Protection of groundwater dependent ecosystems in Canterbury, New Zealand: the Targeted Stream Augmentation Project

Abstract

In Canterbury, New Zealand, native aquatic species habitat has significantly declined over the last century due primarily to land use change and climatic influences. The Canterbury Water Management Strategy (CWMS) aims to improve such habitat while also meeting other economic, environmental, social and cultural objectives. The focus of this paper will be on the Targeted Stream Augmentation (TSA) Project in the Selwyn-Waihora Zone in Canterbury. The semi-arid climate, significant demand for irrigation water and the up-gradient aquifer pressure provided by a coastal lake provide significant aquifer management challenges in this zone. In response to these challenges the local CWMS committee recommended that managed aquifer recharge trials to improve groundwater dependent ecosystems start in a highly targeted manner before gradually increasing the distance from recharge site to the target spring/s. A highly targeted pilot trial has shown the flow, temperature and nutrient concentration benefits for the target surface ecosystem. The implementation of two larger scale concepts combining surface and groundwater ecosystem benefits is now progressing. Lessons learned to date include the importance of keeping engagement processes ahead of technical assessments, and the benefits of high level scoping assessments before committing to detailed investigations and pilot projects.