DSS for setting turbidity limits at peak flows

Instructions

Determine the site at which turbidity levels are to be set within a river network (i.e., identify the latitude and longitude, or NZ Topographical map easting and northing of the site).
Determine the fish species (especially smelt and inanga) that are present at, or above this site, or in the stream reach immediately below the site but above the first tributary below it (NB: fish species above the site can be expected to move through it. Species below the site, but above the first tributary below it, need to be determined because high turbidity levels will not be diluted greatly until the stream reach is joined by another tributary).
Fish distributions can be determined directly by examining records in the New Zealand Freshwater Fish Database and plotting fish distributions on a map of the waterway, or conducting a fish survey. Where there are no records available, then indirect methods may need to be used to indicate occurence/locations.
Work through the DSS from the top down. The graphs referred to in the DSS are shown on the right hand side of this page. If there are no fish present that are known to be sensitive to turbidity, then there is no turbidity level that can be used to protect fish life and other stream values will be more relevant.

More information on the New Zealand Freshwater Fish Database

Indirect methods for assessing fish occurrence

Reference

The DSS for peak flows is based on research results reported in:

Rowe, D.K.; Suren, A.M; Martin, M.; Smith J.P; Smith B.; Williams, E. (2002). Lethal turbidity levels for common freshwater fish and invertebrates in Auckland streams. NIWA Client Report ARC02283.