As part of a relicensing project, FISHBIO conducted a multi-faceted stream assessment to evaluate the condition of the South Fork San Joaquin River downstream of Florence Lake Dam. This project involved conducting four separate studies, including: 1) characterizing the fish population and documenting incidental sightings of other aquatic vertebrates, 2) evaluating the benthic macroinvertebrate community, 3) in situ water quality measurements and collection of water samples for analytical laboratory analysis, and 4) assessing stream bank stability and sedimentation.
To characterize the fish population within the study reach, FISHBIO conducted multiple-pass depletions at two sites using backpack electrofishing. All fish were identified to species, measured, and weighed. These data were used to estimate populations of brown trout and rainbow trout, and to evaluate fish health. FISHBIO also collected habitat data following the Surface Water Ambient Monitoring Program (SWAMP) protocol, which involved collecting benthic macroinvertebrates. In situ water quality sampling included measuring dissolved oxygen, pH, water temperature, electrical conductivity, and turbidity. Channel assessment included conducting cross-sectional profiles of various representative reaches, visually estimating the volume of sediment deposits, and conducting detailed sediment volume calculations. FISHBIO compared the data from all study components to an earlier study to evaluate potential signs of impairment and assess the health of the South Fork San Joaquin River.