Stream Ecological Valuation: revisions to the method for assessing the ecological functions of New Zealand streams

ABSTRACT

The Stream Ecological Valuation (SEV) provides water resource managers with a standardised measure of the ecological functions of a stream reach. Reaches are assessed in terms of their hydrological, biogeochemical, habitat and biological functions. SEV has been widely used for resource consent applications and monitoring in the Auckland region since 2006. End-user feedback, expert review, an accumulated database of SEV data and advances in the underlying science of stream functions prompted a review of the method in 2010. The revised SEV is simpler than the original, and based on slightly fewer functions and variables. Definitions of terms and field methods have been clarified, improving interpretability and reducing subjectivity and field time. In a field test of 19 sites, the revised SEV showed a similar mean (0.68 compared to 0.64) but greater range (0.77 compared to 0.40) of scores than the original, indicating little or no information loss but improved ability to discriminate between pristine and degraded streams.

KEYWORDS:

• Stream
• monitoring
• ecological function
• assessment method

Acknowledgements

We wish to thank Kevin Collier, Chris Hatton, Mike Joy, John Maxted, Stephen Moore, Stephanie Parkyn, Ngaire Phillips and John Quinn who contributed to the original development and revision of the SEV as expert panel members. We also thank Brett Ogilvie and Liza Inglis (Tonkin and Taylor), Nick Carter (Golder and Associates), Eddie Sides (Boffa Miskell), Justine Quinn and Damian Young (Morphum Environmental Ltd) who contributed to the end-user workshops. Additional thanks to Ngaire Phillips for developing the SEV calculator.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by Auckland Council.