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e � �. .�4 0 0 <br />0 DRAFT INSTREAM FLOW RECOMMENDATION <br />Mr. Dan Merriman <br />Colorado Water Conservation Board <br />1313 S hecrm aii utrcCi, Room <br />Denver, Colorado 80203 <br />Dear Mr. Merriman: <br />The Bureau of Land Management (BLM) is writing this letter to formally communicate its <br />instream flow recommendation for Willow Creek, located in Water Division 6. <br />Location and Land Status. Willow Creek is tributary to the Little Snake River north of the <br />Colorado - Wyoming border. This recommendation covers the stream reach beginning at the <br />confluence with Spring Creek and extends downstream to the headgate of the Willow Creek <br />Ditch. Approximately 52% of the 3.95 -mile reach is federally owned, while the remaining 48% <br />is privately owned. <br />Biological Summary. Willow Creek is a moderate gradient stream with small substrate and a <br />stable channel. Water quality, cover, and aquatic insects are good for supporting native fish <br />populations. Fish surveys indicate that the stream supports self - sustaining populations of <br />speckled dace, mottled sculpin, white sucker, minnow, and creek chub. This diversity of native <br />• species is unusual on streams managed by BLM in northwest Colorado. <br />R2Cross Analysis. BLM's data analysis, coordinated with the Division of Wildlife, indicates <br />that the following flows are needed to protect the fishery and natural environment to a reasonable <br />degree. <br />2.45 cubic feet per second is recommended for the high temperature period from May 1 to <br />October 31. This recommendation is driven by the average velocity criteria and wetted <br />perimeter criteria. It is important to provide adequate velocity and physical habitat during <br />this time for fish spawning and incubation of eggs. Protecting flows during this time <br />period is also important for recharging the alluvial aquifer, which discharges water to the <br />stream and maintains flow levels during later summer. <br />2.2 cubic feet per second is recommended from November 1 through April 30. This <br />recommendation is driven by the average depth criteria. This flow rate will allow fish to <br />survive in pools, provide sufficient physical habitat in riffles between pools, and will <br />prevent the riparian environment from being seriously stressed. <br />Water Availability. BLM is not aware of any decreed water rights within this reach. However, <br />the Perkins Fox Ditch is located immediately upstream of the proposed reach. The Perkins Fox <br />Ditch appears to be junior to the Willow Creek Ditch, which is the downstream terminus of the <br />proposed reach. In addition, there are numerous small reservoirs and spring developments <br />