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i the lab where the organisms were sorted from the debris, identified and counted. The Shannon-Wiener Diversity Index (D) was calculated for the I invertebrates using the formula found in Weber (1973). Fish populations were sampled qualitatively by making one pass with 1 backpack electrofishing gear through 100m sections at each station, except Station 1 on Middle Creek where 25m were sampled. Fish captured were identi- ~ fied and counted. MACROPHYTES Aquatic macrophytes are generally uncommon in Rocky Mountain streams due primarily to the lack of suitable substrate for root growth and the abrasive action of the turbulent currents. However, where current slows I down and substrate is finer (i. e., sand and silt), rooted aquatic plants can 1 develop. Although important as habitat, these plants are most commonly used as a food source by invertebrates when they die back, not when living. When present, they are a source of detritus, which is an important food source of the majority of benthic invertebrates. Aquatic macrophytes were common in Middle Creek. Emergent species such as sedge (Carex nebraskensis) and spike-rush (Eleocharis macrostachya) growing along the edge of the stream were the primary representatives at all three stations (Fig. 2, 3 and 4). Station 2 did have a few small beds of submerged pondweed (Potamogeton pectinatus) in riffle sections (Fig. 3). ~ Fish Creek was ve etated with a vatic emer ent macro h tes g q g p y (Carex ~ nebraskensis and Eleocharis macrostachya) along the edge of the stream (Fig. 5 and 6). Station 1 had two small beds of pondweed in riffle sections of the stream (Fig. 5). Station 2 had two large, dense beds of pondweed and two other smaller beds in the stream (Fig. 6) along with a small patch of the alga Chara globularis, which is considered to be a macrophyte due to its j large size. • -4-