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<br />- 001712 <br /> <br />Long Hollow Dam and Reservoir Summary Report-Preliminary Draft <br /> <br />Need a new section added to show ditches in the basin. proiect beneficiaries or ditches benefiting <br />from LHR and the number of shareholders in each ditch. This could be included as part of <br />Proiect description.) <br /> <br />6.5 Findings of Institutional Investigations Retain this section <br /> <br />Based on the work completed, there does not appear to be any fatal flaw for LHR pertaining to <br />institutional issues. <br /> <br />The required Section 404 Permit and NEP A Environmental Assessment will include an ESA <br />Section 7 Consultation with the USF& WS as well as acceptable mitigation plans for impacts to <br />waters of the U.S. and impacts to two prehistoric archaeological sites. If the project is judged by <br />USACE to potentially have significant environmental impacts, an Environmental Impact <br />Statement (EIS) may be needed. <br /> <br />7.0 WATER QUALITY <br /> <br />Potential impacts to water quality in the La Plata River basin from the LHR project were <br />evaluated. For the evaluation, WWE reviewed ef Appendix B-Water Quality to the Final <br />Supplement to the Final Environmental Impact Statement-Animas La Plata Project (DOE and <br />USBR April 1996). This document contains a significant amount of water quality data for the La <br />Plata River. In Appendix B, data were compared to stream water quality standards to assess the <br />amount of exceedances. This Appendix B analysis showed that the standards for mercury, <br />selenium, silver, arsenic, and manganese are exceeded at various locations in the La Plata River <br />(need map), and that the number of exceedances generally increase in a downstream direction. <br />The causes of the exceedances were reported to be metals from historic mining in the upper <br />watershed, and irrigation return flows in the lower watershed. Importantly, the data collected are <br />for total metals while the stream standards are for dissolved metals. This means that the <br />Appendix B analysis is very conservative, and that the La Plata River stream standards may not, <br />in fact, be exceeded often, if at all. (Probably need letter from state WOCC.) <br /> <br />991-077.115 <br />May 2004 <br /> <br />Wright Water Engineers, Inc. <br /> <br />Page 13 <br />