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Last modified
7/14/2009 5:02:30 PM
Creation date
5/20/2009 3:43:19 PM
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UCREFRP
UCREFRP Catalog Number
7618
Author
Rose, K. L. and D. R. Hann.
Title
Summary of Historic Habitat Modeling on the Yampa River Using the Physical Habitat Simulation System
USFW Year
1989.
USFW - Doc Type
Final Report.
Copyright Material
NO
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<br />I- <br /> <br />WUA Predictions <br /> <br />The calibrated data decks were run through the HABTAT4 program to develop WUA <br />versus discharge relationships for adult (size 5; 400+mm) and spawning life <br />stages of the Colorado squawfish, and the adult life stage of the humpback <br />chub (size 5;260+mm). The results suggest that adult Colorado squawfish <br />habitat is maximized at 100 cfs, with spawning habitat maximized at 1200 cfs, <br />and adult humpback chub habitat maximized at 400 cfs. <br /> <br />In comparison to the historic record of mean monthly flows for the Yampa River <br />from 1922 to 1986 (Attachment 2), 100 cfs is exceeded 100.0 percent of the <br />time in June, 98.5 percent in July, 95.0 percent in August, and 84.6 percent <br />of the time in September. Similarly, 1200 cfs is exceeded 98.0, 60.0, and 3.1 <br />percent of the time in June, July, and August respectively; deposition does <br />not occur in September. 400 cfs is exceeded 100.0, 87.7, 46.2 and 23.1 <br />percent of the time in June, July, August and September. The models' <br />predicted optimal flows for adult Colorado squawfish and humpback chub <br />habitats are rare historic events, and probably do not represent optimum <br />biological conditions. <br /> <br />The adult squawfish SI curves used in this analysis are applicable only for <br />the months of July, August and September. Similar to the Spawning Bar, model <br />outputs suggest adult habitats are optimal at flows close or equal to zero <br />(Attachement 1; SI curve velocity coordinates). The adult humpback chub <br />curves are applicable from March to November. The WUA versus flow <br />relationship peaks at 400 cfs, with a gradual decline above 1500 cfs. The <br />depth and velocity SI curves for humpback chub peak at 7.0 feet and 0.23 <br />ft/sec, respectively. <br /> <br />The deposition curves are useable throughout the spawning period, generally <br />June, July, and August. The deposition velocity curve peaks at 2.27 ft/sec, <br />while the depth curve peaks at 2.04 feet. The prediction of WUA for <br />deposition habitat which peaks at 1200 cfs (Table 8), more accurately reflects <br />historic flow conditions. <br /> <br />3. MAYBEll <br /> <br />The Maybell study site, located at RM 72.0, was surveyed and described by Mike <br />Prewitt in 1979 using the three-flow IFG4 model. Wahle made a few minor <br />changes to the original data, recalibrated the deck and reran the model <br />through the HABTAT program. Similar to the Spawning Bar and Replicate sites, <br />the data deck used in this analysis retained the corrected stage-of-zero flow <br />values, the compatible substrate code, and water surface elevations. The <br />Maybell data deck modifications are comparable to those in the Spawning Bar <br />and Replicate data decks, and therefore are not included in a separate table. <br /> <br />The geomorphic stability of this area was evaluated by Wahle and Johnson <br />(1984). The analysis utilized aerial photographs to evaluate the channel <br />morphology. From the photographs, channel substrate formations indicated a <br />stable gravel/cobble/rock combination with relatively little sand (Wahle and <br />Johnson 1984). The area was considered to be in dynamic equilibrium. <br /> <br />10 <br />
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