_GENERAL DOCUMENTS - C1981017 (284)

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CRYSTAL RIVER Four stations were sampled on this stream in April and June. Station 3 was the upper station, Station 1 was the next station downstream, Station 2 was lower, and Station 4 was the lowest station. The lower two stations were below the Coal Creek confluence. When sampled in April, the macro communities at the lower two stations had limited populations, particularly at Station 2. Of 25 taxa present, only three had resident population numbers. There were warning numbers of those taxa tolerant to sedimentation at each of the four stations sampled. The observed numbers of shredders in the communities at the upper two stations (1 and 3) are generally found where riparian habitat is in good condition, and at the lower two stations where riparian habitat is in just fair condition or where instream habitat conditions are not suitable for those species. In addition to sediment impacts at the lower two stations, it appeared that there may be a non—selective toxicant, possibly from chemicals used in the coal mine operation affecting these ecosystems. The DAT at Station 2 was lower than that found at any of the other stations. The other analysis elements remained fairly consistent. There appeared to be less stability at the lower two stations than was observed at the upper two stations on this stream. When sampled in June, the BCI values indicated that conditions were similar, except at Station 4, where the BCI value had dropped from 100 in April to 83 in June. Compared to the upstream station, the macro invertebrate biomass at Station 2 was 74% lower, and at the lowest Station (4) the biomass was 25% lower. At Station 2, the DAT Diversity Index value had dropped to 8.8 compared to 13.3 at the upper stations, and at Station 4 the DAT had dropped from 13 to 11. The community stability had been reduced at the lower two stations, as indicated by fewer species with resident population numbers. The sulfate concentrations of 90 to 110 mg/l at stations sampled on this stream would be limiting to sensitive macro species that might otherwise inhabit these stream reaches. The potential for fisheries on this stream appeared to be fairly good. Cleanwater taxa present at the upper stations indicated that there would be suitable spawning substrate available. The macro invertebrate biomass of 1 .1 and 1.2 g/m2 at the upper two stations would be sufficient to provide nutrients for a fairly good fishery, but the 0.3 g/m2 at Station 2 would be limiting to the fisheries. The BCI values in the 80s and 90s indicated that there was a good assemblage of macroinvertebrates at each of these stations; however, there 11