Laserfiche WebLink
<br />................... <br />....................... <br />....................,.. <br />................... . <br /> <br />.................... <br />........... -......... <br />.... ................ <br />..................... <br />................-... <br /> <br />................ . <br />. ................. <br />. . . . . . . . . . . . . . . . . . . . . . <br /> <br />................. . <br />................. <br />.................. <br />................. <br />.................. <br /> <br />.............. ... <br />. . . . . . . . . . . . . . . . . . <br />.................. . <br />.................. <br />....-. ......"... <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 />SUMMARY OF FINDINGS <br />(Continued) <br /> <br />..-.-...--.------.......... <br />..........____...u. .U.' ... <br />.............-. --.. ...-. <br />......................--.... <br />..............-.....-..... <br />............--............. <br />....-...................... <br />.......-................... <br />............-............. <br />..........- -............... <br />.......-.................. <br />. . . . , . . . . . . . . . . . . . . . . . . . . . <br />................-......... <br />......--..-.....-........... <br />....--..........-........... <br />.............' ............ <br />.............-.-........... <br />.............-............. <br />.....-.--,.-............... <br />.............................. <br />._.......-... ............ <br />.....---.....".........--.. <br />......__....,.._.........u. <br />.--.--.---...-......... ... <br />.......-....-............... <br />..----...-" -..-........ <br />.--.-.-..,-.--............. <br />. . . - . . . . . - - . . . . - - - . . - . . . . . . . <br />.-...--..-............. <br />.--.,--...-.-.-............. <br />........-.--.-............ <br />.--......-...,--............ <br />.-.-..... ------........... <br />.......... ...-...--....... <br />........,-..--............ <br />..........-..,.............. <br /> <br />.....".-......-.. .... <br />......--..----.---.,.----. <br />..._.......-..---. .-,-. <br />............._.....---.. <br />.,-...-...............-.. <br />.................-..-... <br />...--................_... <br />..---................... <br />. - - . . . . . . . . . . . . . . . . . . . . . . <br />..................-... <br />..--.- .................. <br />. . . . . . . . - . . . . . . . . . . . . . <br />......................... <br />......................... <br />...........-............. <br />.........,............... <br />............--........... <br />..............-......... . <br />.............-......-.... <br />........--... .......... <br />.......-.....-....-...... <br />..................... <br />............-..... <br /> <br />~t"ilj::ilfoill~.~~~~T~~:::::..:.; <br /> <br />.......--................. <br />................-......... <br />....._,--................. <br />......................... <br />.....-.--.......-..... <br />. . . - . - . . . . - . . . . . . . . <br /> <br />.....................-.:...-.--..;.:.:.;.:.:.:.:.:.:.:.:.:.:....-::...:.:....:::.:::::::::.::::::::::.:::::::::::::...:.:.:.:':':':.:':':.:-:':.:'=::-:::.:':::::':::::::::::::::::::::::::::::'.:::::: <br />::::::::;:::::::::::::::::::::::;=:=:=:::=:=:=:=:::::::=:::::::::::::::::=::;:::==:;:=::=:::::::::..:.:............. <br />.... ................... ............. ............................--.......----..... <br />................. .............. <br /> <br />Twenty percent of the young Colorado squawfish (larvae, YOY, juveniles) handled in this 4-year study <br />were found stranded in isolated pools. These fish were in over 60 percent of the isolated pools <br />sampled, often in sympatry with fathead minnows and red shiners. Stranding was believed to be a <br />natural phenomenon with these native fish, but the effect of flow withdrawal and regulation (e.g., <br />irrigation, municipal, indust.rial, mainst.em dams) could not be assessed. <br /> <br />...............- .-".. .................-.... ........ . ... ..... ............... <br />. -........ ....... ... .... -. - -..... . -..............,.............. ....... ... .................... -... -. <br />................................. ...-...............................-......................... ...... ..........,................-..-.-.......................-............ <br />........................ ............ ......... ......................... .. ...........-.................................................................... ................. <br />[fj[Hj~~~III_~~Tm .m <br /> <br />A 1-mile reach (RM 200-201) of the Lake Powell Inflow seasonally provided backwaters used as <br />nurseries by small numbers of young Colorado squawfish. These backwaters were always inundated <br />by high runoff flows from about mid-April to mid-June. Lowering lake levels after runoff created <br />backwaters from about mid-June to August., but lower levels in late summer and fall desiccated these <br />areas or created isolated pools. The number and surface area of backwaters in this 1-mile reach was <br />maximized when the surface elevation of Lake Powell was between 3692 and 3698 feet above sea level. <br />It was noted over the 4-year period that fish habitat in the area was dynamic because of large silt <br />deposits and invasion of tamarisk. No specific recommendation for management of lake levels was <br />proposed as a result of this investigation because of these habitat dynamics together with low numbers <br />of endangered fish and large numbers of non-native predators. <br /> <br />...............-.... <br />............-........ <br />................... <br />.................... <br />.................... <br />................... . <br />.................... <br />.................... <br /> <br />...........-.......-..... ........._.....-..-.----..........._._-.,.... ........ ..........._----. ....-..................... <br />................,.. .-... -.....................-.....................................-.............................-: .............................---.-...................-.................... <br />...............,............... <br />............ ........ ..........................._..-.... ............-............ . <br />:FWE:SECDMMEHOATIONS:imf:SUBMITTEDHFOe:CONDAOEb:iStUmes::.;;;;.; .. <br />.. .... ..... ...... ..' . .' :....: - '. . .;-::::..:..:=.:::-:.:.:.:::~;::.::;......:........ ..... . .....: .. ..... . .... .......... ..... ::. >;>):::::::::::/t::>:.:.:.:.:.::;:~.:.:.:.;.:..::.. <br />...'. .. . .';::::~:~:~:~;~'~':':':':............... <br />........................................-.......-.................:.:.:.:.............. .......... ...,.,............................... .........:.:.:.:.:.:...;.;.:.:.:.:.:.:-:.:.:.:-:.:.:.:.:.:.;.: <br />.:.:.:.:-:.:.:.:.:.:.:.: ... ........ <br /> <br />Further st.udies are recommended for the Cataract Canyon Area to refine what was learned from this <br />investigation. These st.udy topics are: (1) Confirm spawning by humpback chub in Cataract Canyon, <br />(2) Assess overwinter survival of YOY Colorado squawfish, (3) Assess transport of endangered fish into <br />Lake Powell during spring runoff, (4) Monitor chubs in Cataract Canyon, and (5) Describe the Gila <br />complex in Cataract Canyon. <br /> <br />x <br />