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<br />Table I' Data
<br />
<br />.
<br />Part" Date () 250 % --to % Summer (3/3) Winter (21.')
<br />BLM 7/8/98 0.51 1.3 - 0,2 3.61 I 0,6
<br />
<br />BlM '" BUrellU of Land ~bnagemrnl r II Pr.-di~'led flo,", otll\ilkorlhe an"lJracy ran!!", of ~1anning', Equation
<br />~"C"meria ntler ml"t In R~C"ROSS S"'glnjl TJbk
<br />
<br />Biologic Flo\\.' Recommendations
<br />The BLM recommended a 2.5 and 1.35 cfs summer flow and a 0.55 cfs winter flo\'.' based on
<br />their July 81h. 1998. data collection effort and their initial water availability analysis. CWCB
<br />slaff has reviewed the data collected by the BL~1. The sununer flow recommendalion. \vhich
<br />meels 3 of 3 criteria bUI falls outside the accuracy range of the R2CROSS model. is 3.6 cfs,
<br />CWCB staff hclieves recommendations that fall outside of the accuracy of the model above
<br />250% of (he measured discharge may overeslimate the required summer flow. The wimer flow
<br />recommendation. which meets 2 of :3 criteria and which is within the accuracy of Ihe R2Cross
<br />model. is 0.6 cfs.
<br />
<br />The BL~1 has indicated that this is a very high pflonly stream segmenl to them. However.
<br />because the summer recommendalion falls outside of Ihe accuracy range of Ihe R:2CROSS
<br />model. staff believes that more dala needs to be collected to accurately predicl the summer flow
<br />recommendation. In the mean lime. staff believes that it would be appropriale for the Board 10
<br />file on a year.round flow of 0,6 cfs. Ihe winter flow recommendation. thus giving Firsl Anvil
<br />Creek some \\..ater right protection unlil additional data can be collected. Staff has consulted with
<br />Ihe Colorado Division of Wildlife and believes 0.6 cfs will he sufficient to protect the natural
<br />environmenllo a reasonable degree unlil additional data can be collected
<br />
<br />Hydrologic Data
<br />
<br />After receiving the cooperaling agencies' biologic recommendation. Ihe CWCB staff conducted
<br />an evaluation of the stream hydrology 10 del ermine if water was physically available for an
<br />inslream flow appropriation. The hydrograph was derived from dala collected by (he USGS
<br />stream gage for Easl Fork Parachule Creek near Anvil Points (lD #(9092960). which has a
<br />drainage area of l.tS square miles (see Gage Summary in Appendix C). The period of record for
<br />this gage is 197610 1983. the period of record used by staff in Iheir analysis was 1976-1983. or
<br />seven years of record. The e~timated drainage area of Firsl Anvil Creek is approximately 2.8
<br />square miles. Table 2 below displays the estimated now of First Anvil Creek at the confluence
<br />wilh East Parachule Creek. in term~ of a percentage of exceedence. The blue shading highlights
<br />how often the year-round flow recommendation has been available.
<br />
<br />TatlleZc Flfsl AnviC'et:'...alCOrlIIU9OCll EaSIForlo; Pa,achureOeek
<br />
<br />, ,,, ., ,,," , , , ,
<br /> .
<br /> , ,. , " ,
<br /> " , . ,
<br /> 20"'; 0" 018 039 H' 18_34 ",. 089 0.. 0" 023 0" 018
<br /> "'" 0" 0" 0" 1_14 '" 141 OSO 029 0" 0" ". 0"
<br /> , , , , , .. ,
<br /> . , " , , ,
<br /> .
<br /> " , , , , , , , ,
<br />
<br />Table :2 shows Ihat Ihe summer and winter recommendalion of 0.6 cfs is available 50% of the
<br />time for the lnonths of Aprillhrough June. 20% of the time in July. 10% of the lime in Augusl
<br />and Ig, of (he time in ~1arch. Based on the above Water availabilily analysis and the requirement
<br />of Ihe CWeB stall 10 balance Ihe needs of mankind wilh a rea.,onable pre-,ervation of Ihe natural
<br />environment Ihe recommended summer and winter now of 0.6 cfs must be reduced further. Staff
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