National Park Service U.S. Department of the Interior Natural Resource Program Center Niobrara National Scenic River Condition Assessment Natural Resource Report NPS/NRPC/NRR—2010/172 ON THE COVER Niobrara National Scenic River Photograph courtesy of the National Park Service Niobrara National Scenic River Condition Assessment Natural Resource Report NPS/NRPC/NRR—2010/172 Sunil Narumalani Gary D. Willson Christine K. Lockert Paul B. T. Merani Great Plains Cooperative Ecosystem Studies Unit 515 Hardin Hall University of Nebraska-Lincoln Lincoln, NE 68583-0985 This report was prepared under Task Agreement J6067070012 of the Great Plains Cooperative Ecosystem Studies Unit (Cooperative Agreement between the National Park Service and the University of Nebraska-Lincoln CAH6000060100). January 2010 U.S. Department of the Interior National Park Service Natural Resource Program Center Fort Collins, Colorado The National Park Service, Natural Resource Program Center publishes a range of reports that address natural resource topics of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report received formal peer review by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data, and whose background and expertise put them on par technically and scientifically with the authors of the information. Views, statements, findings, conclusions, recommendations, and data in this report are those of the author(s) and do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service. This report is available from the Great Plains Cooperative Ecosystem Studies Unit website (http:snr.unl.edu/gpcesu) and the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/NRPM). Please cite this publication as: Narumalani, S., G. D. Willson, C. K. Lockert, and P. B. T. Merani. 2010. Niobrara National Scenic River condition assessment. Natural Resource Report NPS/NRPC/NRR—2010/172. National Park Service, Fort Collins, Colorado. NPS 656/100866, January 2010 ii iii Contents Page Figures ........................................................................................................................................ vii Tables .......................................................................................................................................... xi Executive Summary .................................................................................................................. xiii Acknowledgements .................................................................................................................. xvii Introduction .................................................................................................................................. 1 Ecological Context ....................................................................................................................... 3 Physical Setting ................................................................................................................. 3 History, Location, and Management Direction ......................................................... 3 Climate and Microclimate ......................................................................................... 5 Air Quality ................................................................................................................. 6 Topography and Geology .......................................................................................... 7 Soils ............................................................................................................................ 7 Watershed and Hydrology ......................................................................................... 8 Water Quality ........................................................................................................... 10 Biological Setting ............................................................................................................ 10 Vegetation ................................................................................................................ 10 Mammals .................................................................................................................. 11 Birds ......................................................................................................................... 12 Reptiles and Amphibians ......................................................................................... 14 Fishes ....................................................................................................................... 15 Invertebrates ............................................................................................................ 18 Listed Species .......................................................................................................... 18 iv Contents Land and Visitor Use ....................................................................................................... 18 Important Natural Resources ......................................................................................... 19 Niobrara River Water Quantity and Quality ........................................................... 19 Tributary Springs and Waterfalls ............................................................................ 19 Diverse Plant and Animal Communities including Pleistocene Relicts .................. 20 Sandy Shorelines, Sandbars, and Wetlands ............................................................. 22 Natural Resource Condition ....................................................................................................... 23 Condition Assessment Approach for Niobrara National Scenic River ............................ 23 Indicator Assessment ....................................................................................................... 29 Habitat: Niobrara River and Tributaries ................................................................. 29 Aquatic Macroinvertebrates ................................................................................ 29 River Otter ........................................................................................................... 33 Cool-water Fishes ............................................................................................... 34 Fish Community .................................................................................................. 36 Spiny Softshell Turtle ........................................................................................... 37 Stream Flow ......................................................................................................... 38 Habitat: Upland Forest and Savanna ........................................................................ 41 Elk ........................................................................................................................ 41 Ponderosa Pine ................................................................................................... 43 Land Cover .......................................................................................................... 46 Fire ...................................................................................................................... 48 v Contents Habitat: Spring Branch Canyon and Riparian Forest ............................................. 48 Paper Birch ......................................................................................................... 48 Hybrid Aspen ....................................................................................................... 50 Bailey’s Eastern Woodrat ................................................................................... 52 Bird Hybridization ............................................................................................... 53 Habitat: Grassland ................................................................................................... 54 Grassland Birds ................................................................................................... 54 Sand Hills Prairie ................................................................................................ 56 Land Cover .......................................................................................................... 57 Fire ...................................................................................................................... 57 Habitat: Sandy Shorelines, Sandbars, and Wetlands .............................................. 58 Interior Least Tern and Piping Plover ...............................................................