Invertebrate and fisheries surveys of the Johnson River watershed

Milner, Alexander

This report summarizes three years of investigations from 1995 to 1997 of biotic habitat within the Johnson River and Bear Creek drainages on the west side of Cook Inlet. These investigations were part of water quality information collected by the National Park Service asa baseline with respect to possible future mining activities within the Johnson River valley and road construction to transport the ore to a seawater port. ... The aim of this project was to collect water quality information and macroinvertegrates at a number of sites within the Johnson River valley which could be used as a baseline against future changes. Where appropriate, bioassessment metrics have been calculated to ascertain water quality. Using helicopter access 11 sites were established in 1995 on the Johnson River between June22-24, 1995; six sites on the mainstem Johnson River and five sites on tributary streams. The 1995 study concluded that the mainstem Johnson River was not suitable for macroinvertebrate monitoring with respect to water quality changes as the determination of bioassessment metrics would not be informative due to the major influence of glacial runoff. Nevertheless, Plumiperla, found at a number of downstream sites, could act as a possible indicator species of mainstem changes althrough their abundance was not high. However, it is likely that hte dilution of any contaminants by the Johnson River mainstem will be large and this habitat is unlikely to be affected. A number of Johnson River sites were retained in 1996 and 1997 to increase our understanding of glacier-fed mainstem sites....