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• samples were taken in riffle sections with a Surber square-foot bottom sampler <br />(mesh size 700 um) and two samples were taken in pool habitat with an Ekman <br />4 grab. If no flowing water was found, four Ekman grabs were taken from pools. <br />Each grab sample was placed in a sieve bucket (mesh size 250 um) and rinsed of <br />excess silt. Benthic samples were preserved in the field with 95% ethanol and <br />returned to the lab where the organisms were sorted from the debris, identified <br />t and counted. The Shannon-Weiner diversity index (D) was calculated using the <br />1 formula found in Weber (1973). <br />The fish population of Station 2 on Foidel Creek was sampled qualita- <br />tively by making one pass with backpack electrofishing gear through a 50 m <br />section. Fish captured were identified, counted and released. Oip netting <br />was used to determine presence or absence of fish at the other stations. <br />RESULTS <br />1 Macrophytes <br />Except where suitable substrate and flow conditions exist, aquatic macro- <br />phytic growth in Rocky Mountain streams is rare. The low flow conditions and <br />soft substrate at Foidel Creek Station 2 were quite favorable, allowing large <br />growths of aquatic macrophytes (Fig. 2). Emergent and wetland plants such as <br />sedge (Carex nebraskensis), spike-rush (Eleocharis macrostachya) and manna <br />1 grass (Glyceria maxima) were abundant along the stream banks. Thick growths <br />of the floating leaf plant, smartweed (Persicaria coccinea), were present <br />throughout the section. <br />Benthic Invertebrates <br />1 Benthic invertebrates live in and on the substrate of aquatic habitats. <br />In streams like Foidel Creek and its tributary, many of these organisms are <br />1 the immature forms of aquatic insects with other slow water forms such as <br />crayfish, leeches, worms and snails also common. The life cycles of these <br />organisms in Foidel Creek are closely tied to the flow regime, reaching maximum <br />densities when water is most abundant, i.e., midsummer after the effects of <br />~ spring snowmelt. <br />' Unnamed Tributary to Foidel Creek <br />'; A total of 26 invertebrate taxa were collected from the unnamed tribu- <br />. tary, although only one was found at all three stations. This was probably the <br />-4- <br />