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

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. [ABSTRACT FROM PUBLISHER]