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The creek is located in Mesa and Montrose Counties. The total drainage area of the creek is approximately 47 square miles. South Fork Mesa Creek generally flows in a southwest direction. e The subject of this report is a 10.4 mile segment of South Fork Mesa Creek beginning at the confluence with an unnamed tributary and extending to the confluence with the East Mesa Creek (see Figure 1). This segment is located northwest of the Town of Naturita. To date, the staff has received only one recommendation for this reach. This recommendation is discussed below. Instream Flow Recommendation(s) BLM's instream flow recommendation is 2.0 cfs (April 1 - October 31) and 1.25 cfs (November 1 - March 31). This recommendation has been adjusted, based on water availability concerns. (See discussion below under Hydrologic Data.) Land Status Review Total Length Land Ownership Upper Terminus Lower Terminus (miles) % Private % Public Unnamed tributary North Fork Mesa 12.0 5% 95% Creek Approximately 95% of the reach is located on federal lands managed by the BLM and the US Forest Service. The remaining 5% is located on private lands. e1 Biological Data The BLM has conducted field surveys of the fishery resources on this stream and have found a natural environment that can be preserved. As reported for this reach of stream in BLM's recommendation letter to the CWCB, "Fishery surveys indicate that the stream environment supports a self-sustaining population of rainbow trout." BLM's fisheries report indicates that the fishery is constrained by limited spawning areas, low flows, and high erosion within the watershed. BLM seeks to protect the current flow regime to prevent further stress to the fish population. (See BLM Fish Survey in Appendix B). Field Survey Data BLM staff used the R2Cross methodology to quantify the amount of water required to preserve the natural environment to a reasonable degree. The R2Cross method requires that stream discharge and channel profile data be collected in a riffle stream habitat type. Riffles are most easily visualized as the stream habitat types that would dry up first should streamflow cease. This type of hydraulic data collection consists of setting up a transect, surveying the stream channel geometry, and measuring the stream discharge. Appendix B contains copies of field data collected for this proposed segment. .1 Biological Flow Recommendation The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret output from the R2Cross data collected to develop the initial, biologic instream flow recommendation. This initial recommendation is designed to address the unique biologic requirements of each stream without regard to water availability. Three instream flow hydraulic parameters, average depth, percent wetted perimeter, and average velocity, are used to develop biologic instream flow recommendations. The CDOW has determined that maintaining these - 3 -