Sustaining Minnesota’s Lake Superior Tributaries in a Changing Climate August 2016 Minnesota Department of Natural Resources Natural Resources Research Institute, University of Minnesota Duluth The Nature Conservancy Acknowledgements This study was made possible through the time and energy of the following people: • William Bartsch, Natural Resources Research Institute, University of Minnesota Duluth • Cliff Bentley, Minnesota Department of Natural Resources • Kristen Blann, The Nature Conservancy • Meijun Cai, Natural Resources Research Institute, University of Minnesota Duluth • Jeremy Erickson, Natural Resources Research Institute, University of Minnesota Duluth • Rachael Franks-Taylor, NOAA, Office for Coastal Management • Ralph Garono, Natural Resources Research Institute, University of Minnesota Duluth • William Herb, St. Anthony Falls Laboratory, University of Minnesota • Tom Hollenhorst, US Environmental Protection Agency • John Jereczek, Minnesota Department of Natural Resources • Lucinda Johnson, Natural Resources Research Institute, University of Minnesota Duluth • Clinton Little, Minnesota Department of Natural Resources (Minnesota’s Lake Superior Coastal Program) • Molly MacGregor, Minnesota Department of Natural Resources • Hilarie Sorensen, Minnesota Sea Grant • Amber Westerbur, Minnesota Department of Natural Resources (Minnesota’s Lake Superior Coastal Program) • Mark White, The Nature Conservancy Funding for this project was received from NOAA’s Office for Coastal Management via President Obama’s Great Lakes Restoration Initiative. For more information on the Initiative and Action Plan go to www.glri.us. Suggested Citation Herb, W., K. Blann, L. Johnson, R. Garono, J. Jereczek, M. White and H. Sorensen. 2016. Sustaining Minnesota's Lake Superior Tributaries in a Changing Climate. Final Report to NOAA's Office for Coastal Management. mndnr.gov/eloha. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the views of the NOAA’s Office for Coastal Management or U.S. Department of Commerce. Table of Contents Part I Acronyms………………………………………………………………………………………………………………………i Forward……………………………………………………………………………………………………………………….iii Executive Summary Goals ………...……………………………………………………………………………………………………….. 1 Purpose of the Study…………………………………………………………………………………………… 1 Project Components……………………………………………………………………………………………. 2 Resource Manager Engagement ……………………………………………………………….. 2 Research …………………………………………………………………………………………………. 4 Summary of Management Recommendations ……………………………………………………. 19 Part II Module 1: Introduction Minnesota’s Lake Superior Tributaries …………………………………………………………….. 1-1 Climate Change – What We Have Experienced So Far ……………………………………….. 1-3 Climate Change and Flow Regimes …………………………………………………………………... 1-8 Land Cover and Forest Management Impacts on Flow Regime ………………………….. 1-9 Climate Impacts on Minnesota’s Northern Forests and Land Cover ……………….... 1-13 Climate Change and Flow Ecology ………………………………………………………………….. 1-15 Flow Ecology in Minnesota’s Lake Superior Tributaries ………………………………….. 1-17 Study Watersheds ……………………………………………………………………………………….… 1-21 References …………………………………………………………………………………………….……… 1-24 Module 2: Resource Manager Engagement Introduction …………………………………………………………………………………………………... 2-1 Methods …………………………………………………………………………………………………………. 2-2 Results & Findings ……………………………………………………………………………………….…. 2-4 Conclusions ………………………………………………………………………………………………….… 2-8 For More Information ……………………………………………………………………………………... 2-8 References ……………………………………………………………………………………………………... 2-9 Appendix 2-I: Management Decision Tool ……………………………………………………… 2-10 Module 3: Project Components and Supporting Data Introduction …………………………………………………………………………………………………… 3-1 Project Components ……………………………………………………………………………………...… 3-2 Data Review …………………………………………………………………………………………………… 3-4 Hydrologic Modeling …………………………………………………………………………………….. 3-14 Flow Ecology Relationships …………………………………………………………………………... 3-25 Conclusions ………………………………………………………………………………………………..… 3-26 For More Information ………………………………………………………………………………….... 3-27 References ……………………………………………………………………………………………………. 3-28 Module 4: Hydrologic Stream Classification Purpose ………………………………………………………………………………………………………..… 4-1 Methods …………………………………………………………………………………………………………. 4-1 Results & Findings ………………………………………………………………………………………….. 4-5 Conclusions ………………………………………………………………………………………………….. 4-19 For More Information ………………………………………………………………………………...…. 4-20 References ……………………………………………………………………………………………………. 4-21 Module 5: Hydrologic Models and Flow Statistics Purpose ………………………………………………………………………………………………………..… 5-1 Methods …………………………………………………………………………………………………………. 5-2 HSPF Rainfall Runoff Models ……………………………………………………………….... 5-2 Climate Scenario Selection and Assembly ……………………………………………. 5-13 Historical Climate Trend Analysis ……………………………………………………..… 5-15 Stream Flow Sensitivity to Land Cover and Climate Change …………………. 5-16 Climate and Land Cover Scenario Analysis ………………………………………...… 5-17 Regional Regression Models for Stream Flow Statistics ……………………...… 5-19 Results & Findings ………………………………………………………………………………………... 5-25 Historical Stream Flow Metrics …………………………………………………………… 5-26 Sensitivity Analysis: Response of Stream Flow to Changes in Forest Type, Air Temperature, and Precipitation ………………………………………………………….. 5-28 Response to Land Cover Change Scenarios (2070LE, 2070HE) …………….. 5-32 Response to Climate Scenarios (GFDL, Hadley) ……………………………………. 5-34 Changes in Annual and Seasonal Maximum Flows ……………………………….. 5-38 Regional Extrapolation of HSPF Model Results …………………………………….. 5-45 Current Climate and Flow Trends ……………………………………………………….. 5-49 Conclusions ………………………………………………………………………………………………….. 5-57 For More Information …………………………………………………………………………………… 5-60 References ………………………………………………………………………………………………...….. 5-61 Appendix 5-I: Hydrologic Models and Flow Statistics ……………………………………… 5-64 Module 6: Projected Forest Cover Change Purpose …………………………………………………………………………………………………….…..... 6-1 Methods ……………………………………………………………………………………………………........ 6-1 Results & Findings ………………………………………………………………………………………….. 6-8 Conclusions ………………………………………………………………………………………………….. 6-13 For More Information ………………………………………………………………………………….... 6-16 References ……………………………………………………………………………………………………. 6-17 Module 7: Flow Ecology Relationships Purpose ………………………………………………………………………………………………………….. 7-1 Methods …………………………………………………………………………………………………………. 7-2 Characterizing Biological Communities (Fish and Aquatic Macroinvertebrates) …………………………………………………………………………..… 7-3 Flow Ecology Analysis Methods ………………………………………………………..… 7-11 Anticipating Biological Response under Future Flows: Defining Vulnerability and Resilience ……………………………………………………………………………………. 7-12 Results ……………………………………………………………………………………………………….… 7-14 Ecological Relationships to Flow ………………………………………………………… 7-14 Exploratory Analysis and Key Variable (Multivariate Analysis) ……………. 7-14 Evaluating Threshold Response to Flow Metrics – TITAN Results ………... 7-20 Anticipating Biological Response under Future Flows …………………………. 7-47 Discussion …………………………………………………………………………………………………..... 7-50 Conclusions ………………………………………………………………………………………………..… 7-54 For More Information …………………………………………………………………………………… 7-56 References ……………………………………………………………………………………………………. 7-57 Appendices …………………………………………………………………………………………………… 7-62 Acronyms Acronym Definition AFINCH Analysis of Flows in Networks of Channels: A computer application that can be used to generate a time series of monthly flows at stream segments (flowlines) and water yields for catchments defined in the National Hydrography Dataset Plus (NHDplus) value-added attribute system. BAU Business As Usual BIC Bayesian Information Criterion BFI Baseflow Index BMPs Best management practices BPJ Best Professional Judgement C-CAP Coastal Change Analysis Program : A collection of land cover and land change products of coastal intertidal areas, wetlands, and adjacent uplands for the coastal U.S. CCA Canonical Correspondence Analysis CMIP5 Coupled Model Intercomparison Project Phase 5 CO2 Carbon dioxide DEM Digital Elevation Model EFCs Ecological Flow Conditions ELT Ecological Land Types EPA (U.S.) Environmental Protection Agency EPT EPT Index: The total number of distinct taxa within the groups Ephemeroptera, Plecoptera and Trichoptera. EROM Extended Unit Runoff Method ET Evapotranspiration GCMs Global Climate Models GFDL A global climate model output that represents a relatively cool, wet projected future climate. Ha Hectare Hadley A global climate model output that represents a relatively warm and dry projected future climate. HSPF Hydrologic Simulation Program—Fortran HUC (Huc) Hydrologic Unit Code IBI Index of Biological Integrity km Kilometers i Acronym Definition LANDIS-II LANdscape DISturbance and Succession: A forest landscape simulation model LiDAR Light Detection and Ranging: A remote sensing method m Meter mm Millimeters MNDNR (DNR) Minnesota Department of Natural Resources MPCA (PCA) Minnesota Pollution Control Agency NHD National Hydrography Data Set (NHDPlusV2; NHD+; NHDplus) NLCD National Land Cover Database NOAA National Oceanic and Atmospheric Administration NRCS Natural Resources Conservation Service NRRI Natural Resources Research Institute NWI National Wetland Inventory NWS National Weather Service PCA Principal Components Analysis PET Potential Evapotranspiration ppm parts per million PRESS Predicted Residual Error Sum of Squares PRISM Parameter-elevation Regressions on Independent