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. Reach D Channel Stability Improvements - Reconnect channel with floodplain using rock spill structures. Slraightening and/or dredging of the river along with stream barbs to increase erosion would increase capacily, however, it would have adverse impacts on lower reaches and thus is not recommended. . Reach E Channel Stability Improvements Combine Excelsior, Costilla and Independent Ditches, possible straightening, and reconnection of channel to floodplain with spill struclures. Sediment would be stored in old oxbows providing opportunities for riparian habitat and wetlands development Reach E Diversion Consolidation - Divert the Costilla and Independent decrees at the Excelsior head gate and transfer water to these ditches where they are crossed by the Excelsior. A lateral of the Excelsior could also deliver water to the Westside Canal as a way to eliminate the Wests ide diversion. Westside Diversion Consolidation - Eliminate the problematic Westside Ditch diversion structure by either: (I) installing a low-head pumping station; (2) extending Excelsior Canal through an inverted siphon to deliver Wests ide waler; (3) extending the Empire Canal to the Alamosa Ditch to deliver Westside water; (4) replacing the existing diversion dam with a more suitable diversion structure; (5) using City of Alamosa wastewater effiuenl; or (6) acquiring and retiring the Wests ide Ditch water right. A more detailed feasibility study is needed to select the best alternative. . Alamosa Levee System Improvements - Prevent frequent flooding of Alamosa golf course by improving and extending the levees on the north side of the channel, installing drainage structures beneath the existing levees on the north side of the channel, and performing pro-active removal of sediment and willows prior to predicted flood events. High Priority Non-Structural Measures Perhaps the most cost-effective alternatives for river corridor protection and enhancemenl consist of measures that do not require construction of large capital projects. These non-structural measures include administrative, regulatory, and policy actions, many of which could be applied throughout Ihe study area. The TAC has been considering several policy alternatives during the course of the RGHRP study, and the consultant team has identified other non-structural approaches worthy of consideration. High-priority non- structural measures are briefly described below. River Task Force - Form a task force of agency and community representatives to assume responsibility for implementation of Ihe RGHRP recommendations, including public outreach and technical assistance to residents. buffers . land uses in the Land Use Planning - Amend existing comprehensive land use plans to include special developmenl guidelines for streamside areas. Reach E Floodflow Containment - Prevent flood flows from spreading north of the river and flooding Alamosa by: (I) constructing wasteways in Billings Ditch, San Luis Valley Canal and Costilla Canal; and/or (2) constructing setback levees along existing county road right-of-ways. . . . ES,4.2 areas to manage urban and agricultural target and cattle exclusion guidelines Riparian ButTers - Establish stream and activities in the riparian corridor. - Establish Grazing Management stream corridor. . . . . High Priority Projects ES.4.1 High-priority structural projects were selected to address the most important problems in the study area, based on the sub-reach rankings described previously and the recommendations of the study team regarding other localized problems. High-priority structural projects and the problems they address are listed in Table ES-7. Table ES.7. Hlah prlorltv !:iuuClural t"ro eels Sub-Reach Channel Riparian Diversion Channel Alternative Location CaDacltv Floodnlaln HabUal Access Stabllltv Oel Norte Flood Prolec~on A6 . . 0 South Channel Geomorphic I Riparian BB 1-BB2 . . ImDrovements Q Reach C Geomomhic Imnrovements C1-C3 Consolidated Slough/Pace Headgale 01 Q . Q Imorovements Other Reach 0 Headgate Consolidations 02-D6 Q . Monte Vista Flood Protection 03 Q . Reach 0 Channel Stability Improvements 01-05 Q Q . Reach E Channel Stability Improvements El-E5 Q Q Q Q . Reach E Floodtlow Containment 03, E4, E5 Q . Reach E Oiversion Consolidation E1-E5 Qlo . Q Westside Olversion Consolidation F2 Q Q . AI.mosa Levee System Improvements F1 . . 0 o = Indirect negative impact Del Norte Flood Protection - Prepare a Flood Hazard Mitigation Plan for the Town of Del Norte. As a minimum, investigate non-structural measures and the concepts of a setback levee and a bypass channel. Prepare new floodplain mapping. " = Indirect beneficial impact s briefly described below. . = Oirect beneficial impac Each high-priority structural project . Notes. or eliminate McDonald ulilize compound weir Reach B South Channel Improvements - Change operation of North Channel headworks, establish a pilot (low-flow) channel in the South Channel corridor, install grade control slructures, reconnect oxbows using spill structures and protecl key slructures using engineered solutions. Reach C Geomorphic Improvements - Consolidate, relocate Dilch diversion, combine Monte Vista and Piedra headgales, diversions, reconnect old meanders and utilize fish habitat structures. . . Consolidated Slough/Pace Headgate Improvements - Consolidate Ihe Consolidated Slough, Pace, Monte Vista Canal, and Rio Grande Piedra diversions at Ihe exisling Monte Vista Canal headgate. . D Headgate Consolidations - Redirect or train flows near the Fish Ditch construct bendway weirs or relocate Nichols Diversion, relocate Billings Ditch and improve the Centennial Ditch ditch or consolidale with Empire Canal Other Reach diversion, diversion head gates. . Monte Vista Flood Protection- Prepare a Flood Hazard Miligation Plan for Monte Vista. Investigate non-structural measures and structural projects such as constructing a short setback levee and a drainage culvert with outfall channel in the south floodplain area. Prepare new floodplain mapping. . ES-20 . ES-19