Due to the inconveniences associated with under ice population studies, most aquatic population studies are made during the spring, summer, and fall seasons. Like most lakes little is known about the fall and winter popu-lations of the Utah Lake invertebrates. The purpose of this study is to classify, determine quantitative fall and winter population fluctuations, and obtain life history and ecological information of the macro-invertebrates at . Lincoln Beach, Utah Lake. This lake is the largest, natural occurring body of fresh water in the state and has a high potential for the production of gamefish and water-fowl. As Smart (1960) points out, an estimate of the amount of bottom fauna is the most important single stand-ard for evaluating the potential of a lake to produce fish. It is also an important consideration in the evaluation of waterfowl habitats (Barnett, 1964).

Fish culture for both food and sport utilization has been greatly increasing throughout the world. The editor of Fish Farming Industries (1973) predicted an increase by 1977 in the United States of 83% for catfish producers, 49% for trout farmers, and 91% for bait dealers. Concomitant with the renewed interest in fish culture has been a corresponding need to further understand fish diseases.

Nests of the Black-crowned Night Heron and the Snowy Egret were examined in five central Utah colonies in 1973 to determine the spatial distribution within the colony. Nest locations of the 1085 nests of the two species were plotted to the nearest foot with an alidade and plane table. Tests of randomness, clump size, association, segregation, and T distribution were utilized. No differences between species were noted for the distance to the nearest and the next nearest nest. The Night Heron nested closer to other Night Herons and more often than did the Snowy Egret which non-significantly selected either species to nest closest. The Snowy Egret nests were 1.7 times higher than the Night Heron nests. Both species nests were aggregated within the colony. The association between the species within the habitat was positive but were segregated within the colony. Nest succession within a colony indicates that the Snowy Egret becomes more selective as time progresses but that the Night Heron remains selective throughout the entire season.

Macroinvertebrate populations in the Weber River, Summit County, Utah, were analyzed to determine what effects channelization resulting from Interstate-80 construction and water impoundment had on the standing crop, species diversity and species composition. Bottom samples were collected monthly from riffle areas in channeled and unchanneled sections and above Echo and Wanship Reservoirs. Macroinvertebrate populations in the channeled areas were similar in standing crop, species diversity and species composition to those in unchanged areas within six months following channelization. Species diversities were higher (d=4.1, 3.7) above the reservoirs than below (d=2.0). The reservoirs restricted the distribution of several species of macroinvertebrates. The effects of channelization on the macroinvertebrate fauna in the Weber River were negligible, but water impoundment influenced the species composition and species diversities of the populations occurring in the tailwater.