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.. IN REPLY REFER TO United States Department of the Interior BUREAU OF LAND MANAGEMENT Colorado State Office 2850 Youngfield Slrcet Lakewood, Colorado 80215-7093 U.8.DEPARnoIENTOFTHEloYTCflIOR BlJREAUOFL.....OIllANAGEMENT www.co.blm.gov CO-932 7200 DEe 1 6 2003 Mr. Dan Merriman Colorado Water Conservation Board 1313 Sherman Street, Room 721 Denver, Colorado 80203 Dear Mr. Merriman: The Bureau of Land Management (BLM) is writing this letter to formally communicate its instream flow recommendation for Potter Creek, located in Water Division 4. Location and Land Status. The Potter Creek watershed is located approximately ten miles southwest of Delta. The stream reach that was surveyed begins at the BLM-U.S. Forest Service boundary and extends 9.0 miles downstream to the confluence with Roubideau Creek. Approximately 92 percent of the reach is owned and managed by BLM, while the remaining 8 percent is in private ownership. Biological Summary. Fishery surveys indicate that the stream environment is presently in stable condition and supports a self-sustaining speckled dace fishery. This stream also provides spawning habitat for sensitive cool water fishes, such as the long-nose sucker. Channel stability, bank stability, and substrate are good for supporting a fish population. However, the fishery is limited by lack of cover in some locations and by occasional high temperatures and low stream flows. Accordingly, it is important to provide stream flows that protect the limited amount of available habitat if the continued existence of the fishery is to be assured. R2Cross Analysis. BLM's data analysis, coordinated with the Division of Wildlife, indicates that the following flows are required to protect the fishery and natural environment to a reasonable degree: . 4.0 cubic feet per second is recommended for the April I to October 31 high temperature period. This recommendation is driven by the velocity criteria. Meeting the velocity criteria is important because the stream lacks cover in some reaches and water temperatures can become high. . 1.8 cubic feet per second is Tecommended for the November 1 to March 31 low temperature period. This recommendation is driven by the wetted perimeter criteria. Given the paucity of pools in the lower parts of the reach, adequate physical habitat elsewhere in the stream is especially important during winter.