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excavation by the gravel operation. Further information is needed about <br />the impacts associated with the `gravel operation and how to mitigate these <br />' impacts. Studies should be conducted to determine what level of gravel <br />harvest is sustainable without lowering the base level of the stream <br />channel and further impacting this area. Strategies could then be <br />developed which would allow continued gravel operations while minimizing <br />negative effects to the riparian and aquatic ecosystem. <br />Telluride Gravel proposes to continue extracting material below the <br />confluence of the South Fork and San Miguel Rivers. Continued on-site and <br />off-site environmental impacts associated with the operation, as it is <br />currently described by the applicant, are anticipated to occur. Excavating <br />gravel material from the stream channel would continue to cause changes in <br />the base level of the stream channel and contribute to overall instability <br />of the stream channel and floodplain. <br />The applicant proposes to remove placer aggregate piles located on private <br />land upstream of County Road 625. This activity has the potential to <br />impact aquatic and riparian resources downstream, including resources <br />located on the National Forest. The applicant should only be allowed to <br />remove those placer pile materials which are outside of the stream <br />channel. These placer aggregate piles may contain heavy metals and other <br />substances which could negatively impact water quality. Plans to remove <br />this material should include erosion control measures which will contain <br />potential sediment additions to the stream channel. Ground disturbance <br />and gravel extraction adjacent to the stream channel could result in the <br />addition of sediment and fine material in the immediate area and <br />downstream. This material could settle on existing channel substrate and <br />fill interstitial spaces, which would decrease habitat for aquatic <br />invertebrates and potential spawning habitat for fish. <br />The applicant proposes to excavate almost 20 feet of material from the <br />channel bottom and to create a diversion channel in the placer aggregate <br />area. This activity has the potential to impact the stream channel ahd <br />floodplain within the proposed project area as well as downstream. As <br />previously discussed, excavation within the stream channel causes changes <br />in the base level or channel bed elevation, which causes disequilibritw of <br />the stream system and subsequent channel adjustment processes, such as <br />incision, bank erosion, and headcutting. Excavating and disrupting <br />channel substrata directly impacts aquatic organisms, as well as <br />contributing sediment downstream. Naving equipment in the stream channel <br />also increases the chance for fuel or other contaminants to leak or be <br />spilled in the water, which can result in alteration of water quality and <br />potential fish kills. Dewatering and rerouting the stream channel also <br />negatively impacts aquatic invertebrates and other orranisms by directly <br />altering habitat. The in-channel disturbance and disruption of flows <br />proposed by the applicant could contribute to an overall decline of the <br />aquatic ecosystem and have long-term, cumulative impacts to the immediate <br />area, as well as downstream. <br />The applicant requests the right to use discretion in either constructing a <br />temporary water crossing or a clear-span structure. There are potential <br />