Lapwai Creek Aquatic Assessment Prepared By The Center for Environmental Education, Washington State University For Nez Perce Tribe, Watershed Department The Lapwai Creek aquatic assessment was produced for the Nez Perce Tribe Department of Fisheries, Watershed Division, under BPA Contract #8200100. The contract was to conduct an inventory of Nez Perce Indian Reservation and ceded territory streams, focusing on the physical habitat and associated biological communities. The inventory emphasizes identification of limiting factors for salmon and steelhead production in the Lapwai Creek watershed. The document was produced by the Center for Environmental Education at Washington State University. Authors include T. Cichosz Fisheries Biologist A. Davidson Spatial Ecologist C. Rabe Aquatic Ecologist D. Saul Editor Table of Contents 1 - Introduction.................................................................................................. 1 Purpose.......................................................................................................... 1 Key Issues .................................................................................................. 1 Limitations .................................................................................................. 1 Theoretical Assumptions .............................................................................. 2 2 - Methods ....................................................................................................... 5 Alternate Methods........................................................................................... 5 3 - Geographic Context ....................................................................................... 9 Human Population........................................................................................... 9 Climate..........................................................................................................11 Topography ...................................................................................................13 Geology.........................................................................................................15 Wildlife..........................................................................................................15 Sensitive Species............................................................................................15 Common Name..............................................................................................17 Species Found Within the Lapwai Creek Watershed ..........................................17 Historic Vegetation.........................................................................................18 Current Land Use ...........................................................................................18 4 - History.........................................................................................................23 Original Human Inhabitants ............................................................................24 European Contact ..........................................................................................24 European Settlement......................................................................................25 Water Diversion .............................................................................................25 Transportation ...............................................................................................26 Forest Clearing ..............................................................................................26 Agricultural Industrialization............................................................................26 Channel Modification ......................................................................................26 Urbanization and Flood Control .......................................................................27 Fisheries........................................................................................................27 5 - Channel Habitat Types..................................................................................29 Methods ........................................................................................................29 Classification of Stream Segments ...................................................................32 Low Gradient Confined (LC).........................................................................32 Low Gradient, Moderately Confined (LM)......................................................32 Moderate Gradient, Moderately Confined (MM) .............................................32 Moderate Gradient, Confined Channel (MC) ..................................................33 Moderately Steep, Narrow Valley (MV) .........................................................33 Moderate Gradient Headwater (MH).............................................................33 Steep Narrow Valley (SV) and Very Steep Headwater Headwater (VH) ...........33 Summary.......................................................................................................34 6 - Hydrology and Water Use .............................................................................35 Methods ........................................................................................................35 Hydrology......................................................................................................35 Hydrologic Characterization .........................................................................35 Land Use.......................................................................................................39 ii Forestry .....................................................................................................39 Agricultural and Rangelands ........................................................................42 Forest and Rural Roads...............................................................................46 Urban and Residential.................................................................................48 Water Use .....................................................................................................50 Summary.......................................................................................................56 7 - Riparian Areas and Wetlands.........................................................................57 Methods ........................................................................................................58 Riparian Vegetation Characteristics ................................................................60 Mainstem Lapwai........................................................................................61 Primary Lapwai Tributaries ..........................................................................63 Wetlands.......................................................................................................66 Summary.......................................................................................................66 8 - Sediment Sources.........................................................................................67 Methods ........................................................................................................69 Road Instability ..........................................................................................71 Rural Road Runoff ......................................................................................72 Cropland Erosion ........................................................................................72 Rangeland Erosion......................................................................................75 Sediment Source Characterization .................................................................75 Road Instability ..........................................................................................75 Rural Road Runoff ......................................................................................83 Cropland Erosion ........................................................................................84 Rangeland Erosion......................................................................................88 Summary.......................................................................................................90 9 - Channel Modification ....................................................................................91 Methods ........................................................................................................91 Historic Channel Modification ..........................................................................92 Current Channel Modification ..........................................................................93 Tom Beall Subwatershed.............................................................................93 Lower Lapwai.............................................................................................96 Middle Lapwai ............................................................................................97 Lower Sweetwater ......................................................................................97 Middle Sweetwater .....................................................................................97 Lower Mission ............................................................................................97 Middle Mission............................................................................................98