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AUf 15-2005 MON 04:33 PM FAX NO, P. 02 <br /> 2. Utilization of grouted structures. The use of grout has detrimental impacts on the aquatic <br /> environment due to the loss of interstitial spaces for small trout, native fishes, and macro- <br /> invertebrates. Additional in-stream structures may result in a net increase in interstitial spaces <br /> however all of the existing channel work was completed without grout and has proven stable over <br /> time. Non-grouted rock structures offer superior habitat diversity for aquatic organisms, including <br /> small trout and native fishes. .interstitial spaces in non-grouted structures offer resting and hiding <br /> places for trout and provide desirable habitat for aquatic insects. We fail to recognize a clear need to <br /> grout structures for the purpose of improving"functional habitat"when reasonable and practical <br /> alternatives exist that minimize impacts. <br /> Eliminating grouted structures precludes the need for partial stream de-watering and subsequent <br /> sediment releases associated with constructing temporary cofferdams. Since non-grouted structures <br /> accomplish many of the same objectives, use of grout does not fulfill the applicant's burden to use all <br /> reasonable and practical measures to avoid and minimize impacts. <br /> 3. Extensive use of boulder rip-rap. The CDOW recognizes the detrimental effects of bank instability <br /> and erosion on the aquatic environment and does not discount the need to use boulder rip-rap to some <br /> extent. However, we request the Corps assess the need for rip-rap to the extent outlined in the <br /> proposed action. The extensive use of"hardened"banks has an unfavorable impact on the aquatic <br /> environment by limiting riparian development. The establishment and enhancement of riparian <br /> vegetation may provide bank stability equivalent to or exceeding that of boulder rip-rap while <br /> providing many ancillary benefits to the aquatic environment including shading, invertebrate <br /> production, detritus and woody debris. <br /> The conceptual plan included in this public notice makes little mention about the use of riparian <br /> vegetation. Riparian vegetation is mentioned with terraced seating in Figure 4 of the"drawings and <br /> maps"document http://www.spk.usace.army.mil/pub/outgoing/co/reg/pn/200575106-draw.pdf <br /> Typically high traffic and seating areas are the least likely places to establish vegetation. <br /> We support the Town's desire to enhance the aquatic environment. The section of river below the pedestrian <br /> bridge could benefit substantially from aquatic enhancement appropriately designed to maintain river <br /> "stability"and provide for all life stages of aquatic organisms. The conceptual plan included in this public <br /> notice provides an outline that may achieve these objectives. However, several components of this conceptual <br /> plan fail to meet the applicant's burden to "use all reasonable and practical measures to avoid and minimize <br /> impacts to the aquatic resource." <br /> We appreciate this opportunity to comment. Please feel free to contact our office with questions or to request <br /> additional information. <br /> Since y�, <br /> /)/(tt...r1D<6, <br /> Patt Dorsey <br /> Area Wildlife Manager,Durango <br /> xc: Bredehoft, Spezze, DWMs, laphet, Kloster <br />