Protecting our water quality

City Forests has worked with the Otago Regional Council to set up an appropriate water and water course monitoring system for key waterways in the company’s forests.  Semi-permanent sample points are established in streams that are adjacent to impending, current or post-harvesting operations, and are intended to monitor for changes in water or water course quality due to harvesting operations.

Attributes assessed are:

  • Water clarity (SHMAK rating)
  • Water temperature
  • Water conductivity
  • Any evidence of substrate sedimentation
  • Invertebrate types
  • Condition of riparian vegetation.

Evidence of such monitoring consistently shows the benefits of well managed plantation forests to stream water quality, especially when compared to streams which cross farmland.

Some of City Forests’ plantations form part of Dunedin’s water catchment network, including Flagstaff and Ross Creek forests. This demands diligent monitoring and maintenance of the water quality whenever there is harvesting or roading activity taking place in the catchment.

Currently, Nine active water sampling points are established in significant waterways. In 2020, six of these have been remeasured according to our monitoring protocols, the other three points are scheduled for monitoring later in the year.  The water quality was consistently good or excellent as usual. Water points with rocky streambeds show high numbers of indicator invertebrates which designate good stream health.

Water quality from our thousands of hectares of planted forest consistently remains virtually indistinguishable to that coming from natural forests.  In more than twelve years of routine water quality measurements to July 2020 there has been little evidence of any significant deterioration in water quality in monitored waterways.