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<br />- <br /> <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />eroding bank was not identified but likely exists between the 46,300 foot and 53,500 foot points on the river. Also, in <br /> <br />addition to upstream bank stabilization measures, there will still be the need to harvest excess bedload materials for <br /> <br />several years and monitor the sediment load. <br /> <br />There are many methods to stabilize riverbanks. Given that most of the assessment reach contains flow throughout the <br /> <br />year, rock/boulder structures would likely provide the dual benefit of bank stabilization and fishery habitat <br /> <br />enhancement. Opportunities to acquire rock materials for stabilization of the assessment reach, while work is being <br /> <br />performed downstream of Gunbarrel Road, should be considered. <br /> <br />Excess in-channel materials in the assessment reach (sand, gravel and cobble), that would likely need to be removed if <br /> <br />stabilization work were done, are deposits in the form of lateral bars or mid-channel bars that presently tend to deflect <br /> <br />flow against the riverbanks, create instability and cause erosion. A use for this material will need be identified or a <br /> <br />location for disposal of the material will need to be found. <br /> <br />Conclusions <br /> <br />The assessment confIrmed speculation that the section of the Alamosa River between Terrace Reservoir and GillIbarrel <br /> <br />Road is a potential source of considerable excess sediment in the river system. This material should be taken into <br /> <br />account when designing restoration downstream of Gunbarrel Road. <br /> <br />Based on the estimates of potential bank erosion, the quantity of material introduced from the assessment reach could <br /> <br />likely be managed by an annual harvesting program. In addition, estimates of eroding bank were developed that may <br /> <br />be used to develop a plan to stabilize those banks and reduce the overall influx of sediment. <br /> <br />6 <br />