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<br />. <br /> <br />. <br /> <br />. <br /> <br />miles. Roc Creek generally flows in a southeast direction. There are no significant tributaries to <br />the creek within Colorado. <br /> <br />The subject of this report is a 10 mile segment of Roc Creek beginning at an unnamed tributary <br />and ending at the confluence with the Dolores River (see Figure 1). This segment is located <br />south of the town of Gateway. To date, the staff has received only one recommendation for this <br />reach. This recommendation is discussed below. <br /> <br />Instream Flow Recommendation(s) <br />BLM's instream flow recommendation is 6.50 cfs (March 1- June 30), 3.50 cfs (July 1 - July 30) <br />2.00 cfs (August 1 - August 30), and 1.50 cfs (September 1 - February 28). See BLM letter in <br />Appendix A. This recommendation has been adjusted, based on water availability concerns. <br />(See discussion below under Hydrologic Data.) <br /> <br />Land Status Review <br /> <br /> Total Length Land Ownership <br />Upper Terminus Lower Terminus (miles) % Private % Public <br />Unnamed tributary Dolores River 10.0 28% 72% <br /> <br />Approximately 72% of the reach is located on federal lands managed by the BLM and the US <br />Forest Service. The remaining 28% is located on private lands. <br /> <br />Biological Data <br /> <br />The BLM has conducted field surveys of the fishery resources on this stream and have found a <br />natural environment that can be preserved. As reported for this reach of stream May 2001 letter <br />to the CWCB "Fishery surveys indicate that the stream environment is in excellent condition, <br />and supports self-sustaining populations of bluehead sucker, flannelmouth sucker, and speckled <br />dace. These species are all native to western Colorado. Channel and bank: stability, vegetative <br />cover, pool availability, and food availability are good for dace and suckers. However, the fish <br />population is limited by high erosion, high water temperatures, and by a paucity of spawning <br />habitat. Therefore, BLM seeks to protect the current flow regime to prevent further stress to the <br />fish population." (See BLM Fish Survey in Appendix B). <br /> <br />Field Survey Data <br /> <br />BLM staff used the R2Cross methodology to quantify the amount of water required to preserve <br />the natural environment to a reasonable degree. The R2Cross method requires that stream <br />discharge and channel profile data be collected in a riffle stream habitat type. Riffles are most <br />easily visualized as the stream habitat types that would dry up first should streamflow cease. <br />This type of hydraulic data collection consists of setting up a transect, surveying the stream <br />channel geometry, and measuring the stream discharge. Appendix B contains copies of field <br />data collected for this proposed segment. <br /> <br />Biological Flow Recommendation <br /> <br />The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret <br />output from the R2Cross data collected to develop the initial, biologic instream flow <br />recommendation. This initial recommendation is designed to address the unique biologic <br />requirements of each stream without regard to water availability. Three instream flow hydraulic <br />parameters, average depth, percent wetted perimeter, and average velocity, are used to develop <br />biologic instream flow recommendations. The CDOW has determined that maintaining these <br /> <br />- 3 - <br />