Upper Snake Province Assessment Prepared for the Northwest Power and Conservation Council May 28, 2004 Upper Snake Provincial Assessment May 2004 Table of Contents 1 Overview .............................................................................................................................................1-1 1.1 Background ................................................................................................................................1-1 1.2 Assessment Conceptual Framework ..........................................................................................1-1 1.2.1 Scientific Principles ................................................................................................................... 1-1 1.2.2 Provincial Null Hypotheses........................................................................................................ 1-4 1.3 General Description....................................................................................................................1-5 1.3.1 Province Location ...................................................................................................................... 1-5 1.3.2 Snake Headwaters Subbasin.......................................................................................................1-6 1.3.3 Upper Snake Subbasin ............................................................................................................... 1-7 1.3.4 Closed Basin Subbasin............................................................................................................... 1-7 1.4 Physical Description...................................................................................................................1-7 1.4.1 Drainage Area .......................................................................................................................... 1-11 1.4.1.1 Snake Headwaters Subbasin ................................................................................... 1-11 1.4.1.2 Upper Snake Subbasin .............................................................................................1-11 1.4.1.3 Closed Basin Subbasin............................................................................................ 1-14 1.4.2. Hydrology ................................................................................................................................ 1-16 1.4.2.1 Snake Headwaters Subbasin ................................................................................... 1-16 1.4.2.2 Upper Snake Subbasin ............................................................................................ 1-18 1.4.2.3 Closed Basin Subbasin............................................................................................ 1-21 1.4.3 Geology.................................................................................................................................... 1-21 1.4.3.1 Snake Headwaters Subbasin ................................................................................... 1-21 1.4.3.2 Upper Snake Subbasin ............................................................................................ 1-23 1.4.3.3 Closed Basin Subbasin............................................................................................ 1-24 1.4.4 Climate..................................................................................................................................... 1-25 1.4.4.1 Snake Headwaters Subbasin ................................................................................... 1-25 1.4.4.2 Upper Snake Subbasin ............................................................................................ 1-26 1.4.4.3 Closed Basin Subbasin............................................................................................ 1-26 1.5 Biological Description..............................................................................................................1-27 1.5.1 Aquatic Species........................................................................................................................ 1-27 1.5.1.1 Invertebrate Species ................................................................................................ 1-27 1.5.1.2 Fish Species ............................................................................................................ 1-28 1.5.2 Wildlife .................................................................................................................................... 1-30 1.5.2.1 Mammals ................................................................................................................ 1-32 1.5.2.2 Birds........................................................................................................................ 1-33 1.5.2.3 Reptiles and Amphibians ........................................................................................ 1-36 1.5.3 Vegetation and Floristic Diversity ........................................................................................... 1-36 1.5.3.1 Snake Headwaters Subbasin ................................................................................... 1-37 1.5.3.2 Upper Snake Subbasin ............................................................................................ 1-37 1.5.3.3 Closed Basin Subbasin............................................................................................ 1-37 1.5.4 Rare and Endemic Plants.......................................................................................................... 1-37 1.6 Social Description ....................................................................................................................1-38 1.6.1 Demographics ......................................................................................................................... 1-38 1.6.2 Ownership and Land Use Patterns ........................................................................................... 1-41 1.6.3 Water Diversion and Management........................................................................................... 1-44 1.6.4 Protected Areas ........................................................................................................................ 1-47 1.7 Environmental and Biological Situation ..................................................................................1-51 1.7.1 Water Quality........................................................................................................................... 1-51 1.7.2 Species and Habitat Status and Constraints.............................................................................. 1-52 1.7.3 Disturbance .............................................................................................................................. 1-55 1.7.4 Noxious Weeds ........................................................................................................................ 1-58 i Upper Snake Provincial Assessment May 2004 2 Subbasin Biological Resources ...........................................................................................................2-1 2.1 Key Ecological Functions of Fish and Wildlife Species............................................................2-7 2.1.1 Overview....................................................................................................................................... 2-7 2.1.1.1 Key Ecological Functions and Environmental Correlates......................................... 2-7 2.1.1.2 Functional Specialists and Generalists...................................................................... 2-8 2.1.1.3 Functional Richness .................................................................................................. 2-9 2.1.1.4 Trophic Levels ..........................................................................................................2-9 2.1.1.5 Total Functional Diversity ...................................................................................... 2-11 2.1.1.6 Functional Profiles .................................................................................................. 2-13 2.1.1.7 Critical Functional Link Species............................................................................. 2-15 2.1.2 Focal Species .............................................................................................................................. 2-16 2.2 Aquatic Resources....................................................................................................................2-20 2.2.1 Focal Species .............................................................................................................................. 2-20 2.2.1.1 Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri) .............................. 2-21 2.2.1.2 Bull Trout (Salvelinus confluentus) ........................................................................ 2-55 2.2.1.3 Mountain Whitefish (Prosopium williamsoni)........................................................ 2-60 2.2.1.4 Molluscs.................................................................................................................. 2-60 2.2.2 Important Species........................................................................................................................ 2-63 2.2.2.1 Speckled Dace (Rhinichthys osculus)..................................................................... 2-63 2.2.2.2 Longnose Dace (Rhinichthys cataractae)...............................................................