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<br />17 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />difference multiple-means comparison test (Snedecor and Cochran 1967). For each study, <br />differences between survival curves and the estimated median time to death values from <br />survival curves were analyzed using the accelerated failure time model outlined in Dixon and <br />Newman (1991) and Lawless (1982) based on a Weibull distribution to model the data. <br />Treatment curves were compared by the Bonferroni method to determine significant <br />differences. <br /> <br />RESULTS <br /> <br />Water qualitv <br /> <br />Prior to initiation of the studies, personnel at Ouray NWR used water from the Green <br />River to flood Sheppard Bottom ponds. Water flowed into Sl, then S2 and S4 <br />simultaneously, and from S2 into S3, and from S3 to S5. At the start of 1994, the water <br />level in Sl was full due to gravity water tlow from the Green River, and S2, S3, and S5 <br />were dry; S4 had some water (Dan Schaad, FWS, personal communication 1995). Gravity <br />flow water was intermittently diverted to S2 and S3 from January 5 until February 18. No <br />river water was available from February 4 until late April due to low river elevation. <br />Pelican Lake water (208 AF) was delivered to Sheppard Bottom through the new pipeline <br />from April 10 through May 16. Gravity tlow water from the Green River was diverted to <br />Sheppard Bottom from April 26 through June 12. These waters were co-mingled and <br />diverted to Sl, S2, S3, and S4. Some water entered S5 via the connecting water control <br />structure with S3. The collection site for aquatic invertebrates at S5 was moved on May 27 <br />(day 6 of Study 1; day 1 of Study 2) from near the connecting water control structure for S3 <br />to a location 100 meters south because the S5 site was being substantially diluted by S3 <br />water. <br /> <br />The originally planned reference site was Leota Bottom, but this location was not <br />used because water flow from the Green River was high in Leota Bottom and caused low <br />water temperatures, high turbidity, and low abundance of aquatic invertebrates needed as <br />food in the study. S 1 was selected as the alternate reference site. Water flow in Sheppard <br />Bottom ponds was less disruptive in part due to the long supply canal delivering water from <br />the Green River. <br /> <br />The water quality at the Sl reference site was relatively stable for the first 7 days of <br />use, but the water level started to drop due to evaporation and by day 11 zooplankton <br />abundance had decreased substantially. Consequently, the collection site for reference water <br />used in renewals and zooplankton was moved about 100 meters south on June 2 (day 12 of <br />Study 1; day 7 of Study 2). The new site was about 40 meters from the supply canal and <br />water control structures for S2 and S4. The water quality differed between Sl sites and was <br />closer to Green River water during the latter half of study 1, most of study 2, and all of <br />studies 3 and 4 (Table 1). <br /> <br />The water quality at the six sites where zooplankton were collected differed <br />