Laserfiche WebLink
<br />, ' <br /> <br />Table 4.2. - Flow recommendations for the Gunnison River; measured at the <br />USGS gage near Grand Junction, Colorado (09152500). <br /> <br />. <br /> <br />, <br /> Hydrologic Magnitude <br /> Category (cfs) Discussion/Anticipated Effect <br /> Spring Peak, Mean Daily Flow <br /> Dry; No in~channel scounng of gravel or cobble bars is anticipated ::1[ thIs <br /> 90-100% ,4,000 flow; however. fine material on the surface will be moved and further <br /> exceedence deposition will be slowed. No flooded bottomland habitats will be <br /> provided. but some inundation of tributary mouths will occur. The <br /> small peak will provide spawning clIes for Colorado pikeminnow and <br /> razorback sucker. <br /> Moderately Dry; Limited in-channel maintenance will occur; mitial motion is reached in <br /> 70-90% > 7,000 about 33% of the r.ver, providing clean cobble-gravel substrates for <br /> exceedence egg deposition and invertebrate production in parts of the river. The <br /> limited peak will provide spawning cues for Colorado pikeminnow and <br /> razorback sucker. Floodplain inundation will be very small and very <br /> brief, but will provide some warm, quiet water habitats for growth and <br /> gonad maturation of endangered fish. <br /> A verage, Dry; Initial motion is reached in 75% of the river, providing wide.spread <br /> 50-70% >9,500 cleansing of gravel and cobble bars. Significant motion is reached in <br /> exceedence about 7% of the river, providing some in-channel maintenance of <br /> important haD;tats used by endangered fish in other seasons. Wide- <br /> spread areas with clean substrates for egg deposition and incubation <br /> should provide for maximum reproductive success of Colorado <br /> pikeminnow and increased primary and secondary production. <br /> Floodplain innundation will increase, but will be limited in duration; <br /> however, some warm, quiet-water habitats will be available for growth <br /> and gonad maturation of razorback sucker and Colorado pikeminnow. <br /> Average, Wet; Initial motion is reached in 100% of the river and significant motion is <br /> 30-50% 2 12,500 reached in about 33%. In-channel habitats used by endangered fish <br /> exceedence will be maintained in important river reaches; charmel narrowing will <br /> be slowed or prevented. Floodplain habitats will be widespread (about <br /> 180 ac will be available at Escalante SW A), but duration of flooding <br /> will be brief. Quiet water habitats will be available for use of adult <br /> endangered fish, but flooding duration will be limited. Wide-spread <br /> areas with clean substrates should provide for maximum reproductive <br /> success of Colorado pikeminnow and increased primary and secondary <br /> production. <br /> Moderately Wet; Significant motion is reached in 75% of the river, creating and <br /> 10-30% ,17,000 maintaining important habitats for Colorado pikeminnow and <br /> exceedence razorback sucker in large areas of the river. Gravel is flushed from <br /> pools. creating critical wintering habitat for both species. Floodplains <br /> are extensive (about 300 ac at Escalante SW A at 17,000 cfs); river <br /> flows should exceed 12,500 cfs (providing 180 ac of habitat) for at <br /> least 2 weeks to provide floodplain habitat for growth ,md survival of <br /> larval razorba.ck sucker. <br /> <br />. <br /> <br />. <br /> <br />Draft Final Report <br />January 27, 2000 <br /> <br />Chapter 4 <br /> <br />4-12 <br /> <br />t <br /> <br />l <br /> <br />l <br /> <br />l <br /> <br />, <br /> <br />l <br /> <br />l <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />