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24 I I I I I I I I I I I I I I I I I , I August 14, which indicated they were probably spawned in mid-late July. By September, these young-of-the-year had reached the size of the 1978 year class noted in April, 1979. One squawfish, possibly from the 1977 year class, was collected during June (Figure 2). Both young-of-the-year and juvenile squawfish preferred backwaters although a few juveniles were found in runs (Table 4). A distinct pre- ference for certain types of backwaters was noted in that more young squawfish were found in backwaters that were at least a meter deep. Bony tail and humpback chubs were not taken during the study, and the capture of only 6 razorback suckers provides little information concerning that species beyond verifying its presence in the area. Benthic Macroinvertebrates - The mean number and standard deviation of the three macroinvertebrate samples by month and station are shown in Table 6. The mean total for each station by month is also given. A general trend is indicated where numbers are moderate in April, very low in May and June, then higher in July, August, and September. The major exception to this trend is the May sample at the lower station which recorded the highest monthly mean for that site. This sample was taken on May 15, whereas the samples at the upper and middle stations were taken on May 21. The most prominent taxa during the study were chironomids, baetid and heptageniid mayflies and brachycentrid and hydropsychid caddisflies. Plankton, Periphyton, and Macrophytes - Analysis of the plankton samples showed that little true plankton occurs in the Green River. Zooplankton included a few copepods (Cyclops) and rotifers (Polyartha