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QPQ??gNT OP Ty?i United States Department of the Interior N O ' ' BUREAU OF LAND MANAGEMENT 9 Colorado State Office If 31 ?ab 2850 Youngfield Street IN REPLYAff5POF?:CO-930) Lakewood, Colorado 80215-7093 U8oe mm3ffaFnEwnnm al+Ewov wo?u?u¢mr www.co.blm.gov Mr. Dan Merriman Colorado Water Conservation Board 1313 Sherman Street, Room 721 DEC 1 9 2006 Denver, Colorado 80203 Dear Mr. Merriman: The Bureau of Land Management (BLM) is writing this letter to formally communicate its instream flow recommendation for Alder Creek, located in Water Division 3. Location and Land Status. Alder Creek is tributary to San Luis Creek approximately ten miles northwest of the town of Villa Grove. The stream reach that was surveyed begins at the BLM- Forest Service boundary and runs downstream to the headgate of the Alder Creek Ditch. Of the 0.55-mile reach, 60% of the land is federally owned, while 40% is privately owned. Biological Summary. Alder Creek is a high gradient stream with large substrate size and good vegetative cover. Fishery surveys indicate that the stream environment is in stable condition, and supports a self-sustaining brook trout fishery. Channel stability, bank stability, water quality, food supplies and substrate are good for salmonids. This type of stream environment has steep gradients that typically limit available pool habitat. If the continued existence of the fishery is to be assured, it is important to provide stream flows that protect the limited amount of available habitat. R2Cross Analysis -BLM's data analysis, coordinated with the Division of Wildlife, indicates that the following flows are needed to protect the fishery and natural environment to a reasonable degree. 1.1 cubic feet per second is recommended for the April 15 to June 30 snowmelt runoff period. This recommendation is driven by the average velocity and average depth criteria. It is important to provide as much usable spawning habitat as possible during this period so that the fish population can continue to be self-sustaining. It is also important to recharge the alluvial aquifer during this period, because the aquifer discharges back to the creek to maintain flow levels during late summer and fall. 0.5 cubic feet per second is recommended for the July 1 to April 14 base flow period. This flow meets both the wetted perimeter and average velocity criteria, and should provide for adequate passage between pools during the base flow period.