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A total of 821 usable total length (TL) and weight measurements from <br />known-age trout were taken between October 1979 and October 1981. The <br />majority of samples were taken during October end-of-growing-season <br />surveys in 1979, 1980, and 1981. Valuable growth data were also <br />collected during July 1980, one year following stocking of the 1979 year <br />class; during May 1981, about one year following stocking of the 1980 <br />rainbow trout cohort; and during the winters of 1980 and 1981. Although <br />TL, weight, and age were recorded from numerous samples collected for <br />other purposes, these efforts were not all specifically designed for <br />growth assessment and sample sizes were often insufficient to permit <br />their use.. <br />Response of aquatic invertebrates to the penstock modification was <br />monitored by BIO/WEST, Inc., Logan, Utah, under contract with BOR. <br />Further invertebrate studies were subcontracted by UDWR to Aqua-Tech <br />Biological Consultants, Logan, Utah. Methods employed in invertebrate <br />studies can be found in Holden and Crist (1981) and Gosse (1982). <br />Length-weight data for rainbow and cutthroat trout were analyzed by <br />species, year, and capture site, with respect to time since stocking. <br />Growth increments were calculated based upon mean TL at time of stocking, <br />taken from hatchery records. Individual lengths were measured from fish <br />representing some, but not all, hatchery lots; thus errors due to <br />variation in TL at time of stocking were not systematically accounted <br />for. Trout at large for less than 6 months, most of which were sampled <br />in October, were used to estimate monthly first summer growth; those <br />trout at large for approximately 12 months were used to estimate annual <br />growth. Condition (KTL) was calculated using the formula: <br />KTL = Weight (gm) X 100,000 <br />Total Length (mm)3 <br />-16-