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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />A.I0. SEDIMENTATION <br /> <br />Estimates of sediment yield are complex and Involve numerous assumptions and <br />laboratory determination of site-specific parameters. (Linsley, Ray K., Jr. et al: <br />Hydrology for Engineers, McGraw-Hili, New York. 1982, pp. 311-338. Bureau of <br />Reclamation: Design of Small Dams, U. S. Government Printing Office, Washington, <br />1974, pp. 767-796). Due to the difficulty of conducting this type of study It <br />was determined a reasonable approach would be to utilize previous studies <br />conducted by the Soli Conservation Service for Dams B-2 and B-3. Both of these <br />dams are within 4 to 5 miles of the ~eservolr No. 6 site and have soli charac- <br />teristics similar to Reservoir No. 6 T\1e watershed for B-3 Is very similar to the <br />drainage basin for Reservoir No. 6 In which the flows through the basin are <br />Intermittent and occur only with large rain storms. <br /> <br />Sedimentation for B-3 was estimated at 0.19 watershed-Inches for the design life <br />of 100 years. The watershed for Reservoir No. 6 Is 10.39 square miles Including <br />the drainage area for Reservoir No. 2 and No. 6 Including the reservoir surface <br />area. At the rate utilized by the SCS, the sediment yield would be 105 acre- <br />feet for a 100 year design life. <br /> <br />The sediment yield for B-2 was estimated by the SCS at 0.28 watershed Inches <br />for the 100 year design life. For Reservoir No. 6 that would produce a yield of <br />155 acre-feet. This yield Is expected to be greater than that experienced for <br />Reservoir No. 6 as B-2 Is located on Box Elder Creek which drains a large area <br />with sparse vegetation and experiences continuous stream flows. Also, the <br />reservoir has not experienced any 91gnlflcant siltation problems since being <br />constructed In the late 1800's. The drainage basin also contains North Poudre <br />Reservoir No. 2 and North Poudre Reservoir No.5. Most of the sediment would <br />be trapped In these two reservoirs and less than 50% of the sediment would be <br />expected to reach reservoir No.6. <br /> <br />It Is our conclusion that 100 to 156 acre-feet of sediment would be expected in <br />the basin with no more than 60 to 75 acre-feet reaching Reservoir No.6. <br /> <br />A.ll. RIGHT-OF-WAY <br /> <br />The right-of-way around the reservoir has been reviewed to try to detect any <br />apparent problems with the raiSing of the reservoir water level. The deeds and <br />abstracts have been reviewed and the boundaries plotted for all the properties <br />surrounding the reservoir. Based on this Information there are some potential <br />prOblem areas that will have to be cle/ilred up. <br /> <br />The area along the Bureau of Standards needs to be reviewed further and the <br />area around the dam owned by VanCleave needs further review. No right-Of-way <br />for the outlet Is Indicated and the area adjacent to and Immediately below the <br />dam appears to belong to VanCleave and not North Poudre as expected. This <br />may Indicate right-of-way will have to be acquired for any outlet and spillway <br />option. <br /> <br />Another area that appears to be In question Is the area adjacent to and to the <br />northwest of the saddle dam. A visual Inspection of the site Indicates land <br /> <br />PAG! 15 <br />Cliapler V - No. 6 Vel8iblllty <br />