WSP12345 - Laserfiche WebLink

Home Browse Search

~ - - - _r._~ .. Tl1..-.~c-" ... _ I I I I I I I I I I ATTACHMENT A 1.0INTRODUcnON This document is me 1994 Annual SlUIlIIIary Report for Study #FG-10 entitled Effects of Row Re~lation and lee Forma[ion on Overwinter Nursery Habitat of Aee-O Colorado SQuawfish in the Green River below Flamine Goree Dam. This. Winter lee Study is part of r.he Five Yeaf fuming Gorge Research Program - FY94 of me Recovery Implementation Program for Endangered Flsh Species in me Upper Colorado River Basin. lnclud~ in [his report are findings and prelilllinary data analysis from tbe first year of this three year study. This investigation was conducted under ConU3C1 No. 90-2558 with the Utah Division of Wildlife Resources (UDWR). Study design and progress repom are reviewed by the RaIning Gorge Work Group of tbe Recovery Program. The purpose of this investigation is to measure backwaters on the Green River between Echo Park and Ouray, UT in fall (September) and winter (January and February) to determine the effect of flow fegulation and ice formation on habitat avai1ability. The principal hypothesis is Ho: Ice develooment in backwaters reduces habitat availabililV and therefore. winter survival of aee-O Colorado SQuawtish in the Green River below Ramine Goree Dam. The objectives oC this study are to: 1. Determine availability oC nursery backwater habitat for age-O Colorado squawfish during winter months (December throngh February). 2. Determine longevity of backwaters exposed to winter flow regulation and ice formation. 3. Recommend winter flows and spring habitat maintenance flows to protect nursery habiull of age-O Colorado squawfish. I i Daily fluctuating powerplant rel= from Flaming Gorge Dam, combined with relatively warm hypoUmnetic water, may be producing ice conditions that reduce availability of overwinter nursery habitat for age-O Colorado squawtisb in the Green River. Historically, surface ice formed on the Green River about 4 of 5 years, and together with low steady flows, produced a relalively stable winter ettVironment for fish. Today, warm. ( ...w'C) fluctuating releases from Flaming Gorge Dam. and the steep gradient in Lodore Canyon, create ice-free winter conditions for about 6S miles downstream to the Yampa River. Below this ccnfiuence, fluctuating releases continually break and Jam the ice, altering flow and potentla1ly alfecting fish habitat lor as much as 100 miles downstream. The elfecu of ice fontUrion and flow regulation on age-O Colorado squawlish and tlteir habitat are impottant in undersUlllding winter flow rel= from Flaming Gorge Dam. 2.0 STUDY AREA This investigation wa5 conducted on tlte Green River in Utah.. The study area extended from Island Pm (RM 333), witltin Dinosaur National Monument, to the Ouray Bridge (RM 248) al Ouray. UT (Figure 1). All river miles (RM) cited denote miles upstream from the conlluence o( tlte Green and Colorado rivers. Table 1 provides a list oC sites re(en:nced in this repan witlt corresponding river mi1es and distallce downsueam. from RaIDing Gorge Dam. The study area was divided into three reaches based on cltanJlel morphology and projected influence o( fluctuating flows (ValdC% and Masslich 1989). Reaclt 1 extended !rom Island Park (RM 333) to Split Mountain Canyon (RM 327). This area had a relaLlvely steep gradient with gravel-boulder substrate. Reach 2 extended from the Split Mountain Campground (RM 319) to the Bonanza Bridge (RM 290). This reach had a moderate gradient witlt gravel<obble substrate in the upper regions and sand substrate in the 10I>Cr regiollS. Reach 3 extended from the Bonanza Bridge (RM 290) to Ouray, UT (RM 248). This lower reach had a low-gradient witb primarily sand substrate. The influence of lluClualing flows was projected to be most pronounced in Reach 1, with reduced infiuence in Reaches 2 and 3.