The Wyoming Stream Integrity Index (WSII) – Multimetric Indices for Assessment of Wadeable Streams and Large Rivers in Wyoming THE WYOMING STREAM INTEGRITY INDEX (WSII) – MULTIMETRIC INDICES FOR ASSESSMENT OF WADEABLE STREAMS AND LARGE RIVERS IN WYOMING Eric G. Hargett Wyoming Department of Environmental Quality Water Quality Division 122 W. 25th St. Herschler Building 4-W Cheyenne, Wyoming 82002 Document #11-0787 August 2011 The Wyoming Stream Integrity Index (WSII) – Multimetric Indices for Assessment of Wadeable Streams and Large Rivers in Wyoming TABLE OF CONTENTS EXECUTIVE SUMMARY .............................................................................................. IV INTRODUCTION .......................................................................................................... 1 METHODS AND MATERIALS ........................................................................................ 2 STUDY AREA ................................................................................................................................................................. 2 REFERENCE AND TEST SAMPLES ........................................................................................................................................ 3 MACROINVERTEBRATES ................................................................................................................................................... 3 WATER QUALITY, PHYSICAL HABITAT AND LANDSCAPE CHARACTERIZATION .............................................................................. 5 MODEL CONSTRUCTION .................................................................................................................................................. 6 A. Data Analysis .............................................................................................................................................. 6 B. Classification of Reference Samples ........................................................................................................... 6 C. Large River Abiotic Stressor Index .............................................................................................................. 6 D. Stream Human Stressor Index .................................................................................................................... 8 E. Metric Selection and Screening .................................................................................................................. 8 i. Metric Classification ............................................................................................................................................... 8 ii. Discrimination Efficiency ........................................................................................................................................ 9 iii. Range Test .............................................................................................................................................................. 9 iv. Signal-to-Noise Test ................................................................................................................................................ 9 v. Responsiveness ...................................................................................................................................................... 9 vi. Redundancy and Final Metric Selection ............................................................................................................... 10 F. Metric and Index Scoring .......................................................................................................................... 10 G. Final Index Calculation, Validation and Temporal Variability ................................................................... 10 H. Aquatic Life Use Attainment Category Thresholds ................................................................................... 11 RESULTS....................................................................................................................11 SITE CLASSIFICATION .................................................................................................................................................... 11 LARGE RIVER ABIOTIC STRESSOR INDEX ............................................................................................................................ 20 STREAM HUMAN STRESSOR INDEX .................................................................................................................................. 20 METRIC SCREENING, SELECTION AND INDEX SCORING ......................................................................................................... 20 INDEX PRECISION, VALIDATION AND EVALUATION .............................................................................................................. 21 ATTAINMENT CATEGORY THRESHOLDS ............................................................................................................................. 22 BIOREGION DESCRIPTIONS .....................................................................................32 SE PLAINS ................................................................................................................................................................ 32 NE PLAINS ................................................................................................................................................................ 33 SOUTHERN FOOTHILLS & LARAMIE RANGE ............................................................................................................. 34 SOUTHERN ROCKIES ................................................................................................................................................ 35 BLACK HILLS............................................................................................................................................................. 37 HIGH VALLEYS ......................................................................................................................................................... 38 SEDIMENTARY MOUNTAINS ................................................................................................................................... 39 GRANITIC MOUNTAINS ........................................................................................................................................... 40 VOLCANIC MOUNTAINS & VALLEYS ........................................................................................................................ 41 BIGHORN BASIN FOOTHILLS .................................................................................................................................... 42 WYOMING BASIN .................................................................................................................................................... 43 DISCUSSION .............................................................................................................44 STREAM INDEX ............................................................................................................................................................ 44 LARGE RIVER INDEX ...................................................................................................................................................... 46 METRIC SELECTION ...................................................................................................................................................... 46 MODEL PERFORMANCE ................................................................................................................................................. 48 i The Wyoming Stream Integrity Index (WSII) – Multimetric Indices for Assessment of Wadeable Streams and Large Rivers in Wyoming WSII LIMITATIONS ....................................................................................................................................................... 49 CONCLUSIONS ............................................................................................................................................................. 51 ACKNOWLEDGMENTS ................................................................................................................................................... 51 REFERENCES .............................................................................................................51 LIST OF TABLES Table 1 - Strengths of four stream classifications for benthic macroinvertebrate assemblages from the reference calibration dataset. Classification strength is the ratio of between (B) to within-class (W) similarities calculated from Sørensen (Bray-Curtis) similarity measures from OTU raw taxa counts. Classification strength increases as B/W decreases. ............................................................................ 12 Table 2 - Pearson product-moment correlations of latitude, longitude, elevation, and watershed area with NMS axes for clusters 1 and 2. ........................................................................................................... 13 Table 3 – Within group dissimilarities for all eleven bioregions of the WSII stream component. ............. 20 Table 4 - Spearman rank correlations of individual stressors with large river abiotic stressor indices developed for the Bighorn and North Platte Rivers. ............................................................................. 20 Table 5 – Spearman rank