Salmon Subbasin Assessment Prepared for the Northwest Power and Conservation Council May 28, 2004 DRAFT Salmon Subbasin Assessment 4/20/2004 Table of Contents 1 Overview................................................................................................................................ 1-1 1.1Background....................................................................................................................... 1-1 1.2Assessment Conceptual Framework.................................................................................1-1 1.2.1 Scientific Principles.............................................................................................. 1-1 1.2.2 Overarching Biological Objectives......................................................................1-4 1.2.3 Subbasin Null Hypotheses ...................................................................................1-5 1.3General Description ..........................................................................................................1-6 1.3.1 Importance to the Region.....................................................................................1-6 1.3.2 Subbasin Location................................................................................................1-6 1.4Physical Description .........................................................................................................1-7 1.4.1 Drainage Area......................................................................................................1-7 1.4.2 Geomorphology .................................................................................................1-10 1.4.3 Climate...............................................................................................................1-12 1.5Biological Description ....................................................................................................1-12 1.5.1 Fish Species .......................................................................................................1-12 1.5.2 Wildlife Species.................................................................................................1-14 1.5.2.1 Mammals........................................................................................... 1-18 1.5.2.2 Birds ..................................................................................................1-18 1.5.2.3 Reptiles and Amphibians ..................................................................1-19 1.5.3 Vegetation and Floristic Diversity.....................................................................1-19 1.5.4 Rare and Endemic Plants ...................................................................................1-23 1.6Social Description...........................................................................................................1-24 1.6.1 Demographics ....................................................................................................1-24 1.6.2 Ownership and Land-Use Patterns.....................................................................1-26 1.6.3 Water Diversion Structures and Fish Migration Barriers ..................................1-28 1.6.4 Protected Areas..................................................................................................1-30 1.7Environmental and Biological Situation.........................................................................1-32 1.7.1 Water Quality.....................................................................................................1-32 1.7.2 Species Status and Constraints...........................................................................1-33 1.7.3 Habitat Status and Constraints...........................................................................1-35 1.7.4 Disturbance ........................................................................................................1-37 1.7.5 Noxious and Invasive Exotic Weeds .................................................................1-37 2 Subbasin Biological Resources..............................................................................................2-1 2.1Key Ecological Functions of Fish and Wildlife Species ..................................................2-9 2.1.1 Overview..............................................................................................................2-9 2.1.1.1 Key Ecological Functions and Environmental Correlates ..................2-9 2.1.1.2 Functional Specialists and Generalists..............................................2-10 2.1.1.3 Functional Richness..........................................................................2-10 2.1.1.4 Trophic Levels..................................................................................2-11 2.1.1.5 Total Functional Diversity ................................................................2-12 2.1.1.6 Functional Profiles............................................................................2-13 2.1.1.7 Critical Functional Link Species.......................................................2-15 i DRAFT Salmon Subbasin Assessment 4/20/2004 2.1.2 Focal Species .....................................................................................................2-16 2.2Aquatic Resources ..........................................................................................................2-26 2.2.1 Focal Species .....................................................................................................2-26 2.2.1.1 Chinook Salmon (Oncorhynchus tschawytscha) ..............................2-27 2.2.1.2 Steelhead (Oncorhynchus mykiss)....................................................2-57 2.2.1.3 Bull Trout (Salvelinus confluentus)..................................................2-75 2.2.1.4 Sockeye Salmon (Oncorhynchus nerka) ...........................................2-80 2.2.2 Artificial Propagation.........................................................................................2-84 2.2.3 Disease Issues....................................................................................................2-91 2.2.4 Important Species...............................................................................................2-92 2.2.4.1 Pacific Lamprey (Lampetra tridentata) .............................................2-92 2.2.4.2 White Sturgeon (Acipenser transmontanus) .....................................2-95 2.2.4.3 Westslope Cutthroat Trout (Oncorhynchus clarki lewisi) ................2-96 2.2.5 Nonnative Species ..............................................................................................2-98 2.3Terrestrial Resources ......................................................................................................2-98 2.3.1 Riparian/Herbaceous Wetlands........................................................................2-102 2.3.1.1 Description......................................................................................2-102 2.3.1.2 Focal Species...................................................................................2-104 2.3.2 Shrub-Steppe ....................................................................................................2-108 2.3.2.1 Description......................................................................................2-108 2.3.2.2 Focal Species...................................................................................2-109 2.3.3 Pine/Fir Forests................................................................................................2-111 2.3.3.1 Xeric, Old Forest (Ponderosa Pine/Douglas-Fir)............................2-111 2.3.3.2 Mesic Forest....................................................................................2-113 2.3.4 Native Grasslands............................................................................................2-117 2.3.4.1 Description......................................................................................2-117 2.3.4.2 Focal Species...................................................................................2-118 2.3.5 Aspen ...............................................................................................................2-122 2.3.6 Western Juniper/Mountain Mahogany Woodlands .........................................2-123 2.3.6.1 Description......................................................................................2-123 2.3.6.2 Focal Species...................................................................................2-123 2.3.7 Whitebark Pine.................................................................................................2-124 2.3.7.1 Description......................................................................................2-124 2.3.7.2 Focal Species...................................................................................2-126 2.3.8 Threatened and Endangered Species ...............................................................2-127 2.3.8.1 Bald Eagle (Haliaeetus leucocephalus)...........................................2-128 2.3.8.2 Gray Wolf (Canis lupus) .................................................................2-129 2.3.8.3 Northern Idaho Ground Squirrel (Spermophilus brunneus brunneus).........................................................................................2-130 2.3.8.4 Spalding’s Catchfly (Silene spaldingii) ..........................................2-131 2.3.8.5 MacFarlane’s Four-o’clock (Mirabilis macfarlanei).......................2-131