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Table of Contents <br />Section 1.0 -Introduction .............................................................................................................1-1 <br />1.1 Overview of Alamosa River ~latershed ...............................................................................................1-1 <br />1.1.1 Issues of Historical Significance ..................................................................................................................................1-3 <br />1.2 Master Plan Purpose and Needs ...........................................................................................................1-3 <br />. . <br />1.3 uthorization ...........................................................................................................................................1-4 <br />Section 2.0 -Environmental Impacts ..........................................................................................2-1 <br />2.1 Intro uction to Environmenta Impacts .............................................................................................2-1 <br />2.1.1 Climate ............................................................................................................................................................................2-1 <br />2.1.2 Key Structures in the Watershed ................................................................................................................................ 2-1 <br />2.1.3 Land Ownership ........................................................................................................................................................... 2-3 <br />2.1.4 Segments ........................................................................................................................................................................ <br />2-3 <br />2.2 Channel of Alamosa River and 1Vlajor Tributaries ..............................................................................2-8 <br />2.2.1 Upper Watershed (Reaches T1, 12, and 11) ............................................................................................................ 2-10 <br />2.2.2 Wightman to Beaver Creek (Reaches 10, 9, and 8) ................................................................................................ 2-13 <br />2.2.3 Beaver Creek to French Creek (Reach 7) ................................................................................................................ 2-13 <br />2.2.4 French Creek to Terrace Reservoir (Reach 6) ......................................................................................................... 2-13 <br />2.2.5 Terrace Reservoir (Reach 5) ...................................................................................................................................... 2-14 <br />2.2.6 Terrace Reservoir to Terrace Main Canal (Reach 4) .............................................................................................. 2-16 <br />2.2.7 Terrace Main Canal to Gunbarrel (Reach 3) ........................................................................................................... 2-17 <br />2.2.8 Gunbarrel to County Road 10 (Reach 2) ................................................................................................................. 2-18 <br />2.2.9 County Road 10 to Highway 285 (Reach 1) ............................................................................................................ 2-19 <br />2.2.10Floodplain ~Iapping ................................................................................................................................................... 2-19 <br />2.2.11 Summary of Channel Issues ...................................................................................................................................... 2-19 <br />2.3 Sur ace dater Quantity ........................................................................................................................2-22 <br />2.3.1 Streamflow ................................................................................................................................................................... 2-22 <br />2.3.2 Tributary 1-average Flow Estimate ............................................................................................................................. 2-27 <br />2.3.3 Terrace Reservoir Levels ............................................................................................................................................ 2-30 <br />2.3.4 Flood Frequency ......................................................................................................................................................... 2-31 <br />2.3.5 Flood Events ............................................................................................................................................................... 2-32 <br />2.3.6 Water Rights and Usage ............................................................................................................................................. 2-33 <br />2.3.7 Summary of Surface Water Quantity Issues ............................................................................................................ 2-40 <br />2.4 Sur ace dater Qua ty ........................................................................................................................... 2-40 <br />2.4.1 Effects of Geolo on Re onal Water ualit <br />gY ~ Q y ...................................................................................................... 2-40 <br />2.4.2 The Summitville Legacy ............................................................................................................................................. 2-42 <br />2.4.3 Sources of Water Quality Contamination ................................................................................................................ 2-43 <br />2.4.4 Water uali Data i~Iethodolo <br />Q tY gY ............................................................................................................................. 2-58 <br />2.4.5 Water Quality Standards ............................................................................................................................................ 2-61 <br />2.4.6 Water Quality Changes Related to Summitville ...................................................................................................... 2-65 <br />2.4.7 Current Water Quality in ~~lamosa River Watershed ............................................................................................. 2-76 <br />2.4.8 Seasonal ~rariation in Water Quality ......................................................................................................................... 2-83 <br />2.4.9 Contaminant Loads .................................................................................................................................................... 2-89 <br />2.4.10SuspendedSethments ................................................................................................................................................. 2-91 <br />2.4.11 Expected Future Trends ............................................................................................................................................ 2-92 <br />2.4.12Summary of Water Quality Issues ............................................................................................................................ 2-93 <br 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