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Dames & Moore, 1999 - USDA Forest Service

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To the extent practical, electroshocking was conducted to cover all parts of the sampling area with the<br />

objective of capturing the maximum possible number of fish from that sampling area. The length of time<br />

spent (effort) electroshocking any sampling area depended on numerous water conditions at the location<br />

including, but not' limited to, depth, temperature, conductivity, clarity, and velocity.<br />

All captured fish were initially placed in a holding net during electroshocking passes. The net was<br />

maintained outside the field of electrical influence. At the completion of each pass the fish collected were<br />

transferred to large (5-30 gallon) containers for processing. The intent of this procedure was to process<br />

the fish as quickly and efficiently as feasible to minimize stress to the captured fish.<br />

All fish captured were identified to the lowest practical taxon, measured to the nearest millimeter (total<br />

'length), and weighed to the nearest gram. All data were recorded on field notebooks. After all data for<br />

each fish were recorded, the fish were returned to the stream.<br />

3.9.1.4 Data Evaluation Procedures<br />

The following sections provide descriptions of the procedures employed during the evaluation of benthic<br />

macroinvertebrate and fish data collected during the field sampling phase.<br />

Benthic Macroinvertebrates<br />

Metrics appropriate for evaluating metals-impacted streams were used during the evaluation of the<br />

benthic macroinvertebrate sampling results. These metrics are included in the Region 10 In-Stream<br />

Biological Monitoring Handbook (EPA, 1993) and are as follows:<br />

Taxa (species) richness<br />

Ratio of scrapers to filtering collectors<br />

Ratio of Ephemeroptera, Plecoptera, and Tricoptera (EPT) abundance to chironomid<br />

abundance<br />

Percent of contribution dominant taxon<br />

EPT index<br />

Community loss (similarity) index<br />

Ratio of shredders to total number of individuals collected (applicability as determined<br />

based on the presence of organic matter depositional locations noted in the field)<br />

Although the Hilsonhoff Biotic Index is recommended by EPA (1993), this matrix is not appropriate for<br />

metals-affected communities.<br />

' Fish<br />

/<br />

In general, fish sampling by electrofishing was conducted to document fish species occurrence and<br />

relative abundance. Relative abundance was determined by calculating population estimates of trout<br />

(salmonids) present, where possible. Population estimates for trout for all reference locations were<br />

calculated and compared with the corresponding trout population estimates at each individual sampling<br />

location. Because of the low numbers of fish at each sampling location, length frequency histograms<br />

G:\wpdato\W5\RporUUloldrn-2\riUO.doc<br />

17693-005-019Uuly 19.<strong>1999</strong>;2:07 PM;DRAFT FINAL RI REPORT

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