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<br />llJ;J361
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<br />TABLE OF CONTENTS
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<br />Introduction......,.....,........ ,......... ,.., .................,.."'..........,,................,..,..........., 1
<br />Project Purpose..,.......,.,... ., ............,..., , ......,."..,......,,'.......... ., .....,.'.. .. .... ,. .. 1
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<br />Project Description.,...........,.,.................,...,.......,...,.......". ...,..'..".'.,.......,..,'.. ,.., 1
<br />Existing Elkhead Dam and Reservoir ,.....,...................,....................................1
<br />
<br />. Physical Facilities .............., ... ,...,. ,. ................,..........................." ,......1
<br />Reservoir Operations .'.........'..,...''''.....'''..'''.',.'............, ...",.,..........3
<br />Proposed Elkhead Dam and Reservoir Enlargement .............................................4
<br />
<br />Physical Facilities....................,...,.........,........"..,............,........."......, 4
<br />Reservoir Operations .... .,..,.. .............. ,..,................. ,. .... ......... ,. ... .... ..... 4
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<br />Threatened, Endangered and Candidate Species .......................................................... 7
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<br />Terrestrial Species............,.........................,..................."......"",.............., 7
<br />Bald Eagle (Haliacetus luecocephalus).............................,........................ 7
<br />Peregrine Falcon (Falco peregrinus) ..........,..,......,................................... 7
<br />Ferruginous Hawk (Buteo regalis).. ,.... .,......,...........,........,..'..., ,., ... ..., ...., 8
<br />Black Footed Ferret (Mustela nigripes)..,......................... .......,..... ... .... .....8
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<br />Aquatic Species........... .................,....,....... ,.. ,......,.........................."",..,.,.. 8
<br />Colorado Squawfish (Ptychocheilus Iucius) ,.............,....................... ...... .... 9
<br />Humpback Chub (Gila cypha) ..,....,........,................................,.,.....'.... 10
<br />Razorback Sucker (Xyrauchen texanus) ......................................,........... 10
<br />BonytaiI Chub (Gila elegans) .....................................................,......... 11
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<br />Hydrology.............................,..........,...,...,....""."",. ",.,..,,'...'.','."........, ..... , .. 11
<br />Yampa River and Elkhead Creek Hydrology .......................................,..,......... 11
<br />U.S. Fish and Wildlife Service - Section 7 Baseline FIows .................................. 11
<br />Updated Flow Recommendations ..............,.....................................,..... 13
<br />Hydrosphere Yampa River Basin Model......,.......................................,.......... 14
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<br />Baseline Conditions.......,....... ......,....... ,........,. ............. ..... ................. 14
<br />Elkhead Reservoir.................................................... ................ 14
<br />Elkhead Creek.............,.... ,........,........,... ................ ................. 14
<br />Yampa River - Mayben..,....,........,........ ..................................... 17
<br />Anticipated Future Conditions Without Projecl............................,.,.......... 17
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<br />Elkhead Reservoir ......., ,.... ,.... ...,...................................'.......... 31
<br />EIkhead Creek .................. ,.............................., .........., ,........... 31
<br />Yampa River - Mayben....,.........................................................31
<br />Anticipated Future Conditions With Projecl............................................, 35
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<br />Elkhead Reservoir.........,....,................... ............. ......,............., 35
<br />Elkhead Creek.............,.,...."..,.".""...,.".,.".."......,.,.....,....,..,. 35
<br />Yampa River - Mayben..,.,...........,.."........................,..........,...., 35
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<br />Water Quality... ........ .........,..........'.."",..., ,..',........................."..........,..........., 40
<br />Elkhead Creek and Reservoir. ........., ,..., ,.......,..'...... ,...........",......:....,.......... 40
<br />Dissolved Oxygen............,...,....".......,. ,....... ...........,.,..........,.,.......... 40
<br />Water Temperature ...... ........ ,..........., '...........,..........., ,............... ....... 41
<br />Suspended Sediment ..... ,.'.,.'.'......."... ...................,....,.....".,'.., '....'. ,., 41
<br />Yampa River at Mayben........... .,...,....,..... ,. ...,..... ..........,.... ,............' .,......., 41
<br />Dissolved Oxygen.,..,....,..,..............,..........,....., '.......,.........,..,.......,., 41
<br />Water Temperature.....................".......,.........", '.',............ ,.............., 41
<br />Suspended Sediment. ...,.,.......,.....,................... ,................ ................. 42
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<br />.t.; _~ ;...-
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