4-02CW271 Supplemental Data - Laserfiche WebLink

Home Browse Search

flows in a southeast directi,.i. There are some small spring -fed ti_ _ .Ataries to the creek within Colorado, but they contribute less than 5% of the total flow volume. The subject of this report is a 6.0 mile segment of La Sal Creek beginning at the confluence with Sharp Canyon and ending at the confluence with the Dolores River (see Figure 1). This segment is located south of the Town of Paradox. 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 5.25 cfs (March 1 - August 31) and 2.25 cfs (September 1 to February 28). Land Status Review Upper Terminus Lower Terminus Total Length (miles) Land Ownership % Private % Public Spring Creek Dolores River 5.0 10% 90% Approximately 90% of the reach is located on federal lands managed by the BLM and the US Forest Service. The remaining 10% is located on private lands. 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 the May 2001 letter to the CWCB "Fishery surveys indicate that the stream environment is in excellent condition, and supports self - sustaining populations of bluehead sucker, flannelmouth sucker, mottled sculpin and speckled dace. These species are all native to western Colorado. Channel and bank stability, vegetative cover, pool availability, and food availability are good for dace and suckers. However, the fish population is limited by high erosion, high water temperatures, and by a paucity of spawning habitat. Therefore, 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. 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 - 3 -