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Introduction: <br />In October 2001 a study was completed on the condition of 91 miles of the Rio Grande <br />from the town of South Fork to the Alamosa / Conejos county line. This study was <br />sponsored by the San Luis Valley Water Conservancy District, the originators of the Rio <br />Grande Headwaters Restoration Project (RGHRP). <br />The Study was a detailed analysis of the condition of the river that included the <br />geomorphology, the condition of the riparian zone and terrestrial wildlife habitat and <br />fisheries, the condition of the flood plain, and the number and condition of water <br />diversion structures. <br />The 2001 Study divided the river into thirty (30) sub-reaches. The location of the <br />possible project sites lie within the E4, E5, and F1 sub-reaches of the 2001 study. <br />The following excerpts, with some summarization, from the 2001 Study describe the <br />characteristics of the subject reaches: <br />Geomorphic Analysis: <br />"3.3.4.7 Sub-reaches E4 and E5 <br />Sub-reaches E4 through E5 are shown on Exhibit 9-8. Channel change through <br />this reach between 1941 and1998 has consisted of several meander cutoffs, <br />meander migration and development, and channel avulsion. Channel length <br />increased substantially, approximately 11 %, between 1941 and 1963. This <br />resulted in a sinuosity increase from approximately 1.8 to 2.0. Between 1963 and <br />1998 channel length decreased by approximately 4%, resulting in a corresponding <br />decrease in sinuosity to approximately 1.9. In the upstream portion of this reach, <br />certain sections of the channel appear to have been straightened during the early <br />1940s. Channel modification in conjunction with the higher discharges during the <br />1941 to 1963 period resulted in a decrease in channel slope (e.g., increase in <br />channel). During the 1963 to 1998 period, median discharge decreased and more <br />sediment was being flushed into this reach from upstream. The bed material size <br />in this reach can be generally classified as medium grained sands. Channel <br />gradient averages 0.0005 ft/ft. The shallow gradient and progressive downstream <br />decrease in bed material size results in a reduction of channel width as was <br />observed at various locations within this reach. Reduced channel capacity would <br />result in out-of-bank flows during minor flood events. This action would <br />significantly increase meander migration and avulsion potential. These stability <br />issues must be addressed to ensure functionality of the diversions as well as the <br />ability of the system to convey flood and compact flows. <br />3.3.4.8 Sub-reaches E5, F1, and F2 <br />Sub-reaches E5 through F2 are shown on Exhibit 9-9. The accuracy of the 1941 <br />aerial photographs for this reach is limited, as noted by the broadly defined <br />banklines. During the period between 1941 and 1963 the upstream portion of the <br />reach was characterized by lateral migration of meanders which ultimately <br />resulted in meander tightening. In the downstream portion, the most significant