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5 Stomach contents were separated, identified, and counted into major taxonomic levels or food item categories using a binocular directing scope. Most macroinvertebrates were identified to order, genus, or family while some were unidentifiable because of their mutilated condition (Figure 2). Food item weights for macroinvertebrates and/or fish from fish spe- cies (e.g. Ptychocheilus, Ictalurus, Gila, and Notropis) with relative- ly short stomachs and unconvoluted intestines were obtained using an average value from the length-weight method (Hynes 1961 and Hynes and Coleman 1968) and the weights for the mayfly Ephemerella subvaria (Waters and Crawford 1973). The Hynes method assumes that an insect's shape is that of a cylinder, 5 times as long as wide, and that as it grows linearly its volume increases cubically. This is true for most macroinvertebrates (except Chironomidae-midges and Ceratopogonidae-biting midges which are thinner, approximately 7.5 to 10 times as long as wide) up to a length of 10 mm. The Waters and Crawford weights were obtained from direct weight measurements of mayflies which had been collected for production estimations. For example, the weight of a 4 mm long specimen would be 2.51 mg using an average of these two methods (Figure 3)• The following subsample method was used to obtain food item numbers and biomass for fish species (e.g. Pimephales and Catostomus) which had long convoluted intestines packed with an amorphic paste of silt, debris, and/or seston. The intestine was unraveled and measured by laying it on a plastic ruler. It was cut in the middle and the inside diameter was measured. A 2 mm long section of gut was removed from one intestine half (adjacent to the cut) and the contents were