunt was also carried out.
Hydrology: We needed to know the influence of historic and current drainage on the swamp. In 2017 we contracted Waikato University to complete an Assessment of the Eco-hydrological functioning of Otakairangi WetlandDavid Campbell –Waikato University[RC1] . Positive interaction and discussions between the report’s author and farmers led to identification of practical solutions that farmers could implement to improve the eco-hydrological processes of the wetland.
Resilience: A student involved in the eco-hydrological report went on to complete a Master of Science Thesis: Characterising the degradation and recovery of a wetland remnant- Callum Douglas and David Campbell – Waikato University [RC2] . The goal was to determine the influence of the central drain on the condition of the wetland and determine the extent of natural recovery by characterising the eco-hydrological functioning. This thesis identified significant points where nutrients were entering parts of the Otakairangi Swamp from two adjoining dairy farms, causing degradation of vegetation and impacting on the functioning and recovery of the ecosystem.
Using baseline data to inform and underpin discussions with adjoining dairy farm owners has enabled Living Water to confirm funding for co-designed projects that will modify the drainage channels that are creating the problem.
It has also helped design a water quality monitoring plan with equipment being installed to measure changes to sediment and nutrient levels in the central drain of Otakairangi Swamp and other waterways in the catchment. This will enable Living Water to track the effectiveness of the on-farm projects and potentially scale up our efforts.
Otakairangi Baseline information project
Project start date: 2014