Eagle River Inventory and Assessment (2)

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failure of tactical projects to restore ecosystem amenities and ecological integrity warrants the initial investment in examining these larger questions, Although the recommendations presented in the Eagle River Inventory and Assessment inevitably fall short of providing comprehensive information on all processes and potential projects, the focus on detecting system-level stressors and integration of existing knowledge is requisite for building comprehensive and sustainable strategies to restore the integrity of the Eagle River watershed, ES.3 WATERSHED OVERVIEW, HISTORY, AND POLICY Over the course of the project, CSU reviewed and compiled hundreds of documents. Previous reports and existing data sources that played a critical role in developing the eagle River Inventory and Assessment include the: 2002 Eagle River mater Quality Management Plan (Northwest Colorado Council of Governments (NWCCOG), 2002), Eagle River Watershed Plan (1996), Eagle River Assembly (ERA), U.S. Geological Survey (USGS) reports and water-quality database, Eagle Mine monitoring and analysis reports, instream flow quantification field forms and related reports by the Colorado Water Conservation Board (CWCB) and Colorado Division of Wildlife (CDOW), and numerous historical documents and photographs from the Denver Public Library and other sources, In addition to a brief review of these documents, this report provides a synopsis of watershed characteristics, abrief history of the Eagle River watershed, and a survey of current policies relating to riparian zones and stormwater management. ES.4 ANALYSIS OF WATERSHED CHARACTERISTICS (THE AFFECTED ENVIRONMENT) ES.4.1 Land Use GIS and aerial photograph analyses indicate that the most intense land use change is focused in or near the riparian corridors of the main stem Eagle River and Gore Creek, despite small percentages of developed land use in the overall watershed. For example, an analysis of land cover data suggests that total developed land use in the Gore Creek watershed is approximately 2%. Developed land cover within 100 m and 30 m of Gore Creek between the Black Gore confluence and the Eagle River is estimated at 7% and 35%, respectively. Similar patterns exist in the Eagle main stem, particularly between Minturn and Edwards where basin topography, development practicality, and human desires to be near the water place disproportionate development pressures in alluvial valleys. Results of an analysis of the imperviousness of developed areas (an often-cited indicator of stream health) revealed comparable trends. Future development will continue increasing imperviousness as the population of Eagle County approaches anticipated growth of 75% (Colorado Division of Local Government, 2003) over the next 25 years. These patterns are perhaps not surprising but nonetheless underscore the added challenges surrounding management of impervious surfaces, stormwater, and riparian zones in mountainous watersheds with rapidly growing population centers focused in and near ecologically critical zones. ES.4.2 Water Use Consumptive use accounts f®r appr®ximately 10 t® I5% ®f the Eagle River's average annual yield of 410,000 acre feet at the Gypsum g~ge~ 7Che greatest consumptive use in the basin results from transmountain exports which account for 60°/® of consumptive use Irrigation is the second largest consumptive use at approximately 32%, Domesticlmunicipal and reservoir evaporation uses are estimated at 3% and 4%, respectively. From 1985 to 1995, a shift from irrigation consumptive use to domestic consumptive use was apparent, as was a 54% decrease in irrigation consumptive use. Eagle River Inventory and Assessment ES-4