Detailed Assessment of Phosphorus Sources to · PDF fileDetailed Assessment of Phosphorus...

Detailed Assessmentof

Phosphorus Sourcesto

Minnesota WatershedsVolume 1: Executive Summary and Report

Prepared by Barr Engineering CompanyFebruary 2004

Photo by USDA NRCS Photo by USDA NRCS

Detailed Assessment of Phosphorus Sources to Minnesota Watersheds

Under TMDL Master Contract

Prepared for Minnesota Pollution Control Agency

Submitted by Barr Engineering Company

February 2004

Project Funding/Costs Funding for this project was recommended by the Legislative Commission on Minnesota Resources (LCMR) from the Environmental Trust Fund. The total cost of this report was $400,700, of which $244,000 was provided by the Environmental Trust Fund.

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Acknowledgements

The Detailed Assessment of Phosphorus Sources to Minnesota Watersheds was prepared by Barr Engineering Company, with its partners Limno-Tech, Inc., Dr. David Mulla, and Dr. Prasanna Gowda, under the Total Maximum Daily Load (TMDL) Master Contract for the Minnesota Pollution Control Agency. Funding for this project was recommended by the Legislative Commission on Minnesota Resources (LCMR) from the Environmental Trust Fund. The total cost of this report was $400,700, of which $244,000 was provided by the Environmental Trust Fund. Minnesota Pollution Control Agency Project Manager: Marvin Hora Project Contact/Reviewer: Douglas Hall Technical Coordinator: Mark Tomasek Contracting: Hafiz Munir Contributors: Jim Klang, Dave Wall, Greg Pratt, Ed Swain, Bill Priebe, Joe Magner, Mark

Westpetal, Bruce Wilson, Wayne Anderson, Greg Johnson, Ron Jacobson, Tim Larson, Randy Dunnette, Don Kriens, Gene Soderbeck, Scott Knowles, Jim Strudell, Deb Schumann, Reid Gagle, Joan deMeurisse, Linda Nelson, Carol Sinden, Dennis Wasley, Paul Trapp, Joe Schimmel, George Schwint, Rick Strassman, Keith Cherryholmes, Gretchen Sabel, Wendy Turri, Brian Gove, Lou Flynn, Steve Heiskary, Bruce Monson, Howard Markus, Beth Endersbe, Sandy Bissonnette, Nancy Ellefson, Jan Eckart, Andrea Ebner, Jennifer Holstad, Pat Baskfield

Minnesota Environmental Partnership Soap and Detergent Association Metropolitan Council Environmental Services Minnesota Department of Agriculture Minnesota Department of Natural Resources St. Croix Watershed Research Station of the Science Museum of Minnesota Minnesota State Climatology Minnesota Department of Transportation Minnesota Department of Health Board of Water and Soil Resources Minnesota Environmental Science and Economic Review Board Barr Engineering Team Project Principal: Henry (Hal) Runke Project Manager: Greg Wilson Technical Writers: Barr Engineering Company—Teresa Perry, Nick Nelson, Jeff Lee, Tim

Anderson, Cliff Twaroski, Pat Hirl, Jamie Bankston, Ron Reding, Keith Pilgrim, Greg Wilson; Limno-Tech, Inc.—Hans Holmberg, Joe DePinto, Jagjit Kaur, Dave Dilks; University of Minnesota, Department of Soil, Water, and Climate—David Mulla, Prasanna Gowda

Data Collection/Analysis: Dan Nesler, Scott Sobiech, Sheryl Filby, Christy Hendrikson, Janna Kieffer, Mary Finch, Dave Melmer, Michael Perry

Project Administration: Charles Hathaway, Ruth Lovsted Design, Editing, Report Production: Yvonne Huffman, Karen Kaul, Suzanne Johnson, Anita

Dickson, Tanya Roberts

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Detailed Assessment of Phosphorus Sources to Minnesota Watersheds

Volume I—Table of Contents

Acknowledgements ........................................................................................................................................................i

Executive Summary...................................................................................................................................................... ii Background—The Problem with Phosphorus...................................................................................................... ii

Purpose of Assessment......................................................................................................................................... ii

Methods Used ...........................................................................................................................................vi

Categories of Findings ...................................................................................................................................... viii

Phosphorus Source Category Loadings Statewide .................................................................................viii

Phosphorus Source Category Loadings by Major Basin ...........................................................................x

Statewide Phosphorus Source Category Loadings by Flow Condition ..................................................xiii

Low Flow Conditions...............................................................................................................xiii Average Flow Conditions........................................................................................................xvii High Flow Conditions .............................................................................................................xvii

Major Basin Phosphorus Source Category Loadings by Flow Condition .............................................xvii

Concepts for Lowering Phosphorus Export from Point Sources........................................................................xxi

Lowering Phosphorus Loading Discharged to POTWs..........................................................................xxi

Overall Recommendation for Lowering Phosphorus Loads to POTWs.................................xxiii Lowering Phosphorus Loads to Surface Waters ...................................................................................xxiv

Current Effluent Phosphorus Reduction Efforts by Wastewater Treatment Plants .................xxv Concepts for Lowering Phosphorus Export from Nonpoint Sources ..............................................................xxvii

Agricultural Runoff .............................................................................................................................xxvii

Atmospheric Deposition .....................................................................................................................xxviii

Deicers ..............................................................................................................................................xxviii

Streambank Erosion............................................................................................................................xxviii

ISTS/Unsewered Communities ............................................................................................................xxix

Non-Agricultural Rural Runoff ............................................................................................................xxix

Urban Runoff.........................................................................................................................................xxx

Relative Phosphorus Source Loading Uncertainty/Recommended Refinements..............................................xxx

Overall Conclusions.........................................................................................................................................xxxi

1.0 Introduction ............................................................................................................................................................1 1.1 Background................................................................................................................................................1

1.2 Legislative Mandate to Conduct this Study ...............................................................................................2

1.3 Organization of this Report........................................................................................................................4

1.4 Frame of Reference for Quantifying Phosphorus Source Contributions to Surface Waters ......................4

1.4.1 Surface Waters Defined...............................................................................................................5

1.4.2 Context for Quantifying Phosphorus Source Contributions ........................................................7

2.0 Methods ..................................................................................................................................................................8 2.1 Basin Hydrology ........................................................................................................................................8

2.1.1 Minnesota Basins.........................................................................................................................8

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2.1.2 Calculation of Basin Runoff Volumes.........................................................................................8

2.1.2.1 River Discharge Data ...............................................................................................10 2.1.2.2 Precipitation Data .....................................................................................................10 2.1.2.3 Runoff Frequency Curves.........................................................................................11 2.1.2.4 Precipitation Frequency Curves................................................................................12 2.1.2.5 Runoff Maps.............................................................................................................12

2.2 Phosphorus Sources to POTWs and Minnesota Surface Waters..............................................................12

2.2.1 Point Sources of Phosphorus .....................................................................................................13

2.2.1.1 Data Sources for Wastewater Treatment Facilities...................................................14 2.2.1.2 Approach for Determining Phosphorus Discharged to POTWs ...............................17 2.2.1.3 Approach for Determining Phosphorus Loading to Surface Waters ........................21

2.2.2 Nonpoint Sources of Phosphorus...............................................................................................23

2.2.2.1 Agricultural Runoff ..................................................................................................24 2.2.2.1.1 Cropland and Pasture ...........................................................................24 2.2.2.1.2 Feedlot Runoff .....................................................................................36

2.2.2.2 Atmospheric Deposition...........................................................................................37 2.2.2.2.1 Dry Deposition .....................................................................................38 2.2.2.2.2 Wet Deposition.....................................................................................41

2.2.2.3 Deicing Agents .........................................................................................................42 2.2.2.4 Streambank Erosion..................................................................................................45 2.2.2.5 Individual Sewage Treatment Systems/Unsewered Communities ...........................47 2.2.2.6 Non-Agricultural Rural Runoff ................................................................................51 2.2.2.7 Urban Runoff............................................................................................................57

2.2.3 Bioavailability of Phosphorus by Source...................................................................................61

2.2.3.1 Forms of Phosphorus in the Aquatic Environment...................................................62 2.2.3.2 Bioavailable Phosphorus in POTW Effluent ............................................................63 2.2.3.3 Bioavailable Phosphorus in Runoff ..........................................................................65 2.2.3.4 Bioavailable Phosphorus in Agricultural Runoff......................................................66 2.2.3.5 Bioavailable Phosphorus in Atmospheric Deposition ..............................................68 2.2.3.6 Comparison of Phosphorus Bioavailability from Different Sources ........................69 2.2.3.7 Summary of Literature Review ................................................................................70

2.2.4 Assessment of Effluent Total Phosphorus Reduction Efforts by POTWs.................................74

3.0 Results and Discussion .........................................................................................................................................76 3.1 Basin Hydrology ......................................................................................................................................76

3.1.1 Frequency Curves ......................................................................................................................76

3.1.2 Runoff Maps ..............................................................................................................................76

3.2 Estimated Basin Total Phosphorus Amounts Contributed to POTWs and Surface Waters (by Source) .81

3.2.1 Point Sources .............................................................................................................................81

3.2.1.1 Sources and Amounts of Phosphorus Discharged to POTWs ..................................81 3.2.1.2 Phosphorus Loading to Surface Waters....................................................................87

3.2.2 Agricultural Runoff ...................................................................................................................93

3.2.2.1 Cropland and Pasture Runoff ...................................................................................93 3.2.2.2 Feedlot Runoff........................................................................................................103

3.2.3 Atmospheric Deposition ..........................................................................................................105

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3.2.4 Deicing Agents ........................................................................................................................107

3.2.5 Streambank Erosion.................................................................................................................108

3.2.6 Individual Sewage Treatment Systems/Unsewered Communities ..........................................110

3.2.7 Non-Agricultural Rural Runoff ...............................................................................................113

3.2.8 Urban Runoff...........................................................................................................................115

3.3 Summary of Phosphorus Loadings by Basin .........................................................................................117

3.3.1 Phosphorus Loadings by Source Category ..............................................................................117

3.3.2 Phosphorus Source Category Loadings by Flow Condition ....................................................121

3.4 Phosphorus Sources and Estimated Amounts Contributed to Surface Waters (by Basin, Total and Bioavailable)..........................................................................................................................................125

3.4.1 Statewide Inventory.................................................................................................................125

3.4.1.1 Dry Conditions (Low Flow) ...................................................................................125 3.4.1.2 Average Condition..................................................................................................128 3.4.1.3 Wet Condition (High Flow)....................................................................................131

3.4.2 St. Croix River Basin...............................................................................................................134


3.4.3 Upper Mississippi River Basin ................................................................................................141


3.4.4 Lower Mississippi River Basin................................................................................................151


3.4.5 Red River Basin.......................................................................................................................159


3.4.6 Rainy River Basin....................................................................................................................167


3.4.7 Lake Superior Basin ................................................................................................................175


3.4.8 Missouri River Basin ...............................................................................................................183


3.4.9 Minnesota River Basin ............................................................................................................191

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3.4.10 Cedar River Basin....................................................................................................................199


3.4.11 Des Moines River Basin ..........................................................................................................207


3.5 Comparison of Total Phosphorus Loadings from All Sources With Monitored Loadings in Minnesota and Upper Mississippi River Basins ......................................................................................................215

3.6 Effluent Total Phosphorus Reduction Efforts by Wastewater Treatment Plants ...................................217

4.0 Recommendations ..............................................................................................................................................224 4.1 Recommendations for Lowering Phosphorus and Associated Water Quality Benefits .........................224

4.1.1 Point Sources ...........................................................................................................................224

4.1.1.1 Phosphorus Loading to POTWs .............................................................................224 4.1.1.2 Phosphorus Loading to Surface Waters..................................................................227

4.1.2 Cropland and Pasture Runoff...................................................................................................227


4.1.4 Deicing Agents ........................................................................................................................229




4.1.8 Urban Runoff...........................................................................................................................231

4.2 Recommendations for Reducing Uncertainty and Error Terms in Future Refinements ........................232

4.2.1 Point Sources ...........................................................................................................................233

4.2.2 Agricultural Runoff .................................................................................................................236

4.2.2.1 Cropland and Pasture Runoff .................................................................................236 4.2.2.2 Feedlot Runoff........................................................................................................238


4.2.4 Deicing Agents ........................................................................................................................241




4.2.8 Urban Runoff...........................................................................................................................246

5.0 Overall Conclusions ...........................................................................................................................................248

References .................................................................................................................................................................251

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List of Tables

Table EX-1 Statewide phosphorus contributions of point and nonpoint sources by flow condition ............... xiv Table EX-2 Major Source Category Contributions of Total and Bioavailable Phosphorus to Each Basin and the

State, by Flow Condition........................................................................................................... xx Table EX-3 Reduction Potential for Phosphorus Loads to POTW .............................................................. xxiv Table 1-1 Minnesota River Point and Nonpoint Source Load Contributions at Various Flow Duration

Intervals...................................................................................................................................... 2 Table 2-1 Basin Characteristics................................................................................................................. 10 Table 2-2 Estimated Bioavailable Phosphorus (BAP) Fractions of Samples Collected from the Final Effluent

of Eight Minnesota POTWs....................................................................................................... 65 Table 2-3 Relative Bioavailability of Particulate Phosphorus from Various Sources to the Lower Great

Lakes ........................................................................................................................................ 70 Table 2-4 Proportion of Bioavailable Phosphorus in Total Phosphorus by Different sources ...................... 70 Table 2-5 Estimates of Bioavailable Phosphorus Fractions for Specific Source Categories......................... 72 Table 3-1 Basinwide Runoff and Precipitation .......................................................................................... 80 Table 3-2 Total Phosphorus Load Discharged to POTWs .......................................................................... 81 Table 3-3 Estimated Statewide Phosphorus Loadings to POTWs ............................................................... 85 Table 3-4 Estimated Statewide Phosphorus Loadings to Private WWTP .................................................... 85 Table 3-5 Non-Ingested Phosphorus Loadings to POTWs.......................................................................... 88 Table 3-6 Total Point Source Phosphorus Loads to Surface Waters for Each Basin and the State ............... 89 Table 3-7 Point Source Phosphorus Loads by Facility Type ...................................................................... 90 Table 3-8 Phosphorus Removal in POTWs and Privately Owned Treatment Facilities ............................... 91 Table 3-9 Phosphorus Loadings (kg/yr) to Minnesota Surface Waters from Agricultural Cropland by Major

Drainage Basin Based on an Analysis of Phosphorus Index Values in Major Watersheds ......... 100 Table 3-10 Estimated Annual Phosphorus Loadings for Outdoor Open Lot Feedlot Runoff to Surface Waters104 Table 3-11 Estimated Total Phosphorus Deposition to Minnesota Basins................................................... 106 Table 3-12 Major Basin and Statewide Total Phosphorus Loadings from Deicers for Each Snowfall Scenario107 Table 3-13 Summary of Total Phosphorus Loading Estimates (kg/yr) for Streambank Erosion................... 109 Table 3-14 Summary of Estimated Total Phosphorus Yield (kg/km2/yr) from Streambank Erosion for Average

Flow Conditions...................................................................................................................... 109 Table 3-15 Estimated Annual Phosphorus Loadings for ISTS and Unsewered Communities ...................... 112 Table 3-16 Estimated Annual Phosphorus Loadings for Non-Agricultural Rural Land Cover Types........... 114 Table 3-17 Estimated Annual Phosphorus Loadings for Incorporated Urban Areas .................................... 116 Table 3-18 Statewide phosphorus contributions of point and nonpoint sources by flow condition .............. 122 Table 3-19 Major Source Category Contributions of Total and Bioavailable Phosphorus to Each Basin and the

State, by Flow Condition......................................................................................................... 124 Table 3-20 Wastewater Treatment Plant Phosphorus Removal Summary ................................................... 223 Table 4-1 Reduction Potential for Phosphorus Loads to POTW ............................................................... 226

List of Figures

Figure EX-1 Major Basins and Surface Waters ............................................................................................... iv Figure EX-2 Annual Runoff Volumes, Average Flow Conditions (Period of Record, 1979-2002)................... vii

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Figure EX-3 Total Phosphorus Loads to Major Basin Surface Water for Average Flow Conditions ................. ix Figure EX-4aTotal Phosphorus Loads to Minnesota Surface Waters by Major Basin for Average Flow

Conditions ................................................................................................................................. xi Figure EX-4bWatershed Total Phosphorus Yields to Minnesota Surface Waters by Major Basin for Average

Flow Conditions........................................................................................................................ xii Figure EX-5 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Dry-Low

Flow Water Year....................................................................................................................... xv Figure EX-6 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Statewide: Dry-Low Flow

Water Year .............................................................................................................................. xvi Figure EX-7 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Average

Flow Water Year.................................................................................................................... xviii Figure EX-8 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Wet, High

Flow Water Year...................................................................................................................... xix Figure 1-1 Schematic for Phosphorus Source Contributions to Surface Waters.............................................. 5 Figure 1-2 Major basins w/NLCD surface waters ......................................................................................... 6 Figure 2-1 Major Basins with USGS Flow Gaging Stations .......................................................................... 9 Figure 3-1 Annual Runoff, Low Flow Conditions ....................................................................................... 77 Figure 3-2 Annual Runoff, Average Flow Conditions ................................................................................ 78 Figure 3-3 Annual Runoff, High Flow Conditions ...................................................................................... 79 Figure 3-4A Average Influent Phosphorus Loading to POTWs & Privately Owned Treatment Facilities by

Basin; less than 250,000 kg/yr................................................................................................... 83 Figure 3-4B Average Influent Phosphorus Loading to POTWs & Privately Owned Treatment Facilities by

Basin; greater than 250,000 kg/yr .............................................................................................. 84 Figure 3-5 Cropland and pasture runoff P export coefficients (kg/ha) for major drainage basins in dry,

average, and wet climatic years. ................................................................................................ 99 Figure 3-6 Cropland and pasture runoff phosphorus loads (kg/yr) exported to surface waters in major

drainage basins of Minnesota under dry, average and wet climatic conditions .......................... 101 Figure 3-7 Total Phosphorus Loads to Major Basin Surface Water for Average Flow Conditions .............. 118 Figure 3-8a Total Phosphorus Loads to Major Basin Surface Waters for Average Flow Conditions............. 119 Figure 3-8b Total Phosphorus Loads to Major Basin (Except Upper Mississippi River) Surface Waters for

Average Flow Conditions........................................................................................................ 120 Figure 3-9 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Dry, Low

Flow Water Year..................................................................................................................... 126 Figure 3-10 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Statewide: Dry, Low

Flow Water Year..................................................................................................................... 127 Figure 3-11 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Average

Flow Water Year..................................................................................................................... 129 Figure 3-12 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Statewide: Average Flow

Water Year ............................................................................................................................. 130 Figure 3-13 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Statewide: Wet, High

Flow Water Year..................................................................................................................... 132 Figure 3-14 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Statewide: Wet, High

Flow Water Year..................................................................................................................... 133 Figure 3-15 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—St. Croix River Basin:

Dry, Low Flow Water Year ..................................................................................................... 135 Figure 3-16 Estimated Bioavailable P Contributions to Minnesota Surface Waters—St. Croix River Basin:

Dry, Low Flow Water Year ..................................................................................................... 136 Figure 3-17 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—St. Croix River Basin:

Average Flow Water Year ....................................................................................................... 138

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Figure 3-18 Estimated Bioavailable P Contributions to Minnesota Surface Waters—St. Croix River Basin: Average Flow Water Year ....................................................................................................... 139

Figure 3-19 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—St. Croix River Basin: Wet, High Flow Water Year .................................................................................................... 140

Figure 3-20 Estimated Bioavailable P Contributions to Minnesota Surface Waters—St. Croix River Basin: Wet, High Flow Water Year .................................................................................................... 142

Figure 3-21 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Dry, Low Flow Water Year ................................................................................ 143

Figure 3-22 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Dry, Low Flow Water Year ......................................................................................... 144

Figure 3-23 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Average Flow Water Year .................................................................................. 146

Figure 3-24 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Average Flow Water Year ........................................................................................... 147

Figure 3-25 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Wet, High Flow Water Year ............................................................................... 149

Figure 3-26 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Upper Mississippi River Basin: Wet, High Flow Water Year ........................................................................................ 150

Figure 3-27 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Dry, Low Flow Water Year ................................................................................ 152

Figure 3-28 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Dry, Low Flow Water Year ......................................................................................... 153

Figure 3-29 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Average Flow Water Year .................................................................................. 154

Figure 3-30 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Average Flow Water Year ........................................................................................... 156

Figure 3-31 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Wet, High Flow Water Year ............................................................................... 157

Figure 3-32 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lower Mississippi River Basin: Wet, High Flow Water Year ........................................................................................ 158

Figure 3-33 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Red River Basin: Dry, Low Flow Water Year............................................................................................................. 160

Figure 3-34 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Red River Basin: Dry, Low Flow Water Year............................................................................................................. 161

Figure 3-35 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Red River Basin: Average Flow Water Year ....................................................................................................... 162

Figure 3-36 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Red River Basin: Average Flow Water Year..................................................................................................................... 164

Figure 3-37 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Red River Basin: Wet, High Flow Water Year ............................................................................................................ 165

Figure 3-38 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Red River Basin: Wet, High Flow Water Year ............................................................................................................ 166

Figure 3-39 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Rainy River Basin: Dry, Low Flow Water Year ..................................................................................................... 168

Figure 3-40 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Rainy River Basin: Dry, Low Flow Water Year............................................................................................................. 169

Figure 3-41 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Rainy River Basin: Average Flow Water Year ....................................................................................................... 170

Figure 3-42 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Rainy River Basin: Average Flow Water Year ....................................................................................................... 172

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Figure 3-43 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Rainy River Basin: Wet, High Flow Water Year .................................................................................................... 173

Figure 3-44 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Rainy River Basin: Wet, High Flow Water Year ............................................................................................................ 174

Figure 3-45 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lake Superior Basin: Dry, Low Flow Water Year ..................................................................................................... 176

Figure 3-46 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lake Superior Basin: Dry, Low Flow Water Year ..................................................................................................... 177

Figure 3-47 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lake Superior Basin: Average Flow Water Year ....................................................................................................... 178

Figure 3-48 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lake Superior Basin: Average Flow Water Year ....................................................................................................... 180

Figure 3-49 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Lake Superior Basin: Wet, High Flow Water Year .................................................................................................... 181

Figure 3-50 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Lake Superior Basin: Wet, High Flow Water Year .................................................................................................... 182

Figure 3-51 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Missouri River Basin: Dry, Low Flow Water Year ..................................................................................................... 184

Figure 3-52 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Missouri River Basin: Dry, Low Flow Water Year ..................................................................................................... 185

Figure 3-53 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Missouri River Basin: Average Flow Water Year ....................................................................................................... 186

Figure 3-54 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Missouri River Basin: Average Flow Water Year ....................................................................................................... 188

Figure 3-55 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Missouri River Basin: Wet, High Flow Water Year .................................................................................................... 189

Figure 3-56 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Missouri River Basin: Wet, High Flow Water Year .................................................................................................... 190

Figure 3-57 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Minnesota River Basin: Dry, Low Flow Water Year ..................................................................................................... 192

Figure 3-58 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Minnesota River Basin: Dry, Low Flow Water Year ..................................................................................................... 193

Figure 3-59 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Minnesota River Basin: Average Flow Water Year ....................................................................................................... 194

Figure 3-60 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Minnesota River Basin: Average Flow Water Year ....................................................................................................... 196

Figure 3-61 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Minnesota River Basin: Wet, High Flow Water Year .................................................................................................... 197

Figure 3-62 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Minnesota River Basin: Wet, High Flow Water Year .................................................................................................... 198

Figure 3-63 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Cedar River Basin: Dry, Low Flow Water Year ..................................................................................................... 200

Figure 3-64 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Cedar River Basin: Dry, Low Flow Water Year............................................................................................................. 201

Figure 3-65 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Cedar River Basin: Average Flow Water Year ....................................................................................................... 202

Figure 3-66 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Cedar River Basin: Average Flow Water Year ....................................................................................................... 204

Figure 3-67 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Cedar River Basin: Wet, High Flow Water Year .................................................................................................... 205

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Figure 3-68 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Cedar River Basin: Wet, High Flow Water Year ............................................................................................................ 206

Figure 3-69 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Des Moines River Basin: Dry, Low Flow Water Year ......................................................................................... 208

Figure 3-70 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Des Moines River Basin: Dry, Low Flow Water Year ..................................................................................................... 209

Figure 3-71 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Des Moines River Basin: Average Flow Water Year ........................................................................................... 210

Figure 3-72 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Des Moines River Basin: Average Flow Water Year ....................................................................................................... 212

Figure 3-73 Estimated Total Phosphorus Contributions to Minnesota Surface Waters—Des Moines River Basin: Wet, High Flow Water Year ........................................................................................ 213

Figure 3-74 Estimated Bioavailable P Contributions to Minnesota Surface Waters—Des Moines River Basin: Wet, High Flow Water Year .................................................................................................... 214

Volume II—List of Appendices

Appendix A Basin Hydrology Technical Memorandum

Appendix B Point Sources Technical Memorandum

Appendix C Cropland and Pasture Runoff Technical Paper

Appendix D Feedlot Runoff Technical Memorandum

Appendix E Atmospheric Deposition Technical Memorandum

Appendix F Deicing Agents Technical Memorandum

Appendix G Streambank Erosion Technical Memorandum

Appendix H Individual Sewage Treatment Systems (ISTS)/Unsewered Communities Technical Memorandum

Appendix I Non-Agricultural Rural Runoff Technical Memorandum

Appendix J Urban Runoff Technical Memorandum

Appendix K Bioavailable Phosphorus Technical Memorandum

Appendix L Effluent Total Phosphorus Reduction Efforts by WWTPs Technical Memorandum

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