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suitable habitat for the whitefish. Differences in the production between the <br />Blacksmith Fork dredged and control sites were due to the higher production <br />(more than 2 times) of age 0 and age 1 fish in the dredged site. The annual <br />production of fish two years old and older was approximately the same in both <br />sites. In addition, Ballard Springs was probably an important nursery area for <br />whitefish in the dredged reach that provided recruitments into the population. <br />The mean annual densities (Figure 8) and standing crops of invertebrates <br />showed no significant differences between sites, reflecting the heterogeneity <br />of the stream habitat and its-resultant sampling variability, as well as sea- <br />sonal changes and the relatively short-term effects of alterations to stream <br />channels on the invertebrate communities. Shannon diversity indices for inver- <br />tebrates increased slightly immediately following stream channel alterations, <br />but decreased as recolonization began by the more mobile families such as <br />Chironomids, Simuliids, and Baetids. The duration of the impact by stream <br />channel alteration on the benthic community was largely dependent upon the <br />stability of the substrate. Stream channel alterations drastically reducp-d%! <br />macroin'vertebrate densities but the invertebrates recolonized the perturbed <br />areas quickly - a reflection of the short reaches that were altered, drift from <br />upstream reaches, the mobility of adult invertebrates, and the reproduction <br />potential of the invertebrates. <br />Although landowners in the floodplains of Utah rivers alter stream channels <br />to prevent flooding, their short reach alterations do not last long -- usually <br />less than one year. These landowners are frustrated by upstream activities <br />that produce streambank erosion and deposition, and the lack of comprehensive <br />programs to stabilize the entire stream system. Three needs are apparent to <br />prevent the continued damage to and destruction of streams: (1) Comprehensive <br />basinwide planning to regulating stream channel changes in order to minimize <br />damages to other landowners and to the stream habitat; (2) research to identify <br />methods of controlling the height of the water table under agricultural land <br />with minimal effects on streams; and (3) an effective information and education <br />program to educate landowners about the hydrology of an area and the hydraulics <br />of the river in a floodplain, the consequences of altering streams and <br />producing unstable conditions in the altered areas as well as downstream, and <br />alternative ways to prevent flood damage to crops. <br />11