Helena and Lewis & Clark National Forests Forest Plan Assessment Chapter 3, Watershed, Aquatic, Soil, and Air Resources 2015 Table of Contents Introduction ............................................................................................................................................................... 1 Geographic Areas of the Helena and Lewis & Clark National Forests ................................................................... 1 Broad Scale Context and Key Ecosystem Components ......................................................................................... 3 Watersheds ............................................................................................................................................................... 4 Introduction ........................................................................................................................................................... 4 Existing Information .............................................................................................................................................. 5 Existing Condition .................................................................................................................................................. 5 Trends and Drivers................................................................................................................................................. 8 Information Needs ................................................................................................................................................. 8 Water Resources and Water Quality ......................................................................................................................... 9 Introduction ........................................................................................................................................................... 9 Existing Information .............................................................................................................................................. 9 Existing Condition ................................................................................................................................................ 10 Trends and Drivers............................................................................................................................................... 13 Information Needs ............................................................................................................................................... 13 Aquatic Ecosystems ................................................................................................................................................. 13 Introduction ......................................................................................................................................................... 13 Existing Information ............................................................................................................................................ 15 Existing Condition ................................................................................................................................................ 16 Trends and Drivers: Water Resources, Water Quality, and Aquatic Ecosystems ................................................ 26 Information Needs ............................................................................................................................................... 32 Soil ........................................................................................................................................................................... 32 Introduction ......................................................................................................................................................... 32 Existing Information ............................................................................................................................................ 32 Existing Condition ................................................................................................................................................ 33 Trends and Drivers............................................................................................................................................... 36 Information Needs ............................................................................................................................................... 38 Air Quality ................................................................................................................................................................ 38 Introduction ......................................................................................................................................................... 38 Existing information ............................................................................................................................................ 38 Existing condition ................................................................................................................................................ 39 Trends and reasonably foreseeable future conditions ....................................................................................... 49 Information Needs ............................................................................................................................................... 50 References ............................................................................................................................................................... 50 Tables Table 3.1 Key Ecosystem characteristics ................................................................................................................... 4 Table 3.2 Number of sixth level watersheds by geographic area rated in each category under the WCF ............... 6 Table 3.3 Indicators and attributes most commonly rated Impaired for watersheds by GA ................................... 7 Table 3.4 Number of 303(d) listed streams and causes by GA................................................................................ 10 Table 3.5 Number of 6th level watersheds rated in each category using the WCF Riparian Vegetation Indicator ratings ...................................................................................................................................................................... 12 Table 3.6 WCF soils attribute ratings: number of watersheds by geographic area ................................................ 33 Table 3.7 Monitoring sites for principal air pollutants ............................................................................................ 39 Table 3.8 AQI ranges and explanations ................................................................................................................... 43 Table 3.9 Categories, associated concentrations of PM2.5, and visibility used by the MT DEQ in Today’s Air ........ 44 Table 3.10 Air quality related values associated with wilderness areas in the HLC NFs ......................................... 46 Figures Figure 3.1 Core national watershed condition indicators and attributes ................................................................. 6 Figure 3.2 Big Belts GA: watershed condition framework—functioning classes .................................................... 16 Figure 3.3 Castles GA: watershed condition framework – functioning classes ....................................................... 17 Figure 3.4 Crazies GA: watershed condition framework – functioning classes ...................................................... 18 Figure 3.5 Divide GA: watershed condition framework – functioning classes ........................................................ 18 Figure 3.6 Elkhorn Mountains GA: watershed condition framework—functioning classes ................................... 20 Figure 3.7 Highwoods GA: watershed condition framework – functioning classes ................................................ 20 Figure 3.8 Distribution of monitored stream reaches in the Highwoods GA across properly functioning channel (PFC) condition classes, showing changes between 2005 and 2013 ....................................................................... 21 Figure 3.9 Little Belts GA: watershed condition framework – functioning classes ................................................. 22 Figure 3.10 Rocky Mountain Range GA: watershed condition framework – functioning classes .......................... 23 Figure 3.11 Snowies GA: watershed condition framework – functioning classes................................................... 24 Figure 3.12 Upper Blackfoot GA: watershed Condition framework—functioning classes ..................................... 25 Figure 3.13 Annual average values for PM2.5 in the plan area ................................................................................ 40 Figure 3.14 Location of wildfires in the Bob Marshall Wilderness in the summer of 2013 and temporary smoke particulate monitor sites ......................................................................................................................................... 40 Figure 3.15 Hourly and 24-hr average values of PM2.5 at Ear Mountain in 2013 .................................................... 41 Figure 3.16 Hourly and 24-hr average values of PM2.5 at the Augusta Work Center in 2013 ................................