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II I- I I I I I I I IJ I I I I I I I I I 13 '. adequate to determine if the observed changes in fish population were natural or induced by man. 4.2 Cripple Creek 4.2.1 Water Quality Ariqua Gulch was a metal source to Cripple Creek, Cadmium, copper and zinc were present at acutely andlor chronically toxic levels for waters of normal hardness concentrations. The high hardness levels of Ariqua Gulch mitigated this potential toxicity. This sampling event was limited to one day. No inferences can be made about water quality at other times of the year or changes associated with snowmelt or summer thunderstorms, 4.2.2 Macroinvertebrates The diversity of macroinvertebrates of Cripple Creek was lower than many Colorado headwater steams, Mayfly, stonefly and caddis fly species normally found in Colorado mountain streams were not present in Cripple Creek. The Dipteran species' Limnophora aequifrons was collected upstream and downstream of Ariqua Gulch. This species has only been found by the DOW in California Gulch, a stream that carries a high metals and effluent from domestic wastewater, conditions much like Cripple Creek. At the mouth of Cripple Creek, some species normally found in Colorado mountain streams were present, such as the caddis fly Hydropsyche sp, Evidently, the stream recovered to some degree at the lower terminus of the waterway. A variety of factors, including an upstream domestic wastewater treatment facility, as well as inactive and active mining, were likely responsible for a reduction in macroinvertebrate species in Cripple Creek. 4.2.3 Fish The absence of fish in Cripple Creek near Ariqua Gulch was expected. This stream is small and shallow. There was no winter habitat for fish, Fish could be expected to colonize the lowest section of Cripple Creek at least seasonally, The absence of fish in fall 1995 at the month of Cripple Creek may be attributable to a variety of factors, including an upstream domestic wastewater treatment facility, as well as inactive and active mining. 5.0 Summary Fourmile Creek is a dynamic trout stream, The numbers of brown trout, longnose dace and white suckers decreased in 1995 compared to 1994, The cause of this decrease is not known. Future sampling on Fourmile Creek will gather adequate information over a series of years to differentiate between annual variation and disturbances attributable to human activities, '.