National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Theodore Roosevelt National Park

Natural Resource Condition Assessment

Natural Resource Report NPS/THRO/NRR—2014/776
ON THE COVER

River Bend Overlook in the North Unit of Theodore Roosevelt National Park

Photograph by: (Shannon Amberg, SMUMN GSS) 
Theodore Roosevelt National Park

Natural Resource Condition Assessment

Natural Resource Report NPS/THRO/NRR—2014/776

Shannon Amberg

Kathy Kilkus

Mike Komp

Andy Nadeau

Kevin Stark

Lindsey Danielson

Sarah Gardner

Eric Iverson

Eric Norton

Barry Drazkowski

GeoSpatial Services 

Saint Mary’s University of Minnesota 

700 Terrace Heights, Box #7

Winona, Minnesota 55987

February 2014

U.S. Department of the Interior

National Park Service

Natural Resource Stewardship and Science 

Fort Collins, Colorado
ii

The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, 

Colorado, publishes a range of reports that address natural resource topics. These reports are 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 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 U.S. Government.

This report is available from the Northern Great Plains Inventory and Monitoring Network and 

the Natural Resource Publications Management website 

(http://www.nature.nps.gov/publications/nrpm/). To receive this report in a format optimized for 

screen readers, please email irma@nps.gov.

Please cite this publication as:

Amberg, S., K. Kilkus, M. Komp, A. Nadeau, K. Stark, L. Danielson, S. Gardner, E. Iverson, E. 

Norton, and B. Drazkowski. 2014. Theodore Roosevelt: National Park: Natural resource 

condition assessment. Natural Resource Report NPS/THRO/NRR—2014/776. National Park 

Service, Fort Collins, Colorado.

NPS 387/123911, February 2014
iii

Contents 

Page

Figures............................................................................................................................................ xi

Figures (continued)....................................................................................................................... xii

Figures (continued)...................................................................................................................... xiii

Tables............................................................................................................................................ xv

Tables (continued) ....................................................................................................................... xvi

Plates........................................................................................................................................... xvii

Photos........................................................................................................................................... xix

Photos (continued) ........................................................................................................................ xx

Appendices................................................................................................................................... xxi

Acronyms and Abbreviations .................................................................................................... xxiii

Acknowledgments....................................................................................................................... xxv

Executive Summary.................................................................................................................. xxvii

Chapter 1 NRCA Background Information .................................................................................... 1

Chapter 2 Introduction and Resource Setting ................................................................................. 5

2.1 Introduction........................................................................................................................ 5

2.1.1 Enabling Legislation .................................................................................................. 5

2.1.2 Geographic Setting..................................................................................................... 5

2.1.3 Visitation Statistics.................................................................................................... 7

2.2 Natural Resources.............................................................................................................. 7

2.2.1 Ecological Units and Watersheds .............................................................................. 7

2.2.2 Resource Descriptions ............................................................................................... 7

2.2.3. Resource Issues Overview ........................................................................................ 8

2.3 Resource Stewardship...................................................................................................... 11

2.3.1 Management Directives and Planning Guidance..................................................... 11

2.3.2 Status of Supporting Science ................................................................................... 15

2.4 Literature Cited................................................................................................................ 16

Chapter 3 Study Scoping and Design ........................................................................................... 19
iv

Contents (continued)

Page

3.1 Preliminary scoping ......................................................................................................... 19

3.2 Study Design.................................................................................................................... 20

3.2.1 Indicator Framework, Focal Study Resources and Indicators ................................. 20

3.2.2 General Approach and Methods .............................................................................. 24

3.3 Literature Cited................................................................................................................ 29

Chapter 4 Natural Resource Conditions ....................................................................................... 31

4.1 Fire................................................................................................................................... 32

4.1.1 Description............................................................................................................... 32

4.1.2 Measures.................................................................................................................. 32

4.1.3 Reference Conditions/Values................................................................................... 33

4.1.4 Data and Methods.................................................................................................... 34

4.1.5 Current Condition and Trend ................................................................................... 34

4.1.6 Sources of Expertise ................................................................................................ 49

4.1.7 Literature Cited ........................................................................................................ 50

4.2 Wind and Water Erosion ................................................................................................. 52

4.2.1 Description............................................................................................................... 52

4.2.2 Measures.................................................................................................................. 53

4.2.3 Reference Conditions/Values................................................................................... 53

4.2.4 Data and Methods.................................................................................................... 53

4.2.5 Current Condition and Trend ................................................................................... 54

4.2.6 Sources of Expertise ................................................................................................ 55

4.2.7 Literature Cited ........................................................................................................ 56

4.3 Flooding (Little Missouri River) ..................................................................................... 58

4.3.1 Description............................................................................................................... 58

4.3.2 Measures.................................................................................................................. 58

4.3.3 Reference Conditions/Values................................................................................... 59

4.3.4 Data and Methods.................................................................................................... 59
v

Contents (continued)

Page

4.3.5 Current Condition and Trend ................................................................................... 59

4.3.6 Sources of Expertise ................................................................................................ 65

4.3.7 Literature Cited ........................................................................................................ 66

4.4 Native Grasslands............................................................................................................ 68

4.4.1 Description............................................................................................................... 68

4.4.2 Measures.................................................................................................................. 68

4.4.3 Reference Conditions/Values................................................................................... 69

4.4.4 Data and Methods.................................................................................................... 69

4.4.5 Current Condition and Trend ................................................................................... 69

4.6.1 Sources of Expertise ................................................................................................ 74

4.7.1 Literature Cited ........................................................................................................ 75

4.5 Juniper Forests................................................................................................................. 82

4.5.1 Description............................................................................................................... 82

4.5.2 Measures.................................................................................................................. 82

4.5.3 Reference Conditions/Values................................................................................... 82

4.5.4 Data and Methods.................................................................................................... 82

4.5.5 Current Condition and Trend ................................................................................... 83

4.5.6 Sources of Expertise ................................................................................................ 85

4.5.7 Literature Cited ........................................................................................................ 86

4.6 Floodplain Woodlands..................................................................................................... 90

4.6.1 Description............................................................................................................... 90

4.6.2 Measures.................................................................................................................. 91

4.6.3 Reference Conditions/Values................................................................................... 91

4.6.4 Data and Methods.................................................................................................... 92

4.6.5 Current Condition and Trend ................................................................................... 93

4.6.6 Sources of Expertise .............................................................................................. 105

4.6.7 Literature Cited ...................................................................................................... 106
vi

Contents (continued)

Page

4.7 Woody Draws................................................................................................................ 111

4.7.1 Description............................................................................................................. 111

4.7.2 Measures................................................................................................................ 111

4.7.3 Reference Conditions/Values................................................................................. 111

4.7.4 Data and Methods.................................................................................................. 111

4.7.5 Current Condition and Trend................................................................................. 112

4.7.6 Sources of Expertise .............................................................................................. 115

4.7.7Literature Cited ....................................................................................................... 116

4.8 Upland Shrubland Communities.................................................................................... 121

4.8.1 Description............................................................................................................. 121

4.8.2 Measures................................................................................................................ 121

4.8.3 Reference Conditions/Values................................................................................. 121

4.8.4 Data and Methods.................................................................................................. 122

4.8.5 Current Condition and Trend ................................................................................. 122

4.8.6 Sources of Expertise .............................................................................................. 127

4.8.7 Literature Cited ...................................................................................................... 128

4.9 Aquatic Communities.................................................................................................... 132

4.9.1 Description............................................................................................................. 132

4.9.2 Measures................................................................................................................ 132

4.9.3 Reference Conditions/Values................................................................................. 132

4.9.4 Data and Methods.................................................................................................. 132

4.9.5 Current Condition and Trend ................................................................................. 133

4.9.6 Sources of Expertise .............................................................................................. 136

4.9.7 Literature Cited ...................................................................................................... 137

4.10 Prairie Dogs................................................................................................................. 138

4.10.1 Description........................................................................................................... 138

4.10.2 Measures.............................................................................................................. 138
vii

Contents (continued)

Page

4.10.3 Reference Conditions/Values............................................................................... 138

4.10.4 Data and Methods................................................................................................ 138

4.10.5 Current Condition and Trend............................................................................... 138

4.10.6 Sources of Expertise ............................................................................................ 141

4.10.7 Literature Cited .................................................................................................... 142

4.11 Breeding Birds............................................................................................................. 145

4.11.1 Description........................................................................................................... 145

4.11.2 Measures.............................................................................................................. 145

4.11.3 Reference Conditions/Values............................................................................... 145

4.11.4 Data and Methods................................................................................................ 145

4.11.5 Current Condition and Trend ............................................................................... 148

4.11.6 Sources of Expertise ............................................................................................ 157

4.11.7 Literature Cited .................................................................................................... 158

4.12 Air Quality................................................................................................................... 162

4.12.1 Description........................................................................................................... 162

4.12.2 Measures.............................................................................................................. 162

4.12.3 Reference Conditions/Values............................................................................... 164

4.12.4 Data and Methods................................................................................................ 164

4.12.5 Current Condition and Trend ............................................................................... 166

4.12.6 Sources of Expertise ............................................................................................ 178

4.12.7 Literature Cited .................................................................................................... 179

4.13 Water Quality............................................................................................................... 182

4.13.1 Description........................................................................................................... 182

4.13.2 Measures.............................................................................................................. 182

4.13.3 Reference Conditions/Values............................................................................... 184

4.13.4 Data and Methods................................................................................................ 184

4.13.5 Current Condition and Trend ............................................................................... 187
viii

Contents (continued)

Page

4.13.6 Sources of Expertise ............................................................................................ 197

4.13.7 Literature Cited .................................................................................................... 198

4.14 Soundscape .................................................................................................................. 200

4.14.1 Description........................................................................................................... 200

4.14.2 Measures.............................................................................................................. 200

4.14.3 Reference Conditions/Values............................................................................... 200

4.14.4 Data and Methods................................................................................................ 200

4.14.5 Current Condition and Trend ............................................................................... 200

4.14.6 Sources of Expertise ............................................................................................ 202

4.14.7 Literature Cited .................................................................................................... 203

4.15 Dark Night Skies.......................................................................................................... 204

4.15.1 Description........................................................................................................... 204

4.15.2 Measures.............................................................................................................. 204

4.15.3 Reference Conditions/Values............................................................................... 204

4.15.4 Data and Methods................................................................................................ 204

4.15.5 Current Condition and Trend ............................................................................... 204

4.15.6 Sources of Expertise ............................................................................................ 206

4.15.7 Literature Cited .................................................................................................... 207

4.16 Surface Water Availability .......................................................................................... 208

4.16.1 Description........................................................................................................... 208

4.16.2 Measures.............................................................................................................. 208

4.16.3 Reference Conditions/Values............................................................................... 208

4.16.4 Data and Methods................................................................................................ 208

4.16.5 Current Condition and Trend ............................................................................... 209

4.16.6 Sources of Expertise ............................................................................................ 215

4.16.7 Literature Cited .................................................................................................... 216

4.17 Paleontological Features.............................................................................................. 220
ix

Contents (continued)

Page

4.17.1 Description........................................................................................................... 220

4.17.2 Measures.............................................................................................................. 221

4.17.3 Reference Conditions/Values............................................................................... 221

4.17.4 Data and Methods................................................................................................ 221

4.17.5 Current Condition and Trend ............................................................................... 221

4.17.6 Sources of Expertise ............................................................................................ 225

4.17.7 Literature Cited .................................................................................................... 226

Chapter 5 Discussion .................................................................................................................. 229

5.1 Component Data Gaps................................................................................................... 229

5.2 Component Condition Designations.............................................................................. 232

5.3 Park-wide Condition Observations................................................................................ 234

Appendices.................................................................................................................................. 239

xi

Figures

Page

Figure 1. Symbols used for individual component assessments with condition or 

concern designations along the vertical axis and trend designations along the 

horizontal ...................................................................................................................................... 26

Figure 2. Pre-burn and post-burn percent cover of native and non-native plant species 

(average of 15 monitoring plots)................................................................................................... 44

Figure 3. Southeast Corner burn unit changes in percent cover by life form following 

multi-year, multi-burn, prescribed fire treatments in THRO........................................................ 45

Figure 4. Northwest Corner burn unit changes in percent cover by life form following 

multi-year, multi-treatments (fires) in THRO............................................................................... 46

Figure 5. Shrub density changes post-fire in the Little Missouri burn unit. ................................ 46

Figure 8. Peak discharge (cfs) for the Little Missouri River near Watford City, ND 

(USGS Station No. 06337000) from 1935-2010 .......................................................................... 61

Figure 10. Peak discharge (cfs) for the Little Missouri River at Medora, ND from 

1904-2010 (USGS Station No. 06336000)................................................................................... 62

Figure 12. Snow water equivalent averages from 1971-2000 and 2001-2009 at Cole 

Canyon, Sundance, Wyoming....................................................................................................... 63

Figure 13. Age map of valley floor.............................................................................................. 97

Figure 14. Relative composition of woodland and shrubland floodplain area in 

THRO............................................................................................................................................ 99

Figure 15. Highest recorded peak discharges and recent (2011) peak discharge from 

the USGS gage (06336000) at Medora, ND. .............................................................................. 102

Figure 16. Highest recorded peak stage heights and recent (2011) gage height at the 

USGS gage (06336000) at Medora, ND. .................................................................................... 102

Figure 17. Total acres of prairie dog colonies in THRO, 1984-2011 ........................................ 139

Figure 18. Total acres of prairie dog colonies in the South Unit of THRO, 1997-2011 ........... 139

Figure 19. Total acres of prairie dog colonies in the North Unit of THRO, 1997-2011 ........... 140

Figure 20. Bird Conservation Regions through North America. THRO lies within 

BCR 17........................................................................................................................................ 147

Figure 21. Example of a grid cell created by the RMBO using the IMBCR design.................. 148

Figure 22. Species richness estimates from the annual BBS route in THRO............................ 149

Figure 23. Species richness for IMBCR surveys in both LMNG (16 grids or 

transects) and THRO (two grids or transects) from 2009-2011. ................................................ 150
xii

Figures (continued)

Page

Figure 24. Raptor species richness estimates from the annual BBS route in THRO 

from 1982-2009. The solid red line indicates the 28-year average (three species) for 

the survey.................................................................................................................................... 154

Figure 25. Annual average precipitation-weighted concentrations of nitrate (NO3), 

sulfate (SO4), and ammonium (NH4) (mg/L) in THRO, 2000-2010 (NADP 

monitoring site ND00)................................................................................................................ 167

Figure 26. Composition of nitrogen deposition in THRO, 2007-2009 (Monitoring 

station THRO422)....................................................................................................................... 168

Figure 27. Composition of sulfur deposition in THRO, 2007-2009 (Monitoring 

station THRO422)....................................................................................................................... 169

Figure 28. Average annual ozone (O3) concentration (ppm) for the South Unit of 

THRO, 1999-2010 ...................................................................................................................... 170

Figure 29. Average annual ozone (O3) concentration (ppm) for the North Unit of 

THRO, 1990-2010 ...................................................................................................................... 171

Figure 30. Total mercury deposition near THRO, 2010............................................................ 172

Figure 31. Total mercury concentration near THRO, 2010....................................................... 173

Figure 32. Average annual particulate matter concentration (PM2.5 and PM10) in 

THRO, 2001-2010 ...................................................................................................................... 174

Figure 33. Visibility (in dv) on the 20% clearest and 20% haziest days in THRO, 

2001-2010 ................................................................................................................................... 175

Figure 34. Water monitoring locations in the North Unit of THRO and near the 

Elkhorn Ranch. ........................................................................................................................... 185

Figure 35. Water monitoring locations in and around the South Unit of THRO....................... 186

Figure 36. Mean annual dissolved oxygen concentrations (in mg/L) recorded at two 

monitoring stations on the Little Missouri River in the North and South Units of 

THRO, 1996-2011 ...................................................................................................................... 188

Figure 37. Mean annual fecal coliform concentrations (in CFU/100 mL) recorded at 

two monitoring stations in the Little Missouri River in the North and South Units of 

THRO, 1996-2009 ...................................................................................................................... 190

Figure 38. Mean annual pH (in Standard Units) recorded at two monitoring stations 

on the Little Missouri River in the North and South Units of THRO, 1996-2011 ..................... 192

Figure 39. Mean annual specific conductance (in μs/cm) in the Little Missouri River 

in the North and South Units of THRO, 1996-2011................................................................... 193
xiii

Figures (continued)

Page

Figure 40. Monthly average precipitation at Medora, North Dakota per decade from 

1950-2009 ................................................................................................................................... 209

Figure 41. Monthly average precipitation at Watford City, North Dakota per decade 

from 1920-2010 .......................................................................................................................... 210

Figure 42. Diagram of a typical spring or seep fed water development in THRO .................... 211

Figure 43. Schematic stratigraphic column of rock formations in THRO................................. 220

Figure 44. Symbols used for individual component assessments with condition or 

concern designations along the vertical axis and trend designations along the 

horizontal .................................................................................................................................... 234

xv

Tables 

Page

Table 1. Monthly temperature and precipitation normals (1948-2010) for THRO ....................... 7

Table 2. NGPN Vital Signs selected for monitoring in THRO.................................................... 15

Table 3. THRO natural resource condition assessment framework............................................. 22

Table 4. Scale of measure significance used in determining overall condition. .......................... 24

Table 5. Scale used in determining condition level of individual measures. ............................... 25

Table 6. Number of fires and area burned in THRO by origin and park unit (1984 to 

2010) ............................................................................................................................................. 35

Table 7. Burn severity for the Little Missouri II and Southeast Corner fires .............................. 36

Table 8. Lightning-caused fire numbers and area by decade in THRO....................................... 37

Table 9. Number of fires by month for fires ≥ one acre and those ≥ 10 acres in THRO............. 39

Table 10. Prescribed fire dates, season, and area burned in THRO............................................. 41

Table 11. Flood discharges for the Little Missouri River and tributaries in THRO. 

Discharges in cfs; maximum water-surface elevations are in feet above sea level (asl) .............. 60

Table 12. Native grassland communities of THRO ..................................................................... 68

Table 13. The native grasslands of THRO and the most abundant species in each 

community, as surveyed by Von Loh et al. (2000)....................................................................... 70

Table 14. Area (in hectares) covered by native grasslands in THRO.......................................... 71

Table 15. Non-native species documented in THRO grasslands................................................. 72

Table 16. Tree densities for THRO juniper stands sampled in 1960 ........................................... 84

Table 17. Map unit descriptions and NVCS associations related to floodplain 

woodlands in THRO ..................................................................................................................... 91

Table 18. Abundant species in floodplain shrubland and woodlands of THRO.......................... 93

Table 19. Floodplain shrubland and woodland area and percent composition for each 

THRO unit .................................................................................................................................... 95

Table 20. Non-native plants documented in THRO woody draws in 1992-1993, with 

mean percent cover and quadrat frequencies. ............................................................................. 113

Table 21. Upland shrubland communities of THRO. ................................................................ 121

Table 22. The upland shrub communities of THRO and the most abundant species in 

each community, as surveyed by Von Loh et al. (2000). ........................................................... 124

Table 23. Area (in hectares) covered by shrublands in THRO .................................................. 125
xvi

Tables (continued)

Page

Table 24. Fish species documented in a 1950 survey of the Little Missouri River ................... 133

Table 25. Certified species list for fish in THRO ...................................................................... 134

Table 26. Species of conservation concern observed during the THRO BBS from 

1982-2009. .................................................................................................................................. 151

Table 27. Species of conservation concern observed during the Powell (2000) bird 

survey in 1999............................................................................................................................. 152

Table 28. Species of conservation concern observed during the IMBCR bird 

monitoring in THRO from 2009-2011........................................................................................ 153

Table 29. Raptor species observed on the THRO BBS from 1982-2009. ................................. 153

Table 30. Number of individual raptors observed from 2009-2011 during IMBCR 

surveys in THRO. ....................................................................................................................... 154

Table 31. National Park Service Air Resources Division air quality index values.................... 164

Table 32. Plant and tree species of THRO with high or moderate sensitivities to 

sulfates and ozone ....................................................................................................................... 176

Table 33. North Dakota water quality standards........................................................................ 184

Table 34. Flow rates (in gallons per minute) from man-made water developments in 

THRO over time ......................................................................................................................... 213

Table 35. Fossils at Theodore Roosevelt National Park ............................................................ 222

Table 36. Identified data gaps or needs for the featured components........................................ 230

Table 37. Identified data gaps or needs for the featured components. (continued) ................... 231

Table 38. Summary of current condition and condition trend for featured NRCA 

components. ................................................................................................................................ 232

Table 39. Summary of current condition and condition trend for featured NRCA 

components. (continued)............................................................................................................. 233
xvii

Plates

Page

Plate 1. Native grassland alliances in the North Unit of THRO. ................................................. 77

Plate 2. Native grassland alliances in the South Unit of THRO. ................................................. 78

Plate 3. Native grassland alliances in the Elkhorn Ranch Unit of THRO.................................... 79

Plate 4. The introduced grassland alliance in the North Unit of THRO. ..................................... 80

Plate 5. The introduced grassland alliance in the South Unit of THRO. ..................................... 81

Plate 6. Rocky Mountain Juniper Alliance in the North Unit of THRO...................................... 87

Plate 7. Rocky Mountain Juniper Alliance in the South Unit of THRO...................................... 88

Plate 8. Rocky Mountain Juniper Alliance in the Elkhorn Ranch Unit of THRO....................... 89

Plate 9. Floodplain woodlands in the North Unit of THRO....................................................... 108

Plate 10. Floodplain woodlands in the South Unit of THRO..................................................... 109

Plate 11. Floodplain woodlands in the Elkhorn Ranch Unit of THRO...................................... 110

Plate 12. Green Ash-American Elm Woodland Alliance distribution in the North Unit 

of THRO ..................................................................................................................................... 118

Plate 13. Green Ash-American Elm Woodland Alliance distribution in the South Unit 

of THRO. .................................................................................................................................... 119

Plate 14. Green Ash-American Elm Woodland Alliance distribution in the Elkhorn 

Ranch Unit of THRO.................................................................................................................. 120

Plate 15. Shrubland alliances in the North Unit of THRO......................................................... 129

Plate 16. Shrubland alliances in the South Unit of THRO......................................................... 130

Plate 17. Shrubland alliances in the Elkhorn Ranch Unit of THRO. ......................................... 131

Plate 18. Prairie dog colony extent, South Unit,1984 and 2009. ............................................... 143

Plate 19. Prairie dog colony extent, North Unit, 1997 and 2009. .............................................. 144

Plate 20. Breeding Bird Survey route 64033 in the North Unit of THRO................................. 160

Plate 21. IMBCR points sampled in the South Unit of THRO 2009-2011................................ 161

Plate 22. Known spring and seep locations in the North Unit of THRO. .................................. 218

Plate 23. Known spring, seep, and well locations in the South Unit of THRO. ........................ 219

xix

Photos

Page

Photo 1. River Bend Overlook, North Unit of THRO ................................................................... 5

Photo 2. Concretion formations in the North Unit of THRO......................................................... 6

Photo 3. Plains bison in THRO. ..................................................................................................... 8

Photo 4. Bull elk with cows in THRO ........................................................................................... 9

Photo 5. Feral horses in the South Unit of the THRO.................................................................. 10

Photo 6. Firefighters igniting a prescribed fire in THRO ............................................................ 32

Photo 7. A small landslide in Sentinel Butte strata and a large rotational slump in the 

North Unit ..................................................................................................................................... 53

Photo 8. Record flooding on the Little Missouri River in May 2011 as viewed from 

the MP 27 loop road in the South Unit, THRO ............................................................................ 58

Photo 9. Flooding on the Little Missouri in May 2011 as viewed from the Medora 

Overlook in the South Unit, THRO.............................................................................................. 59

Photo 10. Native grassland in the Peaceful Valley in THRO ...................................................... 68

Photo 11. Rocky Mountain juniper in THRO .............................................................................. 82

Photo 12. Juniper forests in the North Unit of THRO ................................................................. 83

Photo 13. Floodplain woodlands along the Little Missouri River in the North Unit of 

THRO............................................................................................................................................ 90

Photo 14. Understory view of a cottonwood woodland in the North Unit of THRO .................. 91

Photo 15. Woody draw in THRO dominated by green ash with some juniper 

encroachment .............................................................................................................................. 111

Photo 16. Sagebrush on an upland slope in THRO.................................................................... 121

Photo 17. Bison grazing in an upland shrubland habitat dominated by sagebrush.................... 122

Photo 18. Longnose dace (Rhinichthys cataractae)................................................................... 132

Photo 19. Black-tailed prairie dog (Cynomys ludovicianus)...................................................... 138

Photo 20. Pine siskin (Carduelis pinus)..................................................................................... 145

Photo 21. Chokecherry (Prunus virginiana).............................................................................. 171

Photo 22. Little Missouri River at Juniper Campground in the North Unit of THRO............... 182

Photo 23. Wannagan Seeps in THRO’s South Unit................................................................... 208

Photo 24. Collection tank at Tomamichael Well ....................................................................... 210
xx

Photos (continued)

Page

Photo 25. Non-functional water developments at Sheep Pasture Spring in the South 

Unit’s wilderness area................................................................................................................. 212

Photo 26. Fossils from the Sentinel Butte Formation: A leaf, a crocodile scute and 

tooth, and petrified wood ............................................................................................................ 222
xxi

Appendices

Page

Appendix A: Fire History in THRO, 1946 to 2010 ................................................................... 241

Appendix B: Peak Flow Data for the Little Missouri River at Medora, ND............................. 245

Appendix C: Peak Flow Data for the Little Missouri River at Watford City, ND.................... 248

Appendix D: Non-native Plant Species Documented in THRO................................................ 251

xxiii

Acronyms and Abbreviations 

BBS – Breeding Bird Survey

BCR – Bird Conservation Region

CCC – Civilian Conservation Corps

dNBR – Differenced Normalized Burn Ratio

EAB – Emerald Ash Borer

EPA – Environmental Protection Agency

EPMT – Exotic Plant Management Team

FMP – Fire Management Plan

GIS – Geographic Information System

GPRA – Government Performance and Results Act

IMBCR – Integrated Monitoring in Bird Conservation Regions

IRMA – Integration of Resource Management Applications

LMNG – Little Missouri National Grassland

NGPN – Northern Great Plains Inventory and Monitoring Network

NPS – National Park Service

NRCA – Natural Resource Condition Assessment

RMBO – Rocky Mountain Bird Observatory

SMUMN GSS – Saint Mary’s University of Minnesota GeoSpatial Services

SWE – Snow Water Equivalent

THRO – Theodore Roosevelt National Park

USFS – United Stated Forest Service

USGS – United States Geological Survey

WCS – Weighted Condition Score

WICA – Wind Cave National Park
xxiv

WNDD – Wyoming Natural Diversity Database
xxv

Acknowledgments

We acknowledge Theodore Roosevelt National Park staff for the technical expertise provided 

during scoping, through multiple stages of review, and via phone and email; specifically, Chad 

Sexton, Laurie Richardson, Mike Oehler, Rod Skalsky, Bill Whitworth, and Valerie Naylor. 

Northern Great Plains Inventory and Monitoring Network staff, including Kara Paintner-Green, 

Stephen Wilson, Marcia Wilson, Isabel Ashton, and Michael Prowatzke provided logistical 

insight and critical review of interim documents. Ellen Porter of the NPS - Air Resources 

Division, provided review of the air quality component. Dan Swanson provided insight and 

review of the fire document. Rachel Benton, geologist at Badlands National Park, and John 

Hoganson, North Dakota State Paleontologist, provided insight and review of the paleontological 

features document. Jeff Birek, biologist with the Rocky Mountain Bird Observatory, provided 

review of the breeding bird document. We also acknowledge Lusha Tronstad, Jonathan 

Friedman, Jeff Hughes, Joe Zeleznik, Steven Kelsch, and Eleanor Griffin, who were willing to 

discuss specific resources and provide insight when asked. Carmen Thomson, NPS Midwest 

Region Inventory and Monitoring Coordinator, helped with project implementation. Jeff 

Albright, Natural Resource Condition Assessment Coordinator, provided program guidance. 

Thank you to all others who assisted the development of this document.

xxvii

Executive Summary

The Natural Resource Condition Assessment (NRCA) Program aims to provide documentation 

about the current conditions of important park natural resources through a spatially explicit, 

multi-disciplinary synthesis of existing scientific data and knowledge. Findings from the NRCA, 

including the report and accompanying map products, will help THRO managers to develop 

near-term management priorities; engage in watershed or landscape scale partnership and 

education efforts; conduct park planning (e.g., Resource Stewardship Strategy); and report 

program performance (e.g., Department of the Interior’s Strategic Plan “land health” goals, 

Government Performance and Results Act).

The objectives of this assessment are to evaluate and report on current conditions of key park 

resources, to evaluate critical data and knowledge gaps, and to highlight selected existing 

stressors and emerging threats to resources or processes. For the purpose of this NRCA, staff 

from the National Park Service (NPS) and Saint Mary’s University of Minnesota – GeoSpatial 

Services (SMUMN GSS) identified key resources, referred to as “components” in the project. 

The selected components include natural resources and processes that are currently of the 

greatest concern to park management at THRO. The final project framework contains 17 

resource components, each featuring discussions of measures, stressors, and reference 

conditions. 

This study involved examining exisiting literature and short- or long-term datasets, as well as 

expertise from NPS and other outside agency or organization scientists to provide summaries of 

current condition and trends in featured resources. When possible, existing data for the 

established measures of each component is compared to designated reference conditions. A

weighted scoring system was applied to calculate the current condition of the components. 

Weighted condition scores, ranging from zero to one, were divided into three categories of 

condition: low concern, moderate concern, and significant concern. These weighted condition 

scores help determine the overall current condition of each resource. The discussions for each 

component, found in Chapter 4 of this report, represent a comprehensive summary of current 

available data and information for these resources, as well as unpublished park information and 

perspectives of park resource managers, and present a current condition designation when 

appropriate. Each component assessment was subjected to review by THRO park resource 

managers and NPS Northern Great Plains Network Inventory and Monitoring specialists.

In a number of cases, data are unavailable or insufficient for many of the measures of the 

featured components in this assessment. In other instances, data that establishes reference 

condition were limited or unavailable for components, making comparisons with current 

information inappropriate or invalid. Thus, in these cases, it was not possible to assign condition 

for these components. Current condition was not able to be determined for 10 of the 17 

components (58%) due to these significant data gaps. 

For those components with more available data, the overall conditions assigned varied. For some 

components, enough data exist to determine a trend in condition over time; however, for others 

the lack of long-term or comparable data prevented the determination of trends. Several 

components were determined to be in good condition with a stable trend, including air quality, 

the prairie dog population, water quality, and fire. Flooding on the Little Missouri River in the 
xxviii

park was determined to have a condition of moderate concern but with a stable trend, meaning 

the condition is not believed to be degrading or improving from past conditions. Native 

grasslands and woody draws were also determined to be of moderate concern, but a lack of 

historical data does not allow for designating a trend in condition over time. A detailed 

discussion of these designations is presented in Chapter 5 of this report.

Several threats and stressors were identified as park-wide influences on the condition of 

resources in THRO. Those of primary concern include establishment of non-native and invasive 

species, increased oil and gas industry development, and air pollution, especially increased 

emissions from nearby oil, gas, and power plant development. 

Major changes in vegetation communities, from native to more non-native species, could have a 

significant impact on the animal species that use these communities for habitat. A more complete 

understanding of the prevalence of non-natives in the different vegetation communities 

throughout the park would help managers strategize about potential management actions.

Land development around THRO is mainly associated with the growth and expansion of the oil 

and gas industry. This development has increased exponentially in western North Dakota and 

around THRO over the last decade. Such development affects different aspects of park resources,

including impacts to viewsheds with the building of new structures that can be seen from various 

points in the park, impacts to soundscapes with increased industrial activity and vehicle traffic at 

development sites, and greater stresses to air quality from increased vehicle and industrial 

emissions. 

This assessment serves as a review and summary of available data and literature for featured 

components in the park. The information presented here may serve as a baseline against which 

any changes in condition of components in coming years may be compared. Establishing a 

number of monitoring programs would begin to fill in data gaps for the resources viewed as 

important by THRO managers and would help managers better understand the current state of 

these resources throughout the park. Of those components that had sufficient available 

information, current condition was determined to be either good or of moderate concern. 

Understanding this can help managers prioritize management objectives and better focus 

conservation strategies. 
1

Chapter 1 NRCA Background Information

Natural Resource Condition Assessments (NRCAs) evaluate current conditions for a subset of 

natural resources and resource indicators in national park units, hereafter “parks”. For these 

condition analyses they also report on trends (as possible), critical data gaps, and general level of 

confidence for study findings. The resources and indicators emphasized in the project work

depend on a park’s resource setting, status of resource stewardship planning and science in 

identifying high-priority indicators for that park, and availability of data and expertise to assess 

current conditions for the things identified on a list of potential study resources and indicators. 

NRCAs represent a relatively new approach to 

assessing and reporting on park resource 

conditions. They are meant to complement, not 

replace, traditional issue and threat-based resource 

assessments. As distinguishing characteristics, all 

NRCAs:

 are multi-disciplinary in scope1

 employ hierarchical indicator frameworks2

 identify or develop logical reference 

 conditions/values to compare current 

condition data against3,4

 emphasize spatial evaluation of conditions and GIS (map) products5

 summarize key findings by park areas6

 follow national NRCA guidelines and standards for study design and reporting products 

Although current condition reporting relative to logical forms of reference conditions and values 

is the primary objective, NRCAs also report on trends for any study indicators where the

underlying data and methods support it. Resource condition influences are also addressed. This 

can include past activities or conditions that provide a helpful context for understanding current 

 

1 However, the breadth of natural resources and number/type of indicators evaluated will vary by park. 

2 Frameworks help guide a multi-disciplinary selection of indicators and subsequent “roll up” and reporting 

of data for measures  conditions for indicators  condition reporting by broader topics and park areas. 

3 NRCAs must consider ecologically-based reference conditions, must also consider applicable legal and 

regulatory standards, and can consider other management-specified condition objectives or targets; each 

study indicator can be evaluated against one or more types of logical reference conditions.

4 Reference values can be expressed in qualitative to quantitative terms, as a single value or range of 

values; they represent desirable resource conditions or, alternatively, condition states that we wish to 

avoid or that require a follow-on response (e.g., ecological thresholds or management “triggers”).

5 As possible and appropriate, NRCAs describe condition gradients or differences across the park for 

important natural resources and study indicators through a set of GIS coverages and map products. 

6

In addition to reporting on indicator-level conditions, investigators are asked to take a bigger picture 

(more holistic) view and summarize overall findings and provide suggestions to managers on a area-byarea basis: 1) by park ecosystem/habitat types or watersheds, and 2) for other park areas as requested.

NRCAs Strive to Provide...

Credible condition reporting for 

a subset of important park 

natural resources and 

indicators

Useful condition summaries by 

broader resource categories or 

topics, and by park areas
2

park resource conditions. It also includes present-day condition influences (threats and stressors) 

that are best interpreted at park, watershed, or landscape scales, though NRCAs do not judge or 

report on condition status per se for land areas and natural resources beyond the park’s 

boundaries. Intensive cause and effect analyses of threats and stressors or development of 

detailed treatment options is outside the project scope. 

Credibility for study findings derives from the data, methods, and reference values used in the 

project work—are they appropriate for the stated purpose and adequately documented? For each 

study indicator where current condition or trend is reported it is important to identify critical data 

gaps and describe level of confidence in at least qualitative terms. Involvement of park staff and 

National Park Service (NPS) subject matter experts at critical points during the project timeline 

is also important: 1) to assist selection of study indicators; 2) to recommend study data sets, 

methods, and reference conditions and values to use; and 3) to help provide a multi-disciplinary 

review of draft study findings and products. 

NRCAs provide a useful complement to more rigorous NPS science support programs such as

the NPS Inventory and Monitoring Program. For example, NRCAs can provide current condition 

estimates and help establish reference conditions or baseline values for some of a park’s “Vital 

Signs” monitoring indicators. They can also bring in relevant non-NPS data to help evaluate 

current conditions for those same Vital Signs. In some cases, NPS inventory data sets are also 

incorporated into NRCA analyses and reporting products.

In-depth analysis of climate change effects on park natural resources is outside the project scope.

However, existing condition analyses and data sets developed by a NRCA will be useful for 

subsequent park-level climate change studies and planning efforts.

NRCAs do not establish 

management targets for study 

indicators. Decisions about 

management targets must be 

made through sanctioned 

park planning and 

management processes. 

NRCAs do provide sciencebased information that will 

help park managers with an 

ongoing, longer term effort to 

describe and quantify their 

park’s desired resource 

conditions and management 

targets. In the near term, 

NRCA findings assist 

strategic park resource 

Important NRCA Success Factors...

Obtaining good input from park and other NPS 

subjective matter experts at critical points in the 

project timeline

Using study frameworks that accommodate 

meaningful condition reporting at multiple levels 

(measures  indicators  broader resource topics 

and park areas)

Building credibility by clearly documenting the data 

and methods used, critical data gaps, and level of 

confidence for indicator-level condition findings
3

planning7and help parks report to government accountability measures8. 

Due to their modest funding, relatively quick timeframe for completion and reliance on existing 

data and information, NRCAs are not intended to be exhaustive. Study methods typically involve 

an informal synthesis of scientific data and information from multiple and diverse sources. Level 

of rigor and statistical repeatability will vary by resource or indicator, reflecting differences in 

our present data and knowledge bases across these varied study components.

NRCAs can yield new insights about current park resource conditions but in many cases their 

greatest value may be the development of useful documentation regarding known or suspected 

resource conditions within parks. Reporting products can help park managers as they think about 

near-term workload priorities, frame data and study needs for important park resources, and 

communicate messages about current park resource conditions to various audiences. A 

successful NRCA delivers science-based information that is credible and has practical uses for a 

variety of park decision-making, planning, and partnership activities.

Over the next several years, the NPS plans to fund a NRCA project for each of the ~270 parks 

served by the NPS Inventory and Monitoring Program. Additional NRCA Program information 

is posted at: http://www.nature.nps.gov/water/NRCondition_Assessment_Program/Index.cfm.

 

7 NRCAs are an especially useful lead-in to working on a park Resource Stewardship Strategy (RSS) but 

study scope can be tailored to also work well as a post-RSS project. 

8 While accountability reporting measures are subject to change, the spatial and reference-based 

condition data provided by NRCAs will be useful for most forms of “resource condition status” reporting as 

may be required by the NPS, the Department of the Interior, or the Office of Management and Budget.

NRCA Reporting Products...

Provide a credible snapshot-in-time evaluation for a subset of important 

park natural resources and indicators, to help park managers:

Direct limited staff and funding resources to park areas and natural resources 

that represent high need and/or high opportunity situations

(near-term operational planning and management)

Improve understanding and quantification for desired conditions for the park’s 

“fundamental” and “other important” natural resources and values

(longer-term strategic planning)

Communicate succinct messages regarding current resource conditions to 

government program managers, to Congress, and to the general public

(“resource condition status” reporting)

5

Chapter 2 Introduction and Resource Setting

2.1 Introduction

2.1.1 Enabling Legislation

Theodore Roosevelt National Park (THRO) consists of three separate units: North Unit, Elkhorn

Ranch, and South Unit. THRO was first protected as the Roosevelt Regional State Park in 1934, 

when the Civilian Conservation Corps (CCC) camps were sponsored by the North Dakota State 

Historical Society and the National Park System (NPS 1986). On 25 April 1947, the state park 

became Theodore Roosevelt National Memorial Park with the passage of Public Law 38 (61 

Stat. 52) (NPS 1986). The North Unit and the land west of the Little Missouri River, including 

the Elkhorn Ranch Unit, the petrified forest, and some land that was earlier designated 

“recreation demonstration area” (RDA), were added to the park in 1948 (NPS 1986). Several 

years later, on 10 November 1978, the memorial park was designated Theodore Roosevelt 

National Park by Public Law 95-625 (92 Stat. 3467) (NPS 1986).

2.1.2 Geographic Setting

THRO encompasses 28,509 hectares (70,447 acres) (NPS 2011a), making it one of the larger 

national parks in the Northern Great Plains Network (NGPN) (Gitzen et al. 2010). The park 

consists of three units, the North Unit (9,740.91 hectares [24,070.32 acres]), the South Unit 

(18,679.71 hectares [46,158.57 acres]), and the Elkhorn Unit (88.22 hectares [218 acres]) (NPS 

1986, NPS 2011a). All units are connected by the Little Missouri River (NPS 1986). The park 

contains 33.79 km of the Little Missouri River, and 432.59 km of intermittent streams (Gitzen et 

al. 2010). THRO is bordered on the south by the town of Medora, in Billings County with a 

population of 783 people (U.S. Census 2010). The Little Missouri National Grassland, managed 

by the U.S. Forest Service, are adjacent to THRO.

Photo 1. River Bend Overlook, North Unit of THRO (Photo by Shannon Amberg, SMUMN GSS, 2010).
6

The park is covered by predominantly native grassland (40%), forest (21%), barren ground 

(21%), and shrubland (14%) (Von Loh et al. 2000). However, over 400 species of plants and 

trees have been identified in the park, several of which are considered sensitive or vulnerable 

(NPS 2012a). 

THRO is a Class I airshed authorized by the Clean Air Act, and is one of the few national parks 

to maintain long-term air quality monitoring stations within the park (Gitzen et al. 2010). The 

NPS and state agencies operate some of the monitoring stations in THRO and those found in the 

NGPN (Pohlman and Maniero 2005).

The geologic features within the park were formed by river and rainfall erosion, uplift, and 

sediment deposition from the Black Hills and the Rocky Mountains (KellerLynn 2007, Tweet et 

al. 2011). The soils in the Great Plains are commonly nitrogen poor and, for a majority of the 

year, retain little moisture (Seastedt 1995).

THRO has several geological features of 

interest. Most of the park is located on the 

unglaciated Missouri Plateau, which gives 

the park its appearance (including the 

mountains, plateaus, and badland 

formations) (Trimble 1993, as cited by NPS 

2007a). The North Unit of the park has the 

“third largest concentration of petrified wood 

in the United States” (NPS 2011b, as stated 

by the superintendent, Valerie J. Naylor). 

The park’s other geological features include 

concretions and cap rocks (photo 2), glacial 

erratics, oxbows, pediments, sheet-wash 

erosion, sandstone and silcrete, and terraces 

(NPS 2007a).

THRO has a variable climate with windy 

conditions year-round (NPS 2011c). The 

park experiences warm summers with high temperatures above 30°C (86°F) (May through 

September). In the winter months (December through February), the low temperatures have been 

known to drop below -18°C (0°F). The majority of precipitation occurs from mid to late spring 

with an annual average of 37 cm (14.6 in) a year (Table 1; NPS 2011c). 

Photo 2. Concretion formations in the North Unit of 

THRO (Photo by Shannon Amberg, SMUMN GSS, 

2010).
7

Table 1. Monthly temperature and precipitation normals (1948-2010) for THRO (Station 325813, Medora, 

North Dakota) (High Plains Regional Climate Center 2011). Jan Feb Mar Apr May Jun Jul

Aug

Sep

Oct

Nov

Dec

Annual

Average Temperature (°C)

Max -2.7 1.1 6.4 14.6 21.2 26.2 30.7 30.5 23.9 16.3 6.4 -0.4 14.5

Min -16.7 -13.1 -7.8 -1.4 4.8 9.9 12.7 11.6 5.3 -0.83 -7.5 -13.9 -0.39

Average Precipitation (cm)

Total 0.9 0.9 1.6 3.3 5.8 7.9 5.3 3.4 3.4 2.4 1.3 0.9 37.4

2.1.3 Visitation Statistics

On average, THRO receives about 523,885 visitors annually, who come to participate in 

activities such as sightseeing, hiking, and camping (NPS 2011d). In 2010, the park had an annual 

visitor count of 623,748 (NPS 2011a). The park receives the majority of visitors during the 

summer months (June through August) with numbers in the 100,000s (NPS 2011a). 

2.2 Natural Resources

2.2.1 Ecological Units and Watersheds

According to Griffith (2010), THRO falls into the Northwestern Great Plains ecological region. 

This region alone has the widest latitudinal range in North America, and it is characterized by its 

semiarid climate, grasslands, lack of forests, and moderately short topographic features (CEC 

1997). The Great Plains region is habitat for an unusually large amount of sensitive, threatened, 

and endangered species (CEC 1997).

THRO is located approximately midway along the length of the Little Missouri River watershed,

which stretches from northeastern Wyoming into central North Dakota; the Little Missouri River 

flows primarily northeast from the headwaters northeastern Wyoming into North Dakota and 

terminates at the Sakakawea Reservoir in central North Dakota (Berkley et a. 1998). The Little 

Missouri River flows through nine miles of the park’s South Unit, 14 miles of the North Unit, 

forms the boundary of the Elkhorn Unit, and bisects the park’s designated wilderness (Berkley et 

al. 1998). The Little Missouri River is entirely free-flowing and represents the major surface 

water resource throughout the park (Berkley et al. 1998). 

2.2.2 Resource Descriptions

THRO is located in a grassland biome. The grasslands of the Great Plains region are also known 

as mixed prairie. Dominant plant species in the park include blue grama (Bouteloua gracilis), 

green needlegrass (Nassella viridula), western wheatgrass (Pascopyrum smithii), and needleand-thread (Hesperostipa comata) (Von Loh et al. 2000). 

The park supports 34 different species of mammal, 151 bird species, 21 fish species, and 15 

herpetofauna species (NPS 2012b). Porcupine (Erethizon dorsatum), beaver (Castor canadensis),

black-tailed prairie dogs (Cynomys ludovicianus), prairie sharptail grouse (Pedioecetes 

phasianellus), great horned owl (Bubo virginianus), and golden eagle (Aquila chrysaetos) are 

just a few mammal and bird species found in the park (NPS 1999, NPS 2012b). THRO is one of 

the few NPS-managed areas in the western United States where there is a free-roaming feral 
8

horse (Equus caballus) population (NPS 2011e). These feral horses have been found in western 

North Dakota for decades; their existence has dated back to the mid 19th century (NPS 2011e). 

THRO has a large variety of ungulate species, including bison (Bison bison), elk (Cervus 

canadensis), mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), bighorn sheep 

(Ovis canadensis), and pronghorn (Antilocapra americana) (NPS 1994, NPS 2012b). 

2.2.3. Resource Issues Overview

Air contamination is a concern for the park staff at THRO. Serious air pollutants in the region

include nitrate, sulfate, and ammonium because their levels have increased (Pohlman and 

Maniero 2005). The push to develop and obtain more gas and oil resources is the main factor 

influencing this increase in Montana, North Dakota, and Wyoming (Pohlman and Maniero 

2005). In the past, the air quality in THRO has been excellent, with the exception of a few cases, 

which were caused by wildfires and were short-lived (NPS 2008).

Several non-native plant species have become problematic in the park. These include leafy 

spurge (Euphorbia esula), yellow sweetclover (Melilotus officinalis), brome grasses (Bromus 

sp.), Canada thistle (Cirsium arvense), Kentucky bluegrass (Poa pratensis) and crested 

wheatgrass (Agropyron cristatum) (NPS 1999, 2008). The spread of exotic plant species has 

been known to alter fire regimes by increasing leaf litter layers. When applicable, THRO

managers intend to restore the fuel loads as well as the plant community and composition to 

ranges of natural variability using prescribed fires and various chemical and mechanical exotic 

plant treatment methods (NPS 2008).

Managed Species

Bison, elk, and feral horses are three intensively managed species in THRO. Fences surrounding 

each of the North and South Units of the park serve two purposes: to keep the park’s bison and 

feral horses within park boundaries, and to keep domestic cattle on surrounding lands from 

entering the park (NPS 1994). Due to the management intensity, park staff has opted not to 

assess these species as traditional components in the NRCA.

Bison

For almost 10,000 years, plains bison (Photo 

3) were a keystone element of the Great 

Plains, providing food and materials for 

Native Americans and the European settlers 

that arrived in the 18th and 19th centuries 

(NPS 2006). It is not certain how many bison 

were present in North America prior to 

European settlement, but estimates are in the 

millions (NPS 2009). Today, there are a few 

remnant wild populations in North America, 

but most populations occur in parks, 

preserves, or on private ranches. Currently 

only 11 bison herds exist in federally 

protected lands (Halbert et al. 2007). There 

are now two bison herds in THRO, one in the 

North Unit of the park and one in the South 

Photo 3. Plains bison in THRO (Photo by Shannon 

Amberg, SMUMN GSS, 2010).
9

Unit. In 2000-2001, the park estimated the bison population at 312 and 371 bison in the North 

and South Units respectively, and population estimates for 2009 were about 300 for both the 

North and South Units.

Marlow et al. (1984) determined a bison carrying capacity between 200-500 animals in the South 

Unit of THRO and 100-250 animals in the North Unit, based on factors such as potential 

droughts, overgrazing, and competition with other grazing ungulates for resources. The lack of 

natural predators and large area of available open space has forced management to implement 

culling to maintain a healthy population. Bison occasionally are exported to other national parks, 

Native American tribal lands, or zoos, or are transferred through the Inter-Tribal Bison 

Cooperative and other federal, state and non-profit entities (Dratch and Gogan 2010). A total of 

2,992 bison were removed from THRO between 1962 and 2008 (NPS 2009).

Roundups of the bison herds take place within each unit of the park every 3-5 years (NPS 2009, 

M. Oehler, pers. comm., 2011). After examination of age, weight, sex, and presence of disease, 

each animal is assigned an identification number, and the number of animals to remove is 

determined according to a forage allocation model. Genetic variability is a major management 

goal of the NPS as inbreeding can cause decreased heterozygosity, adaptive response (ability of 

herd to adapt to environmental changes), and population viability (Franklin 1980, as cited by 

Halbert et al. 2007). Monitoring and management of bison populations are expected to continue 

in THRO.

Elk

Elk (Photo 4) resided throughout the North Dakota Badlands until extirpation in the late 1800s 

(NPS 2010). In 1985, the NPS reintroduced 47 elk from Wind Cave National Park (WICA) to the 

South Unit of THRO. Following reintroduction, the elk population grew rapidly, exceeding the 

NPS-established maximum population threshold by 1993 (NPS 2010). In 2010, THRO 

developed an Elk Management Plan and 

Environmental Impact Statement to guide 

management actions of the large herd and 

mitigate negative effects on other park 

resources.

The Elk Management Plan established a 

goal of 100-400 individuals in the elk herd. 

This goal allows maintenance of the mixedgrass prairie system in a lightly grazed state 

(NPS 2010). The estimated herd population 

size in 2010 in THRO was approximately

950 individuals; at this population size, 

many different negative outcomes become 

possible. High-density elk populations often 

exhibit poor body condition and reproductive success. In addition, added stress on plant 

communities causes decreased forage availability, which in turn affects other species in the 

population’s ecosystem. The large elk population and the looming negative effects on the THRO 

ecosystem prompted action in the form of a volunteer-based elk reduction effort. 

Photo 4. Bull elk with cows in THRO (NPS Photo).
10

From October 2010 to January 2011, park staff assisted volunteers by leading them to elk and 

instructing them to harvest appropriate animals (adult cow elk). The initial reduction effort 

resulted in the removal of 406 animals from the park. In the fall of 2011, another volunteer-based 

reduction resulted in the removal of 462 animals. The park intends to monitor carefully elk 

population numbers and demographics in the future; this information then will be used to tailor 

specific reduction efforts carried out by NPS employees.

Feral Horses

Modern horses (Equus) (Photo 5) evolved on the North American continent but became extinct 

nearly 10,000 years ago around the end of the Pleistocene epoch (NPS 2011d). Horses were reintroduced to North America in the 16th century by Spanish explorers; Native Americans spread 

these animals across the continent, with horse populations eventually numbering in the thousands 

of individuals (McLaughlin 1989, NPS 2011d). The herd at THRO is a small, isolated 

population, which is comprised of descendents of local ranch stock that either escaped captivity

or were abandoned by their owners. Marlow et al. (1992) examined feral horse distribution and 

habitat use in the park and found that the herd generally isolated itself to the southeastern and 

eastern portion of the South Unit.

When THRO was established in 1947, several 

hundred horses were present in the park 

(McLaughlin 1989). Park land was used by area 

ranchers to graze their horses in the 1940s and 50s;

during this time horses were considered a trespass 

livestock and removal was a priority. The park’s 

goal was to eliminate horses from the South Unit 

(McLaughlin 1989). The decision was made in the 

late 1960s to maintain the horse population as a 

cultural demonstration herd at a maximum of about 

40 horses (NPS 1978). In 1978, the population grew 

to 65-70 horses in the fenced South Unit. Marlow et 

al. (1992) calculated a feral horse carrying capacity 

of 50 to 90 individuals for the South Unit of THRO,

as a larger population would possibly lead to 

significant decline in certain forage plant species.

The feral horse herd is managed now as a cultural 

demonstration herd to preserve the historical context 

of the horses’ presence in the park (NPS 2011d;

Oehler, pers. comm., 2011). The current target 

population size is between 50-90 individuals (NPS 

2011d). However, the herd currently numbers 135 

individuals (Oehler, pers. comm., 2011).

To guard against overpopulation, the herd is rounded up every 3-5 years, during which time 

horses are selected to be removed from the herd and sold at auction. In addition, THRO wildlife 

biologists have recently initiated field trials on a temporary contraception vaccination for females 

aged 2 years and older (Oehler, pers. comm., 2011). The park plans to continue management of 

feral horse populations in order to limit herd size.

Photo 5. Feral horses in the South Unit of

THRO (NPS photo).
11

Other Ungulates

Rocky Mountain bighorn populations are also present in the park; the park plans to restore 

bighorn population sizes, but fences for bison and feral horses may limit the bighorn to less 

suitable habitat (NPS 1994). Deer and pronghorn populations are also present; however, the 

population sizes primarily are monitored and occasionally surveyed (NPS 1994). As for the 

predatory mammal species, the park monitors these populations for vector-borne diseases (NPS 

1994).

Viewshed

A viewshed is the area that is visible from a particular location. The National Park Service 

Organic Act (16 U.S.C. l) implies the need to protect the viewsheds of National Parks, 

Monuments, and Reservations. At THRO, viewsheds are of particular importance because a 

primary reason visitors frequent the park is to view the landscape. Views from within the park 

are expansive in some areas, with NPS and non-NPS lands being the primary visible features. 

Currently, the oil and gas industry is expanding in western North Dakota, which is a cause of 

concern for the viewsheds in THRO, due to rapidly expanding industrial development.

Due to the current dynamic nature of the landscape surrounding the park, a detailed viewshed 

analysis is not appropriate for this document. The evidence of oil and gas development is 

increasing in North Dakota and this makes the viewshed from the park variable in the short-term. 

Therefore, conducting an all-inclusive viewshed analysis at this time is not appropriate, because 

the data would likely be irrelevant quickly. 

Even though a park-wide viewshed analysis is not appropriate at this time, THRO regularly uses 

viewshed analyses to provide specific data regarding anthropogenic development concerns. 

Developed data enrich the understanding of anthropogenic effects on the park’s viewsheds. 

These data allow park management to make informed decisions and pursue appropriate actions 

regarding development. 

2.3 Resource Stewardship

2.3.1 Management Directives and Planning Guidance

THRO has several management plans, including the most recent Elk Management Plan (2010), 

the Centennial Plan (2007), the Fire Management Plan (2008), the Water Resources Management 

Plan (1998), the Resource Management Plan (1994), and the General Management Plan (1987). 

Each plan has its own objectives and goals to improve the park’s resources and increase public 

awareness.

The Elk Management Plan was proposed to ensure long-term preservation and protection of park 

resources. When the elk population increased after its reintroduction, the non-managed herd 

strained plant communities by over grazing; as of 2010, there were approximately 900 elk in the 

South Unit of the park (NPS 2010). The objectives for the elk management plan are as follows:

 Prevent negative effects to the biotic and abiotic components of the park and adjacent 

lands.

 Construct and execute actions parallel to the direction and limits set by the NPS 

Management Policies 2006.
12

 Determine indicators to assist and direct the management of elk.

 Maintain the long-term viability of the elk population while limiting herd manipulation in 

the park.

 Incorporate management flexibility to take action after obtaining information on disease 

or other factors that may adversely affect the elk population.

 Offer opportunities to educate the public about the challenges of elk management when 

limiting that management to park land.

 Collaborate with the stakeholders (e.g., federal agencies, state agencies, and private 

companies) by sharing data on the elk population and it management.

 When applicable, improve the hunting opportunities on the areas of land surrounding the 

park.

In 2007, the park celebrated its 60th anniversary. Its theme was “60 years of Preservation, 

Tradition, and Inspiration” (NPS 2007b). Now, the park’s plan for the next decade is to revise its 

mission and purpose to be connected better with the American public (NPS 2007b). The goals 

for the centennial plan are as follows:

 Enhance the condition of the park by improving its resources and assets.

 Educate and motivate children to give back to the environment by becoming future 

conservationists. 

 Alter park operations to minimize adverse impacts on the environment.

 Inspire the public to become environmentally conscious.

 Encourage all to participate in a shared environmental stewardship.

 Focus national, regional, and local tourism efforts to reach diverse audiences and young 

people and to attract visitors to lesser-known parks.

 Create stimulating media to introduce and excite youth and their families to the national 

parks.

The THRO Wildland Fire Management Plan (NPS 2008) was an addition to the resource 

management plan. Fire is an important factor that plays a large role in the development of most 

terrestrial ecosystems in North America (NPS 2008). This plan is becoming more intensive and 

of greater importance in the park; the objectives of the Wildland Fire Management Plan (NPS 

2008) are:

 Decrease the frequency and severity of fires caused by humans.

 Promote the occurrence of wildland fire in ecosystems dependent on its effects.

 Control and utilize fire as a management tool.

 Protect the park components (e.g., life, property and resources) from adverse effects of 

unwanted fire.
13

 Prevent adverse effects from fire suppression on the ecosystem. 

THRO created the Water Resources Management Plan in 1998 with the purpose of guiding park 

managers in assessing the water resources (NPS 1998). The park, being located in a semiarid 

ecosystem of the northern Great Plains, is particularly concerned with their water resources 

(Berkley et al. 1998). Maintaining plant and animal community diversity is dependent on water 

availability. The Water Resources Plan (1998) objectives include:

 Manage the park’s water resources to maintain an optimal level of species diversity and 

native plant composition.

 Revive and protect the park’s natural springs and developed wells for native wildlife.

 Assure that any development within the park will not negatively impact the water 

resources and water-dependent environments.

 Become knowledgeable about water quality to be able to actively contribute to the local 

and state water management plans while also striving for the optimal level of water 

quality standards for the park.

 Protest the water rights applications that would negatively impact the park and contribute 

to water rights adjudications involving the park lands so that the NPS water rights and 

water-related resources remain protected.

 Obtain a sufficient amount of information to adequately manage the park’s water 

resources while also following the NPS inventory and monitoring requirements.

 Follow NPS Floodplain Management Guidelines to insure minimal damage (e.g., injury, 

property) while also encouraging the occurrence of natural hydrologic and geomorphic 

processes of floods. 

 Create and update maps of the wetlands and riparian areas to make it easier to monitor 

and maintain ideal habitat conditions for the park’s wildlife.

 Educate the public and increase their awareness of the adverse effects done on water 

resources due to human impacts.

 Protect the native fish species (e.g., rare, threatened, and endangered) found in the park 

and surrounding areas by creating and applying effort to a cooperative management plan.

 Identify and assess the NPS water-related resources and any factors outside the park that 

may cause an impact.

 Ensure minimal impact on surface and ground water resources when permitting oil and 

gas operations done on lands adjacent to the park.

The Resource Management Plan (NPS 1994) is a supporting document of the original General 

Management Plan (NPS 1987), so that it would include both the 83 natural and 17 cultural 

resources important to the park (NPS 1994). The plan identifies resources and their components 

and indicates measures to be taken and methods to be used in management. The park’s goal is to 

restore and maintain the resources and processes that form the park’s ecosystem (NPS 1994). 

The Resource Management Plan had the following objectives:
14

 Create a tactical plan that recognizes and establishes priorities for resource management 

and research needs.

 Manage the park as a natural badlands ecosystem, influenced by human activities over 

time, allowing natural processes to continue.

 Prevent negative impacts on essential resources of the park by bearing in mind the effects 

that visitors and park managers may have on the natural and cultural resources with 

everyday activities.

 Create an information system for the Little Missouri Badlands ecosystems to protect the 

natural resources and ecological processes native to each ecosystem.

 Ensure the roadways are maintained and in satisfactory condition to make resource 

management (e.g., natural and cultural) more efficient.

 Follow all appropriate laws, NPS guidelines, and management plans to properly manage 

natural and cultural resources inside the park.

 Maintain resources in the park that are historically connected with Theodore Roosevelt 

(e.g., his life and experience in the Badlands).

 Guarantee that a sufficient collections management program is developed for the park’s 

natural and cultural resources.

One of the earliest management plans for THRO is its General Management Plan (NPS 1987). 

The General Management Plan provides the necessary strategies to guide management, use, and 

development of the park for the next 10 years (NPS 1987). This plan addresses resource 

management (e.g., flood protection, bison management, historic building preservation, and 

visitor use needs) (NPS 1987). 
15

2.3.2 Status of Supporting Science

The Northern Great Plains Inventory and Monitoring Network (NGPN) identifies key resources 

network-wide and for each of its parks that can be used to determine the overall health of the 

parks. These key resources are called Vital Signs. In 2010, the NGPN completed and released a 

Vital Signs monitoring plan (adapted from Gitzen et al. 2010, Table 2). 

Table 2. NGPN Vital Signs selected for monitoring in THRO (adapted from Gitzen et al. 2010). 

Category

Vital Signs Currently Monitored by 

NPGN parks, Other NPS Entities, or 

Other Federal or State Agencies

Vital Signs for Which NGPN Will 

Develop and Implement 

Monitoring Protocols in the Future

Air and climate

 Ozone

 Wet and dry deposition

 Visibility and particulate matter

 Air contaminants

 Weather and climate

Geology and soils  Stream and river channel 

characteristics

Water  Surface water dynamics 

 Surface water chemistry

 Aquatic contaminants

 Aquatic microorganisms

 Aquatic macroinvertebrates

Biological integrity

 Exotic plant early detection

 Raptors

 Prairie dogs

 Ungulates

 Riparian lowland plant communities

 Upland plant communities

 Land birds

Human use  Treatments of exotic infestations

 Visitor use

Landscapes 

(ecosystem pattern 

and process)

 Fire and fuel dynamics, 

 Land cover and use

 Extreme disturbances

 Soundscape

 Viewshed

 Night sky
16

2.4 Literature Cited

Berkley, J., G. R. Reetz., and D. Vana-Miller. 1998. Water resources management plan. 

Theodore Roosevelt National Park. U.S. Environmental Protection Agency, Region VIII. 

National Park Service, Theodore Roosevelt National Park, North Dakota. 

Commission for Environmental Cooperation (CEC). 1997. Ecological regions of North America: 

toward a common perspective. Communications and Public Outreach Department of the CEC 

Secretariat, Montreal, Canada.

Dratch, P. A., and P. J. P. Gogan. 2010. Bison conservation initiative: Bison conservation 

genetics workshop: report and recommendations. Natural Resource Report 

NPS/NRPC/BRMD/NRR—2010/257. National Park Service, Fort Collins, Colorado.

Franklin, I. R. 1980. Evolutionary change in small populations. Pages 135-149 in M. E. Soulé 

and B. A. Wilcox, editors. Conservation Biology: An evolutionary-ecological perspective. 

Sinauer Associates, Sunderland, Massachusetts.

Gitzen, R., M. Wilson, J. Brumm, M. Bynum, J. Wrede, J. Millspaugh, and K. Paintner. 2010.

Northern Great Plains Network Vital Signs monitoring plan. Appendix B: conceptual 

ecological models. Natural Resource Report NPS/NGPN/NRR-2010/186. National Park 

Service, Fort Collins, Colorado.

Griffith, G. 2010. Level III North American terrestrial ecoregions: United States descriptions. 

North American Commission for Environmental Cooperation, Montreal, Canada.

Halbert, N. D., P. J. P. Gogan, R. Hiebert, and J. N. Derr. 2007. The role of history and genetics 

in the conservation of bison on U.S. federal lands. NPS Park Science 24(2):22-29. 

High Plains Regional Climate Center. 2011. Period of record monthly climate summary, Medora, 

North Dakota (325813) 1948-2010. http://hprcc.unl.edu/cgi-bin/cli_perl_lib/

cliMAIN.pl?nd5813 (accessed 9 September 2011).

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. U.S. Department of Interior, 

National Park Service, Denver, CO.

Marlow, C. B., L. L. Irby, and J. E. Norland. 1984. Optimum carrying capacity for bison in 

Theodore Roosevelt National Park. Montana State University, Bozeman, Montana.

Marlow, C. B., L. C. Gagnon, L. R. Irby, and M. R. Raven. 1992. Feral horse distribution, habitat 

use, and population dynamics in Theodore Roosevelt National Park. National Park Service,

Denver, Colorado.

McLaughlin, C. 1989. The history and status of the wild horses of Theodore Roosevelt National 

Park. Theodore Roosevelt Nature & History Association, Medora, North Dakota.

National Park Service (NPS). 1978. Environmental assessment. Proposed feral horse reduction 

Theodore Roosevelt National Memorial Park. National Park Service, Fort Collins, Colorado.
17

National Park Service (NPS). 1987. Theodore Roosevelt National Park general management 

plan, development concept plans, land protection plan, environmental assessment, Theodore 

Roosevelt National Park, North Dakota. National Park Service, Theodore Roosevelt National 

Park, Medora, North Dakota. 

National Park Service (NPS) 1994. Resource management plan: Theodore Roosevelt National 

Park. National Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

National Park Service (NPS). 1999. Theodore Roosevelt National Park fire management plan. 

National Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

National Park Service (NPS). 2006. Bison management plan - Wind Cave National Park. U.S. 

Department of the Interior, Wind Cave National Park, South Dakota. 

http://www.nps.gov/wica/parkmgmt/loader.cfm?csModule=security/getfile&PageID=130778 

(accessed 8 February 2012).

National Park Service (NPS). 2007a. Theodore Roosevelt National Park: Geologic resource 

evaluation report. National Park Service, Theodore Roosevelt National Park, Medora, North 

Dakota.

National Park Service (NPS). 2007b. First annual centennial strategy for Theodore Roosevelt 

National Park. National Park Service, Theodore Roosevelt National Park, Medora, North 

Dakota.

National Park Service (NPS). 2008. Theodore Roosevelt National Park fire management plan. 

National Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

National Park Service (NPS). 2009. Theodore Roosevelt National Park: Bison management. 

http://www.nps.gov/thro/naturescience/bison-management.htm (accessed 8 February 2012).

National Park Service (NPS). 2010. Theodore Roosevelt National Park: Elk management plan 

and final environmental impact statement. National Park Service, Theodore Roosevelt 

National Park, Medora, North Dakota.

National Park Service (NPS). 2011a. Theodore Roosevelt National Park: Park statistics. 

http://www.nps.gov/thro/parkmgmt/statistics.htm (accessed 1 September 2011).

National Park Service (NPS). 2011b. Theodore Roosevelt National Park: Wilderness hike to 

focus on petrified forest. http://www.nps.gov/thro/parknews/july-wilderness-hike.htm

(accessed 6 September 2011).

National Park Service (NPS). 2011c. Theodore Roosevelt National Park: Weather. 

http://www.nps.gov/thro/planyourvisit/weather.htm (accessed 6 December 2011).

National Park Service (NPS). 2011d. NPS stats: NPS 5 year annual recreation visits report. 

http://www.nature.nps.gov/stats/viewReport.cfm (accessed 2 September 2011).
18

National Park Service (NPS). 2011e. Theodore Roosevelt National Park: Feral horses. 

http://www.nps.gov/thro/naturescience/feral-wild-horses.htm (accessed 7 September 2011).

National Park Service (NPS). 2012. Theodore Roosevelt National Park: Plants. 

http://www.nps.gov/thro/naturescience/plants.htm (accessed 4 April 2012). 

National Park Service (NPS). 2012b. NPSpecies online. 

https://nrinfo.nps.gov/Species.mvc/Search (accessed 3 July 2012).

Pohlman, D., and T. Maniero. 2005. Air quality monitoring considerations for the Northern 

Great Plains Network parks. Report submitted to the Northern Great Plains I&M Program. 

National Park Service, St. Paul, Minnesota.

Power, G. 2006. ‘Cross the wide Missouri: Significant Missouri River system biological sites. 

State Game and Fish Department, Bismarck, North Dakota. 

http://www.npwrc.usgs.gov/resource/habitat/cwmiss/index.htm (accessed 6 September 

2011).

Seastedt, T. R. 1995. Soil systems and nutrient cycles of the North American prairie. Pages 157–

176 in A. Joern and K. H. Keeler, editors. The changing prairie: North American grasslands. 

Oxford University Press, New York, New York.

Trimble, D. E. 1993. The geologic story of the Great Plains. Theodore Roosevelt Nature and 

History Association, Medora, North Dakota.

Tweet, J. S., V. L. Santucci, and J. P. Kenworthy. 2011. Paleontological resource inventory and 

monitoring: Northern Great Plains Network. Natural Resource Technical Report 

NPS/NRPC/NRTR—2011/437. National Park Service, Fort Collins, Colorado.

U.S. Census. 2010. 2010 Census data: Billings County, North Dakota. U.S. Census Bureau.

http://2010.census.gov/2010census/data/ (accessed 2 September 2011).

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli.

2000. USGS-NPS vegetation mapping program: Theodore Roosevelt National Park, North 

Dakota. U.S. Department of the Interior, Denver, Colorado.

Wright, H. A., and A. W. Bailey. 1982. Fire Ecology: United States and Canada. John Wiley and 

Sons, New York, New York. 
19

Chapter 3 Study Scoping and Design

This NRCA is a collaborative project between the National Park Service (NPS) and Saint Mary’s 

University of Minnesota Geospatial Services (SMUMN GSS). Project stakeholders include the 

THRO resource management team and NGPN Inventory and Monitoring Program staff. Before 

embarking on the project, it was necessary to identify the specific roles of the NPS and SMUMN 

GSS. Preliminary scoping meetings were held, and a task agreement and a scope of work 

document were created cooperatively between the NPS and SMUMN GSS.

3.1 Preliminary scoping

A preliminary scoping meeting was held on 31 August 2010. At this meeting, SMUMN GSS and 

NPS staff confirmed that the purpose of the THRO NRCA was to evaluate and report on current 

conditions, critical data and knowledge gaps, and selected existing and emerging resource 

condition influences of concern to THRO managers. Certain constraints were placed on this 

NRCA, including the following:

 Condition assessments are conducted using existing data and information.

 Identification of data needs and gaps is driven by the project framework categories.

 The analysis of natural resource conditions includes a strong geospatial component.

 Resource focus and priorities are primarily driven by THRO resource management.

This condition assessment provides a “snapshot-in-time” evaluation of the condition of a select 

set of park natural resources that were identified and agreed upon by the project team. Project 

findings will aid THRO resource managers in the following objectives:

 Develop near-term management priorities (how to allocate limited staff and funding

resources);

 Engage in watershed or landscape scale partnership and education efforts;

 Consider new park planning goals and take steps to further these;

 Report program performance (e.g., Department of Interior Strategic Plan “land health” 

goals, Government Performance and Results Act [GPRA]).

Specific project expectations and outcomes included the following:

 For key natural resource components, consolidate available data, reports, and spatial 

information from appropriate sources including: THRO resource staff, IRMA (Integration 

of Resource Management Applications), Inventory and Monitoring Vital Signs, NGPN 

staff, and available third-party sources. The NRCA report will provide a resource 

assessment and summary of pertinent data evaluated through this project.
20

 When appropriate, define a reference condition so that statements of current condition

may be developed. The statements will describe the current state of a particular resource 

with respect to an agreed upon reference point.

 Clearly identify “management critical” data (i.e., those data relevant to the key 

resources). This will drive the data mining and gap definition process.

 Where applicable, develop GIS products that provide spatial representation of resource 

data, ecological processes, resource stressors, trends, or other valuable information that

can be better interpreted visually.

 Utilize “gray literature” and reports from third party research to the extent practicable.

3.2 Study Design

3.2.1 Indicator Framework, Focal Study Resources and Indicators

Selection of Resources and Measures

As defined by SMUMN GSS in the NRCA process, a “framework” is developed for a park or 

preserve. This framework is a way of organizing, in a hierarchical fashion, bio-geophysical 

resource topics considered important in park management efforts. The primary features in the 

framework are key resource components, measures, stressors, and reference conditions. 

“Components” in this process are defined as natural resources (e.g., prairie dogs), ecological 

processes or patterns (e.g., natural fire regime), or specific natural features or values (e.g., 

geological formations) that are considered important to current park management. Each key 

resource component has one or more “measures” that best define the current condition of a 

component being assessed in the NRCA. Measures are defined as those values or 

characterizations that evaluate and quantify the state of ecological health or integrity of a 

component. In addition to measures, current condition of components may be influenced by 

certain “stressors” which are also considered during assessment. A “stressor” is defined as any 

agent that imposes adverse changes upon a component. These typically refer to anthropogenic 

factors that adversely affect natural ecosystems, but may also include natural processes or 

disturbances such as floods, fires, or predation (adapted from GLEI 2010). 

During the THRO NRCA scoping process, key resource components were identified by NPS 

staff and are represented as “components” in the NRCA framework. While this list of 

components is not a comprehensive list of all the resources in the park, it includes resources and 

processes that are unique to the park in some way, of greatest concern or of highest management 

priority in THRO. Several measures for each component, as well as known or potential stressors, 

were also identified in collaboration with NPS resource staff.

Selection of Reference Conditions

A “reference condition” is a benchmark to which current values of a given component’s 

measures can be compared to determine the condition of that component. A reference condition 

may be a historical condition (e.g., flood frequency prior to dam construction on a river), an 
21

established ecological threshold (e.g., EPA standards for air quality), or a targeted management 

goal/objective (e.g., an elk herd of less than 200 individuals) (adapted from Stoddard et al. 2006).

Reference conditions in this project were identified during the scoping process using input from 

NPS resource staff. In some cases, reference conditions represent a historical reference in which 

human activity and disturbance was not a major driver of ecological populations and processes, 

such as “pre-cattle/sheep grazing” or “pre-fire suppression.” In cases where reference conditions 

were less clearly defined, peer-reviewed literature, ecological thresholds, and consultation with 

resource staff were used to define appropriate reference conditions more clearly. In these 

instances, efforts were made to utilize existing research and documentation of historical

conditions to identify the range of natural variation for reference conditions. 

Finalizing the Framework

An initial framework was adapted from the organizational framework outlined by the H. John 

Heinz III Center for Science’s “State of Our Nation’s Ecosystems 2008” (Heinz Center 2008). 

Key resources for the park were adapted from the NGPN Vital Signs monitoring plan (Gitzen et 

al. 2010) and natural resource reports from THRO. This initial framework was presented to park

resource staff to stimulate meaningful dialogue about key resources that should be assessed. 

Significant collaboration between SMUMN GSS analysts and NPS staff was needed to focus the 

scope of the NRCA project and finalize the framework of key resources to be assessed. 

The NRCA framework was finalized in August 2011 following acceptance from NPS resource 

staff. It contains a total of 17 components (Table 3) and was used to drive analysis in this NRCA. 

This framework outlines the components (resources), most appropriate measures, known or 

perceived stressors and threats to the resources, and the reference conditions for each component 

for comparison to current conditions. The THRO framework also contains several components 

that are contextually important natural resource topics in the park; these include feral horses, 

bison, elk, and viewshed. During scoping, it was agreed that these topics would be addressed in 

Chapter 2 of the report.
22

Table 3. THRO natural resource condition assessment framework.
23
24

3.2.2 General Approach and Methods

This study involved gathering and reviewing existing literature and data relevant to each of the 

key resource components included in the framework. No new data were collected for this study, 

however, where appropriate, existing data were further analyzed to provide summaries of 

resource condition or to create new spatial representations. After all data and literature relevant 

to the measures of each component were reviewed and considered, a qualitative statement of 

overall current condition was created and compared to the reference condition when possible.

Data Mining

The data mining process (acquiring as much relevant data about key resources as possible) began 

at the initial scoping meeting, at which time THRO staff provided data and literature in multiple 

forms, including: NPS reports and monitoring plans, reports from various state and federal 

agencies, published and unpublished research documents, databases, tabular data, and charts. 

GIS data were provided by NPS staff (NGPN and THRO). Access was also granted to NPS 

online data and literature sources, such as NatureBib, NPSpecies, and IRMA . Additional data 

and literature were also acquired through online bibliographic literature searches and inquiries on

various state and federal government websites. Data and literature acquired throughout the data 

mining process were inventoried and analyzed for thoroughness, relevancy, and quality 

regarding the resource components identified at the scoping meeting.

Data Development and Analysis

Data development and analysis was highly specific to each component in the framework and 

depended largely on the amount of information and data available and recommendations from 

NPS reviewers and sources of expertise including NPS staff from THRO and NGPN. Specific 

approaches to data development and analysis can be found within the respective component 

assessment sections located in Chapter 4 of this report.

Scoring Methods and Assigning Condition

A set of measures are useful in describing the condition of a particular component, but all 

measures may not be equally important. A “significance level” represents a numeric 

categorization (integer of 1-3) of the importance of each measure in explaining the condition of 

the component; each significance level is defined in Table 4. This categorization allows 

measures that are more important for determining condition (higher significance level) of a 

component to be more heavily weighted in calculating an overall condition.

Table 4. Scale of measure significance used in determining overall condition.

Significance Level

(SL) Description

1 Measure is of low importance in defining the condition of this component.

2 Measure is of moderate importance in defining the condition of this 

component.

3 Measure is of high importance in defining the condition of this component.

After each component assessment is completed (including any possible data analysis), a 

condition level is calculated for each measure. This is based on a 0-3 integer scale and reflects

the data mining efforts and communications with park experts (Table 5).
25

Table 5. Scale used in determining condition level of individual measures.

Condition Level

(CL) Description

0 Of NO concern. No net loss, degradation, negative change, or alteration.

1 Of LOW concern. Signs of limited and isolated degradation of the component.

2 Of MODERATE concern. Pronounced signs of widespread and uncontrolled 

degradation.

3 Of HIGH concern. Nearing catastrophic, complete, and irreparable degradation 

of the component.

After the significance levels (SL) and condition levels (CL) are assigned, a weighted condition 

score (WCS) is calculated via the following equation:

WCS =

∑ SLi ∗ CLi

# of measures

i=1

3 ∗ ∑ SLi

# of measures

i=1

The resulting WCS value is placed into one of three possible categories: condition of low 

concern (WCS = 0.0 – 0.33); condition of moderate concern (WCS = 0.34 - 0.66); and condition 

of significant concern (WCS = 0.67 to 1.00). Figure 1 displays all of the potential graphics used 

to represent a component’s condition in this assessment. The colored circles represent the 

categorized WCS; red circles signify a significant concern, yellow circles a moderate concern 

and green circles a condition of low concern. Gray circles are used to represent situations in 

which there is currently insufficient data to make a statement about the condition of a 

component. The arrows inside the circles indicate the trend of the condition of a resource 

component. An upward pointing arrow indicates the condition of the component has been 

improving in recent times. A right-pointing arrow indicates a stable condition or trend and an 

arrow pointing down indicates a decline in the condition of a component in recent times. These 

are only used when it is appropriate to comment on the trend of condition of a component. A 

gray, triple-pointed arrow is reserved for situations in which the trend of the component’s 

condition is currently unknown.
26

Figure 1. Symbols used for individual component assessments with condition or concern designations 

along the vertical axis and trend designations along the horizontal.

Preparation and Review of Component Draft Assessments

The preparation of draft assessments for each component was a highly cooperative process 

among SMUMN GSS analysts and THRO staff. Though SMUMN GSS analysts rely heavily on 

peer-reviewed literature and existing data in conducting the assessment, the expertise of NPS 

resource staff also plays a significant and invaluable role in providing insights into the 

appropriate direction for analysis and assessment of each component. This step is especially 

important when data or literature are limited for a resource component.

The process of developing draft documents for each component began with a detailed phone or 

conference call with an individual or multiple individuals considered local experts on the 

resource components under examination. These conversations were a way for analysts to verify 

the most relevant data and literature sources that should be used and also to formulate ideas 

about current condition with respect to the NPS staff opinions. Upon completion, draft 

assessment were forwarded to component experts for initial review and comments.

Development and Review of Final Component Assessments

Following review of the component draft assessments, analysts used the review feedback from 

resource experts to compile the final component assessments. As a result of this process, and 

based on the recommendations and insights provided by THRO resource staff and other experts,

the final component assessments represent the most relevant and current data available for each 

component and the sentiments of park resource staff and resource experts. 

Format of Component Assessment Documents

All resource component assessments are presented in a standard format. The format and structure 

of these assessments is described below.
27

Description

This section describes the relevance of the resource component to the park and the context within 

which it occurs in the park setting. For example, a component may represent a unique feature of 

the park, it may be a key process or resource in park ecology, or it may be a resource that is of 

high management priority in the park. Also emphasized are interrelationships that occur among a 

given component and other resource components included in the broader assessment.

Measures

Resource component measures were defined in the scoping process and refined through dialogue 

with resource experts. Those measures deemed most appropriate for assessing the current 

condition of a component are listed in this section, typically as bulleted items.

Reference Conditions/Values

This section explains the reference condition determined for each resource component as it is 

defined in the framework. Explanation is provided as to why specific reference conditions are 

appropriate or logical to use. Also included in this section is a discussion of any available data 

and literature that explain and elaborate on the designated reference conditions. If these 

conditions or values originated with the NPS experts or SMUMN GSS analysts, an explanation 

of how they were developed is provided.

Data and Methods

This section includes a discussion of the data sets used to evaluate the component and if or how 

these data sets were adjusted or processed as a lead-up to analysis. If adjustment or processing of 

data involved an extensive or highly technical process, these descriptions are included in an 

appendix for the reader or a GIS metadata file. Also discussed is how the data were evaluated 

and analyzed to determine current condition (and trend when appropriate). 

Current Condition and Trend

This section presents and discusses in-depth key findings regarding the current condition of the 

resource component and trends (when available). The information is presented primarily with 

text but is often accompanied by detailed maps or plates that display different analyses, as well 

as graphs, charts, and/or tables that summarize relevant data or show interesting relationships. 

Due to their low importance, measures that are assigned a significance level of 1 do not receive 

an in-depth analysis and are not addressed in the current condition section. These measures are 

briefly discussed in the overall condition section of the document (see below).

Threats and Stressor Factors

This section provides a summary of the threats and stressors that may impact the resource and 

influence to varying degrees the current condition of a resource component. Relevant stressors 

were described in the scoping process and are outlined in the NRCA framework. However, these 

are elaborated on in this section to create a summary of threats and stressor based on a 

combination of available data and literature, and discussions with resource experts and NPS

natural resources staff. 
28

Data Needs/Gaps

This section outlines critical data needs or gaps for the resource component. Specifically, what is 

discussed is how these data needs/gaps, if addressed, would provide further insight in 

determining the current condition or trend of a given component in future assessments. In some 

cases, the data needs/gaps are significant enough to make it inappropriate or impossible to 

determine condition of the resource component. In these cases, stating the data needs/gaps is 

useful to natural resources staff that wish to prioritize monitoring or data gathering efforts.

Overall Condition 

This section provides a qualitative summary statement of the current condition that was 

determined for the resource component using the WCS method. Condition is determined after 

thoughtful review of available literature, data, and any insights from NPS staff and experts, 

which are presented in the Current Condition and Trend section. The Overall Condition section 

summarizes the key findings and highlights the key elements used in determining and justifying 

the level of concern, if any, that analysts attribute to the condition of the resource component. 

Also included in this section are the graphics used to represent the component condition.

Sources of Expertise

This is a listing of the individuals (including their title and affiliation with offices or programs) 

who had a primary role in providing expertise, insight, and interpretation to determine current 

condition (and trend when appropriate) for each resource component.

Literature Cited

This is a list of formal citations for literature or datasets used in the analysis and assessment of 

condition for the resource component. Note, citations used in appendices and plates referenced in 

each section (component) of Chapter 4 are listed in that section’s “Literature Cited” section.
29

3.3 Literature Cited

Gitzen, R., M. Wilson, J. Brumm, M. Bynum, J. Wrede, J. Millspaugh, and K. Paintner. 2010. 

Northern Great Plains Network vital signs monitoring plan. Appendix B: conceptual 

ecological models. Natural Resource Report NPS/NGPN/NRR-2010/186. National Park 

Service, Fort Collins, Colorado.

Great Lakes Environmental Indicators Project (GLEI). 2010. Glossary, Stressor. 

http://glei.nrri.umn.edu/default/glossary.htm (accessed 9 December 2010).

The H. John Heinz III Center for Science, Economics, and the Environment. 2008. The state of 

the nation’s ecosystems 2008: Measuring the land, waters, and living resources of the United 

States. Island Press, Washington, D.C.

Stoddard. J. L., D. P. Larsen, C. P. Hawkins, R. K. Johnson, and R. J. Norris. 2006. Setting 

expectations for the ecological condition of streams: the concept of reference condition. 

Ecological Applications. 16(4):1267-1276.

31

Chapter 4 Natural Resource Conditions

This chapter presents the background, analysis, and condition summaries for the 17 key resource 

components identified in the project framework. Each component assessment is organized into 

the following sections: 

1. Description

2. Measures

3. Reference Condition

4. Data and Methods

5. Current Condition and Trend (including threats and stressor factors, data needs/gaps, and 

overall condition)

6. Sources of Expertise

7. Literature Cited

Components appear in the order they are listed in the project framework (Table 3):

4.1 Fire 

4.2 Wind and water erosion

4.3 Flooding (Little Missouri River)

4.4 Native grasslands

4.5 Juniper forests

4.6 Floodplain forests

4.7 Woody draws

4.8 Upland shrubland communities

4.9 Aquatic communities

4.10 Prairie dogs

4.11 Breeding birds

4.12 Air quality

4.13 Water quality

4.14 Soundscape

4.15 Dark night skies

4.16 Surface water availability

4.17 Paleontological features
32

4.1 Fire 

4.1.1 Description

Fire plays a major role in the ecological processes of North American prairies (Umbanhowar 

1996), and historically, fires have been important naturally occurring events in THRO. These 

fires created natural disturbances that are important for maintaining healthy native plant 

communities in the prairie landscape. Mixed grass prairie, the primary vegetative cover in 

THRO, is approximately 0.61-1.22 m (2 to 4 ft) tall and grows quickly then dies back each year 

(NPS 2008). However, small trees and shrubs 

grow primarily on north aspects and within 

woody draws in the park. Fire in mixed grass 

prairie tends to limit the growth of trees and 

shrubs to places where finer fuels are less 

continuous and natural fire breaks exist (e.g., 

drier, rocky breaks, draws, and riparian areas) 

(NPS 2008).

Fires that are naturally ignited (i.e., wildfires 

starting from lightning strikes) have been quickly 

suppressed for the majority of the park’s 

existence (NPS 2010a). However, wildland fires 

are allowed to burn under certain conditions and

in particular geographic areas of the park (e.g., 

fire management unit no. 2 in the North Unit of 

the park) as described in the Fire Management Plan (FMP) (NPS 2008). Fire was reintroduced to 

THRO in 1999 through prescribed burns, as a native plant community management strategy 

(NPS 2010a). Generally, THRO uses prescribed fire as a management tool for reducing fuel 

loads and stimulating the growth and health of native plant communities adapted to fire. 

However, each fire is set to accomplish individualized resource management objectives, which 

are identified for each fire (project) plan (NPS 2008). The rough terrain and low vegetation 

densities within the park, which consequently contribute to low fuel densities, limit the extent to 

which fire can spread (NPS 2010a). Prescribed fires account for the vast majority of the burned 

area in the park with approximately 93% of the total acreage burned within THRO from 1999 to 

2010 (see Appendix A for information on individual fires). 

4.1.2 Measures

 Frequency

 Severity

 Extent (area burned over time)

 Fire origin (e.g., prescribed, lightning, human-caused, etc.)

 Intensity

 Seasonality

Photo 6. Firefighters igniting a prescribed fire 

in THRO (NPS photo).
33

 Change in native vegetation after prescribed fire

4.1.3 Reference Conditions/Values

Given that reference conditions (i.e., natural fire regime parameters) are not well established and 

that prescribed fire has nearly completely replaced natural fire starts in THRO, the fire 

management goals for the park will serve as the reference condition. As a part of fire 

management in THRO, the NPS can chose from multiple options: wildland fire suppression, 

wildland fire use, prescribed fire, and non-fire fuel treatments. The 2008 THRO fire management 

plan (NPS 2008) contains several objectives. The objectives relevant to the use of wildland fires 

to meet resource objectives include: 

1) permit wildland fire use (lightning-caused) in areas where fire dependency has been 

scientifically proven and the fuel load and vegetation composition are within the range of 

natural variability,

2) use fire to restore plant community structure, composition and maintain cultural 

landscapes similar to those before European settlement,

3) allow wildland fire use within the constraints of policy (DO-18) and the Environmental 

Assessment/Assessment of Effect for the Fire Management Program of Theodore 

Roosevelt National Park.

Objectives relevant to the use of prescribed fires in order to meet management objectives 

include:

1) create and/or maintain defensible wildland fire use boundaries,

2) where applicable, restore fuel loads and plant community structure and compositions to 

ranges of natural variability comparable to pre-European settlement using prescribed fire 

and wildland fire use,

3) restore cultural landscapes similar to those present before European statement,

4) minimize the occurrence of unnaturally intense fires through reduction of hazard fuels by 

prescribed burning,

5) avoid prescribed fires and wildland fire use that would reduce air quality in Medora, 

North Dakota between Memorial Day and Labor Day, 

6) train park staff and cooperators to conduct safe, objective-oriented prescribed fires and 

wildland fire use consistent with DO-18 requirements,

7) provide opportunities for public understanding of fire ecology principles, smoke 

management, and wildland fire program objectives, and

8) monitor and evaluate the effectiveness of the preserved fire program.
34

Generally, fire managers aim to reduce the cover and density of non-native forbs and grasses 

while encouraging native plant species growth; reduce the cover and density of silver sagebrush

(Artemisia cana), and western snowberry (Symphoricarpos occidentalis); and reintroduce fire to

fire-adapted ecosystems in the park. However, each fire is set to achieve a particular set of goals, 

and these may vary based on landscape position, fire history in the area, weather conditions (e.g., 

wind, temperature, and humidity), a variety of fuel dynamics, and availability of fire suppression 

resources such as trained personnel and materials.

4.1.4 Data and Methods

Fire data captured in GIS were obtained from the park for fires that occurred within and near 

THRO from 1946 to 2010 (NPS 2010b). The attributes from the GIS data were used to assess the 

past and current condition of fire. Monitoring Trends in Burn Severity (MTBS 2011) provided 

burn severity data for two fires, specifically highlighting the acreage burned in each severity 

class.

A series of prescribed fire monitoring reports were used to document the extent of most fires in 

THRO and the intensity and severity of each burn. 

Wienk et al. (2007) provided a program review of the Northern Great Plains Fire Ecology 

Program, focusing on research efforts from 1997-2007. This report provided information about 

native and non-native vegetation responses to different fire treatments over time.

4.1.5 Current Condition and Trend

Fire in THRO is monitored and managed to achieve a number of objectives, including restoring 

fire-adapted ecosystems within the park (NPS 2008). The measures used to assess the current 

condition of THRO fire are compared to the historic fire regime and current management 

objectives for fire on the landscape. Fire frequency is assessed by comparing the current fire 

frequency with the historic frequency (prior to European settlement of the region). Historic fire 

frequency is often determined through examination of fire-scars on trees and stumps and by 

charcoal research. However, the primary vegetation type in THRO is mixed grass prairie and 

little fire scar data are available to determine historic fire frequency. In an investigation of fire 

history in Great Plains National Parks, Guyette et al. (2011) found little evidence of fire scars in 

juniper in the South Unit of THRO. The authors suggested that, because of reduced spread of fire 

on the landscape due to natural fire breaks, fire scar history methods would likely not be 

appropriate for describing the history of fire events in the region. Therefore, the pre-European 

settlement fire frequency (i.e., fire return interval), extent (area), severity, and seasonality are not 

well understood in THRO. Wright and Bailey (1980) estimate fire frequency in the northern 

mixed prairie of the Badlands to be 5 to 30 years. While most historic fires originated from 

lightning strikes, historic fire frequency estimates may be confounded by evidence, according to 

pioneer settlers’ reports, that Native Americans intentionally and unintentionally set fires (NPS 

1999). 

Official documentation of fires did not begin in THRO until 1949 (NPS 1999). From 1949 to 

1999, all fires were either accidental or caused by lightning; since 1999, the park has 

increasingly used prescribed fire as a management tool. Since then, resource managers and fire 

researchers have continued to record fire origin, frequency, area burned, and seasonality (dates) 

of fires. In many cases, only area burned has been recorded. These primarily have been 
35

monitored through field reconnaissance and provide a basic assessment and overview of each 

fire (NPS 2003). Intensity and severity are assessed during prescribed burns and by examining 

the post-fire effects on the plant communities.

Frequency

Guyette et al. (2011) suggest pre-European settlement human-caused fires were rare in the 

THRO area because of the low human population density and the variation in topography, which 

inhibited natural fires. Wright and Bailey (1982) estimate that fire should burn every 5 to 10 

years in prairie grasslands with rolling topography, and every 20 to 30 years in topography with 

breaks and rivers; the latter is characteristic of the THRO landscape.

THRO began recording fire dates in 1949 (NPS 1999). Natural wildfires (lightning-caused) are 

permitted to burn in areas where fire dependency is proven (NPS 2008). However, management 

suppresses all human-caused fires (non-prescribed) and does not allow natural wildfires to burn 

more than a few acres if there is direct threat to human life, private property, and park cultural 

resources (NPS 2008). Therefore, fire frequency or fire-return interval is primarily determined by 

burn prescriptions. However, because of the discontinuous, patchy fuel sources and sparsely 

vegetated topography within THRO, some sites may have mean fire-return intervals between 150 

and 400 years (NPS 2003). NPS (1999) reported 90 fires in THRO between 1949 and 1993. 

Since that time, (through 2010) the number of fires has increased to 157, with most fires being 

prescribed burns. In1999, prescribed fire was used for the first time in THRO, and since then an 

average of 4.1 fires occurred per year. Refer to Table 6 for fire frequency, area, and origin by 

major burn unit. The fire history dataset containing fire origin (cause), area, date, name, and burn 

unit from 1946 to 2010 is available in Appendix A.

Table 6. Number of fires and area burned in THRO by origin and park unit (1984 to 2010) (NPS 2010b).

Origin / Burn Unit Number 

of fires

Percent of 

firesa

Acres 

burned

Hectares 

burned

Percent of 

Area

Human 25 23.5 78.0 31.6 1.0

North Unit 6 18.9 8.0 3.2

South Unit 19 27.1 70.0 28.3

Lightning 28 26.4 760.2 307.6 8.8

Elkhorn Ranch Unit 1 25.0 158.0 63.9

North Unit 10 31.2 76.5 31.0

South Unit 17 24.3 525.7 212.7

Prescribed 49 46.2 7,813.7 3,162.1 90.0

Elkhorn Ranch Unit 3 75.0 18.1 7.3

North Unit 14 43.8 3,385.9 1,370.2

South Unit 32 45.7 4,409.8 1,784.6

Unknown 4 <0.1 21 8.5 0.2

North Unit 2 0.1 19.0 7.7

South Unit 2 <0.1 2.0 0.8

Totals: 106 100.0 8,672.9 3,509.8 100.0

a Percentages for origins use the park-wide total and each unit is calculated by the total within that unit.

THRO uses prescribed fire to meet goals for vegetation management and to mimic the natural 

historic fire regime as closely as possible. However, the number of prescribed fires that can 
36

occur depends largely on the funding available each year. Thus, areas of THRO may not see fire 

for 100 to 200 years (R. Skalsky, pers. comm., 2011).

Severity

Fire (or burn) severity is a term used to describe the physical and chemical changes to the soil, 

the conversion of vegetation and fuels to inorganic carbon, and structural or compositional 

transformations that create new microclimates and species assemblages (Key and Benson 2006). 

Severity is measured by the amount of organic matter loss both above and below the surface of 

the ground after a fire (Keeley 2008). 

One method for measuring burn severity is to compare LandSat imagery prior to and after a fire 

to determine a Differenced Normalized Burn Ratio (dNBR). The dNBR data, which represent 

continuous values, are separated into six categories. MTBS (2011b) classifies the six severity 

categories as unburned to low, low, moderate, high, increased greenness, and no data. According 

to MTBS (2011a), an analyst evaluates the dNBR data range and determines where significant 

thresholds exist to discriminate between severity categories. In Sorbel and Allen (2005), the 

accuracy of the dNBR method was tested by sampling Composite Burn Index (CBI) plots 

established on the ground in recently burned areas. CBI methods involve scoring burn severity 

based on 22 variables including soil cover/color change, duff and litter consumption, percent of 

colonizers, percent of altered foliage, and percent of canopy mortality (Sorbel and Allen 2005). 

A comparison of CBI scores and dNBRs for the same areas shows that dNBR is “a suitable 

measure and predictor of burn severity” (Sorbel and Allen 2005, p. 9). MTBS (2011b) provided 

burn severity data in which acreage of severity categories were derived for the Little Missouri II 

and Southeast Corner fires within THRO (Table 7).

Table 7. Burn severity for the Little Missouri II and Southeast Corner fires (MTBS 2011). 

Year Fire Name

Unburned 

to Low 

Severity

Low 

Severity

Moderate 

Severity

High 

Severity

Increased 

Greenness

2002 Little Missouri II

Acres 369 467 505 97 7

Hectares 149 189 204 39 3

% composition 25.5 32.3 34.9 6.7 0.5

2004 SE Corner

Acres 149 454 320 0 0

Hectares 60 184 130 0 0

% composition 16.2 49.2 34.7 0 0

Immediate post-burn severity is also measured by fire monitoring personnel. Severity for some 

prescribed burns can be found in THRO prescribed burn reports. The recent prescribed fire 

reports cite mostly “low” and “moderate” severity with fewer occurrences of “scorched” severity 

(which is less severe than the “low” category) (Lund 2007, Mitchell 2007, Koller and Freeman 

2008, Freeman 2008). Low and moderate severity is a result of the fast-burning nature of THRO 

grassland fires (NPS 1999). When a fire is behaving in a manner that is counter to the 

management goals for the fire, the prescribed burning can be stopped, as was the circumstance 

for the Horse Camp fire of 2007 (Mitchell 2007). 
37

Extent - Area Burned

NPS (1999) suggests that, in comparing the historic presence of fire on the landscape to present 

fire, the largest difference is probably in the area or extent of fires. Currently, large landscape 

fires are not allowed to burn due to widespread agricultural land use and a landscape containing 

many human-created firebreaks (e.g., roads). In addition to land use changes, fire that once was 

used commonly by Native-American cultures and in cattle ranching practices has since ceased 

(NPS 1999).

Wildland fires, typically caused by lightning, rarely burn more than a few acres (Appendix A) 

(C. Sexton, pers. comm., 2011). Where fire dependency is proven for vegetation communities, 

wildland fires are allowed to burn if fuel load and vegetation composition are within the range of 

natural variability (NPS 2008). According to the NPS (2008), the preferred strategy for 

managing fire in the majority of the park is to allow natural processes to occur in order to 

perpetuate and maintain various ecosystems to the maximum extent possible. Naturally-ignited 

fires may burn so long as human life and property are protected and all wildland fires are limited 

to burning in a manner consistent with national policy. Fire is suppressed in the Elkhorn Ranch 

unit and prescribed fire is implemented when it is determined that it can accomplish

predetermined resource objectives (NPS 2008). Appendix A displays the areas burned in THRO 

from 1946 to 2010.

Fire Origin

Fires in the park are typically started by humans (non-prescribed), lightning, or are prescribed 

burns conducted by fire management and natural resource personnel (NPS 2003, Guyette et al. 

2011) (Appendix A). Another possible ignition source exists in the form of lignite (low-grade 

coal seams) (NPS 1999). THRO experiences very few lightning-ignited fires (0.00075 

fires/km2/yr) (Schroeder and Buck 1970, also reviewed by Guyette et al. 2011). Higgins (1984) 

found that between 1949 and 1981, THRO experienced an average of 1.09 lightning-caused fires 

per year. Lightning-caused fires occur most frequently in July and August (Hull Sieg and 

Fletcher 1998). Prescribed fire now accounts for the vast majority of area burned in THRO. 

From 1999 to 2010, prescribed fires accounted for 49 of the 106 fires, and 90% of the area 

burned. However, lightning-caused fires have been allowed to burn over larger areas in the last 

decade and appear more frequent in recent decades (Table 8). Table 6 shows the origin of 

recorded fires in the park from 1999 to 2010.

Table 8. Lightning-caused fire numbers and area by decade in THRO (NPS 2010b).

Decade No. of lightning-caused fires

Area

acres hectares

1950s 15 308 125

1960s 15 45 18

1970s 11 403 163

1980s 39 699 283

1990s 39 1,185 480

2000s 50 6,746 2,730
38

Intensity

Fires in mixed-grass prairie ecosystems are generally fast-burning surface fires that tend to leave 

a mosaic of burned and unburned vegetation (NPS 1999). One goal of THRO fire management is 

to minimize the occurrence of unnaturally intense fires by reducing hazard fuels. Intensity is the 

energy or magnitude of heat produced by a fire (Key and Benson 2006, Keeley 2008). Intensity 

is an indicator to fire managers of the potential effects of fire on soil and vegetation (i.e., fire 

severity) during prescribed burns. Intensity can be measured in two ways: downward penetration 

to the soil, or upward spread to vegetation and the atmosphere. Both measures are dependent on 

residual flame time and are a function of fuel and weather conditions (Key and Benson 2006). 

Mineral soil surface temperatures from grassland headfires increase as the amount of 

uncompacted fine fuels increases (Wright and Bailey 1982). Headfires spread with the wind, 

sometimes uphill; these are different from backfires, which are generally low and burn back into 

the wind slowly (Wright and Bailey 1982). When fuel availability on grasslands in the Great 

Plains range from 1,685 to 7,865 kg/ha, the average soil temperature during burning ranged from 

102° to 388° C (215° to 730°F). Wright and Bailey (1982) suggest that the highest soil surface 

temperatures occur from local accumulations of loosely arranged fuel types and strong winds 

created by fire. Air temperature, relative humidity, and soil moisture do not appear to affect 

surface soil temperature in grassland fires (Britton and Wright 1971, as cited by Wright and 

Bailey 1982).

Grasses have a high surface area to volume ratio and moisture is easily lost or gained as 

combustible material is exposed to the air. These properties result in grass fires that spread 

quickly and end abruptly (Anderson 1982). Grassland fuels also burn with faster rates of spread 

than other fuels during similar observed weather conditions (Anderson 1982). THRO contains 

grassland fuel model 1 (Anderson 1982), where spread of fire is controlled by cured and almost 

cured herbaceous fuels that are fine, porous, or continuous. As wind speed increases, model 1 

develops the fastest rate of spread within grassland models based upon the fine fuels, fuel load, 

and fuel depth relations. The fast rates of spread produce short periods of intense heat production 

in THRO (NPS 1999). 

Seasonality

The season in which a fire burns affects the diversity, density, and composition of the plant 

community (Biondini et al. 1989). Burning in different seasons can affect plants and animals 

differently due to their sensitivity to disturbance at various phenological or reproductive stages 

and seasonal differences in moisture regimes at the site (NPS 2003). Biondini et al. (1989) found

plot diversity of forb species in northern mixed-grass prairies decreased after fall and spring 

burns and remained the same following a summer burn. This same trend was also evident in 

areas left unburned. However, plots left unburned and those burned in the summer showed large 

decreases (54% and 60%, respectively) in density. Smaller declines in density were found in 

plots burned in the fall and spring (9% and 19%, respectively) (Biondini et al. 1989). Across the 

landscape, unburned, spring, and summer burn areas had random distribution patterns of forb 

regrowth, while plots burned in the fall showed high forb clustering (Biondini et al. 1989).

The fire season in THRO is primarily April through September. Prescribed fires usually are 

conducted in either spring or fall, though fire can be used at any time of year to achieve a 

particular management objective (NPS 1999). Wienk et al. (2007) generally recommends late 

summer or fall prescribed burning for areas dominated by native plant species in NGPN park 
39

units. However, Wienk et al. (2007) suggest that for areas dominated by cool-season species 

(e.g., Kentucky bluegrass [Poa pratensis], smooth brome [Bromus inermis], or crested 

wheatgrass [Agropyron cristatum]) spring burning tends to be more effective in reducing nonnative species cover.

Natural fires caused by lightning generally occur in the late spring to early autumn season (NPS 

1999). Since prescribed fire has been used in THRO, most larger fires (≥10 acres or 4 ha) have 

occurred in spring (April and May) and in late summer/fall (August, September, and October) 

(Table 9). Smaller fires (<10 acres) occur throughout the year. Other small fires occurring 

outside these months are typically accidental human-caused fires and suppressed lightningcaused fires.

Table 9. Number of fires by month for fires ≥ one acre and those ≥ 10 acres in THRO (NPS 2011b).

Number of fires

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

Period of record 1949 to 2010

≥ 1 acre 1 4 7 23 16 16 17 29 11 11 - 2

≥ 10 acres - - 3 18 6 3 3 10 7 6 - -

Period of record 1984 to 2010

≥ 1 acre 1 4 4 20 11 12 6 13 6 8 1 2

≥ 10 acres - - 1 16 6 1 1 4 3 6 - -

Changes in Native Vegetation after Prescribed Fires

Management goals for prescribed fires may include to reduce 1-hour dead and down fuels, 

decrease cover of non-native grasses, and increase cover of native grasses, forbs, and sedges. 

Accomplishing vegetation goals and obtaining anticipated results from prescribed fire depends 

largely on such variables as weather and moisture conditions (R. Skalsky, pers. comm., 2011). In 

particular, managers at THRO use prescribed fire to stimulate or manage the growth of the 

following native species: western wheatgrass (Pascopyrum smithii), green needlegrass (Nassella 

viridula), needle-and-thread (Hesperostipa comata), grama grasses (Bouteloua spp.), and common 

yarrow (Achillea millefolium).

Presently, the park contains too few monitoring plots to accurately and statistically measure 

changes in native vegetation in response to prescribed fires. However, the monitoring plots may 

provide possible trend and some insight to the degree of change, though no clear, causal 

relationships can be surmised. Rod Skalsky (pers. comm., 2012) observes that fire clearly 

impacts deciduous and brush species, but it is difficult to differentiate with any degree of 

certainty if changes in grasslands are due to fire, to grazing post-fire, or both. While it is most 

likely the latter, this complex relationship is difficult to measure statistically (Skalsky, pers. 

comm., 2012). Since 2011, the NGP Fire Ecology Program has been installing more sample plots 

within burn units at THRO in ordrer to increase precision and statistical confidence (D. Swanson, 

pers. comm., 2012). In addition, combined monitoring efforts and data from the NGP Fire 
40

Ecology Program and the NGP I&M Program will allow for greater statistical confidence in the 

future, allowing some of the variables to be statistically differentiated. For example, it is 

postulated that variables such as interannual total precipitation and seasonal precipitation may 

have the largest impact on resultant herbaceous diversity and cover. Likewise the timing of 

prescribed fires in terms of the park’s recent precipitation levels (i.e., whether the park is in a 

wet, normal, or droubt cycle) may significantly impact subsequent herbaceous species 

composition and cover (Swanson, pers. comm., 2012).

The NGP Fire Ecology Program established fire monitoring units in 1998 and 1999 based on 

dominant plant species. The NGP Fire Ecology Program established individual post-fire 

vegetation objectives for each monitoring unit. Each unit (named by dominant plant species) may 

be represented in several different burn units (e.g., I-94, Jones Creek, Little Missouri, River 

Corridor). Likewise, some burn units may contain various vegetation types, and therefore distinct 

monitoring units. There are 27 fire-monitoring plots in THRO (NPS n.d.). From 1999 to 2010, 22 

prescribed fires occurred, most in spring (Table 10). Wienk et al. (2007) summarized work 

completed by the NGP Fire Ecology Program from 1997 to 2007 for the prescribed burns in 

THRO and is presented in Table 10.
41

Table 10. Prescribed fire dates, season, and area burned in THRO (from Wienk et al. [2007] and updated 

using NPS [2011b]).

Unit Date(s) Season Size (acres) Size (hectares)

Little Missouri 9/21/99 Fall 650 263

SE Corner 4/19/99 Spring 475 192

SE Corner 4/11/00 Spring 331 134

NW Corner 10/18-21/01 Fall 700 283

Little Mo II 5/13/02 Spring 800 324

Peaceful Valley 5/29/02 Spring 18 7

Skyline Vista 10/9/02 Fall 534 216

I-94 10/10/02 Fall 300 121

Cottonwood CG 4/25/03 Spring 250 101

I-94 5/2/03 Spring 250 101

SE Corner 4/23/04 Spring 910 368

Monitoring results of the above prescribed fires are listed in the following section, the prescribed fires listed 

below are not yet reported for all monitoring unit types

Horsecamp 4/24/07 Spring 92 37

Loop 1 4/17/07 Spring 17 7

Loop 2 4/17/07 Spring 25 10

Loop 3 4/17/07 Spring 6 2

Loop 4 4/17/07 Spring 44 18

Loop 5 4/24/07 Spring 40 16

Radiotower 10/04/07 Spring 95 38

Loop 6 4/13/08 Spring 40 16

Loop 7 4/13/08 Spring 93 38

Loop 8 4/13/08 Spring 20 8

Loop 9 4/13/08 Spring 70 28

NW Corner 1 10/09/08 Spring 70 28

NW Corner 2 10/09/08 Spring 327 132

NW Corner 3 10/09/08 Spring 297 120

Elkhorn Ranch 1 5/07/09 Spring 3 1

Elkhorn Ranch 2 5/07/09 Spring 11 4

Elkhorn Ranch 3 5/07/09 Spring 4 2

Juniper Campground No date Spring 150 61

Loop Unit 1 No date Spring 11 4

North Loop Burn 5/03/09 Spring 150 61

SE Corner 6 4/22/10 Spring 250 101

Sheep 9/14/11 Fall 3641 1474

Longhorn Flats 9/16/11 Fall 460 186

D. Swanson (pers. comm., 2012) suggests that project based plot monitoring is more informative 

to park managers on whether objectives are met for each prescribed fire, since prescribed fires 

occur in both the spring and fall and occur under different temperatures and moisture conditions. 

Starting in 2011, the NGP Fire Ecology Program has been installing a greater number of plots 

within each burn unit to address changes to the vegetation composition and cover at the project 

level.

Crested Wheatgrass (AGCR)

Monitoring units for the non-native crested wheatgrass only exist within the Southeast Corner / I94 prescribed burn unit. Crested wheatgrass and the invasive smooth brome are the dominant 
42

species found in this mostly non-native vegetation unit. The I-94 prescribed fire objectives were 

to burn 60-90% of project area and reduce fuel loads by 50-85% immediately after the burn. The 

goals for changes in post-burn vegetation are as follows:

Immediate post-burn:

 Burn 60-90% of project area;

 Reduce fuel load by 50-85%.

Two years post-burn:

 Reduce non-native grasses by at least 20%;

 Increase native grass cover by at least 20%;

 Keep hardwood mortality to less than 10%.

Five year post-burn:

 Maintain a reduction of non-native species;

 Maintain the increase in native species.

Two-year objectives were partially attained in that non-native grasses decreased by 43%. 

However, native grasses decreased by 39%. Five-year objectives were not met as non-native 

grasses were only 11% lower than the pre-burned state and native grasses were 5% lower than 

the pre-burned state. Western wheatgrass was unchanged after one year and decreased two years 

after the burn. Precipitation is suspected to have affected the re-growth percentages (Wienk et al. 

2007).

The Southeast Corner prescribed fire of 1999 had a pre-burn objective to reduce 1-hour decadent 

fuels by at least 70%. Paintner and Pindel (1999) state this goal was not met and suggest that it 

may have been unrealistic. Thorstenson and Schmitt (2004) indicate that 70-90% of the area 

burned during the 2004 Southeast Corner prescribed fire and the immediate fuel load goal was 

met in blocks (sections of the fire) F, G, and H.

Silver sagebrush shrubland (ARCA)

Four prescribed fire units contain plots for this monitoring unit; two plots burned in 1999 and 

two in 2002.

Immediate post-burn objectives:

 Burn 60-90% of the available project area.

Two years post-burn:

 Reduce silver sagebrush density by 40-60%;

 Increase native herbaceous cover by 20%;

 Reduce non-native cover by 25%, and increase native perennial grass cover by at least 

25%.

Five years post-burn:
43

 Maintain the reduction of shrub density;

 Increase native species;

 Maintain a reduction in non-native species.

The reduction of silver sagebrush density was reached for the two-year post-burn objectives, 

while the increase and reduction goals of native and non-native species were not met. However, 

five years post-burn, non-native grass cover decreased by 55%, while native grass and forb cover 

increased by 18% and 45%, respectively (Wienk et al. 2007).

Cottonwood/Rocky Mountain juniper forest (PODE)

Of the three plots installed for monitoring these forests, two have been burned. Post-burn 

vegetation objectives are:

Immediate post-burn:

 Reduce total fuel loading by 60-80%.

Two years post-burn:

 Reduce total brush density by 30-50%;

 Reduce conifers by 50-70%,

 Acceptable mortality of deciduous overstory trees was 20%.

The Little Missouri II fire decreased total fuel loads by 17% immediately post-burn and total fuel 

load actually increased by 38% at five-year post-burn measurements. However, significant 

decreases in pole-sized stems/acre (from ~90 stems/acre pre-burn to ~15 stems/acre year five) 

were realized at 5 years in this burn unit for cottonwood and very few overstory trees were 

reduced. Conifers were not evaluated in Wienk et al. (2007) for this burn unit.

Green needlegrass mixed-grass prairie (STVI)

Ten plots were installed for the monitoring of this unit; three have burned in the Southeast 

Corner unit and three have burned in the Northwest Corner unit. The Southeast Corner unit is 

dominated by Kentucky bluegrass, whereas the Northwest Corner unit is a more appropriate unit 

to assess the condition of green needlegrass plots, as native species are dominant (Wienk et al. 

2007). Post-burn vegetation objectives are:

Immediate post-burn:

 Reduce thatch by 20-30%.

Two years post-burn:

 Reinvigorate native species and decadent vegetation;

 Reduce brush species;

 Restore and maintain native plant communities;

 Reduce non-native cover by at least 20 to 30%;

 Increase native perennial grass cover by at least 20 to 30%;
44

 Reduce brush by 20 to 30%;

 Increase native herbaceous and shrub cover by 20 to 30%.

Immediate visual estimates of the Northwest Corner fire in 2001 found that about 50% of the 

thatch was removed (Rehman and Thorstenson 2001). Based on the Northwest Corner prescribed 

fire monitoring report, none of the two-year objectives were met (Wienk et al. 2007). While nonnative grass cover was reduced by 53%, non-native forb cover increased by 100%. Five years 

after burning, native grass cover had increased by 40% (Wienk et al. 2007).

Snowberry shrub land (SYOC)

As of 2007, one plot was installed to monitor this mixed-grass prairie vegetation type.

Immediate post-burn:

 Reduce silver sagebrush density by 40-60%.

Two year post-burn:

 Reduce non-native cover by at least 25%;

 Increase native perennial grass cover by at least 25%;

 Reduce silver sage by 50%;

 Reduce total fuel load by 75%.

Immediate post burn goals were inconclusive and silver sage reduction was the only two-year 

post burn objective attained (Wienk et al. 2007).

A park-wide summary of fire monitoring plots in THRO through 2007 indicated that 16 plots 

were burned and 15 of them were visited five years post-burn (Figure 2) (Wienk et al. 2007).

Figure 2. Pre-burn and post-burn percent cover of native and non-native plant species (average of 15 

monitoring plots). Reproduced from Wienk et al. (2007).
45

Since Wienk et al. (2007), several treatments (fires) have been conducted in THRO. Decreases in 

the percent cover of nonnative grasses and increases in both native grass and sedges occurred in 

the Southeast Corner burn unit (which contains three green needlegrass monitoring plots) (Figure 

3). Kentucky bluegrass showed the most notable decrease in cover of five major non-native 

grasses.

Figure 3. Southeast Corner burn unit changes in percent cover by life form following multi-year, multiburn, prescribed fire treatments in THRO.

Similar decreases in non-native grasses and increases in native grasses and sedges also were 

reported in the Northwest Corner burn unit following multiple fire treatments (Figure 4). 

However, it is not clear how the additional influence of livestock and ungulate grazing may 

influence the results of any post-burn measurements.

0

20

40

60

80

100

120

140

160

Non-native forb Native forb Non-native grass Native grass Sedge

Cover (%)

SE Corner - Cover by Lifeform

Pre-burn Trt 1 Yr 1 Trt 1 Yr 2 Trt 2 Yr 1 Trt 2 Yr 2 Trt 2 Yr 5 Trt 3 Yr 1
46

Figure 4. Northwest Corner burn unit changes in percent cover by life form following multi-year, multitreatments (fires) in THRO.

Overall, shrub density objectives for both silver sagebrush and western snowberry were achieved 

in the Little Missouri burn unit, though at ten years post-burn, a slight increase occurred in silver 

sagebrush density from initial post-burn measurements (Figure 5).

Figure 5. Shrub density changes post-fire in the Little Missouri burn unit.

0

50

100

150

200

250

Non-native forb Native forb Non-native grass Native grass Sedge

Cover (%)

NW Corner - Cover by Lifeform 

Pre-burn Trt 1 Yr 1 Trt 1 Yr 2 Trt 1 Yr 5 Trt 2 Yr 1 Trt 2 Yr 2

0

5000

10000

15000

20000

25000

30000

Silver sagebrush Western snowberry

Stems / acre

Shrub Density

Pre-burn Year 1 Year 2 Year 5 Year 10
47

Threats and Stressor Factors

Fire suppression and development adjacent to the park were identified by park managers as 

threats or stressors to the fire regime in THRO. Throughout the early to mid-1900s, fire 

suppression was practiced throughout the northern Great Plains region to protect private property 

and resources. This prevents the natural extent and frequency from occurring, especially in the 

case of large landscape-scale fires.Suppression of nearly all unplanned fires continues as a part 

of the THRO Fire Management Plan, creating a situation in which the fire regime is almost 

completely dependent upon prescribed burning and non-fire fuel treatments.

Increased development adjacent to the park increases the opportunity for fires occurring within 

the park to destroy private property or structures and threaten human life should a fire escape 

park boundaries. This increased risk to private property elevates the need to suppress natural 

fires and requires deliberate, careful planning of prescribed fires in the park in order to achieve 

fire management goals while preserving park structures and private property. As a result, largescale fires are rare in the region and occur at a lower frequency.

Data Needs/Gaps

Immediate monitoring and reporting of burn intensity and severity will assist managers to further 

understand fire’s effects on vegetation. Continued capture/delineation of fire perimeters using 

GPS data (adding to 10 years of consistent data collection) will give managers a clear 

understanding of fire history in each burn unit, and will illustrate areas of the park that have not 

experienced prescribed fire for long periods. Continued and consistent monitoring of established 

vegetation plots will provide a better understanding of the fire effects on vegetation as well as a 

way to determine if management objectives are being met. With additional plots within burn 

units and in combining NGP Fire Ecology Program and NGP I&M data vegetation plots may 

also allow managers to correlate different fire management parameters (e.g., season, fuel loads, 

or weather conditions) with the desired vegetation outcomes.

Overall Condition

Fire over the last several decades in THRO has been managed either through suppression 

(accidental fires or in some cases of lightning-caused) or through prescribed fires. While the 

following measures characterize the present-day fire regime in the park, prescribed fire has 

almost completely replaced natural-start fires. Prescribed fires are set to achieve desired effects 

on vegetation and soils. Therefore, the effects of fire may be considered a more important 

measure of fire’s condition in THRO than various parameters of fire occurrence in the park. The 

desired effects vary by individual burn unit, monitoring unit, and by fire. Understanding how fire 

parameters (e.g., intensity, severity, flame length, wind) influence the effects of burning will 

assist park staff in meeting their management objectives.

Frequency

The Significance Level for frequency is a 3. A fire behavior model suggests that the park should 

have fire-return intervals of 5 to 30 years. However, some areas of THRO do not burn for 100 to 

200 years. For this reason, Condition Level for frequency is a 2, indicating the component is of 

moderate concern.
48

Extent - Area Burned

The Significance Level for area burned is a 3. There is not a target established for number of 

acres to be burned annually in the park. However, some areas in the park have not experienced 

fire in over 200 years, and the declining fuel budget is likely to further decrease the average 

extent burned per year (R. Skalsky, pers. comm., 2011). Thus, the Condition Level for extent of 

area burned is a 2, indicating the condition is of moderate concern.

Intensity

The Significance Level for intensity is a 2. Intensity is measured by the rate of spread and flame 

length. Prescribed fires are heavily monitored and managed during burns and wildfires are 

monitored and sometimes suppressed, depending on location, suppression support, and weather 

conditions. Since managers extinguish fires that are behaving unfavorably, the Condition Level

for intensity is a 0, indicating the component is of no concern.

Severity

The Significance Level for severity is a 2. Fires that burn too hot will destroy vegetation 

completely and damage soils; thus, personnel will extinguish a prescribed fire that has the 

potential to become too severe. The majority of fires in THRO had a reported severity of 

“scorched”, “low”, or “moderate,” largely due to the controlled nature of the fires. The Condition 

Level of severity is a 0, indicating the component is of no concern. This is because fire personnel 

generally control severity, and to date overall severity has been low.

Seasonality

The Significance Level for seasonality is a 2. Prescribed fires usually occur in the fall and spring 

but fire can be used during any season to meet management goals. Since most fires in THRO are 

prescribed, and wildfires only burn a few acres at a time and have minimal effects on vegetation

park-wide, the Condition Level for seasonality is a 0, indicating no concern. The appropriate 

season in which to use prescribed fire to achieve a particular set of objectives (e.g., reducing 

non-native cool season grasses) continues to be a topic of research. Fire effects monitoring 

results will aid in answering this general research question.

Fire Origin

The Significance Level for fire origin is a 2. The Condition Level for fire origin is a 0, indicating 

no concern because 93% of the acres burned since 1984 are of prescribed origin. Since 2000, 

only five human-caused fires have occurred in the park, burning a total of six acres. Wildfires 

generally are suppressed because they are less predictable, and therefore pose threats to property 

within and adjacent to THRO; however, larger areas have burned from 1999 to 2010 due to 

natural wildfire. 

Changes in Native Vegetation

The project team defined the Significance Level for changes in native vegetation as a 2. The 

Condition Level for changes in native vegetation is also a 2, indicating that the component is of 

moderate concern. Weather and moisture variables affect both the way prescribed fires burn and 

the results from prescribed fires. Most immediate prescribed fire goals have been met, while twoyear and five-year goals are sometimes met. Some progress has been realized as is evidenced by 

10-year post-fire effects (e.g., continued reductions in shrub densities).
49

Weighted Condition Score

The Weighted Condition Score (WCS) for the fire component is 0.333 indicating the condition is 

in good condition with a stable trend.

4.1.6 Sources of Expertise

Rod Skalsky, Fire Management Officer, THRO

Dan Swanson, Fire Ecologist, WICA

Chad Sexton, Geographic Information Systems Analyst, THRO
50

4.1.7 Literature Cited

Anderson, H. E. 1982. Aids to determining fuel models for estimating fire behavior. General 

Technical Report Int-122. U.S. Forest Service, Intermountain Forest and Range Experiment 

Station, Ogden, Utah. 

Biondini, M. E., A. A. Steuter, and C. E. Grygiel. 1989. Seasonal fire effects on the diversity 

patterns, spatial distribution and community structure of forbs in the Northern Mixed Prairie, 

USA. Vegetation 85:21-31.

Cutter, B. E., and R. P. Guyette. 1994. Fire frequency on an oak-hickory ridgetop in the Missouri 

Ozarks. The American Midland Naturalist 132:393-398.

Freeman, J. 2008. Loop prescribed fire monitoring report. National Park Service, Theodore 

Roosevelt National Park, Medora, North Dakota.

Guyette, R. P., M. C. Stambaugh, and J. M. Marschall. 2011. A quantitative analysis of fire 

history at national parks in the Great Plains. A report prepared for the National Park Service

and the Great Plains Cooperative Ecosystem Studies Unit, Lincoln, Nebraska.

Higgins, K. F. 1984. Lightning fires in North Dakota grasslands and in pine-savanna lands of 

South Dakota and Montana. Journal of Range Management 37(2):100-103. 

Hull Sieg, C., and R. Fletcher. 1998. Fire nourishes biological diversity in the Northern Great 

Plains. Forestry Research West 4/98:28-32.

Keeley, J. E. 2008. Fire intensity, fire severity and burn severity: a brief review and suggested 

usage. International Journal of Wildland Fire 18:116-126.

Key, C. H., and N. C. Benson. 2006. Landscape assessment. In Lutes, D. C., R. E. Keane, J. F. 

Caratti, C. H. Key, N. C. Benson, S. Sutherland, and L. J. Gangi. FIREMON: Fire effects 

monitoring and inventory system. General technical report RMRS-GTR-164-CD. U.S. Forest 

Service, Rocky Mountain Research Station, Fort Collins, Colorado. 

Koller, M., and J. Freeman. 2008. Northwest corner prescribed fire monitoring report. National 

Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

Lund, M. 2007. Radio Tower RX: Prescribed fire monitoring report. National Park Service, 

Theodore Roosevelt National Park, Medora, North Dakota.

Mitchell, K. 2007. Horse Camp and Loop 5 prescribed fire monitoring report. National Park 

Service, Theodore Roosevelt National Park, Medora, North Dakota.

Monitoring Trends in Burn Severity (MTBS). 2011a. MTBS methods. 

http://www.mtbs.gov/methods.html (accessed 30 June 2011).

Monitoring Trends in Burn Severity (MTBS). 2011b. MTBS data access. 

http://www.mtbs.gov/dataquery/customquery.html (accessed 30 June 2011).
51

National Park Service (NPS). n.d. Fire effects monitoring plan. National Park Service, Theodore 

Roosevelt National Park, Medora, North Dakota.

National Park Service (NPS). 1999. Theodore Roosevelt National Park fire management plan. 

National Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

National Park Service (NPS). 2003. Fire monitoring handbook. National Park Service, National 

Interagency Fire Center, Boise, Idaho. 

National Park Service (NPS). 2008. Theodore Roosevelt National Park fire management plan. 

National Park Service, Medora, North Dakota.

National Park Service (NPS). 2010a. Fire management. 

http://www.nps.gov/thro/parkmgmt/firemanagement.htm (accessed 29 Jul 2011).

National Park Service (NPS). 2010b. fire_history.gdb. geodatabase. GIS data. Received from 

Rod Skalsky. Theodore Roosevelt National Park, Medora, North Dakota.

Paintner, K., and K. Pindel. 1999. Southeast corner prescribed fire monitoring report. National 

Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

Rehman, K., and A. Thorstenson. 2001. Northwest corner prescribed fire monitoring report. 

National Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

Sorbel, B., and J. Allen. 2005. Space-based burn severity mapping in Alaska’s national parks. 

Alaska Park Science 4(1):4-11.

Thorstenson, A., and T. Schmitt. 2004. Southeast/I-94 prescribed fire monitoring report. National 

Park Service, Theodore Roosevelt National Park, Medora, North Dakota.

Umbanhowar, C. E., Jr. 1996. Recent fire history of the northern Great Plains. The American 

Midland Naturalist 135(1):115-121.

Wienk, C., A. Thorstenson, J. Freeman, and D. Swanson. 2007. Northern Great Plains fire 

ecology: 1997-2007 program review. National Park Service, Northern Great Plains Fire 

Ecology Program, Wind Cave National Park, South Dakota.

Wright, H. A., and A. W. Bailey. 1982. Fire ecology: United States and southern Canada. John 

Wiley and Sons Inc., Hoboken, New Jersey.
52

4.2 Wind and Water Erosion

* During initial project scoping, project stakeholders identified wind and water erosion as 

important processes within the park, but little or no data exist to examine their current condition. 

Thus, no data will be summarized nor will the condition of erosion be assessed. Rather, a brief 

overview of the component and a description of potential measures, threats, and stressors are 

provided for the primary purpose of inclusion in a future assessment when appropriate data are 

available.

4.2.1 Description

Wind and water erosion are natural processes that have shaped the landscape of THRO, 

particularly the dramatic geological formations of the badlands. Erosion rates on the badlands 

slopes of western North Dakota have been estimated at 0.28-1.04 cm/year (Tinker 1970 and 

Bluemle 1975, as cited by Von Loh et al. 2000). Factors that influence erosion rates include 

lithology, slope gradient (steepness), and vegetative cover (Butler et al. 1985, KellerLynn 2007). 

The presence of bentonite (a clay material that swells when wet) in a rock formation increases its 

susceptibility to erosion. Bentonite is common in the Sentinel Butte Formation of THRO, where 

most landsliding occurs in the park (KellerLynn 2007). Slope gradient influences water 

infiltration, especially of runoff water, therefore affecting erosion rates (Butler et al. 1985). 

Finally, vegetative cover plays a key role in protecting surfaces from wind, rainsplash, and 

runoff (Wei et al. 2009, Munson et al. 2011).

One significant erosional process of concern to park managers is mass wasting, which is the 

downslope movement of soil and rock material by gravity (e.g., landslides, slumping, soil creep) 

(NPS 2003, KellerLynn 2007). This movement, sometimes sudden and dramatic, can threaten 

park roads, trails, and visitor facilities (NPS 1986). For example, significant slumping due to 

above normal precipitation in 2011 led to the closure of a portion of road in the North Unit 

through Cedar Canyon, as it was deemed unsafe for visitors (Laurie Richardson, THRO Botanist, 

e-mail communication, 2012). Mass wasting in THRO occurs primarily as landslides and soil 

creep (Biek and Gonzalez 2001). Evidence of landslides is common in the North Unit, where 

“rotational slumps” are apparent in several locations (Photo 7). Large slumps with hummocky 

surfaces occur along the Little Missouri River, with the largest occurring on the north flank of 

the Achenbach Hills near Achenbach Spring (Biek and Gonzalez 2001). Another notable 

rotational slump can be found north of the river between the east entrance and Juniper 

Campground. The largest landslides in the South Unit occur along the eastern escarpment, on the 

eastern flank of the Petrified Forest Plateau, and around Buck Hill. Also in the South Unit, soil 

creep is common on steep slopes of the Bullion Creek Formation with north or northeast aspects 

(Biek and Gonzalez 2001).
53

Photo 7. A small landslide in Sentinel Butte strata (left) and a large rotational slump in the North Unit 

(right) (Biek and Gonzalez 2001).

Other erosional processes in the park include rill and gully erosion, common in basal sandstone 

of the Sentinel Butte formation, and piping (KellerLynn 2007). Piping occurs “when surface 

runoff erodes vertically downward through poorly lithified sediments”, creating a network of 

tunnels, small caves, and pseudokarst features that channel runoff underground (Biek and 

Gonzalez 2001, p. 56). It is common in poorly lithified bedrock and associated colluvial, alluvial, 

and landslide deposits, which regularly occur at or near the bottom of steep badlands slopes 

(Biek and Gonzalez 2001). These pipes can eventually collapse, potentially causing subsidence 

or rockslides that could threaten nearby roads or structures. 

Another erosion-related threat to the park is the exposure of lignite beds (also known as “brown 

coal”), which can ignite when exposed to air and trigger fires (Biek and Gonzalez 2001). Once 

ignited at the surface, lignite often burns back into the hillside or formation, creating an empty 

space into which overlying beds settle or collapse. Significant burning and subsidence occurred 

in the Buck Hill area from the early 1950s through the 1970s (Biek and Gonzalez 2001). No 

lignite beds were burning in THRO as of 2007, but several small fires occurred in the South 

Unit’s northeastern corner during the late 1980s and early 1990s (KellerLynn 2007). However, 

outcrops of lignite are a constant concern for the park’s fire management program and can 

influence park planning and management (KellerLynn 2007). 

4.2.2 Measures

 Changes in landscape features

 Amount of material removed (erosion rates)

4.2.3 Reference Conditions/Values

A reference condition for wind and water erosion in the park has not been determined.

4.2.4 Data and Methods

Information regarding erosion in the park was primarily found in Biek and Gonzalez (2001) and 

the THRO Geologic Resources Evaluation Report (KellerLynn 2007). Numerous journal articles 

were consulted regarding the impact of climate on erosional processes. 
54

4.2.5 Current Condition and Trend

Changes in Landscape Features

Wind and water erosion are constantly changing the landscape of THRO. However, no research 

or consistent monitoring of these changes has occurred. 

Amount of Material Removed (Erosion Rates)

To date, no current or historical data are available for erosion rates in the park. 

Threats and Stressor Factors

Climate is a critical factor in erosional processes, especially in semiarid regions (Kuehn 2003, 

Graham 2008). According to Wei et al. (2009, p. 308), “rainfall is the initial and essential driving 

force for natural runoff generation and erosion variation.” Climate variables also impact 

vegetation patterns, which in turn influence erosion across the landscape. An increase in 

precipitation generally is thought to increase erosion rates (as reviewed by O’Neal et al. 2005). A 

decrease in precipitation therefore would be expected to reduce erosion rates; however, a 

reduction in precipitation could reduce vegetative cover, increasing the surface area exposed to 

rainfall and runoff (Clarke and Rendell 2010). A reduction in vegetative cover may increase the 

soil’s exposure to wind erosion as well (Munson et al. 2011). The frequency of precipitation can 

also impact erosional processes. Wei et al. (2007) found that rainfall regimes with strong 

intensities and low frequencies induced more severe runoff and soil erosion than regimes with 

weak intensities and high frequencies.

In semi-arid badlands like those found at THRO, “the ephemeral nature of precipitation and 

runoff means that change is particularly associated with extreme events” (Faulkner 2008, p. 92). 

Rain often comes in sudden showers that can drop several inches per hour (Opdahl et al. 1975, as 

cited by KellerLynn 2007); the resulting runoff typically causes rapid erosion. Heavy downpours 

have increased in frequency and intensity across the U.S. over the past several decades, a trend 

that is expected to continue throughout this century (Karl et al. 2009).

Erosion also can be exacerbated by road construction and trail use. Movement is still occurring 

in landslide deposits under several roads in the park, causing buckled pavement and dips in the 

roads (Biek and Gonzalez 2001). For example, the North Unit’s scenic drive crosses several 

landslide deposits between the Concretion Pullout and the Highway 85 junction. In the South 

Unit, the park road crosses landslides near the Ridgeline Trail trailhead and along the Buck Hill 

road (Biek and Gonzalez 2001, KellerLynn 2007). Disturbance caused by repair activities such 

as placing fill, regrading, or rerouting drainage in these deposits may actually increase instability 

(Biek and Gonzalez 2001, KellerLynn 2007). Intense trail use or poor trail design often result in 

soil erosion and trampled vegetation (NPS 1994). In some places, trails have become deep 

channels that actually concentrate runoff, further exacerbating erosion. The eroded material can 

then impact vegetation and soils in previously undisturbed areas along the trail (NPS 1994).

Data Needs/Gaps

No research has been conducted in the park regarding either changes in landscape features or 

erosion rates. A multi-year study of erosion rates using a variety of sampling techniques (e.g., 

survey stakes and pins, sediment erosion traps, photogrammetry, LiDAR) is currently underway 

at Badlands National Park in South Dakota (Stetler and Benton 2011). The results of this study, 
55

which is scheduled for completion in 2012, could help THRO design an erosion survey and 

monitoring plan. 

Overall Condition

Due to a lack of information and data regarding erosion rates and erosional landscape changes in 

the park, the overall condition of wind and water erosion cannot be assessed at this time.

4.2.6 Sources of Expertise

Bill Whitworth, Chief of Resources, THRO
56

4.2.7 Literature Cited

Biek, R. F., and M. A. Gonzalez. 2001. The geology of Theodore Roosevelt National Park, 

Billings and McKenzie counties, North Dakota. Miscellaneous Series 86. North Dakota 

Geological Survey, Bismarck, North Dakota.

Bluemle, J. P. 1975. Guide to the geology of southwest North Dakota. North Dakota Geological 

Survey Educational Series 9. North Dakota Geological Survey, Grand Forks, North Dakota.

Butler, J., H. Goetz, and J. L. Richardson. 1985. Vegetation and soil – landscape relationships in 

the North Dakota badlands. American Midland Naturalist 116(2):378-386.

Clarke, M., and H. Rendell. 2010. Climate-driven decrease in erosion in extant Mediterranean 

badlands. Earth Surface Processes and Landforms 35:1281-1288.

Graham, J. 2008. Badlands National Park geologic resource evaluation report. Natural Resource 

Report NPS/NRPC/GRD/NRR-2008/036. National Park Service, Denver, Colorado.

Karl, T., J. Melillo, and T. Peterson. 2009. Global climate change impacts in the United States. 

Cambridge University Press, New York, New York.

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. National Park Service, Denver, 

Colorado.

Kuehn, D. 2003. Preliminary geoarcheological reconnaissance in Badlands National Park, South 

Dakota. National Park Service, Midwest Archeological Center, Lincoln, Nebraska.

Munson, S., J. Belnap, and G. Okin. 2011. Responses of wind erosion to climate-induced 

vegetation changes on the Colorado Plateau. Proceedings of the National Academy of 

Sciences 108(10):3852-3859.

National Park Service (NPS). 2003. Explore geology – mass wasting. 

http://www.nature.nps.gov/geology/hazards/mass_wasting.cfm (accessed 7 February 2012).

O’Neal, M., M. Nearing, R. Vining, J. Southworth, and R. Pfeifer. 2005. Climate change impacts 

on soil erosion in Midwest United States with changes in crop management. Catena 61:165-

184.

Opdahl, D. D., W. F. Freymiler, L. P. Haugan, R. J. Kukowski, B. C. Baker, and J. G. Stevens. 

1975. Soil survey of Bowman County, North Dakota. U.S. Soil Conservation Service, North 

Dakota State Office, Bismarck, North Dakota.

Stetler, L., and R. Benton. 2011. Determine erosion rates at select fossil sites to develop a 

paleontological monitoring program. Unpublished study and implementation plan. Badlands 

National Park, Interior, South Dakota.

Tinker, J. R. 1970. Rates of hillslope lowering in the badlands of North Dakota. Dissertation. 

University of North Dakota, Grand Forks, North Dakota.
57

Wei, W., L. Chen, B. Fu, D. Wu, and L. Gui. 2007. The effect of land uses and rainfall regimes 

on runoff and soil erosion in the semi-arid loess hilly area, China. Journal of Hydrology 

335:247-258.

Wei, W., L. Chen, and B. Fu. 2009. Effects of rainfall change on water erosion processes in 

terrestrial ecosystems: a review. Progress in Physical Geography 33(3):307-318. 
58

4.3 Flooding (Little Missouri River)

4.3.1 Description

The Little Missouri River is a tributary of the Missouri River, which begins in northeastern 

Wyoming and flows through all three units of THRO (through 14 km of the South Unit, 23 km 

of the North Unit, and through Elkhorn Ranch) (Miller 2005, KellerLynn 2007). Peak flows of 

the Little Missouri River in the 20th century were lower than in previous centuries; regardless, 

they have subsequently altered floodplain formation (Miller and Friedman 2009). These overall 

decreases in peak flows are postulated to be a result of climatic shifts (changes in precipitation 

and temperature), as the Little Missouri River is mostly unregulated (Miller and Friedman 2009). 

Despite the overall decrease in peak flow magnitude, several park features (Cottonwood and 

Juniper Campgrounds, Peaceful Valley Ranch, South Unit Park Headquarters, and portions of 

park roads) are located within 

the 100-year floodplain, 

leaving a 1% chance each 

year that these features will 

be in the river’s inundation 

zone (KellerLynn 2007). In 

May 2011, the Little Missouri 

River experienced significant 

flooding in THRO and the 

surrounding area following 

heavy spring rain events. 

The National Weather Service 

defines a flood as “any high 

flow, overflow, or inundation 

by water which causes or 

threatens damage (NWS 

2012).” The National Weather 

Service defines gage heights 

that correspond to flooding events at certain gages. For the Little Missori River, two gages are 

most relevant to THRO, one at Medora and one near Watford City (Plate 1). The gage heights 

that represent flooding events at these sites do not correspond to flooding events in the park for 

all high-water events though; in 2011, a high-water event occurred that caused substantial 

flooding in the park, yet the gage height at Watford City did not correspond to a flood event as 

defined by the National Weather Service.

4.3.2 Measures

 Frequency

 Magnitude

 Duration

 Effects of upstream water withdrawal on summer low flows

 Snow pack

Photo 8. Record flooding on the Little Missouri River in May 2011 as 

viewed from the MP 27 loop road in the South Unit, THRO (NPS 

photo).
59

4.3.3 Reference Conditions/Values

The reference condition for flooding is the range of variation since the beginning of data 

collection (1904 and 1935 for Medora and Watford City, ND, respectively).

4.3.4 Data and Methods

Literature provided by THRO (Emerson and Macek-Rowland 1986; KellerLynn 2007; Miller 

2005; Miller and Friedman 2009) and USGS stream gage statistics (USGS 2011a, b, c) were the 

main sources of information for this assessment. Two USGS gage sites were utilized for this 

assessment: Little Missouri River at Medora, ND (USGS Station No. 06336000) and Little 

Missouri River at Watford City, ND (USGS Station No. 06337000). The Medora gage is 

indicative of streamflow characteristics near the South Unit and the Watford City gage is 

indicative of streamflow in the North Unit; there is no stream gage near the Elkhorn Ranch Unit 

of THRO.

4.3.5 Current Condition and Trend

Frequency

Peak flows in the Little Missouri River occur in late March and early April of each year, with 

periodic summer high flows occurring in May through July. Spring peak flows are generally a 

result of snowmelt, but can also result from rain and the breaking up of river ice; summer high 

flows are generally the result of intense thunderstorms (Miller and Friedman 2009). High-flow 

events causing significant floodplain destruction occur every five to ten years on the Little 

Missouri River (Miller and Friedman 2009). Frequent flooding increases erosion and causes 

changes to the channel area, which is important for establishment and regeneration of 

cottonwoods (Populus deltoides). 

Magnitude

Over the last century, there has been a reduction in the magnitude of peak flows on the Little 

Missouri River (Miller and Friedman 2009). Since the Little Missouri River is largely 

unregulated, climatic factors, such 

as temperature and precipitation, 

are thought to be the primary driver 

in the overall reduction in peak 

flow magnitude during the 20th

century. 

Discharge has been monitored 

since 1935 (North Unit) and 1904 

(South Unit), and the overall 

average annual peak flow of the 

Little Missouri River was 15,122 

cfs (mean discharge = 535 cfs) 

(Miller 2005, Miller and Friedman 

2009). However, there are many 

gaps in the available data for the 

South Unit. The largest recorded 

instantaneous peak flow of the 

Photo 9. Flooding on the Little Missouri in May 2011 as viewed 

from the Medora Overlook in the South Unit, THRO (NPS photo).
60

Little Missouri River occurred in 1947, with a peak discharge of 110,000 cfs (Miller and 

Friedman 2009). This 1947 flood was seven times larger than the average annual peak flow on 

the Little Missouri River, and reached a peak height of 20.5 ft at Medora, 5.5 ft above the 

National Weather Service 15-foot Flood Stage (USGS 2011a). The second largest recorded flood 

occurred in 1950, with a peak discharge of 60,000 cfs. Recently, in May of 2011, a high-water 

event occurred; stage height of this event reached 16.70 feet and discharge reached 30,000 cfs at 

the Watford City gage (USGS 2012). At the same time, the stage height exceeded the flood stage 

(15 ft) at Medora, reaching a height of 20.39 ft with a discharge of 35,100 cfs. For the period of 

recorded streamflow, “peak flows along the Little Missouri River have declined over time and 

the active channel area has decreased by 38% since 1939” (Miller and Freidman 2009, p. 754). 

Peak discharge is an important driver of erosion and channel migration (Miller 2005), which are 

both necessary for cottonwood establishment. Therefore, a decrease in flood magnitude could be 

problematic for cottonwood forests. Table 11 displays peak discharge for the Little Missouri 

River at the North and South Units of THRO, along with other tributaries of the Little Missouri 

River. Annual peak flow data recorded at the Medora, ND and Watford City, ND gages are 

included in Appendices A and B, respectively.

Table 11. Flood discharges for the Little Missouri River and tributaries in THRO. Discharges in cfs; 

maximum water-surface elevations are in feet above sea level (asl) (Emerson and Macek-Rowland 1986).

Peak recorded 

discharge

Maximum watersurface elevation Date

100-year 

flood 

discharge

500-year 

flood 

discharge

North Unit 110,000 cfs 1,953.03 ft asl 25 March 1947 78,800 cfs 113,500 cfs

South Unit 65,000 cfs 2,267.25 ft asl 23 March , 1947 65,300 cfs 99,300 cfs

Elkhorn Ranch No data No data n/a 69,000 cfs 103,000 cfs

Knutson Creek No data No data n/a 31,800 cfs

Paddock Creek No data No data n/a 13,500 cfs

Squaw Creek No data No data n/a 24,600 cfs

North Unit

Figure 6 represents peak discharge at the Watford City USGS stream gage near the North Unit of 

THRO. This stream gage gathers continuous data, with no data gaps, making overall trends 

discernable. Since 1980, no higher peak discharges have occurred, such as those seen in 1947, 

1950, 1952, and 1972. 
61

Figure 6. Peak discharge (cfs) for the Little Missouri River near Watford City, ND (USGS Station No. 

06337000) from 1935-2010 (USGS 2011c, 2012).

The National Weather Service determined the flood stage at Watford City to be 20 ft (USGS 

2011b). At Watford City, the Little Missouri River has only reached flood stage twice since 1935 

(in 1947 and 1950) (USGS 2011b). The peak gage height for 1947 and 1950 were 24 and 21.42 

ft, respectively (USGS 2011b). However, there seem to be many years with high peak gage 

heights, but relatively low peak discharge. J. Hughes (pers. comm.) indicated a potential reason 

for some of the discrepancies is that the gage near Watford City has changed location on 

numerous occasions.

South Unit

Figure 7 represents peak discharge at the USGS Medora stream gage near the South Unit of 

THRO at Medora, ND. The stream gage data for this location has many multi-year data gaps. For 

approximately 25 years (from the mid-1970s until 2000), there are no USGS stream gage 

statistics available. In addition, there are multi-year data gaps in years prior to 1945. It is difficult 

to draw any conclusions about peak discharge trends from the data that are available, due to the 

large data gaps.

0

20000

40000

60000

80000

100000

120000

1935194019451950195519601965197019751980198519901995200020052010

Peak Discharge (cfs)

Water Year
62

Figure 7. Peak discharge (cfs) for the Little Missouri River at Medora, ND from 1904-2010 (USGS Station 

No. 06336000) (USGS 2011c, 2012).

The National Weather Service determined the flood stage at Medora to be 15 ft (USGS 2011a). 

At Medora, the Little Missouri River has reached flood stage seven times since 1904 (in 1904, 

1929, 1947, 1952, 1972, 2009, and 2011) (USGS 2011a, 2012). The peak gage heights for 1947, 

2011, 1972, 1952, and 1929 were the highest recorded, with respective gage heights of 20.50, 

20.39, 18.68, 18.35, and 17.20 ft (USGS 2011a). Interestingly, the 1950 peak gage height passed 

flood stage in Watford City, but did not in Medora. All years that passed flood stage at Medora 

(aside from 1947) did not pass flood stage in Watford City, which could be due to the difference 

in flood stage heights (15 versus 20 ft). As expected, all flow events that surpassed flood stage 

heights at Medora correspond to years with a higher-than-normal peak discharge; further 

investigation is needed to determine the actual effects of these high-water events in the park.

Snowpack

Snowpack is often measured in snow water equivalent (SWE). SWE is the water depth that 

would hypothetically result in the event that the entire snowpack melted at one time (NRCS 

2009). This estimate is based off snow depth and snow density information, gathered from 

SNOTEL sampling locations. Snowpack is directly related to the amount of water entering river 

systems, and is therefore important to understand when analyzing flooding. The nearest 

SNOTEL sampling station to the Little Missouri River is located at Cole Canyon, in Sundance, 

Wyoming. This SNOTEL station is located approximately 60 km east of the headwaters of the 

Little Missouri River, and should provide a general trend of the changes in snowpack in the last 

40 years. Figure 8 displays SWE averages from 1971-2000 and 2001-2009 at Cole Canyon. The 

2001-2009 averages are all smaller than the 1971-2000 averages, with 2001-2009 May averages 

at approximately 1/3 of the 1971-2000 May averages. While it may not be appropriate to draw 

further conclusions, this general decreasing trend in snowpack could be associated with the 

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

1904 1909 1914 1919 1924 1929 1934 1939 1944 1949 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 2004 2009

Peak Discharge (cfs)

Water Year
63

conclusions of Miller and Friedman (2009), that climate is the primary driver for the recent 

decrease in peak flow magnitudes on the Little Missouri River.

Figure 8. Snow water equivalent averages from 1971-2000 and 2001-2009 at Cole Canyon, Sundance, 

Wyoming (NRCS 2009).

Duration

The duration of a flood event is related largely to the volume of water received by the stream 

from precipitation and snowmelt events and the location of where runoff enters the stream.

Spring floods are generally longer in duration than summer floods. A positive correlation 

between duration and magnitude exists, with larger floods having longer durations; a flood of 

higher magnitude will have more water, so it will take a longer period of time for the saturated 

soil and upstream tributaries to drain back to normal levels. Contrastingly, summer floods are 

much shorter, as they are generally a result of intense rain and thunderstorms. While duration 

appears to be important in forming the total channel area, peak magnitude appears to be the most 

important factor (Miller 2005). 

Effects of upstream water withdrawal on summer flows

Jeff Hughes (pers. comm., 2012) indicated that he is gathering information on water rights and 

permits for water withdrawal on the Little Missouri River. Currently, the Theodore Roosevelt 

Medora Foundation has a permit to withdraw 11 cfs from the Little Missouri River (3 miles 

upstream of the South Unit of THRO) between 1 March and 1 July. The Medora Foundation 

permit and other similar operations upstream of THRO may affect flow in the Little Missouri 

River and the NPS Water Rights Branch is currently collecting available information on the 

number of water users and the amount of water diverted and withdrawn from the Little Missouri 

River system to determine if adverse impacts could be occurring at the park.

0

1

2

3

4

5

6

7

8

January February March April May

Snow Water Equivalent

1971-2000

2001-2009
64

Threats and Stressor Factors

The climate around THRO is semi-arid, with extreme temperatures in the summer and winter 

months (Miller 2005). On average, the Little Missouri watershed receives 35.6 cm (14 in) of 

precipitation per year, and approximately 76 cm (30 in) of snowfall (average from 1939-2003) 

(Miller 2005). In the last 100 years, there has been a reduction in peak flows, and because the 

Little Missouri is largely unregulated, the cause of this reduction is thought to be related to 

climate. Climate is related directly to precipitation and snowpack, which directly influence the 

amount of water moving through the Little Missouri River system. This reduction in peak flows 

is correlated strongly with a reduction in erosion (Miller 2005), which poses a risk for 

cottonwood regeneration.

Water retention in stock dams (in upriver tributaries and draws) can change the flooding patterns 

of the Little Missouri River. There is no current literature explaining the effects of water 

retention in stock dams in upriver tributaries and draws of the Little Missouri River. Other 

potential concerns include upstream irrigation practices and withdrawals associated with 

hydraulic fracturing. 

Data Needs/Gaps

Peak magnitude and peak gage height for the Medora gage has major data gaps throughout the 

entire period of data collection (1904-present). J. Hughes (pers. comm., 2012) indicated that the 

Medora and Watford City gage locations are largely similar, and statistical models (using the 

Watford City gage data) likely could be used to predict the missing years for the Medora gage.

J. Hughes (pers. comm., 2012) is currently investigating the amount and extent of water permits 

near the Little Missouri River, to get a better idea of the amount of water taken from the river. 

This information would be beneficial in understanding upstream drawdown statistics.

Research investigating the number, location, and extent of stock dams in the upstream tributaries 

of the Little Missouri River would be beneficial to get a better idea of how these might be

affecting floods near THRO.

Overall Condition

Frequency

The project team defined the Significance Level of frequency as a 3. As a result of snowmelt, 

spring floods are still occurring, and summer floods from intense rain and thunderstorms are also 

occurring; thus, a Condition Level of 1 (low concern) was assigned for the frequency measure.

Magnitude

The project team defined the Significance Level of magnitude as a 3. While the spring and 

summer peak flows are still occurring on the Little Missouri, Miller and Friedman (2009) point 

out that the peak flows have dropped over the last century, likely due to climate change. The 

decrease in magnitude, coupled with concerns regarding climate change, result in a Condition 

Level of 2 (moderate concern) for the magnitude measure.

Snowpack

The project team defined the Significance Level of snowpack as a 3. Snowpack is the main driver 

of spring peak flows, and while some years still see heavy snowpack, there has been an overall 
65

decrease in SWE over the last 40 years. Snowpack was given a Condition Level of 3 (significant 

concern) because of these overall decreasing trends.

Duration

The project team defined the Significance Level of duration as a 2. Duration is largely a product 

of magnitude, meaning that a decrease in flood magnitude over the last century has contributed 

to a decrease in flood duration as well. The project team assigned a Condition Level of 2 

(moderate concern) for the duration measure.

Effects of Upstream Water Withdrawal on Summer Flows

The project team defined the Significance Level of effects of upstream water withdrawal on 

summer flows as a 3. However, there are no current data on the amount of water withdrawn from 

the Little Missouri River. Thus, a Condition Level for this measure could not be determined. 

Weighted Condition Score

While spring and summer peak flows are still occurring, decreases in snowpack have resulted in 

lower magnitude and duration of peak flows. The overall Weighted Condition Score of flooding 

was 0.666, meaning it is of moderate concern.

4.3.6 Sources of Expertise

Jeff Hughes, Hydrologist, NPS Water Resources Division 
66

4.3.7 Literature Cited

Emerson, D. G., and K. M. Macek-Rowland. 1986. Flood analysis along the Little Missouri 

River within and adjacent to Theodore Roosevelt National Park, North Dakota. WaterResources Investigations Report 86-4090, prepared in cooperation with the National Park 

Service. U.S. Geological Survey, Bismarck, North Dakota.

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. National Park Service, Denver, 

Colorado.

Miller, J. R. 2005. Quantifying historical channel and floodplain change along the Little 

Missouri River in Theodore Roosevelt National Park, North Dakota. Thesis. Colorado State 

University, Fort Collins, Colorado. 

Miller, J. R., and J. M. Friedman. 2009. Influence of flow variability on floodplain formation and 

destruction, Little Missouri River, North Dakota. GSA Bulletin 121(5/6):752-759.

Natural Resources Conservation Service (NRCS). 2009. SNOTEL Data. Cole Canyon, WY. 

http://www.wcc.nrcs.usda.gov/ftpref/data/snow/ (accessed 20 May 2011).

National Weather Service (NWS). 2012. National Oceanic and Atmospheric Administration’s 

National Weather Service - Glossary. http://w1.weather.gov/glossary/index.php?letter=f

(accessed 30 July 2012).

U.S. Geological Survey (USGS). 2011a. USGS flood tracking 06336000 Little Missouri River at 

Medora, ND. http://nd.water.usgs.gov/floodtracking/charts/0633600.html (accessed 19 April 

2011).

U.S. Geological Survey (USGS). 2011b. USGS flood tracking 06337000 Little Missouri River at 

Watford City, ND. http://nd.water.usgs.gov/floodtracking/charts/0633700.html (accessed 19 

April 2011). 

U.S. Geological Survey (USGS). 2011c. USGS real-time water data for the nation: Daily 

streamflow conditions. http://waterdata.usgs.gov/nwis/rt (accessed 18 April 2011).

U.S. Geological Survey (USGS). 2012. USGS real-time water data for the nation: Daily 

streamflow conditions. http://waterdata.usgs.gov/nwis/rt (accessed 16 April 2012).
67

Plate 1. Watershed boundaries and Little Missouri River gages.
68

4.4 Native Grasslands

4.4.1 Description

Prior to the drought of the 1930s, the mixed-prairie grasslands of the northern Great Plains 

region were used extensively for grazing and agriculture, including the area that now makes up 

THRO. The establishment of THRO in 1947 allowed grassland communities within the park to 

revert to their natural state (Stubbendieck and Willson 1986). Today, native grasslands within 

THRO are widely distributed across areas with deeper soils such as plains, valleys, buttes, sand 

hills, and ridges. Grasslands also are interspersed with shrublands and woodlands throughout the 

park, and grasses sometimes 

comprise the understory of various 

woody habitats (Von Loh et al. 

2000). Native grasslands support a 

wide variety of wildlife, from bison 

and elk to prairie dogs and 

numerous bird species (NPS 2010a). 

The most abundant native grass 

species in THRO include needleand-thread (Hesperostipa comata), 

blue grama (Bouteloua gracilis), 

and threadleaf sedge (Carex

filifolia). Von Loh et al. (2000) 

identified six grassland alliances in 

THRO (five native and one 

introduced). The native grassland 

communities found in the park are 

listed in Table 21. 

Table 12. Native grassland communities of THRO (Von Loh et al. 2000).

Common Name NVCS Association or Complex

Needle-and-Thread Herbaceous Alliance Hesperostipa comata – Bouteloua gracilis – Carex filifolia

Herbaceous Vegetation

Western Wheatgrass Herbaceous Alliance Pascopyrum smithii – Bouteloua gracilis – Carex filifolia 

Herbaceous Vegetation; Pascopyrum smithii – Nassella

viridula Herbaceous Vegetation

Little Bluestem - Sideoats Grama Herbaceous Alliance Schizachyrium scoparium – Bouteloua (curtipendula, 

gracilis) – Carex filifolia Herbaceous Vegetation

Prairie Sandreed Grass Herbaceous Alliance Calamovilfa longifolia – Carex inops ssp. heliophila 

Herbaceous Vegetation

Prairie Cordgrass Temporarily Flooded Herbaceous 

Alliance

Spartina pectinata – Carex spp. Herbaceous Vegetation

4.4.2 Measures

 Species composition

 Distribution

Photo 10. Native grassland in the Peaceful Valley in THRO 

(Photo by Shannon Amberg, SMUMN GSS, 2010).
69

 Prevalence of non-natives

4.4.3 Reference Conditions/Values

The ideal reference condition for this component is the composition and distribution of 

grasslands prior to European settlement. However, no information is available from this 

historical period. The earliest description of native grasslands within THRO comes from Hansen 

et al. (1984), who identified three grassland habitat types in the park: Hesperostipa 

comata/Carex filifolia, Pascopyrum smithii/Carex filifolia, and Schizachyrium scoparium/Carex 

filifolia. These descriptions will be used as reference conditions for species composition in the 

respective grassland types present in the park today. An earlier work by Hanson and Whitman 

(1938) focused on grasslands in western Northern Dakota and included these three grasslands, as 

well as a Calamovilfa longifolia grassland. Although not specific to the park, these descriptions 

also can be used as secondary reference conditions for species composition.

4.4.4 Data and Methods

The USGS-NPS Vegetation Mapping Program document (Von Loh et al. 2000) was a major 

source of information for this component. The NPS Inventory and Monitoring (I&M) Program

implemented this project to map and categorize the vegetation of THRO using aerial 

photography GIS analysis. Multiple sources documented the occurrence of non-natives in the 

park’s grasslands: Hansen et al. (1984), Trammell (1994), Von Loh et al. (2000), and THRO GIS 

data (NPS n.d.)

4.4.5 Current Condition and Trend

Species Composition

Many of the park’s native grasslands have similar species compositions, but with variation in 

which species are dominant. The most common native grassland type in THRO is the Needleand-Thread Herbaceous Alliance, which consists of Needle-and-Thread – Blue Grama –

Threadleaf Sedge Herbaceous Vegetation. In addition to these three grasses, other common 

species include Junegrass (Koeleria macrantha), western wheatgrass (Pascopyrum smithii), 

prairie sagewort (Artemisia frigida), purple coneflower (Echinacea angustifolia), prairie 

coneflower (Ratibida columnifera), and the non-natives field brome (Bromus arvensis) and 

yellow sweetclover (Melilotus officinalis) (Von Loh et al. 2000).

The Prairie Cordgrass Temporarily Flooded Herbaceous Alliance is characterized by prairie 

cordgrass (Spartina pectinata) and sedge species (Carex spp.) Other species in this community 

include western wheatgrass, foxtail barley (Hordeum jubatum), and several non-native grasses. 

Curly-cup gumweed (Grindelia squarrosa), wild bergamot (Monarda fistulosa), and white aster 

(Aster ericoides) are commonly associated forbs, although species richness is generally low in 

cordgrass stands (Von Loh et al. 2000).

In THRO, the Prairie Sandreed Grass Herbaceous Alliance consists of Prairie Sandreed – Longstolon Sedge Herbaceous Vegetation. In these grasslands, prairie sandreed (Calamovilfa 

longifolia) is associated with threadleaf sedge, little bluestem (Schizachyrium scoparium), 

needle-and-thread, and prairie sagewort. Several stands in the South Unit include porcupine grass 

(Hesperostipa spartea) as a co-dominant graminoid species (Von Loh et al. 2000). 
70

The Little Bluestem-Sideoats Grama Herbaceous Alliance, dominated by little bluestem, is rare 

within the park. Other species regularly found with little bluestem include sideoats grama 

(Bouteloua curtipendula), threadleaf sedge, prairie sandreed, porcupine grass, and various forbs 

(Von Loh et al. 2000). 

The Western Wheatgrass Alliance is divided further into two associations. The Western 

Wheatgrass – Blue Grama – Threadleaf Sedge Herbaceous Vegetation Association is dominated 

by western wheatgrass with blue grama and prairie sagewort as major secondary species on drier 

sites and green needlegrass (Nasella viridula) on more mesic sites (Von Loh et al. 2000). Silver 

sagebrush is also common, but typically with less than 25% coverage. In the Western 

Wheatgrass – Green Needlegrass Herbaceous Vegetation Association, western wheatgrass and 

green needlegrass are codominant, although western wheatgrass is more abundant on drier sites 

and green needlegrass increases on more mesic sites. Other common species include blue grama 

and white sagebrush (A. ludoviciana). The exotic species Kentucky bluegrass, yellow 

sweetclover, and leafy spurge are often found in both associations (Von Loh et al. 2000). Table 

13 summarizes the most abundant species in each of these grassland communities.

In 2011, the Northern Great Plains Inventory & Monitoring program established and surveyed 

vegetation in 21 plots in THRO as part of a larger, multi-year vegetation survey (Ashton et al. 

2012). Early results indicate western wheatgrass was the most common species across the plots. 

In 1m2plots, an average of 10 and 12 species were found in the North and South Unit, 

respectively. 

Table 13. The native grasslands of THRO and the most abundant species in each community, as 

surveyed by Von Loh et al. (2000).

Grassland community Most abundant species

Needle-and-Thread Herbaceous Alliance Hesperostipa comata, Bouteloua gracilis, 

Carex filifolia

Western Wheatgrass – Blue Grama – Threadleaf 

Sedge Herbaceous Vegetation

Pascopyrum smithii, Bouteloua gracilis, 

Nasella viridula, Artemisia cana

Western Wheatgrass – Green Needlegrass 

Herbaceous Vegetation

Nassella viridula, Pascopyrum smithii

Little Bluestem - Sideoats Grama Herbaceous Alliance Schizachyrium scoparium, Bouteloua 

curtipendula, Carex filifolia

Prairie Sandreed - Long-stolon Sedge Herbaceous 

Vegetation 

Calamovilfa longifolia, Carex filifolia

Prairie Cordgrass Temporarily Flooded Herbaceous 

Alliance

Spartina pectinata, Pascopyrum smithii, 

Hordeum jubatum
71

Distribution

Native grasslands cover over 10,000 ha of THRO. Their distribution is shown in Plate 2, 

Plate 3, and Plate 4. Needle-and-thread grasslands are the most widely distributed type, with 

western wheatgrass grasslands a distant second. Needle-and-thread occurs in dry areas on plains, 

flats on buttes, plateaus, on top of mesas, and dry hillsides (Von Loh et al. 2000). Large areas of

these grasslands occur on the Petrified Forest Plateau and Big Plateau in the South Unit, and on 

the Achenbach Hills of the North Unit. The Western Wheatgrass Herbaceous Alliance generally 

is found in broad floodplains, moist swales, and slopes below badland formations where runoff 

water is available (Von Loh et al. 2000). 

The Little Bluestem-Sideoats Grama Herbaceous Alliance occurs in small patches on moist north 

and east facing slopes, but is also common in the understory of several shrubland types, 

particularly creeping juniper (Juniperus horizontalis) (Von Loh et al. 2000). Prairie Sandreed 

Grass Herbaceous Alliance grasslands occur in small stands on knolls, hilltops, slopes, and at the 
72

heads of mesic draws in both the North and South Units of THRO, often on gravelly or sandy 

soils. Finally, the Prairie Cordgrass Temporarily Flooded Herbaceous Alliance is found 

sporadically in the Little Missouri River floodplain and is most noticeable near Scenic Drive in 

the North Unit. This vegetation occurs in areas where the water table is close to the surface or in 

depressions holding water following flood events (Von Loh et al. 2000). The area covered by 

each grassland alliance in the park is shown in Table 14.

Table 14. Area (in hectares) covered by native grasslands in THRO. GIS data from Von Loh et. al. 

(2000).

Common Name North Unit South Unit EHR Total

Needle-and-Thread Herbaceous Alliance 2,182.8 7,126.4 3.5 9,312.7

Western Wheatgrass Herbaceous Alliance 369.5 832.2 0.8 1,202.5

Little Bluestem - Sideoats Grama Herbaceous 

Alliance

75.6 9.4 -- 85.0

Prairie Sandreed Grass Herbaceous Alliance 12.8 44.6 -- 57.4

Prairie Cordgrass Temporarily Flooded 

Herbaceous Alliance

11.6 -- -- 11.6

Prevalence of Non-natives

In addition to the five native grasslands, Von Loh et al. (2000) mapped an Introduced Grassland 

Alliance in the park. This alliance covered 146 ha in the North Unit and 192 ha in the South Unit 

for a park-wide total of 338 ha (Plate 5 and Plate 6). Kentucky bluegrass is one of the most 

widespread exotic grasses in THRO, dominating the eastern portion of the South Unit. This 

species is present on many of the more moist areas in the park where western wheatgrass would 

be expected to occur (Von Loh et al. 2000). The other dominant non-native grasses in the park 

are crested wheatgrass and smooth brome. Additional non-native species documented in THRO’s 

grasslands as of 2000 are listed in Table 15. More recent non-native plant survey efforts have not

identified the plant community where each species has been found. A full list of non-native plant 

species in the park (many of which are likely found in native grasslands) can be found in 

Appendix C. Grassland areas sampled in the park during 2011 as part of an NGPN plant 

community monitoring program averaged 17% (±12.4%) non-native species cover in the North 

Unit and 16% (±15.7%) in the South Unit (Ashton et al. 2012). 
73

Table 15. Non-native species documented in THRO grasslands (Hansen et al. 1984, Trammell 1994, Von 

Loh et al. 2000).

Common Name Scientific Name

Field brome Bromus arvensis

Cheatgrass Bromus tectorum

Lambsquarters Chenopodium album

Barnyard grass Echinochloa spp.

Leafy spurge Euphorbia esula

False flax Camelina microcarpa

Prickly lettuce Lactuca serriola

Yellow sweetclover Melilotus officinalis

Alfalfa Medicago sativa

Dandelion Taraxacum officinale

Yellow salsify Tragopogon dubius

Threats and Stressor Factors

Non-native plants have invaded the native grasslands of THRO and have become dominant in 

some areas of the park. In addition to altering native species composition, non-natives can alter 

natural processes such as fire, nutrient cycling, and erosion (Von Loh et al. 2000). As of 1994, 36

non-native plant species had been observed within the park during field surveys (Trammell 

1994). By 2011, over 60 non-native species were documented in the park with many more 

thought to be present (Appendix C). The most problematic and aggressive non-native plants in 

THRO are leafy spurge and Canada thistle (Cirsium arvense). In 2011, THRO and EPMT staff 

chemically treated infestations of Canada thistle in North Unit grasslands and leafy spurge in 

South Unit grasslands (L. Richardson, pers. comm., 2012). Non-native grasses introduced from 

pasture lands include crested wheatgrass, Kentucky bluegrass, and smooth brome (Von Loh et al.

2000). 

Fire suppression is another threat to the park’s native grasslands. Fire is one of the most 

important processes in the maintenance of grassland systems (Anderson 1990), as it reduces 

competition from woody species. Frequent fires are important for maintaining native species 

diversity and also positively impact other grassland components, such as nutrient cycling and 

productivity (Collins and Wallace 1990). Fire suppression often leads to juniper and other woody 

species encroachment into native grasslands (NPS 1994, 2010b) and can favor non-native plants 

over native species (Whisenant and Uresk 1990). Fire was viewed as a danger to people, 

property, and resources for much of the 20th century and was suppressed all across the Great 

Plains (NPS 2010b). Fire returned to the landscape of THRO in the form of prescribed burns in 

the late 1990s. Further discussion of fire in THRO is found in section 4.1 of this assessment. 

Overgrazing is not currently a threat to the park’s grasslands (L. Richardson, pers. comm., 2012). 

Data Needs/Gaps

While the park is monitored annually for non-native species, Von Loh et al.’s (2000) vegetation 

mapping project remains the most comprehensive survey conducted in the park. In 2011, a plant 

community composition and structure monitoring was initiated by the NGPN and baseline data 

was gathered in all network parks. Twenty-one plots (16 upland and five riparian) were sampled 

in THRO (Ashton et al. 2012). Over time, this monitoring data will allow for a better comparison 

of current grassland condition to earlier reports (e.g., Hanson and Whitman 1938, Hansen et al. 
74

1984). An updated vegetation mapping effort would also help to identify the extent of juniper 

and other woody encroachment into park grasslands.

Overall Condition

Species Composition

During initial scoping meetings, THRO staff assigned the measure of species composition a 

Significance Level of 3. Von Loh et al.’s (2000) grassland species composition descriptions are 

slightly different than those in Hansen et al. (1984) and Hanson and Whitman (1938). While Von 

Loh et al.’s (2000) description of the needle-and-thread herbaceous alliance is very similar to 

Hanson and Whitman (1938), it differs from Hansen et al. (1984) who reported very little blue 

grama and more western wheatgrass in the Hesperostipa comata/Carex filifolia habitat type. 

Hansen et al. (1984) also reported minimal blue grama and green needlegrass in the Pascopyrum 

smithii/Carex filifolia habitat type, two grasses that were key “secondary species” in Von Loh et 

al.’s (2000) descriptions. Some of these differences could be natural variation due to climate 

variability, fire regime, and land use shifts (e.g., grazing). These differences are worth further 

investigation and this measure is therefore assigned a Condition Level of 1 indicating low 

concern. In the future, data from the NGPN plant community monitoring can be used to assess 

this measure. 

Distribution

A Significance Level of 3 was assigned to the measure of distribution. Since there are no historic 

or more recent distribution maps that are directly comparable to Von Loh et al.’s (2000) 

distribution data, a Condition Level cannot be assigned. Data from the NGPN plant community

monitoring may also be useful in assessing this measure in the future.

Prevalence of Non-natives

A Significance Level of 3 was assigned to the prevalence of non-native species measure. Nonnative grasses have become dominant in several areas within THRO and have the potential to 

expand further into native grasslands. Several other non-native species, particularly the 

aggressive leafy spurge, have been documented in the park’s native grasslands. This measure 

was assigned a Condition Level of 2, indicating moderate concern.

Weighted Condition Score

The Weighted Condition Score (WCS) for native grasslands in THRO is 0.500, indicating 

moderate concern. The trend is currently unknown, although the new network vegetation 

monitoring program should help to fill this gap in the near future.
75

4.6.1 Sources of Expertise

Laurie Richardson, Botanist, THRO 
76

4.7.1 Literature Cited

Anderson, R. C. 1990. The historic role of fire in the North American grassland. Pages 8–18 in

S. L. Collins and L. L. Wallace, eds. Fire in North American tallgrass prairies. University of 

Oklahoma Press, Norman, Oklahoma.

Ashton, I. W., M. Prowatzke, M. Bynum, T. Shepherd, S. K. Wilson, K. Paintner-Green. 2012. 

Theodore Roosevelt National Park plant community composition and structure monitoring: 

2011 annual report. Natural Resource Technical Report NPS/NGPN/NRTR—2012/545. 

National Park Service, Fort Collins, Colorado.

Collins, S. L., and L. L. Wallace 1990. Fire in North American tallgrass prairies. University of 

Oklahoma Press, Norman, Oklahoma.

Godfread, C. 1994. The vegetation of the Little Missouri Badlands of North Dakota. Pages 17-24 

in Proceedings: Leafy spurge strategic planning workshop, Dickinson, North Dakota. March 

29-30, 1994. 

Hansen, P. L., G. R. Hoffman, and A. J. Bjugstad. 1984. The vegetation of Theodore Roosevelt 

National Park, North Dakota: A habitat type classification. U.S. Forest Service, Rocky 

Mountain Forest and Range Experiment Station, Fort Collins, Colorado.

Hanson, H. C., and W. Whitman. 1938. Characteristics of major grassland types in western 

North Dakota. Ecological Monographs 8(1):57-114.

Higgins, K. F. 1984. Lightning fires in North Dakota grasslands and in pine-savanna lands of 

South Dakota and Montana. Journal of Range Management 37(2):100-103. 

National Park Service (NPS). n.d. NPS_THRO_Exotic_Vegetation_Program_Geodatabase.gdb. 

ArcGIS geodatabase. Theodore Roosevelt National Park, North Dakota.

National Park Service (NPS). 1994. Resource management plan – Theodore Roosevelt National 

Park. National Park Service, Theodore Roosevelt National Park, North Dakota.

National Park Service (NPS). 2010a. Prairies and grasslands - Theodore Roosevelt National 

Park. http://www.nps.gov/thro/naturescience/prairies.htm (accessed 10 February 2012).

National Park Service (NPS). 2010b. Fire management – Theodore Roosevelt National Park. 

http://www.nps.gov/thro/parkmgmt/firemanagement.htm (accessed 13 December 2011).

Stubbendieck, J., and G. Willson. 1986. An identification of prairie in National Park units in the 

Great Plains. National Park Service Occasional Paper No. 7. National Park Service, Fort 

Collins, Colorado.

Trammel, M. A. 1994. Exotic plants of Theodore Roosevelt National Park: extent, distribution, 

and ecological impact. Thesis. University of South Dakota, Vermillion, South Dakota.
77

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli. 

2000. USGS-NPS vegetation mapping program: Theodore Roosevelt National Park, North 

Dakota. U.S. Department of the Interior, Denver, Colorado.

Whisenant, S. G., and D. W. Uresk. 1990. Spring burning Japanses brome in a western 

wheatgrass community. Journal of Range Management 43:205-208.
78

Plate 2. Native grassland alliances in the North Unit of THRO.
79

Plate 3. Native grassland alliances in the South Unit of THRO. 
80

Plate 4. Native grassland alliances in the Elkhorn Ranch Unit of THRO.
81

Plate 5. The introduced grassland alliance in the North Unit of THRO.
82

Plate 6. The introduced grassland alliance in the South Unit of THRO.
83

4.5 Juniper Forests

4.5.1 Description

Juniper forests are considered a distinct vegetation type in THRO and occur primarily on northfacing hill slopes in the park. This forest type, dominated by Rocky Mountain juniper (Juniperus 

scopulorum), is the most common wooded plant community in the park (NPS 2010a). Juniper 

forests are important for slowing erosion on slopes and are the preferred habitat for elk (Cervus

elaphus) in THRO (NPS 2010a). Berry-like cones produced by 

junipers are a critical food source for several bird species in 

the park, including Townsend’s solitaires (Myadestes 

townsendi), cedar waxwings (Bombycilla cedrorum), 

Bohemian waxwings (B. garrulus), and American robins 

(Turdus migratorius) (NPS 2010a).

Juniper forests in the park often are wooded densely with thick 

tree canopies (Von Loh et al. 2000). Green ash (Fraxinus 

pennsylvanica) and chokecherry (Prunus virginiana) are also 

common but at much lower densities. Characteristic 

understory species include little-seed ricegrass (Oryzopsis 

micrantha), mosses and lichens, and false Solomon’s seal 

(Maianthemum stellatum) (Hansen et al. 1984, Von Loh et al. 

2000).

4.5.2 Measures

 Distribution

 Density

4.5.3 Reference Conditions/Values

The ideal reference condition for this component would be the composition and distribution of 

juniper forests prior to European settlement. However, no information is available from this 

historical period. The earliest description of THRO’s juniper forests comes from Ralston (1960), 

who studied the structure and ecology of “north slope juniper stands” in the area. This source 

will act as the reference condition for density in this assessment. For the distribution measure, 

Von Loh et al.’s (2000) 1996-97 vegetation mapping data will serve as the reference condition.

4.5.4 Data and Methods

Von Loh et al. (2000) used remote sensing to map vegetation in THRO and provided the 

majority of information regarding juniper forests in the park, particularly regarding distribution.

Ralston (1960) also provided stand density data for several juniper forests in the park. Density 

measurements were calculated using the quarter method (Cottam and Curtis 1956) in 12 juniper 

stands in the North and South Units of THRO (Ralston 1960).

Photo 11. Rocky Mountain juniper 

in THRO (Photo by Shannon 

Amberg, SMUMN GSS 2010)
83

4.5.5 Current Condition and Trend

Distribution

Rocky Mountain juniper often covers 

steep north-facing slopes in the 

badlands, facing away from direct 

sun where there is less surface 

insolation, conditions are cooler, 

snow remains longer in the spring, 

and moisture evaporates less readily 

(Godfread 1994). It is widely 

distributed across THRO, most often 

forming dense woodlands in 

drainages and draws, but also 

occurring on ridges, hill tops, and 

slumps on side slopes (Von Loh et 

al. 2000). Nelson (1961) states that 

this vegetation type generally is 

found on slopes of scoria or clay, and 

that juniper will generally cover the 

slope from its base to the summit. 

Plate 7, Plate 8, and Plate 9 display the area covered by the Rocky Mountain juniper alliance as 

of 2000 in the North, South, and Elkhorn Ranch Units of THRO, respectively. Based on GIS 

data, this vegetation alliance is slightly more widespread in the North Unit. GIS data are also 

available for the distribution of the Juniperus scopulorum/Oryzopsis micrantha habitat type in 

the park as of 1984 (Norland 1984). Although not directly comparable due to slight methodology 

differences, a comparison of total juniper forest area in 1984 and 2000 suggests that these forests 

have expanded over time. According to 1984 GIS data, the Juniperus scopulorum/Oryzopsis 

micrantha habitat type covered approximately 1,000 ha of THRO (just under 500 ha in the South 

Unit and just over 500 ha in the North Unit). By 2000, GIS data show Rocky Mountain juniper 

woodland covering approximately 3,800 ha of the park (about 2,200 ha in the South Unit and 

1,600 ha in the North Unit) (Von Loh et al. 2000).

Density

No recent information is available regarding the density of THRO’s juniper forests specifically. 

Stand density data is being gathered as part of the NGPN plant community monitoring, but this 

monitoring has just completed its first year.

Ralston (1960) calculated densities for 12 juniper stands in THRO

Photo 12. Juniper forests in the North Unit of THRO (Photo 

by Shannon Amberg, SMUMN GSS 2010).
85

Table 16). Stands with the highest density also exhibited the greatest reproduction rates. Density 

appeared to be related to fire intensity, with stands exposed to higher intensity fires actually 

showing higher densities (Ralston 1960).
86

Table 16. Tree densities for THRO juniper stands sampled in 1960 (Ralston 1960).

Stand Density (trees per acre)

Ash Juniper Total Juniper saplings (trees/m2)

101 19.5 759 778.5 0.30

102 -- 1286 1286 --

103 -- 970.37 970.37 0.20

104 34.3 880.7 915.00 0.2875

105 154.8 619.6 774.4 0.325

106 134 844 978 0.1125

107 292 770 1062 --

109 11.44 903.56 915 0.25

110 1041.7 852.3 1894 --

111 134 763 897 0.162

112 23 906 926 0.10

116 177.4 1241.6 1419 --

Threats and Stressor Factors

Non-native plant species constitute a threat to the juniper forests of THRO. These species can 

impact native species composition and alter natural processes such as fire, nutrient cycling, and 

erosion (Von Loh et al. 2000; as reviewed by Brooks et al. 2004). THRO and EPMT staff have 

been chemically treating infestations of Canada thistle in North Unit juniper forests and leafy 

spurge and Canada thistle in South Unit forests annually for nearly a decade (NPS n.d.). Other 

non-natives documented in juniper stands are field brome, yellow sweet clover, Kentucky 

bluegrass, lambsquarters, dandelion, and yellow salsify (Hansen et al. 1984, Trammell 1994, 

Von Loh et al. 2000).

Rocky Mountain juniper generally is considered intolerant of fire. Particularly intense fires can 

kill all but the largest junipers in a stand (Scher 2000). However, without fire juniper woodlands 

will expand and eventually encroach into other native plant communities (Burkhardt and Tisdale 

1976, NPS 2010b). The majority of Rocky Mountain juniper stands sampled during the THRO 

vegetation mapping program showed evidence of historic burns (Von Loh et al. 2000). Some 

evidence suggests that juniper stands that experienced fires of a certain intensity actually 

increased in stand density and reproduction over time (Ralston 1960).

Data Needs/Gaps

Density and other stand structure data is lacking for THRO’s juniper forests and could help 

managers better understand the juniper encroachment occurring in the park. NGPN plant 

community monitoring will contribute some stand density information over time. Also, the 

distribution of juniper has not been mapped since 2000. Updated distribution data would help 

identify any vegetation changes (e.g., juniper encroachment) occurring in the park. 

Overall Condition

Distribution

A Significance Level of 3 was assigned to the measure of juniper forest distribution. Evidence 

suggests that juniper distribution has expanded in the park over time, perhaps due to a long 

period of fire suppression. Junipers are encroaching on other native plant communities, which is 
87

a concern for park management. Therefore, this measure is assigned a Condition Level of 2, 

indicating moderate concern.

Density 

A Significance Level of 3 was assigned to the measure of juniper forest density. Since no recent 

density information is available for the park, a Condition Level could not be assigned.

Weighted Condition Score

A Weighted Condition Score (WCS) could not be calculated for the juniper forest community in 

THRO, since a Condition Level was only assigned for one of the two measures. As a result, the 

condition and trend of juniper forests in the park are considered unknown.

4.5.6 Sources of Expertise

Laurie Richardson, Botanist, THRO 
88

4.5.7 Literature Cited

Brooks, M. L., C. M. D’Antonio, D. M. Richardson, J. B. Grace, J. E. Keeley, J. M. DiTomaso, 

R. J. Hobbs, M. Pellant, and D. Pyke. 2004. Effects of invasive alien plants on fire regimes. 

Bioscience 54(7):677-688.

Burkhardt, J. W., and E. W. Tisdale. 1976. Causes of juniper invasion in southwestern Idaho. 

Ecology 57:472-484.

Cottam, G., and J. T. Curtis. The use of distance measurements in phytosociological sampling. 

Ecology 37:451-460.

Godfread, C. 1994. The vegetation of the Little Missouri Badlands of North Dakota. Pages 17-24 

in Proceedings: Leafy Spurge Strategic Planning Workshop, Dickinson, North Dakota. 

March 29-30, 1994.

Hansen, P. L., G. R. Hoffman, and A. J. Bjugstad. 1984. The vegetation of Theodore Roosevelt 

National Park, North Dakota: A habitat type classification. U.S. Forest Service, Rocky 

Mountain Forest and Range Experiment Station, Fort Collins, Colorado.

National Park Service (NPS). n.d. NPS_THRO_Exotic_Vegetation_Program_Geodatabase.gdb. 

ArcGIS geodatabase. Theodore Roosevelt National Park, North Dakota.

National Park Service (NPS). 2010a. Forests. http://www.nps.gov/thro/naturescience/forests.htm

(accessed 12 August 2011).

National Park Service (NPS). 2010b. Fire management. 

http://www.nps.gov/thro/parkmgmt/firemanagement.htm (accessed 15 August 2011).

Nelson, J. R. 1961. Composition and distribution of the principal woody vegetation types in the 

badlands of North Dakota. Part 1: The juniper-slope and green ash types. Project W-37-R-7. 

Job No. 9. North Dakota Game and Fish Department, Bismarck, North Dakota. 

Norland, J. E. 1984. Habitat use and distribution of bison in Theodore Roosevelt National Park. 

Thesis. Montana State University, Bozeman, Montana.

Ralston, R.D. 1960. The structure and ecology of the north slope juniper stands of the Little 

Missouri Badlands. Thesis. University of Utah, Salt Lake City, Utah.

Scher, J. S. 2002. Juniperus scopulorum. Fire Effects Information System. U.S. Forest Service, 

Rocky Mountain Research Station, Fire Sciences Laboratory. 

http://www.fs.fed.us/database/feis/ (accessed 1 February 2012).

Trammel, M. A. 1994. Exotic plants of Theodore Roosevelt National Park: extent, distribution, 

and ecological impact. Thesis. University of South Dakota, Vermillion, South Dakota.

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli.

2000. USGS-NPS vegetation mapping program: Theodore Roosevelt National Park, North 

Dakota.
89

Plate 7. Rocky Mountain Juniper Alliance in the North Unit of THRO.
90

Plate 8. Rocky Mountain Juniper Alliance in the South Unit of THRO.
91

Plate 9. Rocky Mountain Juniper Alliance in the Elkhorn Ranch Unit of THRO (based on 1996 aerial imagery). Juniper stands in the northwestern 

corner are no longer visible in 2004 aerial photography, as this area burned in the Elkhorn wildfire that occurred in August 2001.
92

4.6 Floodplain Woodlands

4.6.1 Description

Floodplain woodlands are areas dominated by trees with less than 60% canopy cover (Von Loh 

et al. 2000), occurring along the banks of the Little Missouri River and its major tributaries in 

THRO (Miller 2005). Sometimes referred to as gallery forests (Norland 1984, Girard et al. 

1989), or more broadly as bottomland forests (Nelson 1961), they are primarily characterized by 

cottonwood-willow (Populus-Salix sp.) woodlands (Miller 2005). Floodplain woodlands at 

THRO are dominated by plains cottonwood (Populus deltoides subsp. Monilifera).

Photo 13. Floodplain woodlands along the Little Missouri River in the North Unit of THRO (photo by 

Shannon Amberg, SMUMN GSS 2010).

Native woodlands represent less than 5% of the southwestern North Dakota vegetation (Jakes 

and Smith 1983); floodplain woodlands along the Little Missouri River represent a subset of 

these woodlands. The plant communities/alliances related to floodplain woodlands, along with 

those alliances that may succeed to or from floodplain woodlands, are listed in Table 17.

According to GIS data (Von Loh et al. 2000), cottonwood woodlands and other related map units 

listed in Table 17 make up approximately 55% of the EHR, 7% of the North Unit, and 1% of the 

South Unit, and 3.4% of the total land area across the three units of THRO. Despite the small 

proportion on the landscape, these woodlands and associated alliances provide valuable habitat 

for many wildlife species in THRO including white-tailed deer (Odocoileus virginianus) (Nelson 

1961), numerous bird species, porcupine (Erithizon dorsatum), and beaver (Castor canadensis) 

(NPS 2009).

Reproduction and age structure of cottonwood woodlands are controlled by river flooding and 

channel migration. Survival of woodland species during drought depends upon a water subsidy 

from the river. Reproduction and survival of these woodlands has been impaired globally by 

construction of dams and channel stabilization that limit flooding and channel migration, and by 

summer water withdrawals that cause drought mortality. The Little Missouri River in THRO is a 

rare example of a large river with minimal flow regulation, channel stabilization, or land 

clearing. As a result this forest includes the oldest known plains cottonwood trees in the world 

(up to 371 years, Friedman pers. comm., 2012), and the age structure and spatial patterns of 

cottonwood trees serve as a reference example of the natural condition for this plant community.
93

Table 17Reproduction and age structure of cottonwood woodlands are controlled by river 

flooding and channel migration. Survival of woodland species during drought depends upon a 

water subsidy from the river. Reproduction and survival of these woodlands has been impaired 

globally by construction of dams and channel stabilization that limit flooding and channel 

migration, and by summer water withdrawals that cause drought mortality. The Little Missouri 

River in THRO is a rare example of a large river with minimal flow regulation, channel 

stabilization, or land clearing. As a result this forest includes the oldest known plains cottonwood 

trees in the world (up to 371 years, Friedman pers. comm., 2012), and the age structure and 

spatial patterns of cottonwood trees serve as a reference example of the natural condition for this 

plant community.

Table 17. Map unit descriptions and NVCS associations related to floodplain woodlands in THRO (Von 

Loh et al. 2000).

Map unit description NVCS Association or Complex

Sandbar Willow Temporarily-Flooded Shrubland Alliance a Salix exigua temporarily flooded shrubland

Cottonwood – Peachleaf Willow Floodplain Woodland Populus deltoides – (Salix amygdaloides) / Salix exigua

woodland

Cottonwood Temporarily Flooded Woodland Alliance Populus deltoides temporarily flooded woodland

Cottonwood – Rocky Mtn. Juniper Floodplain Woodland Populus deltoides / Juniperus scopulorum woodland

Green Ash – American Elm Temporarily-Flooded 

Woodland Alliance b

Fraxinus pennsylvanica / Ulmus americana temporarily 

flooded woodland alliance

a An early successional stage of cottonwood woodlands, as it contains some young cottonwoods.

b A late successional stage of cottonwood woodlands.

4.6.2 Measures

 Species composition and abundance

 Changes in species distribution

 Cottonwood woodland area-age distribution

 Non-native species abundance 

4.6.3 Reference Conditions/Values

The ideal reference condition for this component would be the composition and distribution of 

floodplain woodlands prior to European settlement. Successional processes in these forest types 

are described in detatil in Johnson et 

al. (1976). Generally the authors 

conclude that river meandering 

patterns are an important 

determinant of horizontal and 

vertical distribution of the 

cottonwood forests, and that the rate 

of river meandering is a major 

factor in determing the composition 

of foodplain woodland stages (e.g., 

pioneer, transitional, and terminal 

Photo 14. Understory view of a cottonwood woodland in the 

North Unit of THRO (photo by Shannon Amberg, SMUMN 

GSS, 2010).
94

forest types). However, no map information is available from this period. Everitt (1968) provides 

some of the oldest observations of cottonwood stand ages in a 2.4 km (1.5 mi) section of the 

Little Missouri River in THRO. Norland (1984) also provides some older map information

regarding floodplain woodlands; however, the data and specifically map classes are not 

comparable to recent map data developed by Von Loh et al. (2000). Everitt (1968) described the 

cottonwood floodplain forests as a living record of past river channel migrations. Cottonwood 

establishment and survival relies on widening of the river channel after floods and narrowing 

during low flow periods (Everitt 1968, Johnson 1994, Friedman and Lee 2002).

Cottonwood woodlands dominate the floodplain forest of the Little Missouri River. Girard et al. 

(1989) found two specific community types common in the floodplain, P. deltoides/Juniperus 

scopulurum (eastern cottonwood/ Rocky Mountain juniper) and P. deltoides/F. pennsylvanica

(eastern cottonwood/green ash). P. deltoides/Juniperus scopulurum occurs on more recently 

deposited alluvial sites and P. deltoides/F. pennsylvanica on more mature sites (Girard et al. 

1989). Girard et al. (1989) suggest that under certain conditions (e.g., absence of disturbance), 

these communities will likely succeed to F. pennyslvanica/S. occidentalis (green ash/western

snowberry). It is unclear if the Green Ash – American Elm Temporarily-Flooded Woodland 

Alliance identified by Von Loh et al. (2000) represents a transitional gradient of the green ash/

western snowberry community mentioned by Girard et al. (1989). According to the Von Loh et 

al. (2000) GIS data, the Green Ash – American Elm Temporarily Flooded Woodland Alliance is 

a climax community of floodplain woodlands and shrublands. The species composition, 

distribution, and status of cottonwood regeneration in floodplain woodlands may vary over time, 

depending on disturbance regimes. However, cottonwood stand ages can provide an indication of 

what the near future may hold for the previously mentioned measures.

The presence of non-native species, especially those considered invasive, is undesirable for the 

biological integrity of the floodplain woodlands, or any native vegetation community in the park. 

The ideal reference condition for non-native plant species, particularly those considered invasive, 

would be no presence in the park. However, this is an unrealistic goal, given the current density 

and vectors of spread. 

4.6.4 Data and Methods

Two GIS datasets characterize the vegetation communities of THRO, one published in 1984 and 

the other in 2000. The 1984 vegetation dataset is a product of aerial-photo interpretation in 

Norland (1984) (a bison habitat mapping thesis), using 1:12,000 scale color-infrared photos. Map 

units relevant to floodplain woodlands include:

 River bottoms mapping unit: areas mapped by the author and simply defined as areas 

subject to frequent flooding;

 Willows mapping unit: areas dominated by densely growing willow (Salix spp.), with 

little other plant growth;

 Grassed sand floodplain habitat type, or a sandy range (bison) site;

 Populus deltoides – Juniperus scopulorum habitat type: identified in the thesis by 

Michele Girard of North Dakota State University.
95

The other GIS vegetation dataset in THRO is from the USGS-NPS Vegetation Mapping Program 

(Von Loh et al. 2000). These data are classified using the Standardized National Vegetation 

Classification System (NVCS), contain additional plant community types, and also combined 

some land use classes (e.g., transportation, communications, and utilities; mixed urban or builtup land; croplands and pasture). The map product used 1996, 1:24,000 scale aerial photography 

from the USFS. The overall initial accuracy was 74.3% for all mapped vegetation classes (Von 

Loh et al. 2000).

The Von Loh et al. (2000) data contain more detailed information than GIS data derived from the 

earlier study (Norland 1984). Von Loh et al. (2000) identify 39 unique map classes or map units 

(27 natural and semi-natural alliances and associations, two complexes, and 10 Anderson et al. 

[1976] land use classes). However, the two datasets are not quantitatively comparable and cannot 

be used to examine changes in species composition and abundance, changes in species 

distribution, or shifts in cottonwood area-age distribution. Von Loh et al. (2000) is used below to 

report current conditions of floodplain woodlands in THRO.

4.6.5 Current Condition and Trend

Species Composition and Abundance

Von Loh et al. (2000) describe five plant community associations relevant to THRO’s floodplain 

woodlands (Table 17). However, the authors warn that many of the plant associations’ 

compositions are variable and some confusion between associated floodplain shrublands and 

woodlands were revealed during map accuracy assessments. The sandbar willow temporarily 

flooded shrubland alliance (cottonwood seedlings are often present in this alliance) may succeed 

to cottonwood woodlands over time, therefore it is included in the floodplain woodland 

assessment. Cottonwood woodlands also succeed to cottonwood-Rocky Mountain juniper, and 

finally to green ash – American elm temporarily flooded woodland alliance. This alliance is the 

climax vegetation community of the floodplain woodlands, given enough time without flooding 

(Von Loh et al. 2000). The most common species by stratum in each of the map units is 

displayed in Table 18.

Table 18. Abundant species in floodplain shrubland and woodlands of THRO (Von Loh et al. 2000).

Common Name / Stratum Most abundant species

Sandbar Willow Temporarily-Flooded Shrubland Alliance (map unit no. 38)

Tree Canopy Populus deltoides

Short Shrub Salix exigua

Herbaceous Melilotus alba, Xanthium strumarium, Spartina pectinata

Cottonwood – Peachleaf Willow Floodplain Woodland (map unit no. 41)

Tree Canopy Populus deltoides, Salix amygdaloides

Short Shrub Salix exigua, Symphoricarpos occidentalis

Herbaceous Glycyrrhiza lepidota, Melilotus alba, M. officinalis

Cottonwood Temporarily-Flooded Woodland (map unit no. 43)

Tree Canopy Populus deltoides, Juniperus scopulorum, Fraxinus pennsylvanica

Short Shrub Symphoricarpos occidentalis, Prunus virginiana

Herbaceous Poa pratensis, Bromus inermis

Cottonwood – Rocky Mountain Juniper Floodplain Woodland (map unit no. 42)
96

Common Name / Stratum Most abundant species

Tree Canopy Populus deltoides, Juniperus scopulorum,

Short Shrub Symphoricarpos occidentalis, Prunus virginiana

Herbaceous Poa pratensis, Bromus inermis

Green Ash – American Elm Woodland Floodplain (map unit no. 45)

Tree Canopy Fraxinus pennsylvanica, Ulmus pumila

Short Shrub Symphoricarpos occidentalis, Artemisia cana

Herbaceous Poa pratensis, Bromus inermis

The following paragraphs describing the general species composition of the five different 

floodplain woodland/shrubland associations are adapted from Von Loh et al. (2000).

Sandbar willow, usually forming dense cover in the tall shrub layer, is the dominant species in

the Sandbar Willow Temporarily Flooded Shrubland Alliance. Young, shrub-sized cottonwoods 

are also found in this alliance. Non-native white sweetclover (Melilotus alba), yellow 

sweetclover, and native Canada cocklebur (Xanthium strumarium) and prairie cordgrass are the 

most common herbaceous species.

The Cottonwood–Peachleaf Willow Floodplain Woodlands are nearly equally dominated by 

eastern cottonwood and peachleaf willow. These woodlands also contain other woody 

vegetation, including Salix amygdaloides, box elder (Acer negundo), green ash, and Rocky 

Mountain juniper. On dryer sites (river terraces), other shrub species are more common, such as 

redosier dogwood (Cornus sericea), golden currant (Ribes aureum var. villosum), honeysuckle 

(Lonicera spp.), western snowberry, Woods’ rose (Rosa woodsii), skunkbush sumac (Rhus 

trilobata), and the vines western white clematis (Clematis ligusticifolia) and Virginia creeper 

(Parthenocissus quinquefolia) (Von Loh et al. 2000). Native herbaceous species present in this 

type include Canada wildrye (Elymus canadensis), western wheatgrass, wild licorice 

(Glycyrrhiza lepidota), northern bedstraw (Galium boreale), meadow-rue (Thalictrum 

dasycarpum), and smooth scouring-rush (Equisetum laevigatum), but many non-native 

herbaceous plants are also present, namely leafy spurge, Kentucky bluegrass, white sweetclover, 

yellow sweetclover, Canada thistle, smooth brome, and yellow salsify (Von Loh et al. 2000). 

This community is likely successional between the Sandbar Willow Temporarily Flooded 

Shrubland Alliance and the Cottonwood–Rocky Mountain Juniper Woodland (Von Loh et al. 

2000).

Large and mature eastern cottonwood trees that form a distinctive tree canopy characterize the 

Cottonwood Temporarily Flooded Woodlands (Von Loh et al. 2000). Small cottonwood trees 

and secondary tree species such as green ash and Rocky Mountain juniper are sparse or 

sometimes absent. The alliance contains a high diversity of short shrub species, though most 

common are western snowberry. Yellow sweetclover and leafy spurge are very common nonnative understory species in South Unit cottonwood stands. This alliance is closely associated 

with the Silver Sagebrush / Western Wheatgrass Shrubland Alliance, Cottonwood – Rocky 

Mountain Juniper Woodland, and the Cottonwood–Peachleaf Willow Woodlands (Von Loh et al. 

2000).

The Cottonwood – Rocky Mountain Juniper Floodplain Woodlands are stands of old eastern 

cottonwood, where Rocky Mountain juniper and some green ash begin to fill in gaps. 
97

Cottonwood trees remain the dominate species with Rocky Mountain juniper subordinate. Rocky 

Mountain juniper and green ash dominate the tree, tall shrub, and short shrub layers. The 

understory is fairly sparse and similar to the Cottonwood Temporarily Flooded Woodland 

Alliance (Von Loh et al. 2000).

The Green Ash – American Elm Temporarily-Flooded Woodland Alliance is the climax 

community of the floodplain woodlands. They exist on the oldest areas of the floodplain 

woodlands, areas such as meander scars and depressions or along tributaries (Von Loh et al. 

2000). They are dominated by green ash and American elm trees, but many species of shrubs 

establish in the understory of older eastern cottonwood stands. The non-native Siberian elm (Ulmus 

pumila) is a secondary tree species in this alliance. Green ash and western snowberry are common 

small shrub species, along with some Rocky Mountain juniper. The most abundant herbaceous 

species is non-native Kentucky bluegrass (Von Loh et al. 2000).

Table 19. Floodplain shrubland and woodland area and percent composition for each THRO unit. GIS 

data from Von Loh et. al. (2000).

Description no. of 

polygons

area 

(ha)

area 

(ac)

% 

composition*

Elkhorn Ranch Unit (EHR)

Sandbar Willow Temporarily Flooded Shrubland Alliance 13 8.4 20.7 9.1

Cottonwood-Peachleaf Willow Floodplain Woodland 5 3.9 9.5 4.2

Cottonwood Temporarily Flooded Woodland Alliance 1 17.2 42.6 18.7

Cottonwood-Rocky Mountain Juniper Floodplain Woodland 1 0.1 0.3 0.1

Green Ash-American Elm Temporarily Flooded Woodland 

Alliance 5 21.3 52.6 23.0

North Unit (NU)

Sandbar Willow Temporarily Flooded Shrubland Alliance 137 410.3 1013.8 4.2

Cottonwood-Peachleaf Willow Floodplain Woodland 7 9.4 23.3 0.1

Cottonwood Temporarily Flooded Woodland Alliance 0 0 0 0.0

Cottonwood-Rocky Mountain Juniper Floodplain Woodland 34 184.2 74.5 0.3

Green Ash-American Elm Temporarily Flooded Woodland 

Alliance 56 167.8 414.5 1.7

South Unit (SU)

Sandbar Willow Temporarily Flooded Shrubland Alliance 192 92.9 229.6 0.5

Cottonwood-Peachleaf Willow Floodplain Woodland 30 29.1 72 0.2

Cottonwood Temporarily Flooded Woodland Alliance 28 70.4 174 0.4

Cottonwood-Rocky Mountain Juniper Floodplain Woodland 24 18.2 45.1 0.1

Green Ash-American Elm Temporarily Flooded Woodland 

Alliance 70 55.1 136.2 0.3

Park-wide (all units combined)

Sandbar Willow Temporarily Flooded Shrubland Alliance 342 511.6 1264.1 1.8

Cottonwood-Peachleaf Willow Floodplain Woodland 42 42.4 104.8 0.2

Cottonwood Temporarily Flooded Woodland Alliance 29 87.6 216.6 0.3

Cottonwood-Rocky Mountain Juniper Floodplain Woodland 63 223.7 172.2 0.2

Green Ash-American Elm Temporarily Flooded Woodland 

Alliance 126 222.9 550.7 0.8
98

*calculated as a percent of total area in unit, EHR = 95.3 ha (228.2 ac), NU = 9,751.7.3 ha (24,096.9), SU 

= 18,635.2 ha (45,048.6 ac), total area all units = 28,479.2 ha (69,373.7 ac).

Changes in Species Distribution

Floodplain woodlands are found on alluvial soils adjacent to the Little Missouri River and along 

its major tributaries across southwest North Dakota (Godfread 1994). In THRO, most 

cottonwood woodlands are restricted to the floodplain of the Little Missouri River, though some 

stands exist along Box Elder, Beaver, Cherry, Paddock and Corral Creeks. Cottonwood 

woodlands typically are distributed along the Little Missouri River as bow-shaped stands of 

even-aged trees, with older stands farther away from the river channel (Miller 2005).

Changes in the distribution of cottonwood woodlands are expected over time, with channel 

migration and the deposition of new alluvium. However, Miller (2005) found that the high 

instantaneous peak flows typically occurring during spring snowmelt have decreased in 

magnitude over time (1939 to 2003), causing a decrease in the active channel area and an 

increase in the floodplain area. High flows allow for the continued establishment of cottonwood 

forests, as high peak discharges tend to cause more “floodplain turnover” (Miller 2005). The 

spring 2011 high peak flows and stage heights may have caused significant changes in 

successional trajectories of floodplain woodlands. In a study related to water rights issues on the 

Little Missouri River, Miller (2005) recommended that high flows should be protected and that 

reductions in summer flows should be avoided to limit drought mortality of floodplain trees.

Von Loh et al.’s (2000) GIS data provide the most current distribution and extent of cottonwood 

forests in THRO, based on 1996 aerial photography. All three units contain stands of cottonwood 

woodland types. The North Unit did not contain any Cottonwood-Rocky Mountain juniper 

floodplain woodlands (Plate 10), whereas the South Unit contains a significant portion of this 

community type (Plate 11). A mix of the various cottonwood woodlands and some Sandbar 
99

Willow Temporarily-Flooded Shrubland Alliance areas are present in the EHR Unit (

Plate 12).

Cottonwood Woodland Area-Age Distribution

The last specific assessment of cottonwood stand ages in THRO was the dendrologic work by 

Everitt (1968) in a small section the Little Missouri River in the North Unit of the park (Figure 

9).
100

Figure 9. Age map of valley floor. Reproduced from Everitt (1968).
101

Floodplain riparian forest (woodland) ages are determined by the spatial and temporal variation 

in historic flood events (Miller 2005). This is because cottonwood seedlings require freshly 

deposited alluvium for establishment, as older established cottonwood woodlands do not reseed 

themselves in their under-stories (Everitt 1968). Cottonwood seedling survival depends on these 

sites being relatively safe from future flooding disturbance, which are typically rare in the 

riparian landscape (Scott et al. 1996). The creation of new alluvium requires transport and 

deposition of sediment, mainly through high river discharges, important for the establishment of 

new cottonwood seedlings (Miller 2005). The seedlings initially form dense stands of 

cottonwoods or willows on point bars in the Little Missouri River; then, as the channel migrates, 

narrow bands of cottonwoods mature along older abandoned channels and show an orderly 

increase in age moving up-valley away from the channel (Everitt 1968, Godfread 1994).

Cottonwood trees along the Little Missouri typically reach approximately 90 years of age before 

their health begins to decline (Wali et al. 1980), after which cottonwood forests will eventually 

succeed to green ash-American elm woodlands in the absence of flooding (Von Loh et al. 2000).

Everitt (1968) found cottonwood stands to exhibit an age distribution similar to a steady-state 

exponential relation described in Merigliano et al. (2012). However, research that is more recent 

found instantaneous high flows have decreased on the Little Missouri, resulting in a larger 

floodplain area and smaller active river channel area (Miller 2005, Miller and Friedman 2009). 

The authors suggest the age distribution of the Little Missouri River floodplain is now far from a 

steady state. However, high peak flows occurring in late-May 2011 may have since reset 

succession of riparian vegetation in some areas with increased channel migration.

According to GIS data developed by Von Loh et al. (2000), the three aforementioned 

cottonwood communities, the Sandbar Willow Temporarily Flooded Shrubland Alliance, and the 

Green Ash-American Elm Temporarily Flooded Alliance community cover approximately 3.4% 

of the total park area (all units combined). Most of the floodplain woodlands were classified as 

Cottonwood Temporarily Flooded Woodland Alliance and a relatively large proportion of Green 

Ash-American Elm Temporarily Flooded Alliance. Smaller proportions were early successional 

floodplain vegetation stages (Sandbar Willow and Cottonwood-Peachleaf Willow) (Figure 10). 

This is consistent with Miller and Friedman’s (2009) conclusion that old floodplain forest is 

more abundant than young floodplain areas. Again, this may have changed since 1996 (date of 

aerial photography used to create GIS data), and given the large magnitude flooding that 

occurred in spring 2011.
102

Figure 10. Relative composition of woodland and shrubland floodplain area in THRO. GIS data from Von 

Loh et. al. (2000).

A floodplain with very few cottonwood seedlings or young cottonwood trees could cause 

concern for the future of this community type in THRO. However, Friedman (pers. comm., 

2012) suggests that using the relative area of young vegetation classes by itself as an index of 

establishment rate of floodplain woodlands is problematic since cottonwood and willow 

reproduction are closely linked to channel migration driven by floods, which are uncommon and 

unevenly distributed in time. That is, the Little Missouri River is dominated by lasting effects of 

infrequent flooding events (Merigiliano et al. 2012). Instead, Friedman (pers. comm., 2012) 

suggests that in using aerial photography or satellite imagery to detect channel migration rates 

along with monitoring the areas of different vegetation types, the NPS can gauge forest 

reproduction and survival rates. It is important to note that these measures are most valuable 

when used together, repeatedly, and over a long time-period.

Friedman (pers. comm., 2012) recommends protecting factors that promote channel migration, 

because riparian vegetation depends so heavily upon this channel migration. Examples of this 

type of protection include limiting construction activities on the floodplain in or near the park, 

limiting upstream water withdrawals, and monitoring annual variation in peak flows at the USGS 

gages in Watford City and Medora, North Dakota. Riparian vegetation is also dependent upon a 

water subsidy provided by the river. Therefore, summer low flows should be monitored at the 

USGS gages, upstream water withdrawals should be monitored, and instream flows should be 

protected during drought.

Non-Native Species Abundance 

According to Ashton et al. (2012), non-native species are more abundant in riparian forests than 

the surrounding upland areas of THRO. Russian olive trees are a specific non-native woody 

species representing a threat to Sandbar Willow Shrublands, Cottonwood-Peachleaf Willow, and 

Cottonwood Woodlands in THRO. Once located by NPS invasive plant survey efforts, Russian 

olive seedlings are immediately removed (L. Richardson, pers. comm., 2012). Another woody 

species that could threaten floodplain woodlands is saltcedar.

7%

5%

55%

9%

24%

Sandbar Willow

Temporarily Flooded

Shrubland Alliance

Cottonwood-Peachleaf

Willow Floodplain

Woodland

Cottonwood Temporarily

Flooded Woodland

Alliance

Cottonwood-Rocky

Mountian Juniper

Floodplain Woodland

Green Ash-American Elm

Temporarily Flooded

Woodland Alliance
103

Other abundant non-native invasive species are herbaceous. The Cottonwood–Peachleaf Willow 

Floodplain Woodlands of THRO contain non-native yellow sweetclover and white sweetclover 

(Von Loh et al. 2000). In the Cottonwood Temporarily-Flooded Woodland Alliance, common 

invasive plants include yellow sweetclover, leafy spurge, smooth brome, Kentucky bluegrass, 

and yellow salsify. Cottonwood – Rocky Mountain Juniper Floodplain Woodlands also contain 

leafy spurge, Kentucky bluegrass, smooth brome, white sweetclover, yellow sweetclover, and

alfalfa. In the Green Ash-American Elm alliance, the primary non-native plant species is 

Kentucky bluegrass (Von Loh et al. 2000).

Leafy spurge, a species long noted as an aggressive invasive (Bowes and Thomas 1978), was 

first noted to occur in the river floodplain of THRO, followed by its spread to wooded draws and 

grasslands (Trammell 1994). More recently, leafy spurge and Canada thistle were found to occur 

at such densities and large areas as to warrant their own map units in Von Loh et al.’s (2000) 

mapping efforts. The Leafy Spurge Herbaceous Alliance occurs in many areas of the park, 

including on floodplains, especially in the South Unit. Since 2002, the EPMT and THRO park 

staff have utilized integrated pest management practices to reduce/eliminate invasive plant 

species. The primary focus of these efforts has been on species listed on the North Dakota 

Noxious Weed List (NPS 2010). 

According to GIS data collected by the EPMT, leafy spurge and Canada thistle are the primary 

invasive non-native plant species in terms of treatment effort in or adjacent to the floodplain 

woodlands in THRO. However, other typical non-native plant species include Kentucky 

bluegrass and smooth brome, though less targeted by invasive plant management control efforts. 

In 2009, nearly 500 acres were treated for these species in or near floodplain woodlands of the 

park. Multiple herbicides and methods (e.g., helicopter, backpack, ATV) are employed by the 

EPMT and by THRO park staff. According to the NPS THRO Exotic Vegetation Program 

Geodatabase (GIS data), THRO staff and NGP EPMT also used biological control on Canada 

thistle and leafy spurge, releasing biological control agents (e.g., beetles) from 1988 to 2005 in 

hundreds of locations across the park. Since significant invasive plant treatments began, most of 

the efforts have been focused in the South Unit of the park.

Threats and Stressor Factors

Non-native Species

Non-native species, especially those considered invasive, can alter the composition and structure 

of native plant communities. They are considered threats in THRO “because they: 1) replace 

native species, 2) reduce the land’s carrying capacity for livestock and grazing wildlife, 3) may 

be poisonous to livestock or wildlife, 4) decrease plant species diversity and can further 

reduce/imperil populations of rare plant species, 5) may carry detrimental insects, diseases, or 

parasites, 6) can alter fire patterns and intensity, 7) can increase soil nitrogen levels to be 

detrimental to native species, 8) can result in increased soil erosion and runoff, and 9) can 

generally degrade or destroy wildlife habitat” (Trammell 1994, CNAP 1999; as cited by Von 

Loh et al. 2000, p. 2-18).

Although it is a native species, Rocky Mountain juniper is encroaching on some of the floodplain 

forests (at least those on drier river terraces), along with many of the upland grassland 

communities. Rocky Mountain juniper forms a sub-canopy beneath larger cottonwood trees in 
104

the riparian areas along the Little Missouri River (Von Loh et al. 2000). Juniper encroachment 

into the floodplain forest community can replace both green ash and cottonwood trees as terraces 

dry (Godfread 1994, Von Loh et al. 2000). While its encroachment into floodplain woodlands is 

part of natural succession occurring as floodplain areas age, the increasing prevalence of this 

species across the park and its potential influence on other floodplain species is concerning to 

park staff.

Changes in Flooding Regime

In a study examining the influence of flow variability on the formation and destruction of the 

Little Missouri River floodplain, discharge of the highest one or two flow events of a decade 

were correlated most strongly with floodplain destruction (Miller and Friedman 2009). In 

addition, half of the suspended sand was transported via discharges that occur on average only 

one day per year (Miller and Friedman 2009). This suggests the geomorphological importance of 

peak flows in determining the amount of floodplain destruction (i.e., creation of new alluvial 

surfaces). This is especially true in more arid and smaller watersheds (Merigliano et al. 2012). 

Miller and Friedman’s (2009) time sequence mapping of floodplain ages were similar to stand 

age maps created through dendrologic examinations (Everitt 1968), and they suggest that this 

confirms the concept that riparian tree establishment occurs mainly on recent channel locations 

in the Little Missouri River. Miller and Friedman (2009) found that, from 1939 to 2003, the 

magnitude of these influential instantaneous peak flows decreased, and suggested that this was 

primarily due to climatic conditions (i.e., precipitation and temperature patterns). This decrease 

generally reduced channel migration and erosion rates, thereby reducing the amount of new 

alluvial surfaces for the establishment of early successional shrubs (willows) and cottonwood 

trees.

Miller and Friedman (2009) suggest that, “the age distribution of the floodplain is far from 

steady state” (Miller and Friedman 2009, p. 758). However, this was found to be influenced by 

an uncommon increase in tree establishment from a large flood in 1947 (Merigliano et al. 2012). 

Miller (2005) recommended that the NPS should protect high instantaneous peak flows along the 

Little Missouri to support new cottonwood habitat formation. In addition, during July and 

August, near Watford City, North Dakota, the Little Missouri River flow can be greatly reduced 

and has even been known to cease (Everitt 1968). Therefore, Miller (2005) also recommended 

avoiding reductions in summer low flows because of the potential for drought-caused mortality 

of trees. 

Since the Miller and Friedman (2009) study, a high spring discharge occurred on the Little 

Missouri in May 2011. This represented a large magnitude flood due to large snowpack in the 

upper reaches of the watershed. The peak discharge of 36,200 cfs on this day represented the 

fifth highest flow on record at the USGS gage in Medora, ND (Figure 11) and the second highest 

recorded gage height, at 6.21 m (20.39 ft) (Figure 12). This likely caused geomorphological 

changes to the river channel and the riparian vegetation. Refer to Section 4.3 for more 

information regarding Little Missouri River flooding.
105

Figure 11. Highest recorded peak discharges and recent (2011) peak discharge from the USGS gage 

(06336000) at Medora, ND.

Figure 12. Highest recorded peak stage heights and recent (2011) gage height at the USGS gage 

(06336000) at Medora, ND.
106

Ice Jams

Ice jams have been witnessed by park staff in the winter months, leading to flooding that can 

impact streambanks (Berkeley et al. 1998). This is more typical during the spring snowmelt 

season (Miller 2005). Spring ice-jams are natural events that cause damage (abrasion) to 

cottonwood trees. They leave scars on tree trunks for years which act as references for the 

approximate stage height of past ice-jam floods (Miller 2005). A concern regarding ice-jam 

floods is the potential for climate/weather changes to alter the hydrologic regime (including the 

magnitude and frequency of ice-jam flooding events) of the Little Missouri, thereby possibly 

altering the composition and abundance of floodplain vegetation over time.

Data Needs/Gaps

No specific information is available that examines the species composition and abundance of 

each floodplain woodland alliance. A NGPN plant community monitoring will help address this 

gap. However, only five riparian plots have been sampled to date (Ashton et al. 2012). In 2015, 

the NGPN plant community monitoring program plans to implement a large survey of riparian 

forests in the park that will examine stand structure and forest health (Symstad et al. 2012). 

An assessment of cottonwood woodland stand ages in THRO would give park managers a better 

understanding of the age composition of these woodlands in order to provide insight for the 

future of cottonwood forests (e.g., if regeneration is keeping pace with vegetation succession and 

tree mortality). This research is ongoing in both the North and South Units of the park.

The Von Loh et al. (2000) GIS data describing the extent and distribution of various floodplain 

woodlands across the three park units was developed using 1996 aerial photography (now nearly 

16 years old). An update would provide park management a contemporary understanding of the 

extent and distribution of floodplain woodlands and would allow for an assessment of changes in 

community distribution and composition in the park. The 2011 spring flooding likely caused 

significant alterations to the river channel and riparian vegetation along the Little Missouri River 

in THRO. These interactions of the river’s hydrologic regime and changes in the relative 

composition of floodplain vegetation classes are important to examine in order to understand the 

current status of the floodplain woodlands and potential trajectories.

Overall Condition

Species Composition and Abundance

The project team defined the Significance Level of frequency as a 3. No specific information 

examining species-level composition and abundance is currently available, outside of broad 

categorizations of dominant species for each plant community association in Von Loh et al. 

(2000); therefore, a Condition Level is not assigned. The main issue affecting native species 

composition and abundance is the influx and expansion of invasive plant species. In the future, 

data from NGPN plant community monitoring can be used to assess this measure.

Changes in Species Distribution

The project team defined the Significance Level of changes in species distribution as a 3. No 

species-level distribution information is currently available for THRO, only relatively recent 

community distribution information from Von Loh et al.’s (2000) GIS data. The Condition Level
107

is not assigned. Data from NGPN plant community monitoring may also be useful in assessing 

this measure in the future.

Cottonwood Area-Age Distribution

The project team defined the Significance Level of cottonwood area-age distribution as a 3. 

Unlike Everitt’s (1968) assessment of stand ages in the North Unit of the park where floodplain 

ages more closely matched a steady-state exponential relationship, Miller and Friedman (2009) 

found that floodplain ages were far from a steady state, and that floodplain destruction decreased 

from 1939 to 2003 on the Little Missouri River. Miller and Friedman (2009) also found that the 

proportion of older woodlands was higher than younger woodlands. This proportion also was 

illustrated in examining the relative composition of various successional stages of the floodplain 

shrubland and woodlands in the Von Loh et al. (2000) GIS data. Merigliano et al. (2012) suggest 

that there is too much variability in annual peak flows because of local conditions affecting ice 

jams to detect climate-induced changes in peak flows. Recently, the distribution of cottonwood 

area-ages has likely changed following the May 2011 flooding. However, given a low level of 

flow regulation and land clearing, the absence of channel stabilization, the existence of record 

tree ages, and the natural age structure characteristics of these woodlands, the level of concern 

for this measure is low (J Hughs, pers. comm., 2012). A Condition Level for cottonwood areaage distribution is assigned a value of one, indicating low concern.

Non-native Species Abundance 

The project team defined the Significance Level of non-native species abundance as a 3. Specific 

data defining the abundance of non-native species in each of the floodplain woodlands are 

lacking. However, a few non-native invasive plant species are abundant in many of these 

woodlands. Despite not having data that specifically estimate abundances, yellow and white 

sweetclovers, leafy spurge, and Kentucky bluegrass contribute a significant proportion of the 

species composition in many of the floodplain woodlands. Therefore, this measure is assigned a 

Condition Level of 3, signifying a significant concern for the biological integrity of these 

floodplain woodlands. Although they currently exist in very low numbers, invasive Russian olive 

trees present a looming threat to floodplain vegetation of the park.

Weighted Condition Score

Given the lack of information for most of the measures, a Weighted Condition Score is not 

appropriate for this component. However, Friedman (pers. comm., 2012) suggests if, for 

example, young woodlands decreased in area during and after a period of high river flows, it 

would be cause for concern especially if channel migration rates were shown to decrease during 

the same time-period. As another example, if large areas of mature floodplain woodlands were to 

die-off at a time when upstream withdrawals increased and summer low flows became more 

extreme, it would also be a cause for concern.
108

4.6.6 Sources of Expertise

Jonathan Friedman, Hydrologist, USGS, Fort Collins, Colorado

Laurie Richardson, Botanist, THRO
109

4.6.7 Literature Cited

Anderson, J. R., E. E. Hardy, J. T. Roach, and R. E. Witmer. 1976. A land use and land cover 

classification system for use with remote sensing data. U.S. Geological Survey Profession 

Paper 964. U.S. Geological Survey, Reston, Virginia.

Berkeley, J., G. R. Reetz, and D. Vana-Miller. 1998. Water resources management plan: 

Theodore Roosevelt National Park, North Dakota. National Park Service, Theodore 

Roosevelt National Park, North Dakota.

Bowes, G. G., and A. G. Thomas. 1978. Longevity of leafy spurge seeds in the soil following 

various control programs. Journal of Range Management 31:137-140.

Colorado Natural Areas Program (CNAP). 1999. Draft: Creating an integrated weed 

management plan, a handbook for owners and managers of lands with natural values.

Colorado Division of Parks and Outdoor Recreation Caring for the Land Series, Volume IV. 

Colorado Department of Agriculture, Denver, Colorado. 

Everitt, B. L. 1968. Use of the cottonwood in an investigation of the recent history of a flood 

plain. American Journal of Science 266:417-439.

Jakes, P. J., and W. B. Smith. 1983. A second look at North Dakota timber land. Resource 

Bulletin NC-58. U.S. Forest Service, North- Central Forest and Range Experiment Station, 

St. Paul, Minnesota.

Johnson, WC, Burgess RL, and Keammerer WR. 1976. Forest overstory vegetation and 

environment on the Missouri River floodplain in North Dakota: Ecological Monographs 

46:59-84

Johnson, W. C. 1994. Woodland expansion in the Platte River, Nebraska: patterns and causes. 

Ecological Monographs 64(1):45-84.

Godfread, C. 1994. The vegetation of the Little Missouri Badlands of North Dakota. Pages 17-24

in Proceedings: Leafy spurge strategic planning workshop, Dickinson, North Dakota. March 

29-30, 1994.

Miller, J. R. 2005. Quantifying historical channel and floodplain change along the Little 

Missouri River in Theodore Roosevelt National Park, North Dakota. Thesis. Colorado State 

University, Fort Collins, Colorado.

Miller, J. R., and J. M. Friedman. 2009. Influence of flow variability on floodplain formation and 

destruction, Little Missouri River, North Dakota. GSA Bulletin 121(5/6):752-759. 

Merigliano, M. F., J. M. Friedman, and M. L. Scott. 2012. Tree-ring records of variation in flow 

and channel geometry. Treatise on Geomorphology, In-press.

National Park Service (NPS). 2009. Floodplains - Theodore Roosevelt National Park. 

http://www.nps.gov/thro/naturescience/floodplains.htm (accessed 12 August 2011).
110

Nelson, J. R. 1961. Composition and distribution of the principal woody vegetation types in the 

Badlands of North Dakota. North Dakota Game and Fish Department, Bismarck, North 

Dakota.

Norland, J. E. 1984. Habitat use and distribution of bison in Theodore Roosevelt National Park. 

Thesis. Montana State University, Bozeman, Montana.

Scott, M. L., J. M. Friedman, and G. T. Auble. 1996. Fluvial process and the establishment of 

bottomland trees. Geomorphology 14:327–339.

Trammell, M. A. 1994. Exotic plants of Theodore Roosevelt National Park: extent, distribution 

and ecological impact. Thesis. University of South Dakota, Vermillion, South Dakota. 

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli.

2000. USGS-NPS vegetation mapping program: Theodore Roosevelt National Park, North 

Dakota. U.S. Department of the Interior, Denver, Colorado.

Wali, M. K., K. T. Killingbeck, R. H. Bares, and L. E. Schubert. 1980. Vegetation-environment

relationships of woodland and shrub communities, and soil algae in western North Dakota. 

ND REAP Project No. 7-01-1. University of North Dakota, Grand Forks, North Dakota.
111

Plate 10. Floodplain woodlands in the North Unit of THRO (Von Loh et al. 2000).
112

Plate 11. Floodplain woodlands in the South Unit of THRO (Von Loh et al. 2000).
113

Plate 12. Floodplain woodlands in the Elkhorn Ranch Unit of THRO (Von Loh et al. 2000). Shown with 2004 USDA National Agriculture Imagery 

Program (NAIP) imagery.
114

4.7 Woody Draws

4.7.1 Description

Woody draws are small, forested areas that occur in ravines or drainage areas within the 

badlands landscape (Hull Sieg 1997). The hardwood communities are a small portion of the 

overall landscape in the northern Great Plains, but provide an important structural contrast to the 

surrounding grasslands and 

shrublands (Sullivan et al. 

1989). Woody draws provide 

food and cover for a variety of 

wildlife species in THRO, 

including white-tailed deer, 

mule deer (Odocoileus

hemionus), porcupine, and 

forest-dwelling birds. This

plant community is dominated 

by green ash, and support 

American elm and box elder

to a lesser extent (Von Loh et 

al. 2000).

4.7.2 Measures

 Species composition 

and abundance

 Distribution

 Prevalence of non-natives

4.7.3 Reference Conditions/Values

The ideal reference condition for this component would be the composition and distribution of 

woody draws prior to European settlement. However, no information is available from this 

historical period. The earliest description of THRO’s woody draws comes from Hansen et al.’s 

(1984) habitat type classification of the park’s vegetation. Their characterization of the Fraxinus 

pennsylvanica/Prunus virginiana habitat type will be used as the reference condition for species 

composition in this assessment.

4.7.4 Data and Methods

Irby (2000) monitored 12 green ash draws in the South Unit of THRO between 1985 and 1996 

for changes in plant species composition. North Dakota green ash draws were also studied 

previously by Butler (1983).

Von Loh et al. (2000) used remote sensing to map vegetation in THRO and provided information 

regarding the composition and distribution of woody draws in the park.

Trammel (1994) surveyed the distribution and extent of exotic species throughout THRO, 

including in woody draws.

Photo 15. Woody draw in THRO dominated by green ash with some 

juniper encroachment (photo by Shannon Amberg, SMUMN GSS, 2010).
115

4.7.5 Current Condition and Trend

Species Composition and Abundance

Green ash is one of the dominant tree species found in hardwood draws of the northern Great 

Plains (Sullivan et al. 1989). Other tree species found in the hardwood draws of THRO include 

American elm and box elder (Butler 1983, Von Loh et al. 2000). Woody draws sampled by Von 

Loh et al. (2000) in THRO exhibited 30% mean foliar cover by green ash, followed by 12% 

mean foliar cover for American elm and 3% for box elder. The shrub layer is typically 

dominated by chokecherry but can also include Saskatoon serviceberry (Amelanchier alnifolia), 

common snowberry (Symphoricarpos albus), western snowberry, currants (Ribes spp.), 

skunkbush sumac, and American plum (Prunus americana) (Irby et al. 2000, Von Loh et al. 

2000). Northern bedstraw, wild bergamot, and early meadow rue (Thalictrum venulosum) are 

forb species commonly found in these communities (Hansen et al. 1984, Godfread 1994). 

Common graminoids include Virginia wild-rye (Elymus virginicus), Sprengel sedge (Carex 

sprengelii), and Kentucky bluegrass (Butler 1983, Von Loh et al. 2000). The herbaceous layer 

(forbs and graminoids) in THRO woody draws averaged 45% foliar cover (Von Loh et al. 2000).

Irby et al. (2000) noted that graminoids, forbs, and invasive forbs all showed significant 

increases in the 12 green ash stands monitored during their 1985-1996 study. The study found a 

few directional changes in these communities, including a decrease in mature chokecherry and 

Saskatoon serviceberry and an increase in ground cover plants. These changes did not appear to 

be due to overuse by ungulates and may be part of natural stand succession. Green ash canopy 

cover showed little change over the study period (Irby et al. 2000).

Distribution

Woody species are primarily found in draws in THRO, which have greater soil moisture (Hull 

Sieg 1997). Woody draws rarely comprise more than 2% of the plains landscape due to a lack of 

moisture (Boldt et al. 1978 and Girard et al. 1989, as cited by Sullivan et al. 1989). The Green 

Ash-American Elm Woodland Alliance is the dominant woody plant community in THRO 

draws, in which green ash is the dominant species (Von Loh et al. 2000). Von Loh et al. (2000) 

states that green ash-American elm draws generally occur in north facing mesic draws or 

drainages and on moderately steep slopes, but occasionally on east-west oriented sites where 

moisture requirements are met.

Plate 13, Plate 14, and Plate 15 display the distribution of Green Ash-American Elm Woodland 

draws in the North, South, and Elkhorn Ranch Units of THRO, respectively.

Prevalence of Non-Natives

Trammel (1994) found 14 non-native plant species present in the hardwood draw vegetational 

class in a survey of the park. Kentucky bluegrass was the most widespread in the park, with leafy 

spurge occuring in many of the South Unit draws (Trammel 1994). In recent years Canada thistle 

has become more common in woody draws as well (L. Richardson, pers. comm., 2012). Table 20

displays non-native plant species documented in THRO hardwood draws in a 1992-1993 survey, 

along with their mean percent cover and quadrat frequency.
116

Table 20. Non-native plants documented in THRO woody draws in 1992-1993, with mean percent cover 

and quadrat frequencies (Trammel 1994). Nine hundred thirty-five quadrats were sampled in 1992 with 

150 different quadrats sampled in 1993.

Scientific Name Common Name

% Cover -

1992 plots

Quadrat freq. -

1992 plots

% Cover -

1993 plots

Quadrat freq. -

1993 plots

Agropyron cristatum crested wheat grass T* 0.7

Bromus inermis smooth brome 0.9 3.1 0.4 2.6

Bromus arvensis field brome T 0.1 0.2 2.6

Bromus tectorum cheat grass T 0.7

Chenopodium album lambsquarters T 0.6

Convolvulus arvensis field bindweed 0.1 4.0

Euphorbia esula leafy spurge 8.8 29.7

Lactuca serriola prickly lettuce T 0.5

Lappula echinata stickseed T 0.6

Melilotus officinalis yellow sweetclover 0.1 1.3

Poa compressa Canada bluegrass T 0.5

Poa pratensis Kentucky bluegrass 4.8 25.2 6.0 66.6

Taraxacum officinale dandelion 0.6 5.6 T 2.0

Tragopogon dubius yellow salsify 0.1 1.5

* T= Trace (cover < 0.1%)

Irby et al. (2000) found that non-native grasses increased over the 12-year study period but 

remained low in comparison to natives. Invasive forbs increased more than palatable forbs 

during this period, although invasive species were a small percentage of total ground cover. Von 

Loh et al. (2000) noted that Kentucky bluegrass, leafy spurge, burdock (Arctium minus), yellow 

sweetclover, and smooth brome were prevalent in THRO hardwood draws.

Threats and Stressor Factors

Non-native species are a significant threat to the native woody draw communities in THRO. 

Leafy spurge is a particularly aggressive non-native, which is problematic at the park. The 

species has proven difficult to control by conventional means (Butler and Trammell 1995), can 

displace native species (Trammell 1994), and is toxic or unpalatable to some wildlife (Selleck et 

al. 1962, as cited by Butler and Trammell 1995). Observations suggest that heavily infested areas 

are sometimes avoided by bison, elk, and deer (Butler and Trammell 1995); however, this has 

not been validated with an experimental research design. Despite an increase in non-native

grasses in the 12-year Irby et al. (2000) study, invasive species remained a small percentage of 

ground cover in the woody draws that were sampled.

Ungulate foraging is a potential threat to woody draws in THRO if populations grow too large;

however, Irby et al. (2000) found no evidence of overgrazing of the green ash woodlands 

sampled in the South Unit of the park. Elk and mule deer are the two most common ungulates 

that use woody draws for browse (Irby et al. 2000). Godfread (1994) noted that disturbance by 

cattle in woody draws allowed non-native plants such as burdock and dandelion (Taraxacum

officinale) to invade; it is possible that heavy native ungulate activity in THRO could cause 

similar disturbances (although likely to a lesser degree) in these communities.
117

Several tree diseases pose a potential threat to woody draws in THRO. A variety of diseases can 

impact the Fraxinus genus, including anthracnose, scorch, ash rust, several heart rots, leafspots, 

and ash yellows (NDSU 1995). The Prunus genus is affected by black knot, plum pockets, and X 

disease, the latter of which has wiped out many chokecherry stands in the northern Great Plains 

(NDSU 1995). During a brief visit to THRO in August 2010 to investigate ash die back in 

several South Unit stands, NDSU researchers found evidence of several ash pathogens, including 

the fungus Perenniporia fraxinophila, wood borers, and bark beetles (Walla and Zeleznik 2010). 

Ash yellows damage was also observed in one tree. However, this survey was limited to just five 

green ash stands in the South Unit and does not necessarily reflect conditions throughout the 

park. Further research is needed to determine if these pathogens are impacting woody draws as a 

whole.

The emerald ash borer (EAB) (Agrilus planipennis) is an invasive insect recently introduced to 

North America, which has quickly spread across much of the eastern United States and Canada 

and is now present as far west as Minnesota (USFS et al. 2011). Emerald ash borer larvae kill ash 

trees by feeding on the inner bark, disrupting the tree’s ability to transport water and nutrients 

(USFS et al. 2011). Emerald ash borer has already decimated large populations of ash trees, and 

could be devastating to ash trees in the woody draws of THRO if it becomes introduced to the 

area. The U.S. Department of Agriculture monitors for EAB in the park each summer (L. 

Richardson, pers. comm., 2012).

Data Needs/Gaps

Green ash draw sites measured by Irby (2000) could be revisited to examine changes in the plant 

community over time. However, it may be difficult with such a small sample size to determine if 

any differences represent actual changes or simply natural variation. There is no information 

currently available regarding the prevalence of diseases in woody draws. Non-native species 

abundance has not been closely examined specifically in woody draws for a number of years.

Research into how these non-natives impact woody draw composition and structure would be 

helpful in understanding the condition of this plant community in the park.

Overall Condition

Species Composition and Abundance

The THRO project team assigned a Significance Level of 2 for species composition and 

abundance. The most recent description of THRO woody draw composition (Von Loh et al. 

2000) is very similar to earlier reports by Butler (1983) and Hansen et al. (1984). Since there is 

currently no evidence of change in the composition or abundance of woody draws, this measure 

was assigned a Condition Level of 1.

Distribution

A Significance Level of 3 was assigned to the measure of distribution. Unfortunately, there is 

only one source of information addressing the distribution of woody draws in THRO (Von Loh 

et al. 2000). Since there is no historic or more recent distribution information for comparison, a 

Condition Level cannot be assigned for this measure.
118

Prevalence of Non-natives

A Significance Level of 2 was assigned to the measure of prevalence of non-natives. While nonnative species comprised a small percentage of the ground cover in woody draws when they 

were last surveyed, the presence of aggressive invasives such as leafy spurge and Canada thistle 

makes this measure of moderate concern (Condition Level = 2). 

Weighted Condition Score

The Weighted Condition Score (WCS) for woody draws in THRO is 0.500, which is of moderate 

concern. Since woody draws have not been surveyed in any detail over the past decade, the trend 

in their condition is unknown.

4.7.6 Sources of Expertise

Laurie Richardson, Botanist, THRO 
119

4.7.7Literature Cited

Boldt, C., D. Uresk, and K. Severson. 1978. Riparian woodlands in jeopardy on the Northern 

Great Plains. Pages 184-189 in Strategies for protection and management of floodplain 

wetlands and other riparian ecosystems. U.S. Forest Service, Washington, D.C.

Butler, J. 1983. Grazing and topographic influences on selected green ash (Fraxinus 

pennsylvanica) communities in the North Dakota badlands. Thesis. North Dakota State 

University, Fargo, North Dakota.

Butler, J., and M. Trammel. 1995. Exotic plants of Theodore Roosevelt National Park: Extent, 

distribution, and ecological impact. National Park Service, Theodore Roosevelt National 

Park, North Dakota.

Girard, M., H. Goetz, and A. Bjugstad. 1989. Native woodland habitat types of southwestern 

North Dakota. Research paper RM-281. U.S. Forest Service, Rocky Mountain Forest and 

Range Experiment Station, Fort Collins, Colorado.

Godfread, C. 1994. The vegetation of the Little Missouri Badlands of North Dakota. Pages 17-24

in Proceedings: Leafy spurge strategic planning workshop, Dickinson, North Dakota. March 

29-30, 1994. 

Hansen, P. L., G. R. Hoffman, and A. J. Bjugstad. 1984. The vegetation of Theodore Roosevelt 

National Park, North Dakota: A habitat type classification. U.S. Forest Service, Rocky 

Mountain Forest and Range Experiment Station, Fort Collins, Colorado.

Hull Sieg, C. 1997. The role of fire in managing for biological diversity on native rangelands of 

the northern Great Plains. U.S. Forest Service, Rapid City, South Dakota.

Irby, L. R., J. E. Norland, M. G. Sullivan, J. A. Westfall, and P. Andersen. 2000. Dynamics of 

green ash woodlands in Theodore Roosevelt National Park. The Prairie Naturalist 32(2):77-

102.

North Dakota State University (NDSU). 1995. Deciduous tree diseases. 

http://www.ag.ndsu.edu/pubs/plantsci/hortcrop/pp697-2.htm#Parasitic (accessed 18 April 

2011). 

Selleck, G. W., R. T. Coupland, and C. Frankton. 1962. Leafy spurge in Saskatchewan. 

Ecological Monographs 32:1-29.

Sullivan, M. G., L. R. Irby, and C. B. Marlow. 1989. Potential green ash browse in hardwood 

draws in Theodore Roosevelt National Park. Prairie Naturalist 21(4):211-217.

Trammel, M. A. 1994. Exotic plants of Theodore Roosevelt National Park: Extent, distribution, 

and ecological impact. Thesis. University of South Dakota, Vermillion, South Dakota. 

U.S. Forest Service (USFS), Michigan State University, Purdue University, and Ohio State 

University. 2011. Emerald ash borer. http://www.emeraldashborer.info/index.cfm (accessed 

18 April 2011).
120

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli. 

2000. USGS-NPS vegetation mapping program: Theodore Roosevelt National Park, North 

Dakota. U.S. Department of the Interior, Denver, Colorado.

Walla, J., and J. Zeleznik. 2010. Summary of observations on dieback of ash trees: Theodore 

Roosevelt National Park (South Unit), August 2010. North Dakota State University, Fargo, 

North Dakota.
121

Plate 13. Green Ash-American Elm Woodland Alliance distribution in the North Unit of THRO (mapped in 2000).
122

Plate 14. Green Ash-American Elm Woodland Alliance distribution in the South Unit of THRO (mapped in 2000).
123

Plate 15. Green Ash-American Elm Woodland Alliance distribution in the Elkhorn Ranch Unit of THRO (mapped in 2000).
126

4.8 Upland Shrubland Communities

4.8.1 Description

Shrubland communities are found on a wide variety of landform types in THRO, including 

floodplains, flats, slopes, slumps, draws, hills, and ridges (Von Loh et al. 2000). This assessment 

focuses on shrubland communities found in upland habitats of the park. These areas provide 

important resources for wildlife, including elk and North Dakota conservation priority species 

such as the lark bunting (Calamospiza melanocorys) and black-billed cuckoo (Coccyzus 

erythropthalmus) (NPS 2010). Von Loh et al. (2000) identified nine shrubland community types 

that occur in the park’s upland areas. These are listed in Table 21.

Table 21. Upland shrubland communities of THRO (Von Loh et al. 2000).

Common Name NVCS Association or Complex

Silver Sagebrush / Western Wheatgrass Shrub Prairie Artemisia cana / Pascopyrum smithii Shrubland 

Wyoming Big Sagebrush - Spiny Saltbush Shrubland Artemisia tridentata - Atriplex confertifolia Shrubland 

Wyoming Big Sagebrush / Western Wheatgrass 

Shrubland 

Artemisia tridentata ssp. wyomingensis / Pascopyrum 

smithii Shrubland 

Rubber Rabbitbrush / Bluebunch Wheatgrass Shrub 

Prairie 

Ericameria nauseosa/ Pseudoroegneria spicata

Shrubland 

Creeping Juniper / Little Bluestem Dwarf-shrubland Juniperus horizontalis / Schizachyrium scoparium

Dwarf-shrubland 

Silver Buffaloberry Shrubland Shepherdia argentea Shrubland 

Western Snowberry (Buckbrush) Shrubland Symphoricarpos occidentalis Shrubland 

Skunkbush Sumac / Thread-leaved Sedge Shrub Prairie Rhus trilobata / Carex filifolia Shrub Herbaceous 

Vegetation 

Greasewood / Western Wheatgrass Shrub Prairie Sarcobatus vermiculatus / Pascopyrum smithii -

(Elymus lanceolatus) Shrub Herbaceous Vegetation 

4.8.2 Measures

 Species composition

 Distribution (including changes)

 Prevalence of non-natives

4.8.3 Reference Conditions/Values

The ideal reference condition for this component 

would be the composition and distribution of these 

communities prior to European settlement. However, 

no information is available from this historical period. 

The earliest description of THRO’s shrubland 

communities comes from Hansen et al.’s (1984) 

habitat type classification of vegetation in the park. 

This report identified four shrubland community types 

in the park: Artemisia tridentata/Pascopyrum smithii, 

Artemisia cana/Pascopyrum smithii, Juniperus 

horizontalis/ Schizachyrium scoparium, and 

Photo 16. Sagebrush on an upland slope 

in THRO (Photo by Shannon Amberg, 

SMUMN GSS 2010).
126

Symphoricarpos occidentalis. These descriptions are used as the reference condition for species 

composition within those communities in this assessment. No reference condition could be found 

for the other shrublands in the park.

4.8.4 Data and Methods

In 1997-98, the USGS and NPS collaborated on a vegetation mapping program of THRO to 

classify the major plant community types (Von Loh et al. 2000). This report provides the 

majority of information on the upland shrub communities in the park. Trammel (1994) surveyed 

the distribution and extent of exotic species throughout THRO, including in several shrubland 

community types.

4.8.5 Current Condition and Trend

Species Composition 

One of the first scientific records of 

western North Dakota shrublands 

comes from Hanson and Whitman 

(1938), who described the sagebrush 

flat type community, in which silver 

sagebrush is the primary shrub species. 

Silver sagebrush generally occurs on 

floodplain terraces, but is also found on 

some upland flats and slopes. It is often 

associated with western wheatgrass and 

is sometimes co-dominant with or 

dominated by western snowberry (Von 

Loh et al. 2000).

Western snowberry, also known as 

buckbrush, is widespread throughout 

the park, occupying upland depressions, mesic swales and heads of mesic draws, and is an 

understory of all woodland types in THRO. Western snowberry forms dense thickets, typically 

75-90% aerial cover. The species most commonly associated with western snowberry is the nonnative Kentucky bluegrass (Von Loh et al. 2000).

Silver buffaloberry (Shepherdia argentea) forms very dense stands in lowland areas, but also 

occurs at the top of mesic draws. Major stands of buffaloberry are found near the turn-around at 

the west end of Scenic Drive in the North Unit and along the Wind Canyon Trail in the South 

Unit (Von Loh et al. 2000).

Skunkbush or three-leaved sumac stands are found on ridges, hills, and slopes that consist mostly 

of scoria outcrops or soils derived from scoria. This species is often associated with silver 

sagebrush and chokecherry, as well as a variety of herbaceous species in the understory (Von 

Loh et al. 2000).

Rabbitbrush (Ericameria nauseosa) is a dominant shrub on slumps, which are soils disturbed by 

sliding down steep slopes (Von Loh et al. 2000). This is an uncommon shrub in THRO; the main 

examples are found on the slump-slope below the Painted Canyon Overlook, the Interstate 94 

Photo 17. Bison grazing in an upland shrubland habitat 

dominated by sagebrush (Photo by Shannon Amberg, 

SMUMN GSS 2010).
126

right-of-way near Medora, and the slump-slope south of the Long X Trail Pullout. Rabbitbrush is 

often associated with silver sagebrush and western snowberry on these slump locations (Von Loh 

et al. 2000). 

On the higher hillslopes of the park, horizontal or creeping juniper is commonly found in dense 

patches, sharing habitat with the silver buffaloberry and skunkbush sumac shrubland alliances, as 

well as the little bluestem - sideoats grama herbaceous alliance (Von Loh et al. 2000). Nelson 

(1961) noted that horizontal juniper was commonly found on scoria knobs and in the open 

prairies, and in lesser amounts in the juniper slope forests in his survey of the western North 

Dakota Badlands.

Wyoming big sagebrush - saltbush shrubland occurs on slopes and ridges in the park, often 

mixed with sparse badlands vegetation (Von Loh et al. 2000). Plants are typically short and 

relatively sparse, with total cover ranging from 20-40%. Spiny saltbush (Atriplex confertifolia)

and broom snakeweed (Gutierrezia sarothrae) are common secondary shrubs (Von Loh et al. 

2000). Wyoming big sagebrush also occurs in a shrubland community with western wheatgrass. 

In this community, shrubs are widely spaced with approximately 25% cover (Von Loh et al. 

2000). In addition to western wheatgrass, the understory includes needle-and-thread and blue 

grama.

Greasewood (Sarcobatus vermiculatus) stands are the rarest shrub type in THRO, dominating in

only two locations in the South Unit (Von Loh et al. 2000). However, the species is also found in 

sparse vegetation alliances or mixed with other shrubs. Greasewood forms open stands with 

prairie sagewort, western wheatgrass, field brome, and Canada bluegrass (Poa compressa). 

Individual greasewood shrubs are interspersed with sagebrush and saltbush shrubs on badlands 

formations (Von Loh et al. 2000).
127

Table 22 summarizes the most abundant shrub and herbaceous species in each of these shrub 

communities. 
128

Table 22. The upland shrub communities of THRO and the most abundant species in each community, 

as surveyed by Von Loh et al. (2000).

Shrub community Most Abundant Species

Shrubs Herbaceous

Silver sagebrush/Western wheatgrass 

(Artemisia cana / Pascopyrum smithii)

Artemisia cana, Symphoricarpos 

occidentalis, Prunus virginiana

Pascopyrum smithii, Bromus 

inermis, Euphorbia esula

Wyoming big sagebrush - Spiny saltbush 

(Artemisia tridentata - Atriplex confertifolia)

Artemisia tridentata, Atriplex 

confertifolia, Gutierrezia sarothrae

Pascopyrum smithii, Bouteloua 

gracilis, Muhlenbergia cuspidata

Wyoming big sagebrush /Western 

wheatgrass (Artemisia tridentata -

Pascopyrum smithii)

Artemisia tridentata, Atriplex 

confertifolia, Ericameria nauseosa

Pascopyrum smithii, 

Hesperostipa comata, Bouteloua 

gracilis

Rubber rabbitbrush / Bluebunch wheatgrass 

(Ericameria nauseosa / Pseudoroegneria 

spicata)

Ericameria nauseosa, Prunus 

virginiana, Symphoricarpos 

occidentalis

Pascopyrum smithii, Elymus 

trachycaulus, Melilotus officinalis

Creeping juniper / Little bluestem (Juniperus 

horizontalis / Schizachyrium scoparium)

Juniperus horizontalis, Prunus 

virginiana, Dasiphora fruticosa, 

Rhus trilobata

Schizachyrium scoparium, 

Calamovilfa longifolia

Silver buffaloberry (Shepherdia argentea) Shepherdia argentea, 

Symphoricarpos occidentalis, 

Prunus virginiana

Poa pratensis, Pascopyrum 

smithii

Western snowberry (Symphoricarpos 

occidentalis)

Symphoricarpos occidentalis, 

Prunus virginiana

Pascopyrum smithii, Poa 

pratensis, Nassella viridula

Skunkbush sumac / Threadleaf sedge (Rhus 

trilobata / Carex filifolia)

Rhus trilobata, Prunus virginiana Muhlenbergia cuspidata, 

Melilotus officinalis

Greasewood / Western wheatgrass 

(Sarcobatus vermiculatus / Pascopyrum 

smithii)

Sarcobatus vermiculatus Pascopyrum smithii

Distribution

The distribution of shrub communities in the North and South Units of THRO are displayed in 

Plate 16 and Plate 17 respectively. Elkhorn Ranch Unit (EHR) shrublands are shown in Plate 18. 

Sandbar willow communities were excluded from these maps since they do not occur in the 

park’s uplands (they are included in the floodplain woodland section of this report). The 

Wyoming big sagebrush shrublands also are not shown, as they were combined with the sparse 

vegetation mapping units rather than being mapped separately.

Western snowberry is the most widespread shrub species in THRO, followed by silver sagebrush 

and skunkbush sumac (Von Loh et al. 2000). The area covered by each mapped shrub 

community type in the park is shown in Table 23. Note that these areas include shrublands in 

both floodplains and upland locations, as these were not separated in the Von Loh et al. (2000) 

mapping project. 
129

Table 23. Area (in hectares) covered by shrublands in THRO. GIS data from Von Loh et. al. (2000).

Common Name North Unit South Unit EHR Total

Western Snowberry (Buckbrush) Shrubland 735.0 846.0 11.7 1,592.7

Silver Sagebrush / Western Wheatgrass Shrub Prairie 601.8 586.8 8.7 1,197.3

Skunkbush Sumac / Thread-leaved Sedge Shrub 

Prairie 

161.2 816.5 1.4 979.1

Creeping Juniper / Little Bluestem Dwarf-shrubland 1.7 82.4 0.5 84.6

Rubber Rabbitbrush / Bluebunch Wheatgrass Shrub 

Prairie 

5.2 34.0 -- 39.2

Silver Buffaloberry Shrubland 9.9 14.2 -- 24.1

Greasewood / Western Wheatgrass Shrub Prairie 0.8 0.4 -- 1.2

Total 1,515.6 2,380.3 22.3 3,918.2

Prevalence of Non-Natives

Non-native species occur in all plant communities in THRO, including upland shrubland 

habitats. These plants can impact native species composition and alter natural processes such as 

fire, nutrient cycling, and erosion (Von Loh et al. 2000). Silver sagebrush communities have 

been heavily invaded by leafy spurge in the South Unit of THRO, particularly along the Little 

Missouri River, and Knutson and Paddock Creeks (Von Loh et al. 2000). Leafy spurge has also 

been found in creeping juniper shrublands, where it has caused a decrease in species richness 

(Butler and Cogan 2004). Yellow sweetclover is often associated with the skunkbush sumac 

shrubland alliance on south-facing ridges. Western snowberry stands are most frequently invaded 

by Kentucky bluegrass (Von Loh et al. 2000). Other non-native species documented in park 

shrublands include field brome, field bindweed (Convolvulus arvensis), dandelion, yellow 

salsify, smooth brome, and Canada thistle (Trammel 1994, Von Loh et al. 2000). A full list of 

non-native plants confirmed in THRO, some of which may also be found in shrublands, is 

included in Appendix C.

Threats and Stressor Factors

Ungulate browsing and grazing impacts the park’s upland shrub communities, as well as the 

distribution of non-native plants such as leafy spurge (Vitousek et al. 1996). Heavy grazing and 

the associated soil disturbance have been known to promote exotic grass invasion (Knight 1994). 

Some shrub communities may be replaced by shortgrass species in areas where grazing occurs.

In the North Unit of the park, western snowberry shrublands “literally stop at the fenceline and are 

replaced by shortgrasses on annually grazed areas on the non-park side of the fenceline” (Von Loh et 

al. 2000). In big sagebrush shrublands, grazers may trample sagebrush seedlings, inhibiting 

reproduction. However, grazing can also reduce competition from grasses, increasing shrub 

density and sagebrush establishment (Beck and Mitchell 2000).

Data Needs/Gaps

THRO’s shrubland communities have not been surveyed in depth since the Von Loh et al. (2000) 

study in 1997-98. The NGPN began a long-term monitoring program in 2011 to examine plant 

composition and structure in THRO. While the focus is not on shrublands in particular, all of the 

21 plots visited in 2011 had a substantial shrub component (Ashton et al. 2012). These and future 

data should provide information on the species composition and exotic cover in shrublands. 

Updated information is needed on plant species composition, particularly regarding the 

prevalence and impact of non-native species specifically within these shrubland communities. 
130

More recent distribution information would also help managers determine if the extent of these 

communities is changing. 

Overall Condition

Species Composition

During initial scoping meetings, THRO staff assigned the measure of species composition a 

Significance Level of 2. The species composition of the four shrubland habitat types surveyed by 

Hansen et al. (1984) was similar to that found by Von Loh et al. in 2000, with the exception of a 

few additional non-native species. No reference condition could be established for the remaining 

upland shrublands, so no comparisons could be made for these communities. Therefore, a 

Condition Level could not be assigned at this time for the upland shrub communities as a whole. 

In future assessments, data from NGPN plant community monitoring will likely be useful in 

evaluating this measure.

Distribution

A Significance Level of 3 was assigned to the measure of distribution. However, there is only one 

source of information addressing the distribution of all the shrubland communities in THRO 

(Von Loh et al. 2000). Since neither a historic or more recent distribution map is unavailable for 

comparison, Condition Level is unknown. Data from NGPN plant community monitoring may 

also be useful in assessing this measure in the future.

Prevalence of Non-natives

A Significance Level of 2 was assigned to the measure of prevalence of non-native species. Leafy 

spurge has severely infested several shrublands in the park, causing an apparent decrease in plant 

species richness (Butler and Cogan 2004). In the early 1980s, Hansen et al. (1984) found a small 

amount of this species in only one of their shrubland sampling plots. Numerous other non-native 

species have been documented in the park’s upland shrublands. As a result, the Condition Level

for this measure is a 2, signifying moderate concern.
131

Weighted Condition Score

Since Condition Levels for two of the three upland shrubland communities are unknown, a 

Weighted Condition Score (WCS) was not calculated for this component.

4.8.6 Sources of Expertise

Laurie Richardson, THRO Botanist
132

4.8.7 Literature Cited

Ashton, I. W., M. Prowatzke, M. Bynum, T. Shepherd, S. K. Wilson, K. Paintner-Green. 2012. 

Theodore Roosevelt National Park plant community composition and structure monitoring: 

2011 annual report. Natural Resource Technical Report NPS/NGPN/NRTR—2012/545. 

National Park Service, Fort Collins, Colorado.

Beck, J. L., and D. L. Mitchell. 2000. Influences of livestock grazing on sage grouse habitat. 

Wildlife Society Bulletin 28:993-1002.

Butler, J. L., and D. R. Cogan. 2004. Leafy spurge effects on patterns of plant species richness. 

Journal of Range Management 57:305-311.

Hansen, P. L., G. R. Hoffman, A. J. Bjugstad. 1984. The vegetation of Theodore Roosevelt 

National Park, North Dakota: a habitat type classification. U.S. Forest Service, Fort Collins, 

Colorado.

Hanson, H., and W. Whitman. 1938. Characteristics of major grassland types in Western North 

Dakota. Ecological Monographs 8(1):57-114.

Knight, D. H. 1994. Mountains and plains: the ecology of Wyoming landscapes. Yale University 

Press, New Haven, Connecticut.

National Park Service (NPS). 2010. Theodore Roosevelt National Park elk management plan and 

final environmental impact statement. National Park Service, Theodore Roosevelt National 

Park, North Dakota.

Nelson, J. R. 1961. Composition and distribution of the principal woody vegetation types in the 

Badlands of North Dakota. Project W-37-R-7, Job No. 9. North Dakota Game and Fish 

Department, Bismarck, North Dakota.

Trammel, M. A. 1994. Exotic plants of Theodore Roosevelt National Park: Extent, distribution, 

and ecological impact. Thesis. University of South Dakota, Vermillion, South Dakota. 

Vitousek, P. M., C. M. D’Antonio, L. L. Loope, and R. Westbrooks. 1996. Biological invasions 

as global environmental change. American Scientist 84(5):468-478.

Von Loh, J., D. Cogan, J. Butler, D. Faber-Langendoen, D. Crawford, and M. J. Pucherelli.

2000. USGS-NPS Vegetation Mapping Program: Theodore Roosevelt National Park, North 

Dakota.
133

Plate 16. Shrubland alliances in the North Unit of THRO. 
134

Plate 17. Shrubland alliances in the South Unit of THRO.
135

Plate 18. Shrubland alliances in the Elkhorn Ranch Unit of THRO.
136

4.9 Aquatic Communities

4.9.1 Description

Water is a scarce and highly valuable resource in the semi-arid landscape of THRO. While 

wetland and riparian areas are important habitats for some aquatic species in the park (Berkeley 

et al. 1998), the aquatic communities of THRO are mainly limited to the Little Missouri River, 

which connects all three units of the park, and tributary streams that feed into the river. The 

Little Missouri River is the only water body that supports a fish community in the park (NPS 

2010). The river is primarily suited for small, 

non-game fish species; game species are more 

productive during wet years with high water 

levels (Duerre 1986, as cited in Berkley et al. 

1998). There are 29 species of fish present in 

the Little Missouri River (NPS 2011). Little is 

known about the macroinvertebrate 

community in the Little Missouri River and 

other park water bodies, although limited 

research suggests that species diversity and 

abundance appear to be low in some stretches 

of the river (Rust 2006).

4.9.2 Measures

 Native fish species composition and abundance

 Macroinvertebrate composition and abundance

4.9.3 Reference Conditions/Values

The reference condition for aquatic communities is the range of abundance and diversity of 

native fish and macroinvertebrate species over the duration of available survey and monitoring 

data. Historic fish species lists are cross-referenced to identify potential changes or shifts in 

abundance and diversity.

4.9.4 Data and Methods

Kelsch (1994) conducted a fish survey of the Little Missouri River at 24 sample sites between

the towns of Marmarth and Medora in North Dakota in 1993.

USFWS (1999) also conducted a fish survey of the Little Missouri River in 1998 as part of the 

sturgeon chub (Macrhybopsis gelida) reintroduction project.

Rust (2006) collected water quality samples for several parameters on the Little Missouri River 

in THRO in 2004-2005. The objective of the research was to provide baseline descriptions of 

macroinvertebrate communities in the aquatic systems of national parks in the NGPN (including 

THRO), as well as select optimal metrics for use in future monitoring efforts by park resource 

managers. Chemical, physical, and habitat parameters were assessed for streams, rivers, and 

springs during the 2004 and 2005 summer seasons. The diversity and abundance of 

macroinvertebrate species was sampled at three locations on the Little Missouri River during this 

time.

Photo 18. Longnose dace (Rhinichthys 

cataractae) (NPS photo).
137

4.9.5 Current Condition and Trend

Native Fish Species Composition and Abundance

Minnows (Cyprinidae), perches (Percidae), suckers (Catostomidae), and catfishes (Ictaluridae) 

make up 70% of the native fish fauna of the northern Great Plains region (Berkley et al. 1998). 

Hankinson (1929) was the first to survey fish species in the Little Missouri River, describing 17 

species. Personius and Eddy (1955) reportedly identified 13 species during a survey from the 

headwaters in Wyoming to the junction with the Missouri River in central North Dakota. The list 

of fish species from Personius and Eddy (1955) is displayed in Table 24. It is important to note 

that this survey did not focus specifically on the stretch of river passing through THRO, but 

covered the entire Little Missouri River.

Table 24. Fish species documented in a 1950 survey of the Little Missouri River (Personius and Eddy 

1955).

Scientific Name Common Name

Carpiodes carpio carpio northern river carpsucker

Catostomus commersoni commersoni common white sucker

Cyprinus carpio carp

Hybopsis gracilis communis plains flathead chub

Hybopsis plumbea northern chub

Hybopsis meeki sickelfin chub

Rhinichthys cataclae longnose dace

Notropis deliciosus missuriensis plains sand shiner

Hybognathus placita plains minnow

Pimephales promelas promelas northern fathead minnow

Ictalurus punctatus channel catfish

Ameiurus melas melas northern black bullhead

Stizostedion canadense sauger

The current NPS Certified Species List for THRO fish expands upon the list developed by 

Personius and Eddy (1955). Table 25 displays fish species confirmed to be present in THRO. 

The plains flathead chub (Platygobio gracilis, previously Hybopsis gracilis communis) was 

documented by Personius and Eddy (1955) but is not included on the current park species list.
138

Table 25. Certified species list for fish in THRO (NPS 2011).

Scientific Name Common Name

Ameiurus melas black bullhead

Aplodinotus grunniens freshwater drum

Carpiodes carpio river carpsucker/carpsucker

Catostomus commersonii white sucker

Couesius plumbeus lake chub

Culaea inconstans brook stickleback

Cyprinus carpio carp/European carp

Esox lucius northern pike

Etheostoma exile Iowa darter

Hiodon alosoides goldeye

Hybognathus argyritis western silvery minnow

Hybognathus hankinsoni brassy minnow

Hybognathus placitus plains minnow

Ictalurus punctatus channel catfish

Lepomis cyanellus green sunfish

Lepomis macrochirus bluegill

Lota lota burbot

Moxostoma macrolepidotum shorthead redhorse

Notemigonus crysoleucas golden shiner

Notropis atherinoides emerald shiner

Notropis stramineus sand shiner

Noturus flavus stonecat

Phoxinus eos northern redbelly dace

Pimephales promelas fathead minnow, flathead minnow

Platygobio gracilis flathead chub

Rhinichthys cataractae longnose dace

Sander canadensis sauger

Sander vitreus walleye

Semotilus atromaculatus creek chub

Kelsch (1994) surveyed the Little Missouri River in 1993 and documented 13 fish species. Three 

species were commonly found during the survey: flathead chub (Platygobio gracilis), plains 

minnow (Hybognathus placitus), and the longnose dace (Rhinichthys cataractae). These three 

species comprised 95% of individuals captured during the study; the flathead chub alone 

represented 72% of individuals captured. Generally, species diversity and abundance were low 

during the survey; only three sample sites out of 24 yielded more than five fish species (Kelsch 

1994). Two species of special concern were captured during the study, the northern redbelly dace 

(Phoxinus eos) and the lake chub (Couesius plumbeus). The survey results may not have been 

representative of normal conditions on the Little Missouri River, as the study was conducted 

after a drought followed by unusually high flow and velocity (Kelsch 1994).
139

USFWS (1999) found that fish abundance in the Little Missouri River was dominated by a few 

species: flathead chubs, Hybognathus spp., sandshiners, and longnose dace comprised 90% of 

fish biomass in the survey. These results are quite similar to the findings of Kelsch (1994).

The sturgeon chub and sicklefin chub (Macrhybopsis meeki) are listed as Level I species by the 

North Dakota Game and Fish Department, meaning they are “species in the greatest need of 

conservation” within the state (NDGFD 2010). Neither species is federally-listed as threatened or 

endangered in the United States (Rahel and Thel 2004). The sturgeon chub and sicklefin chub 

now are considered extirpated from the Little Missouri River, and a sturgeon chub reintroduction 

effort conducted between 1998 and 2000 was unsuccessful (Rahel and Thel 2004).

Macroinvertebrate Composition and Abundance

Rust (2006) collected invertebrates in the Little Missouri River within THRO and found a low 

level of species diversity, with 47% of total abundance composed of the order Diptera (true 

flies). Twenty-four percent of macroinvertebrates in the survey were attributed to EPT 

(Ephemeroptera, Plecoptera, and Trichoptera) orders. Macroinvertebrate abundance in the Little 

Missouri River also was considered low by Rust (2006). This was the first and only study to 

examine the macroinvertebrate community in THRO. The Wyoming Natural Diversity Database 

sampled the macroinvertebrate community in THRO in 2011 (L. Tronstad, pers. comm., 2012). 

Data currently are being analyzed and are not yet available for comparison with Rust’s (2006) 

findings. 

Threats and Stressor Factors

Non-native species threaten native fish and macroinvertebrate populations in the Little Missouri 

River, and are present in part due to habitat alterations caused by reservoir construction (Rahel 

and Thel 2004). Non-native fish species present in the Little Missouri River include the common 

carp (Cyprinus carpio), and piscivorous fish species such as walleye (Zander vitreum), striped 

bass (Morone saxatilis), and largemouth bass (Micropterus salmoides) that have been stocked in 

Little Missouri River reservoirs in an attempt to develop sport fisheries (Rahel and Thel 2004).

Habitat alterations to the Little Missouri River, including conversion of riverine habitat to 

standing water habitat, reduction of turbidity, and fragmentation, have altered the natural water 

quality (Rahel and Thel 2004). Reduction of turbidity in particular has led to the replacement of 

fish species tolerant of turbid water with species characteristic of clearer waters. Species such as 

the sturgeon chub particularly have been affected by these water quality changes, with an 

increase in clear water fish that often prey on the chub (Rahel and Thel 2004). 

Data Needs/Gaps

Kelsch (1994) stated that additional fish surveys during periods of both normal and low flow 

would be necessary to truly understand diversity and abundance in the Little Missouri River. The 

few surveys conducted to date have been sporadic and only present a snapshot of the fish 

community under certain conditions. There have been no published studies on fish populations in 

or near THRO over the past decade.

There is little data available regarding macroinvertebrate diversity and abundance. Rust (2006) 

provided some baseline data on the community in the Little Missouri River and the Wyoming 

Natural Diversity Database recently sampled the macroinvertebrate community in THRO, 
140

although this data is not yet available. Continued monitoring of macroinvertebrates could help 

managers identify any changes in the park’s aquatic community and possibly water quality.

Overall Condition

Native Fish Species Composition and Abundance

The THRO project team defined the Significance Level for native fish species composition and 

abundance as a 3. Documented fish species diversity has increased over time in THRO, though 

this is likely due to more intensive sampling. There is not enough historic and current diversity 

and abundance data to determine a Condition Level.

Macroinvertebrate Composition and Abundance

A Significance Level of 2 was assigned for the measure of macroinvertebrate composition and 

abundance. Because there has only been one published study on the macroinvertebrate 

community in the Little Missouri River to date, there is not enough data to determine a Condition 

Level for this measure. 

Weighted Condition Score

A Weighted Condition Score (WCS) cannot be assigned at this time due to lack of data on 

component measures.

4.9.6 Sources of Expertise

Steven Kelsch, Associate Professor of Biology, University of North Dakota
141

4.9.7 Literature Cited

Berkley, J., G. R. Reetz, and D. Vana-Miller. 1998. Water resources management plan: Theodore 

Roosevelt National Park, North Dakota. National Park Service, Theodore Roosevelt National 

Park, North Dakota.

Duerre, D. 1986. The Little Missouri River fishery. Unpublished report. North Dakota Game and 

Fish Department, Bismarck, North Dakota.

Hankinson, T. 1929. Fishes of North Dakota. Papers of the Michigan Academy of Science, Arts, 

and Letters 10:439-460.

Kelsch, S. W. 1994. Lotic fish-community structure following transition from severe drought to 

high discharge. Journal of Freshwater Ecology 9:331-341.

National Park Service (NPS). 2010. Rivers and streams. 

http://www.nps.gov/thro/naturescience/rivers.htm (accessed 28 July 2011).

National Park Service (NPS). 2011. Certified species list for fish in Theodore Roosevelt National 

Park. https://nrinfo.nps.gov/Species.mvc/Search (accessed 27 July 2011).

North Dakota Game and Fish Department (NDGFD). 2010. Wildlife action plan.

http://gf.nd.gov/conservation/levels-list.html#levelI (accessed 30 August 2011).

Personius, R. G., and S. Eddy. 1955. Fishes of the Little Missouri River. Copeai 1:41-43.

Rahel, F. J., and L. A. Thel. 2004. Sturgeon chub (Macrhybopsis gelida): A technical 

conservation assessment. U.S. Forest Service, Rocky Mountain Region, Golden, Colorado.

Rust, J. 2006. Establishing baseline data for aquatic resources in national parks of the Northern 

Great Plains Network. Thesis. South Dakota State University, Brookings, South Dakota.

U.S. Fish and Wildlife Service (USFWS). 1999. Little Missouri River 1998 fall sampling 

summary. U.S. Fish and Wildlife Service, Bismarck, North Dakota.
142

4.10 Prairie Dogs

4.10.1 Description

Black-tailed prairie dogs (Cynomys ludovicianus), hereafter prairie dogs, are stout, burrowing 

rodents commonly associated with early successional vegetation (NRCS 2012). Grasses 

comprise a majority of their diet, but forage varies across the species’ range. Prairie dogs are 

gregarious animals; they live in social groups called towns or colonies. Within these towns are 

multiple burrows connected through underground tunnels. Prairie dogs are a keystone species in 

their environments as they provide essential food and shelter for other prairie species. At THRO, 

some of the species that utilize towns include burrowing owls (Athene cunicularia), ferruginous 

hawks (Buteo regalis), and mountain plovers (Charadrius montanus); these species depend on 

prairie dogs for food, use of their burrows, and other reasons (Antolin et al. 2002).

4.10.2 Measures

 Extent of prairie dog colonies

4.10.3 Reference Conditions/Values

There is not an established reference 

condition for this component. Park 

management actively observes the dog 

colonies throughout the year to be prepared 

in case management action is necessary. 

However, the use of active management 

techniques by park staff is rare with this 

species. Future assessments should 

incorporate the new prairie dog 

management plan that is currently in 

development.

4.10.4 Data and Methods

The primary source of data for this component is the THRO Wildlife Program Geodatabase. This 

database holds polygon feature classes with the extent of prairie dog colonies for 12 years: 1984, 

1996, 1997, 1999, 2000-2003, 2005, and 2007-2011. Mike Oehler, THRO Wildlife Biologist, 

indicated that data gathered after 2000 is of higher quality due to adjusted methods. Attributes 

from this dataset used in this assessment include colony name, area (acres), and perimeter 

(meters). Data from the extent feature classes were extracted to an Excel table, where fields were 

dissolved in order to allow for easy development of tables and graphs.

4.10.5 Current Condition and Trend

Extent of Prairie Dog Colonies

From 1984 to 2008, the total area of prairie dog colonies in THRO increased to a maximum 

recorded area of 1,879 acres (Figure 13). Then, from 2009 to 2011, prairie dog acreage decreased 

each year, with total acreage in 2011 being 1,151 acres. In 1984, the total area occupied by 

prairie dogs in the South Unit was 422 acres, according to a vegetation map produced by Jack 

Norland of North Dakota State University. In 2008, the acreage in the South Unit was at an alltime high, since recordkeeping began, with 1,742 acres (Figure 14). The earliest date that prairie 

Photo 19. Black-tailed prairie dog (Photo by Shannon 

Amberg, SMUMN GSS, 2010).
143

dog mapping occurred in the North Unit was 1997. In 1997, the total acreage in the North Unit 

was 108 acres. Since 1997, the extent of prairie dogs in the North Unit has been stable (mean = 

112, range = 31-145), not showing any particular trend (Figure 15). However, the most recent 

occupied acreage, in 2011, was the second lowest on record at 72 acres.

Figure 13. Total acres of prairie dog colonies in THRO, 1984-2011 (THRO 2010).

Figure 14. Total acres of prairie dog colonies in the South Unit of THRO, 1997-2011 (THRO 2010).

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1980 1985 1990 1995 2000 2005 2010 2015

Acres

Year

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1980 1985 1990 1995 2000 2005 2010 2015

Acres

Year
144

Figure 15. Total acres of prairie dog colonies in the North Unit of THRO, 1997-2011 (THRO 2010).

Increases in prairie dog acreage within the South Unit in the mid-2000s occurred during years of 

drought, possibly because colonies must expand to access more forage (M. Oehler, pers. comm., 

2012). If this is true, even though acreage is expanding, the relative change in total population 

over that time is still unknown. THRO typically allows colonies to expand and contract 

according to natural processes. The only exception is when a colony infringes upon park 

infrastructure. In the North Unit of the park, prairie dog acreage is relatively stable over the 

duration of the available data; the reason for the stability is not described in the literature, but 

rough terrain and limited suitable habitat are two possibilities identified by park staff (M. Oehler,

C. Sexton, pers. comm., 2012).

Threats and Stressor Factors

Sylvatic plague, caused by the bacterium Yersinia pestis, is the most well-known stressor to 

prairie dog populations and one of the four primary causes for the rangewide decline in prairie 

dog distribution and abundance over the past century (Van Putten and Miller 1999, Antolin et al. 

2002, Pauli et al. 2006). It is the only major factor that limits prairie dog abundance that is 

beyond human control (Cully and Williams 2001). Black-tailed prairie dogs are highly 

susceptible to plague, exhibiting near 100% mortality, compared to approximately 85% mortality 

in white-tailed prairie dogs (Barnes 1993, Cully and Williams 2001). Additionally, plague results 

in smaller and more isolated prairie dog colonies, which reduces genetic variability through 

inbreeding and genetic drift (Trudeau et al. 2004). Sylvatic plague occurred in THRO in 1986, 

1993, and on a few later occasions, but data are unpublished (C. Sexton, pers. comm., 2012).

Data Needs/Gaps

There are currently no data gaps for the prairie dog population at THRO. Park staff performs 

yearly delineations of the prairie dog colonies to inform their management.

0

20

40

60

80

100

120

140

160

1996 1998 2000 2002 2004 2006 2008 2010 2012

Acres

Year
145

Overall Condition

Extent of Prairie Dog Colonies

The Significance Level of this measure is a 3 because prairie dog management at the park focuses 

nearly exclusively on prairie dog acreages. THRO’s active management of the prairie dog 

colonies is minimal; this allows natural processes to govern the size and location of the dog 

towns. Currently, sylvatic plague is not present in the park and other stressors common to prairie 

dogs elsewhere are absent in the park. Therefore, the Condition Level for this component is 0, 

indicating minimal concern; because there is only one measure for this component, the Weighted 

Condition Score is also 0.

4.10.6 Sources of Expertise

Mike Oehler, Wildlife Biologist, THRO

Chad Sexton, Geographic Information Systems Analyst, THRO
146

4.10.7 Literature Cited

Antolin, M. F., P. Gober, B. Luce, D. E. Biggins, W. E. Van Pelt, D. B. Seery, and M. Lockhart. 

2002. The influence of sylvatic plague on North American wildlife at the landscape level, 

with special emphasis on black-footed ferret and prairie dog conservation. Transactions of 

the North American Wildlife and Natural Resources Conference, 2002, ed. Jennifer Rahm 

(Washington, D.C., 2002).

Barnes, A. M. 1993. A review of plague and its relevance to prairie dog populations and the 

black-footed ferret. Pages 28-37 in J. L. Oldemeyer, D. E. Biggins and B. J. Miller, eds., 

Proceedings of the symposium on the management of prairie dog complexes for the 

reintroduction of the black-footed ferret. Biological Report 13. U.S. Department of the 

Interior, Washington, D.C.

Cully, J. F., and E. S. Willaims. 2001. Interspecific comparisons of sylvatic plague in prairie 

dogs. Journal of Mammalogy 82(4):894-905.

Milne, S. A. 2004. Population ecology and expansion dynamics of black-tailed prairie dogs in 

western North Dakota. Thesis. University of North Dakota, Grand Forks, North Dakota.

National Park Service (NPS). 2000. Environmental assessment for the control of black-tailed 

prairie dog population encroaching high visitor use areas. National Park Service, 

Washington, D.C.

Natural Resources Conservation Service (NRCS). 2001. Black-tailed prairie dog (Cynomys 

ludovicianus). Fish and Wildlife Management Leaflet. 

http://wildlife.state.co.us/SiteCollectionDocuments/DOW/WildlifeSpecies/SpeciesOfConcer

n/BlackTailedPrairieDog/PDF/NRCS_Bulletin.pdf (accessed 3 March 2012).

Pauli, J. N., S. W. Bushkirk, E. S. Williams, and W. H. Edwards. 2006. A plague epizootic in the 

black-tailed prairie dog (Cynomys ludovicianus). Journal of Wildlife Diseases 42(1):74-80.

Plumb, G. E., G. D. Willson, K. Kalin, K. Shinn, and W. M. Rizzo. 2001. Black-tailed prairie 

dog monitoring protocol for seven prairie parks. U.S. Geological Survey, Reston, Virginia.

Svingen, D. 2006. Black-tailed prairie dog conservation assessment and strategy for the Medora 

ranger district. Dakota Prairie Grasslands, internal report. May 5, 2006.

Theodore Roosevelt National Park (THRO). 2010. 

NPS_THRO_Wildlife_Program_Geodatabase.gdb. Spatial Data. Geodatabase. Received

October 2010.

Trudeau, K. M., H. B. Britten, and M. Restani. 2004. Sylvatic plague reduces genetic variability 

in black-tailed prairie dogs. Journal of Wildlife Diseases 40(2):205-211.

Van Putten, M., and S. D. Miller. 1999. Prairie dogs: The case for listing. Wildlife Society 

Bulletin 27:1,113-1,120.
147

Plate 19. Prairie dog colony extent, South Unit,1984 and 2011.
148

Plate 20. Prairie dog colony extent, North Unit, 1997 and 2011.
150

4.11 Breeding Birds

4.11.1 Description

Bird populations are excellent indicators of 

an ecosystem’s health (Morrison 1986, Hutto 

1998, NABCI 2009). Birds are typically easy 

to observe and identify, and bird 

communities often reflect the abundance and 

distribution of other organisms with which 

they co-exist (Blakesley et al. 2010).

THRO is home to a unique diversity of 

habitats including floodplain forests, native 

grasslands, and juniper slope forests. These 

habitats provide the avian species in the park 

with nesting habitat and food sources. Over 

185 bird species have been confirmed in the 

park (NPS 2011). Monitoring avian 

population health and diversity in these 

habitats will be important for detecting 

ecosystem change.

There has not been a formal effort to classify which species in THRO breed in the area annually. 

Therefore, this assessment will include all species observed during surveys conducted during the 

breeding season (e.g., Breeding Bird Surveys [BBS], Integrated Monitoring in Bird Conservation 

Regions [IMBCR] surveys).

4.11.2 Measures

 Species richness

 Number of species of conservation concern

 Raptor species richness

4.11.3 Reference Conditions/Values

There have been limited bird surveys in THRO, and because of this, the reference condition will 

be the characteristics of the breeding bird population from the nearby Little Missouri National 

Grassland (LMNG). This grassland has established IMBCR sampling grids similar to grids

recently established in THRO. The LMNG grids serve as a comparison for the THRO grids. If 

IMBCR grid sampling is continued in THRO, the data from 2009-2012 could serve as a baseline 

reference condition for this component in the future.

4.11.4 Data and Methods

The NPS Certified Bird Species List (NPS 2011) for THRO was used for this assessment. This 

list represents all of the confirmed bird species present in the park. 

In 1999, Powell (2000) began a breeding bird study at four national park units (Agate Fossil 

Beds National Monument, Scott’s Bluff National Monument, Badlands National Park, and 

Photo 20. Pine siskin (Carduelis pinus) (NPS Photo, 

Nathan King).
150

THRO). The specific objective of this study was to investigate and identify the quantity of 

grassland-associated species in these Great Plains parks. Powell (2000) utilized fixed-radius 

point counts to survey breeding birds in THRO. The sample points were located in grassland 

habitats and were spaced 250 m apart; points were sampled for 5 minutes. All birds seen or heard 

within a 100 m radius were counted.

Because the objectives of Powell (2000) were specifically concerning grassland birds, the point 

counts focused only on the grassland habitats in THRO. Thus, these point counts may have 

missed breeding species that are not dependent upon grassland habitats.

The THRO breeding bird survey route is part of the large-scale North American Breeding Bird 

Survey (BBS), which began in 1966 and is coordinated by the USGS and the Canadian Wildlife 

Service (Robbins et al. 1986). The standard BBS route is approximately 40 km (25 mi) long with 

survey points at every 0.8 km (0.5 mi). The survey begins 1⁄2 hour before sunrise, and at each 

survey point the number of birds seen and heard within a 0.4-km (0.25-mi) radius during a threeminute interval is recorded. Only BBS route 64033 (Roosevelt Park Route) crosses within the 

park’s North Unit boundaries (Plate 21). This route was surveyed annually from 1982-2009 

(USGS 2011).

The Rocky Mountain Bird Observatory (RMBO) and its partners monitor land bird populations 

in several Bird Conservation Regions (BCRs) across North America; THRO lies within Bird 

Conservation Region 17 (BCR 17: Badlands and Prairies) (Figure 16) and has been monitored by 

RMBO and its partners since 2009 (White et al. 2011). Land bird monitoring in THRO is part of 

the IMBCR program, and utilizes a spatially-balanced sampling design during survey efforts 

(White et al. 2011).
150

Figure 16. Bird Conservation Regions through North America. THRO lies within BCR 17. Image 

reproduced from (http://www.nabci-us.org/map.html).

The IMBCR land bird monitoring program established a series of strata and super-strata (White 

et al. 2011). Within these strata, RMBO and its partners utilized generalized random-tessellation 

stratification (GRTS) to select sample units (Stevens and Olson 2004, White et al. 2011). 

According to White et al. (2011, p. 8):

The IMBCR design defined sampling units as 1-km2cells that were used to create a 

uniform grid over the entire BCR. Within each grid cell we established a 4 x 4 grid of 16 

points spaced 250 m apart (Figure 17, Plate 22).

The IMBCR program surveys all land bird species during the typical breeding season. Data and 

analyses in this document represent the likely breeding landbirds.
150

Selected transects (Plate 22) were sampled early in 

the breeding season after all migratory species had 

returned to their breeding areas. Care was taken not 

to survey too early in the season, as an early survey 

could potentially miss migratory breeding species or 

could sample transient birds that are migrating 

through the area (Hanni et al. 2011). Each point on a 

transect was sampled for 6 minutes using methods 

that allow for estimating detection probability 

through the principles of distance sampling 

(Buckland et al. 2001, Thomas et al. 2010), removal 

modeling (Farnsworth et al. 2002) and occupancy 

estimation (MacKenzie et al. 2002, MacKenzie 

2006). All bird species detected were recorded, 

along with several variables such as distance from 

the observer, habitat type, weather, and land

ownership (Hanni et al. 2011).

4.11.5 Current Condition and Trend

Species Richness

Breeding Bird Survey

Species counts for each year of the BBS were calculated (Figure 18). The average number of 

species observed on the THRO BBS from 1982-2009 was 53.4 species. There does not appear to 

be an increasing or decreasing trend in species richness observed each year (Figure 18). 

However, there may be undetected changes in species richness of native species compared to 

non-native species, or in Neotropical migrant species compared to resident species. Such changes 

would not be apparent in Figure 18. The THRO BBS only surveys the North Unit of the park 

(Plate 21), and does not survey any part of the South Unit. Thus, species richness values shown 

here may not be truly indicative of the overall species richness for THRO.

Figure 17. Example of a grid cell created by 

the RMBO using the IMBCR design. 

Reproduced from White et al. (2011).
150

Figure 18. Species richness estimates from the annual BBS route in THRO. The solid red line indicates 

the 28-year average (53 species) for the survey.

Powell (2000) Grassland Bird Inventory

Powell (2000) conducted a fixed-radius point count of breeding bird species (with emphasis on 

the grassland species in THRO) at 18 points in the park. During this 1-year survey, Powell 

(2000) found 650 individuals of 49 species on point counts. When not restricted to the species 

observed on the point counts, Powell (2000) reported 76 species observed. Approximately 31%

of the breeding species recorded were grassland-associated species; the most abundant species 

observed were spotted towhee (Pipilo maculatus), vesper sparrow (Pooecetes gramineus), field 

sparrow (Spizella pusilla), and yellow-breasted chat (Icteria virens).

IMBCR Land Bird Sampling

RMBO surveyed two grids under the IMBCR design during visits to the South Unit of THRO 

from 2009-2011 (ND-BCR17-NP1 and ND-BCR17-NP3) (Plate 22). In 2009, 35 bird species 

were observed on 21 points along both grids, while 37 species were observed at 20 points along 

both grids in 2010. In 2011, 39 bird species were identified at 22 points along both grids. 

The IMBCR grids within THRO have been surveyed for only 3 years, and deciphering any 

trends from these data is not appropriate at this time. Continued monitoring with increased 

sampling intensity will allow for long-term species richness trend comparisons and may provide 

insights into the habitat availability for bird species in the park from year to year.

The IMBCR grids in THRO present an opportunity to compare the park’s species richness to that 

of the nearby LMNG. LMNG is also part of the RMBO’s IMBCR program, and has several 

established transects in the grassland. LMNG is in a similar habitat type as THRO, and serves as 

an appropriate reference condition for the breeding birds in THRO (J. Birek, pers. comm., 2012). 

From 2009-2011, LMNG had an average of 77.6 species observed. In 2009, 76 species were 

observed at 146 points, while 83 species were observed at 123 points in 2010 (Figure 19). In 

2011, 74 species were identified at 83 points in LMNG (Figure 19). These estimates of species 

30

35

40

45

50

55

60

65

Number of Species

Year
150

richness are higher than those reported for THRO. However, LMNG has 16 established grids

while THRO only has two, which may result in some discrepancy when comparing the data.

Figure 19. Species richness for IMBCR surveys in both LMNG (16 grids or transects) and THRO (two 

grids or transects) from 2009-2011.

Number of Species of Conservation Concern

Breeding Bird Survey

Partners in Flight (PIF) compiles a list (RMBO 2005) of species of regional importance for each 

BCR in North America. Seventeen species identified on this list were observed on the BBS in 

THRO from 1982-2009 

0

10

20

30

40

50

60

70

80

90

2009 2010 2011

Number of Species

Year

LMNG

THRO
150

Table 26). Similarly, the U.S. Fish and Wildlife Service (USFWS) compiles a list of birds of 

conservation concern for all BCRs in North America (USFWS 2008). During the THRO BBS, 

ten species from this list were identified within the park 
156

Table 26).
150

Table 26. Species of conservation concern observed during the THRO BBS from 1982-2009.

Species

USFWS 

(2008)a

PIF 

SRIb NDGFD (2004)c

sharp-tailed grouse X

American white pelican X

northern harrier X

Swainson's hawk X X

golden eagle X X

prairie falcon X

upland sandpiper X X

black-billed cuckoo X X X

red-headed woodpecker X X

Say's phoebe X

loggerhead shrike X X

black-billed magpie X

northern rough-winged swallow X

mountain bluebird X

Sprague's pipit X X X

vesper sparrow X

lark bunting X X

grasshopper sparrow X X X

Baird's sparrow X X X

chestnut-collared longspur X X X

a = USFWS Species of Conservation Concern, 2008

b = Partners in Flight Species of Regional Importance for BCR 17 (RMBO 2005)

c = North Dakota's 100 Species of Conservation Priority

NDGFD (2004) identifies 100 species of conservation priority in North Dakota. However, the 

species identified in this report are not limited to only avian species. This report separates the 

species into three levels: Level-I, Level-II, and Level-III. For this report only avian species 

identified as Level-I species are considered. A Level-I species is defined by NDGFD (2004, p. 3) 

as:

Species having a high level of conservation priority because of declining status either in 

North Dakota or across their range; or a high rate of occurrence in North Dakota 

constituting the core of the species’ breeding range, but are at-risk range wide, and nonSWG [State Wildlife Grants] funding is not readily available to them.

Within THRO, nine Level-I species were identified on the THRO BBS route from 1982-2009 (
158

Table 26).

Powell (2000) Grassland Bird Inventory

During a 1999 breeding bird inventory, Powell (2000) documented 17 species listed as species of 

conservation concern by USFWS (2008), 23 species of regional importance (RMBO 2005), and 

11 Level-I species identified in NDGFD (2004) (Table 27).

Table 27. Species of conservation concern observed during the Powell (2000) bird survey in 1999.

Species

USFWS 

(2008)a

PIF 

SRIb NDGFD (2004)c

northern goshawk X

golden eagle X X

ferruginous hawk X X X

Swainson's hawk X X

northern harrier X

bald eagle X

prairie falcon X

peregrine falcon X

American white pelican X

upland sandpiper X X

long-billed curlew X

Wilson's phalarope X

black-billed cuckoo X X X

sharp-tailed grouse X

dickcissel X X

black-billed magpie X

Baird's sparrow X X X

grasshopper sparrow X X X

lark bunting X X

chestnut-collared longspur X X X

vesper sparrow X

northern rough-winged swallow X

western meadowlark X

loggerhead shrike X X

Sprague's pipit X X X

mountain bluebird X

Say's phoebe X

red-headed woodpecker X X

short-eared owl X X

burrowing owl X X

a = USFWS Species of Conservation Concern, 2008

b = Partners in Flight Species of Regional Importance for BCR 17 (RMBO 2005)

c = North Dakota's 100 Species of Conservation Priority

IMBCR Land Bird Sampling
159

On the two IMBCR transects in THRO, three species of conservation concern (USFWS 2008), 

10 species of regional importance (RMBO 2005), and three species identified in NDGFD (2004) 

were observed (Table 28).
160

Table 28. Species of conservation concern observed during the IMBCR bird monitoring in THRO from 

2009-2011.

Species

USFWS 

(2008)a

PIF 

SRIb NDGFD (2004)c

black-billed magpie X

golden eagle X X

grasshopper sparrow X X X

lark bunting X X

mountain bluebird X

northern harrier X

Say's phoebe X

sharp-tailed grouse X

upland sandpiper X X

vesper sparrow X

western meadowlark X

a = USFWS Species of Conservation Concern, 2008

b = Partners in Flight Species of Regional Importance for BCR 17 (RMBO 2005)

c = North Dakota's 100 Species of Conservation Priority

Raptor Species Richness

No raptor-dedicated survey effort currently exists in THRO. The available data for raptors in the 

area come from the aforementioned surveys and reports.

Breeding Bird Survey

From 1982-2009, 11 raptor species were observed on the annual BBS route in THRO (Table 29). 

The average raptor species richness on the THRO BBS was three species per year; the highest 

number of raptor species was observed in 1987 (seven species), while only one species was 

observed in 1989, 1999, 2002, and 2007 (Figure 20).

Table 29. Raptor species observed on the THRO BBS from 1982-2009.

Common Name

Number of years 

observed

turkey vulture 12

northern harrier 11

sharp-shinned hawk 4

Cooper's hawk 5

Swainson's hawk 2

red-tailed hawk 9

golden eagle 3

American kestrel 25

prairie falcon 9

eastern screech-owl 1

great horned owl 2
161

Figure 20. Raptor species richness estimates from the annual BBS route in THRO from 1982-2009. The 

solid red line indicates the 28-year average (three species) for the survey.

Powell (2000) Grassland Bird Inventory

The Powell (2000) grassland bird inventory only recorded the presence of species, and did not 

indicate the number of observations of each species. In 1999, seven raptor species were 

observed: sharp-shinned hawk, golden eagle, Swainson’s hawk, northern harrier, turkey vulture, 

American kestrel, and great horned owl (Powell 2000).

IMBCR Land Bird Sampling

The two IMBCR transects in THRO have been surveyed annually since 2009. During these 

surveys, five raptor species have been observed. In 2009, two species were observed (northern 

harrier and turkey vulture), while only one raptor species was observed in 2010 (turkey vulture). 

2011 had three raptor species observations (American kestrel, golden eagle, and red-tailed 

hawk). Table 30 represents the total number of individuals observed during the IMBCR transect 

surveys.

Table 30. Number of individual raptors observed from 2009-2011 during IMBCR surveys in THRO.

Species 2009 2010 2011

American kestrel 3

golden eagle 1

northern harrier 1

red-tailed hawk 1

turkey vulture 1 1

Threats and Stressor Factors

One of the major threats facing bird populations across all habitat types is land cover change 

(Morrison 1986). Land cover change is not restricted to breeding habitat; many species depend 

0

1

2

3

4

5

6

7

8

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008

Number of Raptor Species

Year
162

on specific migratory and wintering habitat types. Altered habitats can compromise the 

reproductive success or wintering survival rates of species adapted to that habitat. Priority 

species in THRO, such as Sprague’s pipit (Anthus spraugueii) and Baird’s sparrow

(Ammodramus bairdii), often require specific vegetative communities (e.g., tall prairie grasses 

and ample ground cover) for successful nesting to occur. A loss or alteration of these vegetative 

structures could compromise the nesting success of these species in THRO.

Another threat facing land bird populations is shifts in reproductive phenology. Several bird 

species depend on temperature ranges or weather cycles to cue their breeding. As global 

temperatures change, some bird species have adjusted by moving their home range north (Hitch 

and Leberg 2007). Other species have adjusted their migratory period and have begun returning 

to their breeding grounds earlier in the spring; American robins (Turdus migratorius) in the 

Colorado Rocky Mountains are now returning to their breeding grounds 14 days earlier 

compared to 1981 (NABCI 2009). A concern is that this shift in migration may be out of sync 

with food availability and could ultimately lead to lowered reproductive success.

The North American Bird Phenology Program (BPP) is currently analyzing the migration 

patterns and distribution of migratory bird species across North America (USGS 2008). 

Information from this analysis will provide new insights into how bird distribution, migration 

timing, and migratory flyways have changed since the later part of the 19th century. This 

information may also be applied to estimate changes in breeding initiation periods in specific 

habitats.

Data Needs/Gaps

Breeding bird surveys provide snapshots in time of species richness. However, only one 

survey/visit per year yields little information in terms of population trends. Further observation 

could help to remedy this data gap and could potentially help the park better understand the 

status of breeding bird species in the park as well. BBS route 64033 (Roosevelt Park) in the 

North Unit was surveyed annually from 1982-2009. Resuming this survey, despite its limited 

coverage of THRO, would be beneficial for future analysis.

Increased sampling under the IMBCR spatially balanced land bird protocol would allow for 

density and occupancy estimates to be calculated in the future. These estimates could provide 

baseline values that would serve as sources of comparison for future studies. Expansion of the 

IMBCR land bird monitoring effort would also provide a more accurate depiction of the breeding 

bird composition in both the North and South Units of THRO. The spatially-balanced nature of 

these transects would provide a more reliable assessment of current breeding bird composition. 

Data and results would also be directly comparable to and combinable withnearby IMBCR strata 

and super-strata (e.g., LMNG, BCR 17).

With so many priority species lists in existence, it is often difficult for managers to isolate which 

species in a park are in need of particular attention. The establishment of a priority species 

population monitoring program, or even just a yearly breeding survey of a few species, could 

provide park managers with insights into the overall breeding health of these species in THRO. 

A program such as this could also provide valuable information about habitat use and potentially 

provide new information about the overall health of high-priority habitats.
163

Currently, THRO does not conduct in-depth raptor-specific monitoring. The establishment of a 

raptor monitoring program, or an in-depth analysis of prey species composition of raptors, would 

not only give managers insights into the health of the THRO raptor population, but could also 

provide information about the health and abundance of prey species (e.g., small mammals). 

Although not monitored in detail, THRO staff do observe activity on the few know Golden eagle 

nests in the park each spring. However, systematic searches for raptor nests are not conducted. 

With a few modifications, the same sampling frame and sampling grids from the GRTS-based 

design used in the IMBCR program can be used for monitoring of raptors and other species in 

THRO.

Overall Condition

Species Richness

The measure species richness was assigned a Significance Level of 3. Data for this measure are 

limited to two surveys (IMBCR transects from 2009-2011, and BBS routes from 1982-2009) and 

one grassland bird inventory in 1999 (Powell 2000). While the data suggest that species richness 

has not fluctuated much and appears stable, a more comprehensive data source is needed to 

accurately assess the condition of this measure in THRO. Compared to the reference condition, 

the THRO IMBCR surveys yielded species richnesses that were just over half those of LMNG. 

This is likely due to the disparity in sample size and number of transects in the park, but 

nonetheless it highlights the need for expansion of survey efforts to accurately assess the 

condition of this measure in THRO. For this reason, a Condition Level for species richness was 

not assigned.

Number of Species of Conservation Concern

The number of species of conservation concern was assigned a Significance Level of 2. Data 

from all available sources indicate that several species designated as species of conservation 

concern exist in the park. However, no study has investigated the population trends or nesting 

success of these species. Such trend data would provide for a more accurate assessment of this 

measure. There does not appear to be particular concern in THRO for this measure, although an 

investigation of priority species that may be conspicuously absent could benefit managers. This 

measure was assigned a Condition Level of 1. 

Raptor Species Richness

A Significance Level of 2 was assigned to the raptor species richness measure. There has been no 

raptor-specific monitoring within THRO. The data that do exist for this measure are from general 

bird surveys, and the number of raptor observations is sparse. This is largely affected by the large 

geographic ranges of raptors, the limited temporospatial extent of current sampling and a lack of 

raptor-specific monitoring efforts in THRO. Because of this data gap, a Condition Level for this 

measure was not assigned.
164

Weighted Condition Score

A Weighted Condition Score for breeding birds in THRO was not assigned because >50% of the 

measures had unknown Condition Levels.

4.11.6 Sources of Expertise

Jeff Birek, Outreach Biologist, Rocky Mountain Bird Observatory
165

4.11.7 Literature Cited

Blakesley, J. A., D. C. Pavlacky Jr., and D. J. Hanni. 2010. Monitoring bird populations in Wind 

Cave National Park. Technical Report M-WICA09-01. Rocky Mountain Bird Observatory, 

Brighton, Colorado.

Buckland, S. T., D. R. Anderson, K. P. Burnham, J. L. Laake, D. L. Borchers, and L. Thomas. 

2001. Introduction to distance sampling: estimating abundance of biological populations. 

Oxford University Press, Oxford, United Kingdom.

Farnsworth, G. L., K. H. Pollock, J. D. Nichols, T. R. Simons, J. E. Hines, and J. R. Sauer. 2002. 

A removal model for estimating detection probabilities from point-count surveys. Auk 

119:414-425.

Hanni, D. J., C. M. White, R. A. Sparks, J. A. Blakesley, J. J. Birek, N. J. Van Lanen, and J. A. 

Rehm-Lorber. 2011. Field protocol for spatially-balanced sampling of landbird populations. 

Unpublished report. Rocky Mountain Bird Observatory, Brighton, Colorado. 

Hitch, A. T., and P. L. Leberg. 2007. Breeding distributions of North American bird species 

moving north as a result of climate change. Conservation Biology 21(2):534-539.

Hutto, R. L. 1998. Using landbirds as an indicator species group. Avian conservation: Research 

and management. Island Press, Washington, D.C. 

MacKenzie, D. I., J. D. Nichols, G. B. Lachman, S. Droege, J. A. Royle, and C. A. Langtimm. 

2002. Estimating site occupancy rates when detection probabilities are less than one. Ecology 

83:2248-2255.

MacKenzie, D. I., J. D. Nichols, J. A. Royle, K. H. Pollock, L. L. Bailey, and J. E. Hines. 2006. 

Occupancy estimation and modeling: inferring patterns and dynamics of species occurrence. 

Elsevier, Burlington, Massachusetts.

Morrison, M. L. 1986. Bird populations as indicators of environmental change. Current 

Ornithology 3:429-451.

National Park Service (NPS). 2011. NPSpecies online. 

https://nrinfo.nps.gov/Species.mvc/Search (accessed 7 March 2012).

North American Bird Conservation Initiative, U.S. Committee (NABCI). 2009. The State of the 

Birds, United States of America, 2009. U.S. Department of the Interior, Washington, D.C. 

North Dakota Game and Fish Department (NDGFD). 2004. North Dakota’s 100 species of 

conservation priority. North Dakota Outdoors, July 2004.

Powell, A. N. 2000. Grassland bird inventory of seven prairie parks. Final Report to the Great 

Plains Prairie Cluster Long-Term Ecological Monitoring Program, National Park Service, 

Republic, Missouri.
166

Robbins C. S., D. Bystrak, and P. H. Geissler. 1986. The Breeding Bird Survey: its first fifteen 

years, 1965-1979. U.S. Fish and Wildlife Service, Resource Publication 157.

Rocky Mountain Bird Observatory (RMBO). 2005. BCR 17 – Species of regional importance.

http://www.rmbo.org/pif/jsp/BCRBreedConcern.asp?submit=Show+Only+Regionally+ 

Important+Species (accessed 7 March 2012).

Stevens, D. L., Jr., and A. R. Olsen. 2004. Spatially balanced sampling of natural resources. 

Journal of the American Statistical Association 99:262-278. 

Thomas, L., S. T. Buckland, E. A. Rexstad, J. L. Laake, S. Strindberg, S. L. Hedley, J. R. B. 

Bishop, T. A. Marques, and K. P. Burnham. 2010. Distance software: design and analysis of 

distance sampling surveys for estimating population size. Journal of Applied Ecology 47:5-

14.

U.S. Fish and Wildlife Service (USFWS). 2008. Birds of conservation concern 2008. United 

States Department of Interior, Fish and Wildlife Service, Division of Migratory Bird 

Management, Arlington, Virginia. 

U.S. Geological Survey (USGS). 2008 North American bird phenology program. 

http://www.pwrc.usgs.gov/bpp/about.cfm (accessed 7 March 2012).

U.S. Geological Survey (USGS). 2011. North American Breeding Bird Survey website. 

https://www.pwrc.usgs.gov/BBS/PublicDataInterface/index.cfm (accessed 6 March 2012).

White, C. M., N. J. Van Lanen, D. C. Pavlacky Jr., J. A. Blakesley, R. A. Sparks. J. M. Stenger, 

J. A. Rehm-Lorber, M. F. McLaren, F. Cardone, J. J. Birek and D. J. Hanni. 2011. Integrated 

monitoring of bird conservation regions (IMBCR): 2010 annual report. Tech. Report # SCIMBCR-01. Rocky Mountain Bird Observatory, Brighton, Colorado. 
167

Plate 21. Breeding Bird Survey route 64033 in the North Unit of THRO.
168

Plate 22. IMBCR points sampled in the South Unit of THRO 2009-2011.
169

4.12 Air Quality

4.12.1 Description

Air pollution can significantly affect natural resources and their associated ecological processes.

Consequently, air quality in parks and wilderness areas is protected and regulated through the 

1916 Organic Act and the Clean Air Act of 1977 (CAA) and the CAA’s subsequent 

amendments. The CAA defines two distinct categories of protection for natural areas, Class I and 

Class II airsheds. Class I airsheds receive the highest level of air quality protection as offered 

through the CAA; only a small amount of additional air pollution is permitted in the airshed 

above baseline levels. For Class II airsheds, the increment ceilings for additional air pollution 

above baseline levels are slightly greater than for Class I areas and allow for moderate 

development (EPA 2008a). However, new and modified sources of air pollution must be 

analyzed for potential impacts to ambient air quality and visibility prior to development. THRO

is designated as a Class I airshed. 

Parks designated as Class I and II airsheds typically use the Environmental Protection Agency 

(EPA) National Ambient Air Quality Standards (NAAQS) for criteria air pollutants as the ceiling 

standards for allowable levels of air pollution. The EPA believes these standards, if not 

exceeded, protect human health and the health of natural resources (EPA 2008a). The CAA also 

establishes that current visibility impairment in these areas must be remedied and future 

impairment prevented (EPA 2008a). However, the EPA acknowledges that the NAAQS are not 

necessarily protective of ecosystems and is currently developing secondary NAAQS for ozone, 

nitrogen, and sulfur compounds to protect sensitive plants, lakes, streams, and soils (EPA 2010a, 

2010b). To comply with CAA and NPS Organic Act mandates, the NPS established a monitoring 

program that measures air quality trends in many park units for key air quality indicators, 

including atmospheric deposition, ozone, and visibility (NPS 2008).

Although THRO is located in a rural part of the country, several sources of air pollution threaten 

the park’s air quality. The more persistent and permanent sources include oil and gas 

development in western North Dakota, vehicle emissions, and emissions from the nearby 

operation and development of coal-fired power plants (Peterson et al. 1998). Smoke from

wildland fires, agricultural burning, and prescribed burning can also periodically affect air 

quality in THRO (Peterson et al. 1998), but these are of short duration compared to more 

permanent sources.

4.12.2 Measures

 Nitrogen deposition

 Sulfur deposition

 Ozone concentration

 Mercury deposition/concentration

 Concentration of particulate matter (PM 2.5 and 10)

 Visibility
170

Atmospheric Deposition

Nitrogen and sulfur oxides are emitted into the atmosphere primarily through the burning of 

fossil fuels, industrial processes, and agricultural activities (EPA 2008b). While in the 

atmosphere, these emissions form compounds that may be transported long distances and settle 

out of the atmosphere in the form of pollutants such as particulate matter (e.g., sulfates, nitrates, 

ammonium) or gases (e.g., nitrogen dioxide, sulfur dioxide, nitric acid, ammonia) (EPA 2008b, 

NPS 2008). Atmospheric deposition can be in wet (i.e., pollutants dissolved in atmospheric 

moisture and deposited in rain, snow, low clouds, or fog) or dry (i.e., particles or gases that settle 

on dry surfaces as with windblown dusts) form (EPA 2008b). Deposition of sulfur and nitrogen 

can have significant effects on ecosystems including acidification of water and soils, excess 

fertilization or increased eutrophication, changes in the chemical and physical characteristics of 

water and soils, and accumulation of toxins in soils, water, and vegetation (NPS 2008, reviewed 

in Sullivan et al. 2011a and 2011b). Grassland prairie and meadow communities are sensitive to 

increased levels of nitrogen and may be impacted by excess nitrogen enrichment via deposition 

(reviewed in Sullivan 2011b); the predominant landcover in THRO is grassland and meadow 

(NPS 2005, Pohlman and Maniero 2005, Sullivan et al. 2011c). On the other hand, many nonnatives, such as the invasive cheatgrass, prefer nitrogen rich environments and may displace 

native species as nitrogen deposition increases in these sensitive communities (Sullivan et al. 

2011a, b, and c). 

Ozone

Ozone occurs naturally in the earth’s atmosphere where, in the upper atmosphere, it protects the 

earth’s surface against ultraviolet radiation (EPA 2008b). However, it also occurs at the ground 

level (i.e., ground-level ozone) where it is created by a chemical reaction between nitrogen 

oxides and volatile organic compounds (VOCs) in the presence of heat and sunlight (NPS 2008). 

Ozone is also one of the most widespread pollutants affecting vegetation in the U.S. (NPS 2008). 

Considered phytotoxic, ozone can cause significant foliar injury and growth effects for sensitive 

plants in natural ecosystems (EPA 2008a, NPS 2008). Specific effects include reduced 

photosynthesis, premature leaf loss, and reduced biomass, and prolonged exposure can increase 

vulnerability to insects and diseases or other environmental stresses (NPS 2008). At high 

concentrations, ozone can aggravate respiratory and cardiovascular diseases, reduce lung 

function, cause acute respiratory problems, and increase susceptibility to respiratory infections 

(EPA 2008b, 2010c); this would be a concern for visitors and staff engaging in aerobic activities 

in the park, such as hiking.

Mercury

Sources of atmospheric mercury include fuel combustion and evaporation (especially coal-fired 

power plants), waste disposal, mining, industrial sources, and natural sources such as volcanoes 

and evaporation from enriched soils, wetlands, and oceans (EPA 2008b). Mercury deposited into 

rivers, lakes, and oceans can accumulate in various aquatic species, resulting in exposure to 

wildlife and humans that consume them (EPA 2008b).

Particulate Matter (PM) and Visibility

Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets

suspended in the atmosphere. PM is categorized as fine particles (PM2.5), which are 2.5 

micrometers in diameter or smaller, and inhalable coarse particles (PM10), which are smaller than 

10 micrometers (the width of a single human hair) (EPA 2009a). Particulate matter largely 
171

consists of acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust 

particles (EPA 2008a, 2009a). Fine particles are a major cause of reduced visibility (haze) in 

many national parks and wildernesses (EPA 2010b). PM2.5 can be directly emitted from sources 

such as forest fires, or they can form when gases emitted from power plants, industries, and/or 

vehicles react with air (EPA 2009a, 2010d). Sources of coarse particles (PM10) include grinding 

or crushing operations and windblown or stirred up dust from dirt surfaces (e.g., roads, 

agricultural fields). Particulate matter either absorbs or scatters light. As a result, the clarity, 

color, and distance seen by humans decreases, especially during humid conditions when 

additional moisture is present in the air (EPA 2010d). PM10 and PM2.5 are also a concern for

human health as these particles can easily pass through the throat and nose and enter the lungs 

(EPA 2008b, 2009a, 2010d). Short-term exposure to these particles can cause shortness of 

breath, fatigue, and lung irritation (EPA 2008b, 2009a).

4.12.3 Reference Conditions/Values

The NPS Air Resources Division (ARD) developed an approach for rating air quality conditions 

in national parks, based on the current NAAQS, ecosystem thresholds, and visibility 

improvement goals (Table 31) (NPS 2010a). Assessment of current condition of nitrogen and 

sulfur atmospheric deposition is based on wet (rain and snow) deposition. Ozone condition is 

based on the NAAQS standard of 75 parts per billion (ppb). Visibility conditions are assessed in 

terms of a Haze Index, a measure of visibility derived from calculated light extinction (NPS 

2010a). The NAAQS standard for PM10 is 150 μg/m3over a 24-hour period; this level may not 

be exceeded more than once per year on average over three years (EPA 2010d). The standard for 

PM2.5 is 15.0 μg/m3 weighted annual mean or 35 μg/m3in a 24-hour period over an average of 

three years (EPA 2010d). Currently, there is no standard or threshold established for mercury 

deposition. Finally, NPS ARD recommends the following values for determining air quality 

condition (Table 31). The “good condition” metrics may be considered the reference condition 

for THRO.

Table 31. National Park Service Air Resources Division air quality index values (NPS 2010a).

Condition

Ozone 

concentration

(ppb)

Wet Deposition 

of N or S 

(kg/ha/yr)

Visibility

(dv)

Significant Concern ≥ 76 > 3 > 8

Moderate 61-75 1-3 2-8

Good ≤ 60 < 1 < 2

4.12.4 Data and Methods

Monitoring in the Park

Substantial monitoring efforts have been ongoing in THRO since the early 1980s and, thus, 

monitoring data for the period of record may be examined for trends in air quality. Air quality 

monitoring in the park includes ozone monitoring (NPS Gaseous Pollutant Monitoring Program 

[GPMP]), wet deposition monitoring of atmospheric pollutants, including nitrogen, sulfur, and 

ammonium (National Atmospheric Deposition Program [NADP]), dry deposition monitoring of 

atmospheric pollutants (Clean Air Status and Trends Network [CASTNet]), and visibility 

monitoring (Interagency Monitoring of Protected Visual Environments Program [IMPROVE]) 

(Pohlman and Maniero 2005). Data from these on-site monitors are used to evaluate trends in air 

quality at the park, most recently for the period 1999-2008 (NPS 2010b).
172

NPS Data Resources

In addition, NPS ARD provides estimates of ozone, wet deposition of nitrogen and sulfur, and 

visibility that are based on interpolations of data from all air quality monitoring stations operated 

by NPS, EPA, various states, and other entities, averaged over five years (2005-2009). These 

estimates are available from the Explore Air website (NPS 2011) and are used to evaluate air 

quality conditions. Note that on-site or nearby data are needed for a statistically valid trends 

analysis, while a five-year average interpolated estimate is preferred for the condition 

assessment. NPS ARD (2010b) reports on air quality conditions and trends in an annual report 

for over 200 park units, including THRO. 

Other Air Quality Data Resources

The National Atmospheric Deposition Program–National Trends Network (NADP) database 

provides access to annual average summary data for nitrogen and sulfur concentration and 

deposition in THRO (monitoring site ND00) (NADP 2011). 

The Clean Air Status and Trends Network (CASTNet) provides access to summaries of the 

composition of nitrogen and sulfur deposition in THRO (site number THR422) (EPA 2012a). 

The EPA Air Trends database provides access to annual average summary data for ozone 

concentrations in the North and South Units of THRO (North Unit monitoring site = 380530002; 

South Unit monitoring site = 380070002) (EPA 2012b). 

The Visibility Information Exchange Web System (VIEWS) database provided average annual 

visibility monitoring data (in deciviews [dv]) for THRO from 2001 through 2004 (VIEWS 

2010). The IMPROVE Program provided access to annual summary data for particulate matter 

concentrations and average visibility (in dv) in the park (IMPROVE 2011). 

Special Air Quality Studies

Pohlman and Maniero (2005) reports on the estimated risk of foliar injury from ozone on native 

vegetation in national parks in the NGPN. Information on ozone sensitive plant species present 

in the parks, levels of ozone exposure, and relationships between exposure and soil moisture are 

synthesized into a risk assessment of foliar injury for each park, including THRO.

Sullivan et al. (2011a) assessed the relative sensitivity of national parks to the potential effects of 

acidification caused by acidic atmospheric deposition from nitrogen and sulfur compounds. The 

relative risk for each park was assessed by examining three variables: the level of exposure to 

emissions and deposition of nitrogen and sulfur; inherent sensitivity of park ecosystems to 

acidifying compounds (N and/or S) from deposition; and level of mandated park protection 

against air pollution degradation (i.e., Wilderness and Class I). The outcome was an overall risk 

assessment that estimates the relative risk of acidification impacts to park resources from 

atmospheric deposition of nitrogen and sulfur (Sullivan et al. 2011a). Using the same approach, 

Sullivan et al. (2011b) assessed the sensitivity of national parks to the effects of nutrient 

enrichment by atmospheric deposition of nitrogen. The outcome was an overall risk assessment 

that estimates the relative risk to park resources of nutrient enrichment from increased nitrogen 

deposition.
173

4.12.5 Current Condition and Trend

Atmospheric Deposition

Five-year interpolated averages are used to estimate the condition of most air quality parameters; 

this offsets annual variations in meteorological conditions, such as heavy precipitation one year 

versus drought conditions in another. The current 5-year average (2005-2009) estimates total wet 

deposition of nitrogen in THRO to be 2.26 kg/ha/yr, while the wet deposition of sulfur is 0.93

kg/ha/yr (NPS 2011). Overall, deposition of nitrogen and sulfur appears to be stable. Based on 

NPS ratings for air quality conditions, the current estimates for nitrogen deposition fall into the 

Moderate Concern category, while the current estimates for sulfur deposition fall into the Good 

Condition category (see Table 31 for ratings values). However, several factors are considered 

when rating the condition of atmospheric deposition, including effects of deposition on different 

ecosystems (NPS 2010a). Based on the NPS process for rating air quality conditions, ratings for 

parks with ecosystems considered potentially sensitive to nitrogen or sulfur deposition are 

typically adjusted up one condition category. In general, native grassland and meadow 

ecosystems can be sensitive to increased levels of nitrogen, as acidification and nutrient 

enrichment can cause shifts in native species composition and encourage encroachment of exotic 

species and grasses (reviewed in Sullivan et al. 2011a and 2011b). THRO comprises native 

grassland/prairie vegetation communities, which may be at risk from increased nitrogen 

deposition. Thus, the condition in THRO typically would be considered of Significant Concern 

for nitrogen deposition and Moderate Concern for sulfur deposition, based on natural 

background and current average nitrogen deposition rates. However, trend analysis of wet 

deposition data collected in THRO from 1999-2008 indicates nitrogen deposition is of moderate 

concern with a stable trend, while sulfur deposition is in good condition with a stable trend (NPS 

2010b).

Concentrations (mg/L) of nitrogen, sulfur, and ammonium compounds in wet deposition can be 

used to evaluate trends in deposition of total nitrogen and sulfur. Since atmospheric wet 

deposition can vary greatly depending on the amount of precipitation that falls in any given year, 

it can be useful to examine concentrations of pollutants, which factor out the variation introduced 

by precipitation. Figure 21 shows the annual average concentrations of sulfate, nitrate, and 

ammonium recorded in THRO from 2000-2010. Despite a slight increase in concentrations in 

2002 and 2006, annual averages indicate that sulfate and nitrate concentrations in the park have 

been decreasing overall, while ammonium deposition appears stable (NADP 2011).
174

Figure 21. Annual average precipitation-weighted concentrations of nitrate (NO3), sulfate (SO4), and 

ammonium (NH4) (mg/L) in THRO, 2000-2010 (NADP monitoring site ND00) (Source: NADP 2011).

Dry deposition (dust, particles, and aerosols) also contributes significantly to total deposition in 

the region around THRO. CASTNet data indicate that dry forms contribute about one-fourth

(26%) to total deposition of nitrogen, and about 30% to total sulfur deposition (EPA 2012a) (see

Figure 22 and Figure 23). Figure 26 indicates that reduced forms of nitrogen (i.e., ammonium 

[NH4]) contribute approximately 50% of total nitrogen deposition; this is likely an underestimate 

because ammonia gas is not included in the measurements. 

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Concentration (mg/L)

NO3

SO4

NH4
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Figure 22. Composition of nitrogen deposition in THRO, 2007-2009 (Monitoring station THRO422) (EPA 

2012a).
176

Figure 23. Composition of sulfur deposition in THRO, 2007-2009 (Monitoring station THRO422) (EPA 

2012a). 

Sullivan et al. (2011a) ranked THRO as having moderate acidifying (nitrogen and sulfur) 

pollutant exposure, moderate ecosystem sensitivity to acidification in its grassland ecosystem, 

and very high park protection (Class I airshed) against air pollution. The relative ranking of 

overall risk from acidification due to acid deposition is high relative to other parks (Sullivan et 

al. 2011a). In a separate examination, Sullivan et al. (2011b) used the same approach to assess 

the sensitivity of national parks to nutrient enrichment effects from atmospheric nitrogen 

deposition relative to other parks. Risk relative to other parks was assessed by examining 

exposure to nitrogen deposition, inherent sensitivity of park ecosystems, and mandates for park 

protection. THRO was ranked as being at low risk for nitrogen pollutant exposure, very high 

ecosystem sensitivity of grasslands and meadows, and very high park protection mandates (Class 

I airshed). The ranking of overall risk of effects from nutrient enrichment due to atmospheric 

nitrogen deposition was determined to be very high relative to other parks (Sullivan et al. 

2011b).

Ozone Concentration

The NAAQS standard for ground-level ozone is the benchmark for rating current ozone 

conditions within park units. The condition of ozone in NPS park units is determined by 

calculating the 5-year average of the fourth-highest daily maximum of 8-hour average ozone 

concentrations measured at each monitor within an area over each year (NPS 2010a). The current 

5-year average (from 2005-2009) for THRO indicates an average ground-level ozone 

concentration of 60.0 ppb (NPS 2011), which falls under the Good Condition category based on 
177

NPS guidelines. Based on trend analysis of annual average data from 1999-2008, ozone 

concentrations in THRO are in good condition with a stable trend (NPS 2010b). Figure 24 and 

Figure 25 show the trends for average annual ozone concentrations in the South and North Units 

of THRO (Note: concentrations are in ppm, while NPS thresholds are in ppb) from 1991 to 2010 

with respect to the national standard (EPA 2012b). Data suggest ozone concentrations vary 

slightly, but overall, concentrations appear to be stable and within the EPA national standard.

Figure 24. Average annual ozone (O3) concentration (ppm) for the South Unit of THRO, 1999-2010 

(Source: EPA 2012b).
178

Figure 25. Average annual ozone (O3) concentration (ppm) for the North Unit of THRO, 1990-2010 

(Source: EPA 2012b).

Pohlman and Maniero (2005) assessed ozone concentrations in the NPGN and the risk of injury 

to plant species that are sensitive to sustained ozone exposure. Data from 1995-1999 indicate 

ozone concentrations in THRO during this time frequently exceeded 60 ppb for a few hours each 

year, but only exceeded 80 ppb a few times in one year out of the five; ozone concentrations 

never exceeded 100 ppb. Sensitive plant species begin to experience foliar injury when exposed 

to ozone concentrations of 80-120 ppb/hour for extended periods of time (8 hours or more) 

(Pohlman and Maniero 2005). Thus, the risk of foliar injury to plants was determined to be low 

(Pohlman and Maniero 2005). However, if ozone concentrations should increase in the future, an 

on-site monitoring program that assesses foliar injury and growth progress may be necessary 

(Pohlman and Maniero 2005). 

Various plant and tree species are monitored to track 

air pollution impacts. THRO has 18 plant species 

known to be sensitive to excessive or extended 

concentrations of ozone, including a number of species 

that are highly sensitive. Highly sensitive species 

include Ponderosa pine (Pinus ponderosa), 

chokecherry, quaking aspen (Populus tremuloides), 

spreading dogbane (Apocynum androsaemifolium), 

paper birch (Betula papyrifera), Virginia strawberry 

(Fragaria virginiana), common snowberry, and green 

ash (Peterson et al. 1998, NPS 2006). Photo 21. Chokecherry (NPS photo).
179

Mercury Concentration

THRO does not have a monitoring station that records mercury deposition. The nearest 

monitoring station is located in Eagle Butte, South Dakota. However, it is approximately 322 km 

(200 mi) southeast of THRO and, thus, it is inappropriate to estimate deposition rates in the park 

from this monitor. For locations in the U.S. that do not have mercury monitoring stations, 

deposition is interpolated from the nearest sites in areas with sufficient numbers of samplers; this 

data can be used to estimate conditions in a particular area, but should be used with caution in 

considering current condition or in determining trends. Figure 26 shows the most recent 

interpolated average mercury wet deposition for monitoring sites across the U.S. (the 

approximate location of THRO is marked with a yellow star). Recent average deposition data 

indicate wet deposition of mercury in the region of the park is approximately 4-6 μg/m2(NADP 

2012).

Figure 26. Total mercury deposition near THRO, 2010 (Source: NADP 2012). Yellow star indicates the 

approximate location of THRO.

Wet deposition of mercury can vary greatly depending on variations in the amount of 

precipitation that has fallen in an area across a year or several years. Mercury concentrations 

more accurately reflect patterns in mercury emissions. Figure 27 shows the most recent 

interpolated average mercury concentrations for monitoring sites across the U.S. (approximate 

location of THRO is marked with a yellow star). Recent average concentration data indicate 

D

E

T

O

THRO
180

mercury concentrations in the region of THRO are approximately 10-14 ng/L (NADP 2012). 

Reliable data for both concentration and deposition of mercury prior to 2009 are unavailable.

Figure 27. Total mercury concentration near THRO, 2010 (Source: NADP 2012). Yellow star indicates 

the approximate location of THRO.

Concentration of Particulate Matter (PM2.5 and PM10)

Concentrations of particulate matter (PM2.5 and PM10) are recorded at an IMPROVE monitoring 

site located in THRO (site THRO1). Data for average concentrations in the park are available 

from 2001 through 2010, and are summarized as annual average concentrations (IMPROVE 

2011). The NAAQS standard for PM10 is 150 μg/m3over a 24-hour period; this level may not be 

exceeded more than once per year on average over three years (EPA 2010d). The standard for 

PM2.5 is a weighted annual mean of 15.0 μg/m3or 35 μg/m3in a 24-hour period over an average 

of three years (EPA 2010d). Since 2001, PM2.5 concentrations have remained stable around 3.5-

4.5 μg/m3, while average concentrations of PM10 fluctuated between 8.5-11.5 μg/m3 (Figure 28)

(IMPROVE 2011). Values for both PM2.5 and PM10 are well within the EPA standards for levels 

that are protective of human health and visibility. 

THRO

D

E

T

O
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Figure 28. Average annual particulate matter concentration (PM2.5 and PM10) in THRO, 2001-2010 

(IMPROVE 2011).

Visibility

Visibility impairment occurs when airborne particles and gases scatter and absorb light; the net 

effect is called “light extinction,” which is a reduction in the amount of light from a view that is 

returned to an observer (EPA 2003). In response to the mandates of the CAA of 1977, federal 

and regional organizations established IMPROVE in 1985 to aid in monitoring of visibility 

conditions in Class I airsheds. The goals of the program are to 1) establish current visibility 

conditions in Class I airsheds; 2) identify pollutants and emission sources causing the existing 

visibility problems; and 3) document long-term trends in visibility (NPS 2009). 

The most current 5-year average (2005-2009) estimates visibility in THRO to be 6.8 dv (this is 

an estimate minus the estimated natural conditions). This falls into the Moderate Concern

category for NPS air quality condition assessment (NPS 2011). 

The clearest and haziest 20% of days each year also are examined for parks. Figure 29 depicts 

estimated visibility conditions (in dv) for the 20% haziest and 20% clearest days in THRO. 

Conditions measured near 0 dv are clear and provide excellent visibility, and as deciview

measurements increase, visibility conditions become hazier. Estimated visibility conditions 

appear relatively consistent for both the 20% haziest and clearest days over the last 10 years. 

Trend analysis of data from 1999-2008 indicates visibility to be of moderate concern with a 

stable trend (NPS 2010b). 

0

20

40

60

80

100

120

140

160

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Concentration (μg/m3

)

PM 2.5

PM10

National Standard PM 2.5

National Standard PM 10
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Figure 29. Visibility (in dv) on the 20% clearest and 20% haziest days in THRO, 2001-2010 (IMPROVE 

2011).

Threats and Stressor Factors

The most substantial threat to air quality in THRO is energy development in the region, 

particularly crude oil and natural gas. Western and central North Dakota have experienced a 

significant increase in oil and gas development in the last two decades (Peterson et al. 1998). The 

major sources of pollution that could affect protected areas in this region have been associated 

with oil and gas operations as well as coal-fired power plants; these sources add sulfur dioxide

and nitrogen oxide emissions to the air (Peterson et al. 1998). Several power plants, the largest 

sources of sulfur dioxide emissions in the region, are located near the park (Peterson et al. 1998), 

where winds can carry emissions into the park. Although THRO is unlikely to be affected by 

acidification from sulfur dioxide and associated sulfate deposition, these coal-burning power 

plants also release mercury into the atmosphere that, when transformed to toxic methylmercury 

in wetlands, can bioaccumulate in fish and wildlife. Nitrogen oxide emissions from oil and gas 

development may increase nitrogen deposition to THRO grasslands and wetlands, which could 

affect plant communities and promote growth of annual grasses and invasive species. 

Smoke produced by wildfires or human-caused fires have long been a part of the Great Plains 

ecosystem. Though fires are not considered a long-term source of pollution in the northern Great 

Plains (including THRO), if persistent and substantial in extent, they may result in periods of 

decreased visibility and increased concentrations of particulate matter (Peterson et al. 1998). 

Data Needs/Gaps

Though monitoring of air quality parameters is quite thorough in THRO, little emphasis has been 

placed on tracking the plant and animal species that are sensitive to increases in certain 

pollutants. Peterson et al. (1998) indicate that a primary concern in THRO is sulfur exposure and 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Visibility (dv)

20% clearest days 20% haziest days
183

the effects of such exposure on native vegetation. Nitrate, sulfate, and ammonium deposition and 

ozone could become more of a concern in the future as new point and area sources of pollution 

emerge (e.g., increase in development of oil and gas wells, and operation of coal-fired power 

plants) and increase ambient pollution levels (Peterson et al. 1998). If air pollution increases in 

the future, plant and trees species can be monitored to track air pollution impacts. 

THRO has a number of species that are quite sensitive to increases in ozone and sulfates 

(Peterson et al. 1998 provide a detailed list). Several of these species could be used as 

bioindicators to track potential increases in certain criteria air pollutants as well as long-term 

health of the ecosystem. Table 32 summarizes the vascular plant and tree species that have 

known sensitivities, either medium or high, to sulfates and ozone. While it is impractical to 

monitor all sensitive plant species, park staff may identify key species to use as bioindicators. 

Table 32. Plant and tree species of THRO with high or moderate sensitivities to sulfates and ozone 

(adapted from Peterson et al. 1998; Pohlman and Maniero 2005, NPS 2006b).

Scientific Name Common Name SO2

Sensitivity1

O3

Sensitivity

Amelanchier alnifolia Saskatoon serviceberry H M

Betula papyrifera Paper birch H H

Convolvulus arvensis Field bindweed H

Corylus cornuta Beaked hazelnut H

Fragaria virginiana Virginia strawberry H

Fraxinus pennsylvanica Green ash M H

Helianthus anuus Common sunflower H

Pinus ponderosa Ponderosa pine M H

Populus tremuloides Quaking aspen H H

Prunus virginiana Chokecherry M H

Rhus aromatica Fragrant sumac H

1Sensitivity: M=medium; H=high

In an effort to quantify harmful pollution levels and set goals for resource protection on federal 

lands, natural resources managers are increasingly using a “critical loads” approach for tracking 

and monitoring a variety of pollutants, in particular nitrogen and sulfur compounds (Porter et al. 

2005). Critical loads are defined as “the quantitative estimate of an exposure to one or more 

pollutants below which significant harmful effects on specified sensitive elements of the 

environment do not occur according to present knowledge” (Nilsson and Grennfelt 1988, as cited 

in Porter et al. 2005, p. 603). Essentially, critical loads describe the amount of pollution that 

stimulates negative impacts or harmful changes in sensitive ecosystems (Porter et al. 2005, NPS 

2007). Porter et al. (2005) developed an approach for determining critical loads for nitrogen and 

sulfur using two national parks as case studies, and research is underway in other park units to 

aid in communicating resource condition. Their methodology can be tailored to fit most national 

park lands, depending on the baseline information that is available. Since there are a variety of 

plant species found in THRO that are sensitive to increases in air pollutants and because 

grasslands are particularly vulnerable to excess deposition of nitrogen (Peterson et al. 1998), 

park managers at THRO may be able to develop and implement a critical load approach for 

managing air pollutants and to set goals for resource protection within the park. 
184

Overall Condition

Nitrogen Deposition

The project team defined the Significance Level for atmospheric deposition of nitrogen as a 3. 

Sullivan et al. (2011b) rate the grassland ecosystems in THRO as at very high risk of nutrient 

enrichment due to nitrogen deposition. NADP data suggest nitrogen deposition may be declining 

slightly in recent years. NPS (2010b) trend analysis from 1999-2008 indicates nitrogen 

deposition is of moderate concern with a stable trend. Therefore, deposition of nitrogen is of 

moderate concern (Condition Level = 2).

Sulfur Deposition

The project team defined the Significance Level for atmospheric deposition of sulfur as a 3. 

Sullivan et al. (2011a) suggest the moderate sensitivity to acidification, coupled with a moderate 

risk of pollutant exposure, make the grassland ecosystems in THRO at high risk of acidification 

by sulfur and other acids. NADP data suggest sulfur deposition may be declining slightly in 

recent years and has largely remained stable. Current measurements fall into the moderate 

concern category based on NPS criteria for rating air quality, however, NPS (2010b) trend 

analysis from 1999-2008 specifies that sulfate deposition is in good condition with a stable trend. 

Therefore, deposition of sulfur is of low concern (Condition Level = 1).

Ozone Concentration

The project team defined the Significance Level for ozone concentration as a 3. Current average 

ground-level ozone concentrations fall into the good concern category based on NPS criteria for 

rating air quality, with annual average concentrations (measured in ppm) indicating a stable 

trend. Therefore, the Condition Level for ozone concentration is a 0, of no concern.

Mercury Deposition/Concentration

The project team defined the Significance Level for mercury concentration as a 3. Current data 

suggest mercury deposition and concentration in the northern Great Plains are low relative to 

other regions of the U.S. However, these data are interpolated from monitoring stations some 

distance from THRO and serve only as estimates for the region versus data collected in or near 

the park. Limited data make it impossible to determine a Condition Level for this measure.

Particulate Matter Concentration (PM 2.5 and PM 10)

The project team defined the Significance Level as 3 for concentration of fine particulate matter 

(PM 2.5 and 10). Concentrations for both PM2.5 and PM10 in THRO are well within the EPA 

standards for levels that are protective of human health. Trends in average concentrations show 

consistent stability over the last decade. The Condition Level for PM2.5 and PM 10 is a 0, of no 

concern.

Visibility

The project team defined the Significance Level for visibility as a 3. Current average visibility 

falls into the moderate concern category based on NPS criteria. Average visibility conditions on 

the 20% clearest days are improving slightly over the last decade, while visibility for the 20% 

haziest days may be declining slightly. The Condition Level for visibility is a 2, of moderate 

concern.
185

Weighted Condition Score

The Weighted Condition Score (WCS) for the air quality component is 0.333, indicating the 

condition is of low concern with a stable trend.

4.12.6 Sources of Expertise

Ellen Porter, Biologist, National Park Service, Air Resources Division.
186

4.12.7 Literature Cited

Environmental Protection Agency (EPA). 2003. Guidance for estimating natural visibility 

conditions under the Regional Haze Rule. EPA-454/B-03-005. Office of Air Quality 

Planning and Standards. Emissions, Monitoring and Analysis Division, Research Triangle 

Park, North Carolina.

Environmental Protection Agency (EPA). 2008a. Air and radiation: Clean Air Act Title I. 

http://epa.gov/oar/caa/title1.html#ic (accessed 10 January 2012).

Environmental Protection Agency (EPA). 2008b. National air quality: Status and trends through 

2007. EPA-454/R-08-006. Office of Air Quality Planning and Standards, Air Quality 

Assessment Division, Research Triangle Park, North Carolina.

Environmental Protection Agency (EPA). 2009a. Air quality index: A guide to air quality and 

your health. EPA-456/F-09-002. Office of Air Quality Planning and Standards, Outreach and 

Information Division, Research Triangle Park, North Carolina.

Environmental Protection Agency (EPA). 2009b. Air and radiation: Air trends data for 

particulate matter. http://www.epa.gov/airtrends/pm.html (accessed 18 August 2010).

Environmental Protection Agency (EPA). 2010a. Proposed rule, National Ambient Air Quality 

Standards for ozone. Federal Register/Vol. 75, No. 11/Tuesday, January 19, 2010.

Environmental Protection Agency (EPA). 2010b. Policy assessment for the review of the 

Secondary National Ambient Air Quality Standards for NOx and SOx: Second External 

Review Draft. EPA452/P-10-008. September, 2010. 

Environmental Protection Agency (EPA). 2010c. Ground-level ozone standards designations. 

http://www.epa.gov/ozonedesignations/ (accessed 13 February 2012).

Environmental Protection Agency (EPA). 2010d. Air & radiation: particulate matter. 

http://www.epa.gov/air/ (accessed 18 February 2012).

Environmental Protection Agency (EPA). 2012a. CASTNet monitoring site information: 

Theodore Roosevelt National Park (site THR422). 

http://www.epa.gov/castnet/javaweb/site_pages/THR422.html (accessed 3 March 2012).

Environmental Protection Agency (EPA). 2012b. Air and radiation: Air trends data for ozone. 

http://www.epa.gov/airtrends/ozone.html#ozloc (accessed 5 March 2012).

Interagency Monitoring of Protected Visual Environments (IMPROVE). 2011. Regional Haze 

Rule summary data through 1988-2010: Means for best, middle, and worst 20% visibility 

days. http://vista.cira.colostate.edu/improve/Data/IMPROVE/summary_data.htm (accessed 3 

March 2012).

National Atmospheric Deposition Program (NADP). 2011. National Atmospheric Deposition 

Program – National Trends Network Monitoring location ND00 (at THRO).

http://nadp.sws.uiuc.edu/sites/sitemap.asp?state=nd (accessed 18 February 2012).
187

National Atmospheric Deposition Program-Mercury Deposition Network (NADP). 2012. 

National Atmospheric Deposition Program–Mercury Deposition Network. Mercury 

concentration isopleths maps. http://nadp.sws.uiuc.edu/maps/Default.aspx (accessed 29

February 2012).

National Park Service (NPS). 2005. Air quality and air quality related values monitoring 

considerations for the Northern Great Plains Network. National Park Service, Northern Great 

Plains Network, Rapid City, South Dakota.

National Park Service (NPS). 2006. Ozone sensitive plant species, by park. November 2006. 

National Park Service, Air Resources Division. 

http://www.nature.nps.gov/air/permits/aris/docs/ Ozone_Sensitive_ByPark_3600.pdf

(accessed 2 March 2012).

National Park Service (NPS). 2007. Explore air: Effects of air pollution. 

http://www.nature.nps.gov/air/AQBasics/effects.cfm (accessed 24 August 2011). 

National Park Service (NPS). 2008. Air Atlas summary tables for I & M Parks. 

http://www.nature.nps.gov/air/permits/aris/networks/docs/SummariesAirAtlasRevised11072

003.pdf (accessed 10 January 2012). 

National Park Service (NPS). 2009. Air quality monitoring and access to data. 

http://www.nature.nps.gov/air/monitoring/index.cfm (accessed 24 February 2012).

National Park Service (NPS). 2010a. Rating air quality conditions. Air Resources Division, 

Natural Resources Program Center. PDF found at: 

http://www.nature.nps.gov/air/Planning/docs/20100112_Rating-AQ-Conditions.pdf

(accessed 10 January 2012).

National Park Service (NPS). 2010b. Air quality in national parks: 2009 annual performance and 

progress report. Natural Resource Report NPS/NRPC/ARD/NRR—2010/266. National Park 

Service, Denver, Colorado.

National Park Service (NPS). 2011. NPS Air quality estimates: ozone, wet deposition, and 

visibility. http://www.nature.nps.gov/air/Maps/AirAtlas/IM_materials.cfm (accessed 11

December 2011).

Peterson, D. L., T. J. Sullivan, J. M. Eilers, S. Brace, D. Horner, K. Savig, and D. Morse. 1998. 

Assessment of air quality and air pollutant impacts in national parks of the Rocky Mountains 

and Northern Great Plains. Technical Report NPS D-657. National Park Service, Denver, 

Colorado.

Pohlman, D., and T. Maniero. 2005. Air quality monitoring considerations for the Northern 

Great Plains Network parks. National Park Service, St. Paul, Minnesota.

Porter, E., T. Blett, D. U. Potter, and C. Huber. 2005. Protecting resources on federal lands: 

Implications of critical loads for atmospheric deposition of nitrogen and sulfur. BioScience 

55(7):603-612.
188

Sullivan, T. J., G. T. McPherson, T. C. McDonnell, S. D. Mackey, and D. Moore. 2011a. 

Evaluation of the sensitivity of inventory and monitoring national parks to acidification 

effects from atmospheric sulfur and nitrogen deposition: main report. Natural Resource 

Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado.

Sullivan, T. J., T. C. McDonnell, G. T. McPherson, S. D. Mackey, and D. Moore. 2011b. 

Evaluation of the sensitivity of inventory and monitoring national parks to nutrient 

enrichment effects from atmospheric nitrogen deposition: main report. Natural Resource 

Report NPS/NRPC/ARD/NRR—2011/313. National Park Service, Denver, Colorado.

Sullivan, T. J., T. C. McDonnell, G. T. McPherson, S. D. Mackey, and D. Moore. 2011c. 

Evaluation of the sensitivity of inventory and monitoring national parks to nutrient 

enrichment effects from atmospheric nitrogen deposition: Northern Great Plains Network 

(NGPN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/322. National Park 

Service, Denver, Colorado.

Visibility Information Exchange Web System (VIEWS). 2010. Air quality data, tools, and 

resources: Trends analysis – Theodore Roosevelt National Park. 

http://views.cira.colostate.edu/web/Trends/ (accessed 2 March 2012). 
189

4.13 Water Quality

4.13.1 Description

In recent years, water quality monitoring has been identified as a priority for NGPN parks, 

including THRO, for tracking ecological health in the park, assessing compliance with water 

quality standards, and detecting threats to human health. A core set of water quality measures 

will be monitored, including such parameters as dissolved oxygen, concentration of fecal 

coliform bacteria, pH, and water temperature (NPS 2012).

The Little Missouri River is a primary feature on the THRO landscape, running through all three 

units of the park. It provides support and habitat for a variety of plants, birds, terrestrial animals, 

and fish. For many of the park’s large animals, such as bison, feral horses, and elk, the Little 

Missouri River provides one of the only consistent sources of water (NPS 2010). Additionally, 

some popular visitor activities include fishing, float trips down the river, and wildlife viewing

(NPS 2010). Thus, impaired water quality could substantially affect both animals and people in 

the park.

4.13.2 Measures

 Dissolved oxygen (DO)

 Fecal coliform

 pH

 Macroinvertebrates

 Specific conductance 

 Temperature

 Turbidity

Dissolved Oxygen

Dissolved oxygen (DO) is critical 

for organisms that live in water. 

Fish and zooplankton filter out or 

“breathe” dissolved oxygen from the water to survive (USGS 2010). Oxygen enters water from 

the atmosphere or through ground water discharge. As the amount of DO drops, it becomes more 

difficult for water-based organisms to survive (USGS 2010). The concentration of DO in a water 

body is closely related to water temperature; cold water holds more DO than does warm water 

(USGS 2010). Thus, DO concentrations are subject to seasonal fluctuations as low temperatures 

in the winter and spring allow water to hold more oxygen, and warmer temperatures in the 

summer and fall allow water to hold less oxygen (USGS 2010). 

Fecal Coliform

Fecal coliform bacteria are an accurate indicator of fecal contamination in water by warmblooded animals. It is tested by counting colonies that grow on micron filters placed in an 

incubator for 22-24 hours. High numbers of fecal coliform can be an indicator of harmful 

Photo 22. Little Missouri River at Juniper Campground in the North 

Unit of THRO (Photo by Shannon Amberg, SMUMN GSS, 2010).
190

bacteria as well as other disease-causing organisms such as viruses and protozoans (USGS 

2011). 

pH

pH is a measure of the level of acidity or alkalinity of water and is measured on a scale from 0 to 

14, with 7 being neutral (USGS 2010). Water with a pH of less than 7.0 indicates acidity, 

whereas water with a pH greater than 7.0 indicates alkalinity. Aquatic organisms have a 

preferred pH range that is ideal for growth and survival (USGS 2010). Chemicals in water can 

change the pH and harm animals and plants living in the water; thus, monitoring pH can be 

useful for detecting natural and human-caused changes in water chemistry (USGS 2010). 

Macroinvertebrates

Because aquatic macroinvertebrates spend most or all of their life cycles in water, they are well 

known as indicators of watershed health and the quality of water in aquatic systems (EPA 

2011b). Some species are tolerant of pollution or poor water quality, while others are highly 

sensitive to it. Thus, the presence or absence of tolerant and intolerant species can be an 

indication of the condition of the water body and water quality (EPA 2011b). The life cycles of 

many macroinvertebrate species are short (sometimes one season in length), though some species 

live longer, and many have limited mobility; thus, in a discrete area from year to year, it can be 

easy to detect population fluctuations that may indicate a change (positive or negative) in water 

quality (EPA 2011b). 

Specific Conductance

Specific conductance is a measure of the ability of water to conduct electrical current, which 

depends largely on the amount of dissolved solids in the water (USGS 2010). Conductivity is 

affected by inorganic dissolved solids that may be present, such as chloride, nitrate, sulfate, and 

phosphate anions (having a negative charge) or sodium, magnesium, calcium, iron, and 

aluminum cations (having a positive charge) (EPA 2012a). Water with low amounts of dissolved 

solids (such as purified or distilled water) will have a low specific conductance, while water with 

high amounts of dissolved solids (such as salty sea water or other minerals) will have a much 

higher specific conductance (USGS 2010). Specific conductance is an important water-quality 

parameter to monitor because high levels can indicate that water is unsuitable for drinking or 

aquatic life (USGS 2010).

Water Temperature

Water temperature greatly influences water chemistry and the organisms that live in aquatic 

systems. Not only can it affect the ability of water to hold oxygen, water temperature also affects 

biological activity and growth within water systems (USGS 2010). All aquatic organisms, from 

fish to insects to zoo- and phytoplankton, have a preferred or ideal temperature range for 

existence (USGS 2010). As temperature increases or decreases too far past this range, the 

number of individuals and species able to live there eventually decreases. In addition, higher 

temperatures allow some compounds or pollutants to dissolve more easily in water and can be 

more toxic to aquatic life (USGS 2010).

Turbidity

Turbidity assesses the amount of fine particle matter (such as clay, silt, plankton, microscopic 

organisms, or finely divided organic or inorganic matter) that is suspended in water by 
191

measuring the scattering effect that solids have on light that passes through water (USGS 2010a). 

For instance, the more light that is scattered, the higher the turbidity measurement will be. The 

suspended materials that make water turbid can absorb heat from sunlight, increasing the water 

temperature in waterways and reducing the concentration of DO in the water (USGS 2010a). The 

scattering of sunlight by suspended particles decreases photosynthesis by plants and algae, which 

contributes to decreased DO concentrations in the water (USGS 2010a). Suspended particles also 

irritate and clog the gill structures of many fish or amphibians, making it difficult to thrive 

(USGS 2010).

4.13.3 Reference Conditions/Values

The reference condition for THRO’s water quality is the North Dakota Standards of Water 

Quality for the State for surface waters (NDDH 2001). The Little Missouri River is classified as 

a Class II stream by these standards, requiring that water quality be suitable for propagation or 

protection, or both, of resident species and other aquatic biota and for swimming, boating, and

other water recreation (NDDH 2001). When state standards are unavailable, the EPA’s water 

quality criteria for surface waters were used. The water must be safe for freshwater organisms,

for human bathing, and must meet drinking water standards. Table 33 displays water quality 

parameter standards set by the state of North Dakota and EPA. There are no established 

thresholds for specific conductance at the state level, although the EPA (2012a) suggests that 

waterways with conductivity greater than 500 microsiemens per centimeter (μs/cm) may be 

unsuitable for some species of fish or macroinvertebrates. 

Table 33. North Dakota water quality standards (North Dakota Department of Health 2001, EPA 2012b).

Parameter North Dakota standard

Temperature <85°F or 29.4°C (for Class II streams)

Dissolved oxygen ≥5 mg/L

Turbidity 50 NTU (EPA standard)

pH ≥7.0 – ≤9.0 (up to 10% of representative samples collected during any 3-year 

period may exceed this range provided that lethal conditions are avoided)

Fecal coliform ≤126 CFU/100 mL (for recreational waters from May 1 – September 30) 

4.13.4 Data and Methods

NPS (1997) presents the results of surface-water quality data retrievals for THRO using six of 

the EPA national databases: Storage and Retrieval (STORET) water quality database 

management system, River Reach File (RF3), Industrial Facilities Discharge (IFD), Drinking 

Water Supplies (DRINKS), Water Gages (GAGES), and Water Impoundments (DAMS) (NPS 

1999). Results located nine active or inactive USGS water gages in the study area, which 

includes the park and surrounding area within the same watershed. Results of the STORET query 

yielded 19,534 observations for various parameters collected by NPS, USGS, EPA, U.S. Army 

Corps of Engineers, and the North Dakota Health Department at 76 monitoring sites on the Little 

Missouri River, tributaries to the Little Missouri River, and ponds and springs in and around 

THRO. Thirty-three of these sites were located within park boundaries; however, most of these 

monitoring sites were either single-time or one-year intensive sampling efforts. Four stations on 

the Little Missouri River (THRO 0005, THRO 0006, THRO 0046, and THRO 0050) yielded the 

longest-term data for several parameters and accounted for approximately 89% of the total water 

quality observations in the study area (NPS 1997). Figure 30 and Figure 31 show the locations of 

all monitoring sites identified in the NPS (1997) inventory. 
192

Figure 30. Water monitoring locations in the North Unit of THRO and near the Elkhorn Ranch (Source: 

NPS 1997). Note: yellow arrow identifies monitoring sites THRO 0005 and 0006, which provide longerterm water quality monitoring data. 
193

Figure 31. Water monitoring locations in and around the South Unit of THRO (Source: NPS 1997). Note: 

yellow arrow identifies monitoring sites THRO 0046 and 0050, which provide longer-term water quality 

monitoring data.

Rust (2006) collected water quality samples for several parameters on the Little Missouri River in 

2004-2005. The objective of the research was to provide baseline descriptions of macroinvertebrate 

communities in the aquatic systems of national parks in the NGPN (including THRO), as well as 

select optimal metrics for use in future monitoring efforts by park resource managers. Chemical, 

physical, and aquatic habitat parameters were assessed for the Little Missouri River during the 2004 

and 2005 field summer seasons. Water quality parameters measured in the study included dissolved 

oxygen, temperature, turbidity, fecal coliform concentration, pH, and diversity and abundance of 

macroinvertebrate species as well as other parameters.
194

A project to monitor macroinvertebrate communities in the Little Missouri River in THRO is 

currently underway and led by Dr. Lusha Tronstad, an invertebrate zoologist with the Wyoming 

Natural Diversity Database (WNDD). In August 2011, Dr. Tronstad collected aquatic 

invertebrate and water quality samples at four sites along the Little Missouri River at THRO. 

Parameters examined include diversity of macroinvertebrate taxa, water temperature, dissolved 

oxygen, specific conductance, salinity, pH, turbidity, and concentration of coliform bacteria. 

Preliminary results are available for chemical and physical water quality parameters; analysis of 

macroinvertebrate taxa is still underway (Dr. Lusha Tronstad, WNDD Invertebrate Zoologist, 

telephone communication, 21 May 2012).

The EPA STORET database provided water quality data recorded from 1996 through 2011 at 

two North Dakota Department of Health (NDDH) monitoring stations located on the Little 

Missouri River adjacent to THRO: NDDH station 380022 is located at Medora in the South Unit 

and station 380059 is located at Hwy 85 at the entrance to the North Unit (EPA 2012c). Data for 

the parameters of interest were summarized by range (minimum and maximum values), yearly 

mean, and median values where appropriate. There are two USGS gage stations located near the 

park, one in Medora and one in Watford City. Data collected at these two stations include 

measurements for water temperature, specific conductance, and pH parameters. However, only 

two observations have been collected each year since 2005 for each parameter. Because water 

quality parameters can vary largely on a daily, monthly, and seasonal basis, data from these 

gaging stations were determined to offer little insight for this assessment.

4.13.5 Current Condition and Trend

Dissolved Oxygen

NPS (1997) reported that dissolved oxygen was measured 794 times at five monitoring stations

on the Little Missouri River from 1968 through 1994. Of these observations, three were less than 

the 5 mg/L state criterion for protection of freshwater aquatic life. Across five stations, DO 

measurements ranged from 0.9 to 13.3 mg/L. Measurement ranges are consistent for the river in 

both the North and South Units. Median DO concentrations were approximately 10.0 mg/L in the 

Little Missouri River in both units of the park.

In 2004 and 2005, Rust (2006) collected 90 DO samples along three reaches (10 transects/reach) 

of the Little Missouri River throughout the park; two reaches were located in the South Unit and 

one reach was located in the North Unit. DO levels ranged from 7.2 to 9.1 mg/L. The mean and 

median DO levels during this time were 8.2 and 8.3 mg/L respectively. 

In August 2011, Dr. Lusha Tronstad recorded dissolved oxygen levels at four sites along the 

Little Missouri River; three sites were located near Medora and one site was located in the North 

Unit near the Hwy 85 bridge. DO levels ranged from 8.0 to 8.3 mg/L in the South Unit and 8.8 

mg/L in the North Unit. These measurements, and the Rust (2006) observations, are well within 

EPA criterion for protection of freshwater aquatic life.

Two NDDH monitoring stations on the Little Missouri River, one in the North Unit and one in 

the South Unit of the park, recorded some three to eight dissolved oxygen observations per year 

from 1996 through 2011. Figure 32 shows the mean annual dissolved oxygen concentrations at 

each monitoring station for the last 15 years. During this time, mean DO concentrations ranged 
195

from 8.8 to 10.96 mg/L; observations ranged from 4.6 to 15.4 mg/L (EPA 2012c). All mean 

values are well above the minimum standards for protection of coldwater aquatic organisms 

(EPA ≥ 4 mg/L, State of North Dakota ≥ 5 mg/L).

Figure 32. Mean annual dissolved oxygen concentrations (in mg/L) recorded at two monitoring stations 

on the Little Missouri River in the North and South Units of THRO, 1996-2011 (Source: EPA 2012c). 

Note: NDDH monitoring station 380022 is located at Medora (South Unit) and NDDH monitoring station 

380059 is located at Hwy 85 (North Unit).

Fecal Coliform

NPS (1997) reported that total coliform concentrations were measured 98 times at three 

monitoring sites (THRO 0004, 0006, and 0050) on the Little Missouri River from 1968 through 

1976. Measurements ranged from 1.0 to 300,000 CFU/100 mL; the median was 200 CFU.

Thirty-seven observations at two stations (THRO 0004 [North Unit] and 0050 [South Unit]) 

exceeded the criteria for safe bathing (1,000 CFU/100 mL). Thirty-six of these observations were 

recorded in the Little Missouri River at Medora (THRO 0050) from 1969-1976. 

NPS (1997) also summarized fecal coliform concentrations recorded at various locations in the 

park from 1971-1994. A total of 220 observations were recorded at four monitoring sites along 

the Little Missouri River in THRO (THRO 0004, 0005, 0006, and 0050). Measurements ranged 

from 2 – 46,000 CFU/100 mL; the median was 80 CFU. Fifty-four observations exceeded the 

WRD criteria for safe bathing water (200 CFU/100 mL). Just over 60% of exceedences, 

including the highest recorded value of 46,000 CFU (June 1977), occurred in the Little Missouri 

River at Medora (THRO 0050) from 1972-1992.

Rust (2006) collected three fecal coliform samples on the Little Missouri River in THRO in the 

summer months of 2004 and 2005. Two measurements were recorded in the South Unit (20 and 

0

1

2

3

4

5

6

7

8

9

10

11

12

1996199719981999200020012002200320042005200620072008200920102011

mg/L

Station 380022 South Unit Station 380059 North Unit

EPA Standard ≥ 4 mg/L
196

2,300 CFU/100 mL), the higher of which exceeded the state water quality criteria for safe 

bathing. A third observation was recorded in the North Unit (40 CFU/100 mL). 

In August 2011, Dr. Lusha Tronstad recorded fecal coliform samples along the Little Missouri 

River; three sites were sampled near Medora and one site was sampled in the North Unit near the 

Hwy 85 bridge. Fecal coliform concentrations exceeded the maximum concentration that is 

measurable without dilution (L. Tronstad, pers. comm., 2012). All measurements exceeded state 

standards for safe bathing.

Two NDDH monitoring stations on the Little Missouri River, in both the North and South Units 

of the park, recorded anywhere from two to eight samples per year from 1996 through 2009 to

test for presence and prevalence of fecal coliform bacteria. Figure 33 shows mean annual fecal 

coliform concentrations at each monitoring station from 1996 through 2009. Mean calculations 

are based on samples with quantifiable bacteria counts; some samples collected contained 

bacteria concentrations but they were present above or below the quantification limits for a 

specific test used (EPA 2012c). Overall, fecal coliform bacteria concentrations fluctuated widely 

from 1996 to 2009. During this time, individual bacterial colony concentrations ranged from 0 to 

6,200 CFU/100 mL. A number of annual means exceeded the North Dakota criterion for safe 

bathing (EPA ≤200 CFU/100 mL). However, some years experienced as few as two

observations, and thus, the data may not reflect normal conditions in the Little Missouri River.

As of 2010, a large reach of the Little Missouri River immediately upstream from Medora and 

bordering the South Unit of THRO was listed as 303[d] impaired for fecal coliform 

contamination. Likewise, a large reach of the Little Missouri flowing through the North Unit of 

THRO also was listed as 303[d] impaired for fecal coliform bacteria (EPA 2011a).
197

Figure 33. Mean annual fecal coliform concentrations (in CFU/100 mL) recorded at two monitoring 

stations in the Little Missouri River in the North and South Units of THRO, 1996-2009 (Source: EPA 

2012c). Data points marked in blue represent averages based on only two observations. Note: NDDH 

monitoring station 380022 is located at Medora (South Unit) and NDDH monitoring station 380059 is 

located at Hwy 85 (North Unit).

Macroinvertebrates

In 2004 and 2005, Rust (2006) sampled benthic macroinvertebrates from five randomly chosen 

transects along three reaches in the Little Missouri River. Samples at each reach were pooled into 

one composite sample for that reach on each sample date; each reach was sampled on three 

different dates for a total of nine combined samples. Mean total abundance of macroinvertebrates 

found in the Little Missouri River in THRO was 25, with a range of 3 to 100 individuals 

collected across nine samples. Species richness was low, with an average of six species 

represented across nine samples (range = 2 to 12 species observed). The majority (47%) of these 

species were Diptera, while 24% represented Ephemeroptera, Plecoptera, and Trichoptera (EPT), 

the three pollution-sensitive orders of macroinvertebrates commonly used to assess water quality. 

The richness of species considered tolerant and intolerant of poor water quality was similar for 

all sampling in the Little Missouri during this time. 

In August 2011, Dr. Lusha Tronstad collected macroinvertebrate samples at four sites along the 

Little Missouri River; three sites were sampled near Medora and one site was sampled in the 

North Unit near the Hwy 85 bridge. Examination of taxa diversity and abundance is currently 

underway (L. Tronstad, pers. comm., 2012).

pH

NPS (1997) reported that pH was measured 1,011 times at 52 monitoring sites throughout THRO 

from 1949 through 1996. Of these, three observations on the Little Missouri River were outside 

0

200

400

600

800

1000

1200

1400

1997199819992000200120022003200420052006200720082009

CFU/100 mL

Station 380022 South Unit Station 380059 North Unit

EPA Standard 200 CFU
198

of the pH range (7.0-9.0) considered by state standards to be protective for freshwater aquatic 

life. Two observations were found to be above 9.0, while one was below 6.5. pH values in the 

Little Missouri River at Medora in the South Unit (monitoring sites THRO 0046 and 0050) 

ranged from 6.9-8.8, while values recorded in the North Unit (THRO 0005 and 0006) ranged 

from 4.3-9.23. 

Rust (2006) collected 90 pH measurements on the Little Missouri River during the summer 

months of 2004 and 2005. During this sampling, pH levels ranged from 7.6 to 8.6. The median 

pH level during this time was 8.5 (no mean was given). All samples fell within the state criteria 

range for protection of aquatic life.

In August 2011, Dr. Lusha Tronstad collected pH samples at four sites along the Little Missouri 

River; three sites were sampled near Medora and one site was sampled in the North Unit near the 

Hwy 85 bridge. pH ranged from 8.41 to 8.49 (L. Tronstad, pers. comm., 2012). All samples were 

within the state criteria range for protection of aquatic life. 

NDDH monitoring stations in the North and South Units recorded three to 10 pH measurements

per year from 1996 through 2011. Figure 34 shows the mean annual pH at each monitoring 

station for the last 15 years. During this time, mean pH ranged from 7.8 to 8.7, and individual 

observations ranged from 6.9 to 10.7 (EPA 2012c). Although several individual measurements 

were at the lower and upper end of the thresholds protective of aquatic life, most observations 

and all annual mean values were well within the state criterion for protection of freshwater 

aquatic organisms (> 7.0 – < 9.0).
199

Figure 34. Mean annual pH (in Standard Units) recorded at two monitoring stations on the Little Missouri 

River in the North and South Units of THRO, 1996-2011 (Source: EPA 2012c). Note: NDDH monitoring 

station 380022 is located at Medora (South Unit) and NDDH monitoring station 380059 is located at Hwy 

85 (North Unit).

Specific Conductance

NPS (1997) reported that specific conductance was measured 860 times at 39 monitoring sites 

throughout the study area from 1949 through 1996. Approximately half of these observations 

occurred from 1985 through 1996. Specific conductance values in the Little Missouri River 

measured at Medora (THRO 0046 and 0050) ranged from 300-4,200 μs/cm; median values were 

1,655 μs/cm at THRO 0050 and 1,590 μs/cm at THRO 0046. Values recorded in the North Unit 

(THRO 0005 and 0006) ranged from 400-4,900 μs/cm; median values were 1,580 μs/cm at 

THRO 0005 and 1,630 μs/cm at THRO 0006.

Rust (2006) collected 90 measures for specific conductance on the Little Missouri River 

throughout THRO in the summer months of 2004 and 2005. Conductivity ranged from 167 to 

1,684 μs/cm; mean and median conductivity were 1,289 and 1,303 μs/cm respectively. These 

data suggest that, during the time of sampling, the Little Missouri in THRO contained higher 

levels of dissolved inorganic solids.

In August 2011, Dr. Lusha Tronstad collected specific conductance samples at four sites along 

the Little Missouri River; three sites were sampled near Medora and one site was sampled in the 

North Unit near the Hwy 85 bridge. Specific conductance ranged from 2,421 to 2,617 μs/cm

during this time (L. Tronstad, pers. comm., 2012), indicating higher levels of dissolved inorganic 

solids. 

0

1

2

3

4

5

6

7

8

9

10

1996199719981999200020012002200320042005200620072008200920102011

mg/L

Station 380022 South Unit Station 380059 North Unit EPA threshold
200

NDDH monitoring stations in the North and South Units recorded four to eight specific 

conductance measurements per year from 1996 through 2011. Figure 35 shows the mean annual 

specific conductance at each monitoring station for the last 15 years. During this time, mean 

conductivity ranged from 1,350 to 2,780 μs/cm, and individual observations ranged from 400 to 

5,300 μs/cm (EPA 2012c). These measurements indicate high levels of dissolved inorganic 

solids in the Little Missouri River. 

There is no established standard or threshold for specific conductance in waterways, mainly 

because conductivity can vary widely depending on the geology of the area through which a 

waterway flows as well as water temperature. Thus, high conductivity could be a natural 

characteristic of a waterway based on these factors. The highly erodible landscape in THRO 

likely contributes to the high conductivity conditions in the Little Missouri River. Despite this, 

the EPA suggests that waterways with conductivity greater than 500 μs/cm may be unsuitable for 

some species of fish or macroinvertebrates (2012a) and as a result, waterways with naturally 

high conductivity will likely support a different diversity of aquatic life.

Figure 35. Mean annual specific conductance (in μmhos/cm) in the Little Missouri River in the North and 

South Units of THRO, 1996-2011 (Source: EPA 2012c). Note: NDDH monitoring station 380022 is 

located at Medora (South Unit) and NDDH monitoring station 380059 is located at Hwy 85 (North Unit).

Water Temperature

NPS (1997) reported that water temperature was measured 949 times at 16 monitoring sites in 

the study area from 1949 through 1996. Values on the Little Missouri at Medora (THRO 0046 

and 0050) ranged from -1 to 30.5°C throughout sampling, while values in the North Unit (THRO 

0005 and 0006) ranged from 0 to 28.5°C.

0

500

1000

1500

2000

2500

3000

1996199719981999200020012002200320042005200620072008200920102011

μmhos/cm

Station 380022 South Unit Station 380059 North Unit
201

Rust (2006) collected 30 temperature measurements on the Little Missouri River in THRO 

during the summer months of 2004 and 2005. During this sampling, temperature measurements 

ranged from 12.1 to 29.2°C. Mean and median temperatures during this time were 20.5° and 

20.6°C respectively.

In August 2011, Dr. Lusha Tronstad recorded water temperatures at four sites along the Little 

Missouri River; three sites were sampled near Medora and one site was sampled in the North 

Unit near the Hwy 85 bridge. Water temperatures ranged from 19.9 to 25.5°C (L. Tronstad, pers. 

comm., 2012). All measurements were within the state standards for Class II streams.

NDDH monitoring stations in the North and South Units recorded three to eight temperature 

measurements throughout each year from 1996 through 2011. In total, 182 observations were 

recorded: 97 observations were recorded in the South Unit at Medora and 85 were recorded in 

the North Unit. Temperature measurements during this time ranged from -0.2 to 28.3°C in the 

South Unit and -2.1 to 27.7°C in the North Unit. 

It should be noted that temperature data presented here are not time-series data, meaning samples 

were not collected consistently on a daily or monthly basis. Thus, it can be difficult to determine 

the trends in high, low, and mean temperatures on a daily or monthly basis. This should be taken 

into account when considering overall condition.

Turbidity

NPS (1997) reported that turbidity was measured 182 times at 24 monitoring sites in the study 

area from 1971 through 1994. A total of 116 observations at 10 monitoring sites exceeded WRD 

screening criterion (50 NTU); 111 of these observations were collected on the Little Missouri 

River. Monitoring sites THRO 0005 and 0006 in the North Unit of the park recorded 84% of the 

observations that exceeded water quality criterion during this time, including the highest reported 

value of 15,000 NTU recorded in May 1974 at THRO 0005. 

Rust (2006) collected six turbidity measurements in the Little Missouri River in THRO during 

the summer months of 2004 and 2005. Sample measurements ranged from 157 to 116,000 NTU. 

The mean and median turbidity measurements were 20,632 NTU and 1,430 NTU respectively. 

Rust (2006) described the Little Missouri as a turbid river based on these measurements, all of 

which exceeded the EPA criterion. Rust’s 2006 report represented the most recent data on 

turbidity for the Little Missouri River in THRO.

Threats and Stressor Factors

Runoff from agricultural, development, and ranching activities upriver from THRO can 

contribute to water quality impairment by increasing the concentration of various nutrients in the 

water (such as nitrogen, phosphorus, and ammonium) and levels of suspended sediment and 

dissolved solids in the waterway. Runoff from heavy precipitation events, coupled with the 

highly erosive badlands landscape that is characteristic of THRO, may also significantly 

contribute to elevated turbidity and total suspended and dissolved solids levels in the Little 

Missouri River. 

Currently, there is a golf course located next to the Little Missouri River immediately upriver 

from Medora and THRO; fertilizer applications and runoff from this operation may contribute to 
202

higher than normal nutrient concentrations in the river. Rust (2006) measured concentrations of 

various nutrients in the Little Missouri River in THRO and found that nitrates exceeded North 

Dakota water quality standards in two of six samples (July 2004 and June 2005) and total 

phosphorus exceeded water quality standards in eight of nine samples (range=0.222-4.650 

mg/L). Consistent monitoring of nutrients in the Little Missouri River would provide greater 

insight to managers about condition of the main water resource in the park.

Other potential anthropogenic sources of contaminants include wastewater effluent; mining and 

quarrying operations; and oil and natural gas development (NPS 1997).

Data Needs/Gaps

Currently, consistent monitoring of water quality parameters does not occur in THRO. The 

NGPN will initiate long-term monitoring of water quality and E. coli at the USGS Medora 

stream gaging station and at the USGS Watford City stream gaging station in 2013. It is possible 

to query (through STORET) and analyze data collected at water quality stations managed by 

other agencies, as was done for this assessment. While these monitors will provide access to the 

basic water quality parameters for understanding threats to human health, these parameters may 

not always meet park needs for understanding water quality for protection of freshwater aquatic 

organisms in THRO. Likewise, there are two active USGS stream gages adjacent to THRO, one 

at Medora and one located near the entrance to the North Unit on Hwy 85. However, since 2005, 

only one to two observations per year have been collected at these gages for temperature, 

specific conductance, and turbidity. Scant observations of parameters may not be representative 

of consistent conditions of the water quality throughout the course of each year.

In addition, consistent monitoring of aquatic macroinvertebrate populations in the park is 

lacking. The presence or absence of species that are tolerant and intolerant to pollution can be an 

indication of the condition of the water body and water quality. To date, Rust (2006) represents 

the most recent examination of the benthic macroinvertebrate community in the Little Missouri 

River in THRO that has been completed. In August 2011, Dr. Lusha Tronstad collected aquatic 

invertebrate samples at four sites along the Little Missouri River. Three sites were located 

upstream from the park entrance at Medora in the South Unit and one site was located in the 

North Unit at the Hwy 85 bridge. Examination of Dr. Tronstad’s macroinvertebrate samples is 

still underway and results should be available in late 2012. Results from these two surveys could 

be used as baseline information to which the results from future monitoring efforts may be 

compared.

Overall Condition

Dissolved Oxygen

The project team defined the Significance Level for dissolved oxygen as a 3. Water quality 

monitoring data on the Little Missouri River across the last 60 years indicate that dissolved 

oxygen concentrations are consistently well above the EPA criterion for freshwater aquatic 

organisms. Thus, the condition of dissolved oxygen is currently of no concern (Condition Level

= 0).
203

Fecal Coliform

The project team defined the Significance Level for fecal coliform as a 3. Fecal coliform 

measurements have fluctuated widely since 1996, with many observations far exceeding EPA 

and North Dakota standards for safe bathing. As of 2010, a large reach of the Little Missouri 

River bordering the South Unit of the park, as well as a large reach flowing through the North 

Unit, were listed as 303[d] impaired for fecal coliform contamination. Therefore, the condition of 

fecal coliform concentration is of high concern (Condition Level = 3). 

Macroinvertebrates

The project team defined the Significance Level for macroinvertebrates as a 3. Rust (2006) 

compiled nine different composite samples from 2004 - 2005. Total abundance and total richness 

were both found to be low, and richness of species considered tolerant and intolerant of poor 

water quality were similar (Rust 2006). However, these data are nearly 10 years old and may not 

reflect current conditions in this stretch of river. Therefore, a Condition Level for 

macroinvertebrates was not assigned.

pH

The project team defined the Significance Level for pH as a 3. pH measurements consistently 

have remained between 7.5 and 8.5 since 1996. All but just a few observations have occurred 

well within the EPA and North Dakota criterion for protection of freshwater aquatic organisms. 

Therefore, the condition of pH is of no concern (Condition Level = 0).

Specific Conductance

The project team defined the Significance Level for specific conductance as a 3. In the last 15 

years, mean conductivity ranged from 1,350 to 2,780 μs/cm, with some observations ranging as 

high as 5,300 μs/cm. These measurements indicate higher-than-typical levels of dissolved 

inorganic solids in the Little Missouri River. High conductivity can be a natural characteristic of 

a waterway based on the geology of the region and water temperature, and the highly erodible 

landscape in THRO likely contributes to the high conductivity conditions in the Little Missouri 

River. However, it is not clear if conductivity has always been this high or if increased 

development or other activities upriver from THRO contribute to the amount of dissolved solids 

in the river or if aquatic life in the river has been affected over time. Thus, the condition for 

specific conductance is of low concern (Condition Level = 1).

Temperature

The project team defined the Significance Level for temperature as a 3. Over the last 50 years, 

water temperature observations in the Little Missouri River have ranged from approximately 0 to 

30.0°C. Temperatures fluctuate during summer and winter seasons, and some temperatures in the 

summer months may reach as high as 28 to 30°C for short periods of time. This may affect some 

fish species’ ability to thrive in the Little Missouri River, but may suit other species better 

adapted to warmer water temperatures. Thus, the condition for water temperature is of low 

concern (Condition Level = 1).

Turbidity

The project team defined the Significance Level for turbidity as a 3. Turbidity observations 

through 1994 indicated measurements consistently above EPA criterion. Likewise, Rust’s (2006) 

observations indicated that the Little Missouri River was highly turbid, with all observations
204

exceeding EPA criterion. Rust’s (2006) observations represent the most recent turbidity 

monitoring for the park and are nearing 10 years old. Thus, these measurements may not 

represent the current conditions for turbidity in the Little Missouri River. For these reasons, a 

Condition Level for turbidity was not assigned.

Weighted Condition Score

The Weighted Condition Score for water quality in THRO is 0.333, indicating water quality is in 

good condition with a stable trend.

4.13.6 Sources of Expertise

Dr. Lusha Tronstad, Invertebrate Zoologist, Wyoming Natural Diversity Database
205

4.13.7 Literature Cited

Environmental Protection Agency (EPA). 2011a. My WATERS Mapper. 

http://watersgeo.epa.gov/mwm/?layer=305B&feature=ND-10110203-025-

S_00&extraLayers=null (accessed 26 March 2012).

Environmental Protection Agency (EPA). 2011b. Biological indicators of watershed health: 

Invertebrates as indicators. U.S. Environmental Protection Agency. 

http://www.epa.gov/bioiweb1/html/invertebrate.html (accessed 16 March 2012).

Environmental Protection Agency (EPA). 2012a. Water monitoring and assessment: 

Conductivity. http://water.epa.gov/type/rsl/monitoring/vms59.cfm (accessed 15 March 2012).

Environmental Protection Agency (EPA). 2012b. National recommended water quality criteria. 

U.S. Environmental Protection Agency. 

http://water.epa.gov/scitech/swguidance/standards/current/index.cfm (accessed 15 March 

2012).

Environmental Protection Agency (EPA). 2012c. STORET data warehouse.

http://www.epa.gov/storet/dw_home.html (accessed 26 March 2012).

National Park Service (NPS). 1997. Baseline water quality data inventory and analysis: Theodore 

Roosevelt National Park. Technical Report NPS/NRWRD/NRTR-97/100. National Park 

Service, Water Resources Division, Fort Collins, Colorado.

National Park Service (NPS). 2010. Theodore Roosevelt National Park: Rivers and streams. 

http://www.nps.gov/thro/naturescience/rivers.htm (accessed 18 March 2012).

National Park Service (NPS). 2012. Northern Great Plains Network monitoring: Water quality. 

http://science.nature.nps.gov/im/units/ngpn/monitor/waterquality/waterquality.cfm (accessed 

18 March 2012).

North Dakota Department of Health (NDDH). 2001. Standards of quality for waters of the state: 

NDAC Chapter 33-l 6-02. North Dakota Department of Health. Found at: 

http://water.epa.gov/scitech/swguidance/standards/upload/2002_05_02_standards_wqslibrary

_nd_nd_8_swq.pdf (accessed 22 March 2012).

Rust, J. 2006. Establishing baseline data for aquatic resources in National Parks of the Northern

Great Plains Network. Thesis. South Dakota State University, Brookings, South Dakota.

U. S. Geological Survey (USGS). 2010. Common water measurements: USGS water science for 

schools. U.S. Geological Survey. Information from “A Primer on Water Quality” by 

Swanson, H.A. and Baldwin, H.L., U.S. Geological Survey, 1965. 

http://ga.water.usgs.gov/edu/characteristics.htmL (accessed 1 March 2012).

U. S. Geological Survey (USGS). 2011. Bacteria in water. 

http://ga.water.usgs.gov/edu/bacteria.htmL (accessed 3 March 2012). 
206

U. S. Geological Survey (USGS). 2012. USGS water-quality historical instantaneous data for 

North Dakota. http://nwis.waterdata.usgs.gov/nd/nwis/uv? (accessed 26 March 2012).
207

4.14 Soundscape

4.14.1 Description

The definition of a soundscape in a national park is the total ambient sound level of the park, 

comprised of both natural ambient sound and human-made sounds (NPS 2000). The National 

Park Service’s mission is to preserve natural resources, including the natural soundscape 

associated with the national park units. According to a survey conducted by the NPS, many 

visitors come to national parks to enjoy, equally, the natural soundscape and natural scenery. 

Intrusive sounds are of concern to park visitors, as they detract from their natural and cultural 

resource experiences (Gramann 1999). The General Management Plan for THRO identifies noise 

pollution as a resource management concern for the park (NPS 1986).

4.14.2 Measures

 Occurrence of human-caused and unnatural sounds

 Natural ambient sound level

4.14.3 Reference Conditions/Values

The reference condition for soundscape in THRO is a natural experience, or a soundscape not 

influenced by unnatural sounds.

4.14.4 Data and Methods

No quantitative soundscape data are currently available for THRO. This assessment relies on 

qualitative descriptions of non-natural sounds present in the park.

4.14.5 Current Condition and Trend

Occurrence of Human-caused and Unnatural Sounds

Oil and gas developments are very common on public and private lands around and adjacent to 

THRO, creating a major source of unnatural sounds in the park, which can carry for miles under 

favorable atmospheric conditions (NPS 1991). Drilling also creates extra vehicle traffic in the 

area, generating additional non-natural sounds. At lower densities, these activities can be 

mitigated by restricting oil drilling and trucking to periods of low visitor use and locating future 

oil wells and roads behind ridges or slopes (NPS 1991). However, development in the THRO 

area has now become so dense that mitigation may no longer be possible (C. Sexton, pers. 

comm., 2012).

Rosendahl et al. (2002) conducted a visitor survey at THRO in 2001, in which one question 

asked visitors to rate the effect of noise from outside park boundaries on their experience of the 

park. A total of 13.3% of respondents said that outside noise detracted from their experience, 

ranging from ‘slightly detracted’ to ‘very seriously detracted’; the remaining 86.7% of 

respondents were unaffected by noise (Rosendahl et al. 2002). 

Threats and Stressor Factors

Oil drilling and other forms of development are threats to the natural soundscape in THRO. The 

park is located in the Williston Basin, which is a highly productive oil and gas development area 

in western North Dakota (KellerLynn 2007). Hundreds of oil wells are located on the public and 

private lands surrounding the park. Drilling occurs 24 hours a day for weeks at a time, creating 
208

noise that can carry for miles and disrupt both wildlife and humans within the park (NPS 1991). 

Unnatural noises can arise from a variety of mining activities related to oil and gas development, 

including exploration, drilling, blasting, stripping (overburden removal), hauling, maintenance, 

and beneficiation (KellerLynn 2007).

Road traffic is another threat to the natural soundscape of THRO as Interstate 94 passes through 

a portion of the South Unit and Highway 85 passes through the North Unit. Trains frequently 

pass through the Little Missouri River valley, introducing unnatural noise into the park 

soundscape. The park staff is particularly concerned with traffic noise near the Elkhorn Ranch 

site which is historically significant as Theodore Roosevelt’s “home ranch” and treasured for the 

peace and solitude it once offered. The soundscape of the ranch is threatened by traffic noise as 

well as oil development in the area (NPS 2010). Drilling recently began near Elkhorn Ranch and 

many development sites are now visible from the entrance roads (L. Richardson, pers. comm., 

2012).

Data Needs/Gaps

Acoustic monitoring is needed in order to quantify levels of ambient and unnatural sounds in and 

around THRO. Visitor surveys could be repeated to determine if visitor experience has been 

impacted by noise from increased development outside the park. In August 2012, a park request 

was approved for technical assistance in monitoring energy development impacts on THRO’s 

natural soundscapes. This assessment could provide insight into current impacts to soundscape 

and identify long-term needs for soundscape management in the park.

Overall Condition

Occurrence of Human-caused and Unnatural Sounds

During initial scoping meetings, THRO staff assigned the measure of human-caused and 

unnatural sounds a Significance Level of 3. This indicates that the measure is vital to define 

condition of this component. Since no acoustic monitoring has been conducted in the park, a 

Condition Level cannot be assigned.

Natural Ambient Sound Levels

THRO staff assigned the measure of natural ambient sound levels a Significance Level of 1, 

indicating that the measure is of minimal use in defining the condition of this component.

Natural ambient sound levels are not a concern related to soundscape, but rather provide a 

baseline from which to measure unnatural sounds. Because no data have been collected on the 

ambient sound levels in the park, a Condition Level cannot be assigned.

Overall Condition

A Weighted Condition Score (WCS) cannot be assigned without data on the component 

measures.
209

4.14.6 Sources of Expertise

Chad Sexton, Geographic Information Systems Analyst, THRO

Laurie Richardson, Botanist, THRO
210

4.14.7 Literature Cited

Gramann, J. 1999. The effects of mechanical noise and natural sound on visitor experiences in 

units of the national park system. National Park Service Social Science Research Review 

1:1–16.

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report.

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. National Park Service, Denver, 

Colorado.

National Park Service (NPS). 1986. General management plan: Theodore Roosevelt National 

Park. National Park Service, Theodore Roosevelt National Park, North Dakota.

National Park Service (NPS). 1991. Visual quality management guidelines: Theodore Roosevelt 

National Park, North Dakota. National Park Service, Theodore Roosevelt National Park, 

North Dakota.

National Park Service (NPS). 2000. Directors order #47: soundscape preservation and noise 

management. http://www.nps.gov/policy/DOrders/DOrder47.html (accessed 15 September

2010).

National Park Service (NPS). 2007. Theodore Roosevelt National Park: oil and gas development 

http://www.nature.nps.gov/geology/parks/thro/oil_gas.cfm (accessed 11 January 2011). 

National Park Service (NPS). 2010. Soundscape / noise. 

http://www.nps.gov/thro/naturescience/soundscape.htm (accessed 14 December 2011). 

Rosendahl, J. M., D. H. Anderson, and J. L. Thompson. 2002. Results of a summer 2001 visitor 

study at Theodore Roosevelt National Park: summary of visitor characteristics and 

investigation of group differences. University of Minnesota, Saint Paul, Minnesota.
211

4.15 Dark Night Skies

4.15.1 Description

A lightscape is a place or environment characterized by the natural rhythm of the sun and moon 

cycles, clean air, and of dark nights unperturbed by artificial light (NPS 2007). The NPS directs 

each of its units to preserve, to the greatest extent possible, these natural lightscapes (NPS 2006). 

Natural cycles of dark and light periods during the course of a day affect the evolution of species 

and other natural resource processes such as plant phenology (NPS 2006, 2007). Several species 

require darkness to hunt, hide their location, navigate, or reproduce (NPS 2007). In addition to 

the ecological importance of dark night skies, park visitors expect skies to be free of light 

pollution and allow for star observation. 

4.15.2 Measures

 V magnitude

 Ambient light pollution

4.15.3 Reference Conditions/Values

The reference condition for THRO is the absence of anthropogenic light pollution, which is in 

accordance with NPS management policies.

4.15.4 Data and Methods

No dark night skies data have been summarized by the NPS in THRO. The NPS Night Sky Team 

visited the North Unit of the park (near the Oxbow Overlook), but no data or summary report are 

available. Albers and Duriscoe (2001) assigned a Schaff scale score to the park, but data used in 

this assignment were not collected in the park and did not utilize V magnitude measurements. 

4.15.5 Current Condition and Trend

Darkness - V Magnitude

The NPS uses a charged coupled device (CCD) digital camera connected to a robotic mount and 

laptop computer to conduct night sky assessments and to determine darkness of park nightscapes 

(NPS 2007). A mosaic image of the entire night sky is created by stitching together multiple 

short exposure images (NPS 2007). The images are filtered using a green filter to approximate 

human night vision sensitivity, and the data are calibrated using the known brightness of certain 

stars. The resulting data are in units of V magnitude, which is an astronomical brightness system 

(NPS 2007). Weather conditions and phases of the moon limit the number of suitable nights for 

measuring V magnitude (NPS 2007). Data from the Night Sky Team’s visit to THRO are not yet 

available for this assessment. 

Ambient Light Pollution

NPS defines ambient light pollution as “the illumination of the night sky caused by artificial light 

sources, decreasing the visibility of stars and other natural sky phenomena” (NPS 2007). 

Unfortunately, ambient light pollution has not been recorded or monitored in THRO.

Schaff Scale Scores

Albers and Duriscoe (2001) developed a GIS that evaluated the nighttime visibility of NPS units. 

This model used the Schaaf scale, which is a 1 through 7 scale with a value of 1 representing 
212

extreme light pollution and a value of 7 representing pristine skies. Albers and Duriscoe (2001) 

overlaid Schaff scale score maps with park boundaries, and then extracted the mean Schaff score 

for the entire area of a given park. THRO received a Schaaf score of 7.00 out of 7.00; this score 

represents pristine night sky conditions (Albers and Duriscoe 2001). This value must be 

interpreted with caution though, as the original Schaff scale maps were from 1991 and no parkspecific data were used in the calculation. In addition, this model is not sensitive to small 

amounts of light pollution and tends to over-predict sky quality in dark locations. The clear air 

and high altitudes of the western United States make distant cities more visible (C. Moore, pers. 

comm., 2011).

Threats and Stressor Factors

Light pollution is highest in areas with high human densities and can include glare, the use of 

light or intrusion of light in areas not requiring lighting, and any other disturbance of the natural 

nighttime lightscape (NPS 2007). 

The major negative impact to THRO’s dark night environment stems from the nearby 

development from oil and gas facilities (NPS 1991). THRO lies within one of the largest 

structural and sedimentary basins in North America. The basin has been active in oil and gas 

development since the mid 1970s. In the past 20-30 years, many wells have been developed 

outside of the park boundaries on public and private lands; some of the wells are within a few 

hundred feet of THRO’s boundary (NPS 1991). In 2008, the National Parks Conservation 

Association (NPCA) identified THRO as one of ten National Parks most threatened by pollution 

from new coal-fired plants (NPCA 2008). The lights associated with these structures have the 

potential to affect THRO visitor’s night sky viewing experience. KellerLynn (2007, p. 6) stated,

Energy development on lands adjacent to the park is negatively affecting air and water 

quality; scenic views; dark night skies; wildlife and plants, including threatened and 

endangered species; cultural resources; and natural quiet.

Another threat also associated with oil and gas development is the large scale “flaring” or 

burning of waste natural gas and other gaseous compounds at production wells (Sexton, pers. 

comm., 2012). This practice has dramatically increased near the park’s boundaries in the past 

two years and represents a major threat to the quality and integrity of the dark night skies in the 

park. 

Another source of point-source light pollution is the city of Medora, ND. Medora is located on 

the South Unit’s southern border and is a busy tourist hub location during the summer months. 

Shop lights, traffic lights, and traffic along U.S. Interstate 94 are all sources of light pollution 

that may influence the overall quality of darkness in THRO.

In addition to human sources of light, airborne particulates also affect night sky brightness (NPS 

2007). Chapter 4.12 of this document provides detailed information about airborne particulates in 

THRO.

Data Needs/Gaps

There has been no collection of baseline data at THRO in regards to dark night skies. Without 

this data, an assessment of the condition of the night skies cannot be completed. An investigation 
213

into the effects of “flaring” operations is also necessary; Bill Whitworth, THRO Chief of 

Resource Management, has indicated that plans for such an investigation are currently in 

development (pers. comm., 2012).

Overall Condition

V Magnitude

During initial scoping meetings, THRO staff assigned the measure of V magnitude a 

Significance Level of 3. However, due to the lack of appropriate data, a Condition Level for V 

magnitude cannot be assigned at this time. 

Ambient Light Pollution

Ambient light pollution was also assigned a Significance Level of 3. Overall, there is insufficient 

data describing ambient light pollution. Albers and Duriscoe (2001) rated the night skies in the 

park as 7.00 out of 7.00 in terms of schaff scale scores, which is the only quantitative estimate of 

dark night skies for THRO. However, this rating must be taken with caution as no measurements 

were taken within THRO. SMUMN GSS did not assign this measure a Condition Level as there 

is insufficient data for such an assessment.

Weighted Condition Score

Because SMUMN GSS could not assign condition levels to the component, no Weighted 

Condition Score was assigned. 

4.15.6 Sources of Expertise

Bill Whitworth, THRO Chief of Resource Management.

Chad Moore, NPS Night Sky Program Manager.

Chad Sexton, THRO GIS Analyst
214

4.15.7 Literature Cited

Albers, S., and D. Duriscoe. 2001. Modeling light pollution from population data and 

implications for National Park Service lands. The George Wright FORUM 18(4):56-68.

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR – 2007-006. National Park Service, Denver, 

Colorado.

National Parks Conservation Association (NPCA). 2008. Dark horizons: 10 National Parks most 

threatened by new coal-fired power plants. http://www.npca.org/darkhorizons (accessed 21 

February 2011).

National Park Service (NPS). 1991. Visual quality management guidelines. National Park 

Service, Theodore Roosevelt National Park, North Dakota.

National Park Service (NPS). 2006. Management policies 2006. ISBM 0-16-076874-8. U.S. 

Department of the Interior. National Park Service, Washington, D.C.

National Park Service (NPS). 2007. Air resources division – natural lightscapes. 

http://www.nature.nps.gov/air/lightscapes/ (accessed 9 August 2010). 
215

4.16 Surface Water Availability

4.16.1 Description

THRO is located in the semi-arid region of the Northern Great Plains, which makes surface 

water an important and scarce resource in the park (Berkley et al. 1998). The Little Missouri 

River is the main surface water resource in the park, flowing through 23 km of the North Unit, 

14 km of the South Unit, and along Elkhorn Ranch (NPS 1994). The river’s flow varies greatly, 

depending on the season and weather conditions (NPS 1994). Tributaries of the Little Missouri

River within THRO include Knutson, Paddock, Jones, Jules, and Squaw Creeks, many of which 

are intermittent streams (Berkley et al. 1998). 

Seeps and springs are another source of 

surface water in THRO. These sources 

provide water for wildlife in the park’s 

backcountry (Berkley et al. 1998, Photo 23). 

Flow rate and chemical characteristic data 

have been collected for 10 developed springs 

and 15 flowing wells in the park, while an 

innumerable number of other seeps and 

springs have not been inventoried or studied 

(NPS 1994). According to Berkley et al. 

(1998), little information and data is 

available for surface water features (springs 

and seeps) in THRO, including surface and 

ground water quantity and quality. 

4.16.2 Measures

 Precipitation

 Prevalence (location) of seeps and springs

 Flow rates of man-made water developments

4.16.3 Reference Conditions/Values

The reference condition for precipitation is the historic period of record (pre-2000) for the two 

weather stations near THRO. Reference conditions could not be established for prevalence of 

seeps and springs or flow rates of man-made water developments. 

4.16.4 Data and Methods

Precipitation data acquired by the High Plains Regional Climate Center (HPRCC) was analyzed 

by decadal monthly average. Weather stations at Medora and Watford City, North Dakota (near 

THRO’s South and North Units respectively), were analyzed to show a regional perspective of 

precipitation. 

Many of the park’s seeps and springs have been developed to provide water for wildlife. These 

locations were provided by the park in a GIS layer. Several additional undeveloped springs were 

identified on USGS topographic quad maps of the park from 1997. These locations were 

digitized to create a map of all known springs and seeps in the park.

Photo 23. Wannagan Seeps in THRO’s South Unit 

(photo by Nathan King).
216

4.16.5 Current Condition and Trend

Precipitation

The average annual precipitation in western North Dakota is 38 cm (15 in) (Berkley et al. 1998). 

Around THRO precipitation occurs quickly in rain showers, with some areas receiving up to 

several inches of rain per hour (KellerLynn 2007). About 50% of the total annual precipitation 

falls between May and July (Berkley et al. 1998). No significant change in precipitation has been 

detected at weather stations near THRO during the period of record (Figure 36 and Figure 37) 

(HRPCC 2011). 

Figure 36. Monthly average precipitation at Medora, North Dakota per decade from 1950-2009 (HPRCC 

2011). Months with more than five days missing were excluded from monthly averages (based on 

methodology from the High Plains Regional Climate Center).

0

2

4

6

8

10

12

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Precipitation in cm

Monthly Average per Time Period

1950-1959

1960-1969

1970-1979

1980-1989

1990-1999

2000-2009
217

Figure 37. Monthly average precipitation at Watford City, North Dakota per decade from 1920-2010

(HPRCC 2011). Months with more than five days missing were excluded from monthly averages (based 

on methodology from the High Plains Regional Climate Center). 

Prevalence of Seeps and Springs

The locations of 14 seeps and springs identified in park GIS data and on USGS topographic 

maps are shown in Plate 23 and Plate 24. Five of these springs are in the North Unit and nine are 

in the South Unit. Most of these water sources are in the western portions of both the North and 

South Units. Ground-truthing may be necessary to confirm that these springs are still producing 

water. The presence of water at some springs may depend on precipitation; in dry years, 

groundwater recharge and therefore the water table may decline, causing springs and seeps to dry 

up.

Flow Rates of Man-made Water 

Developments

Man-made water developments in the park 

include drilled wells and natural springs and 

seeps developed to capture water for 

animals. Most of these developments 

occurred before the park’s establishment and 

were meant to provide reliable water for 

livestock and, in some cases, for fire 

protection (Oehler and Sexton 2010). Some 

were developed later by the NPS to provide 

water for wildlife. A typical spring-fed water 

development is shown in Figure 38.

0

2

4

6

8

10

12

14

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Precipitation in cm

Monthly Average per Time Period

1920-1929

1930-1939

1940-1949

1950-1959

1960-1969

1970-1979

1980-1989

1990-1999

2000-2010

Photo 24. Collection tank at Tomamichael Well (NPS 

photo). 
218

Figure 38. Diagram of a typical spring or seep fed water development in THRO (Oehler and Sexton 

2010).

Flow rate data is available for several springs or wells in the park that have been developed to 

provide water for wildlife (Table 34). However, the majority of this data is from the 1980s, with 

only a few measurements taken from 2007-2009. Flow rates generally vary depending on 

precipitation and distance to remote water sources (Oehler and Sexton 2010). Most park water 

developments have not been maintained since the 1990s or earlier due to the considerable cost of 

maintenance, and many have fallen into disrepair. Spring boxes, pipes, and tanks may be leaking, 

allowing water to escape from the collection system before reaching the tank. As a result, recent 

measurements may not be comparable to historic data when these developments were 

maintained, since flow rate measurements are typically taken at collection tanks (C. Sexton, pers. 

comm., 2012). A number of these developments occur in the Wilderness Area of the park (Plate 

23 and Plate 24) and may be removed when they stop functioning in an effort to restore the 

wilderness character of the park, unless they serve “a compelling need” for wildlife or visitors 

(M. Oehler and C. Sexton 2010, Photo 25).
219

Photo 25. Non-functional water developments at Sheep Pasture Spring in the South Unit’s wilderness 

area (NPS photo).
220

Table 34. Flow rates (in gallons per minute) from man-made water developments in THRO over time (Berkley et al. 1998, Oehler and Sexton 

2010, unpublished data).

Spring/Well Unit 1982 1983 1985 1986 1988 1990 1992 2007 2008 2009 Status

Achenbach Spring North 30 40 1.9 0.06

Stevens Spring North 15 12 9 13 0.02 0.01

Hagen Spring North 45 23 30 15 1.1 0.8

Overlook Spring North 300 300 300 300

Ekblom Well South 60 68 103 1.6 1.9 Operational

Tomamichael Well South 6 6 5 5 0.01 0.1 0.08 Functional, in need of 

maintenance

Rough Rider Well South 78 68 68 64

SE Corner Spring South 0 37 28 24 17 Seep is active, developments 

non-functional

Sheep Creek Well South 152 180

Sheep Butte Spring South 15 75 7 10 7

Seep active, but 

developments non-functional

Mike Auney Well South 138 30 42 126 0.2 0.07 Operational

Lone Tree Spring South 30 60 35 35 16 13 0.4 Seep active, but 

developments non-functional

Big Plateau Spring South 60 30 19 19 15 15 Active natural seep

Boicourt Spring South 12 4 6 6 2 7 Operational

VA Well South 15 11 10 6

Ceased functioning after 

2004

Jones Creek Well South 168 180 146 140 0.2 0.5 Operational

Sheep Pasture Spring South No apparent flow
221

Threats and Stressor Factors

Water Retention in Stock Dams

Water retention in stock dams (in upriver tributaries and draws) can change the flow and 

flooding patterns of the Missouri River. There is no current literature explaining the effects of 

water retention in stock dams in upriver tributaries and draws of the Missouri River.

Ice Jamming (impacts to stream banks and vegetation)

Ice jams are frequent during the spring melting season (Everitt 1968, Miller 2005) and were 

responsible for the spring flooding of the Little Missouri River in 2009 (Macek-Rowland and 

Gross 2011). The Little Missouri River is unusual in that it flows to the north. As weather to the 

south of North Dakota warms, snow and ice flows downstream to the colder north, where the 

water is still frozen (Macek-Rowland and Gross 2011). The snow and ice flowing to the north 

meets a frozen channel and an ice jam forms. River stage rises and the flow spills over the banks 

(Macek-Rowland and Gross 2011). These high spring flows can undercut the river bank, leading 

to channel instability (Miller 2005). Cottonwood seedlings and saplings can be destroyed by ice 

and major floods (Friedman et al. 1998); however, scouring and sand bar development due to 

flooding can also create new substrates for cottonwood development. 

Changes in Flood Regime

High-flow events causing significant floodplain destruction have occurred every 5-10 years on 

the Little Missouri River (Miller and Friedman 2009). Over the last century, there has been a 

reduction in the magnitude of peak flows on the Little Missouri River (Miller and Friedman 

2009). Since the Little Missouri River is largely unregulated, climatic factors such as 

temperature and precipitation are thought to be the primary drivers in the overall reduction of 

peak flow magnitude during the 20th century. Flooding is discussed further in section 4.3 of this 

assessment.

Data Needs/Gaps

A park-wide inventory of springs and seeps would identify additional surface water sources and 

regular monitoring could help to determine if spring flows are changing over time. A study of the 

relationship between coal seams, ground water, and surface water would also be beneficial. 

Research investigating the number, location, and extent of man-made developments (e.g., stock 

dams) in the upstream tributaries of the Little Missouri River would be a first step in better 

understanding how these might be affecting surface waters in THRO. Quantifying the impact of 

these developments upon water flow, while more difficult, would help managers understand the 

severity of this threat to park surface water availability. A survey of groundwater use in the 

region could also be helpful in understanding impacts on the water table, which may influence 

the supply of water for seeps and springs.

Overall Condition

Precipitation

The Significance Level for precipitation was a 2. No significant changes in precipitation have 

been observed at the two weather stations near the park. The Condition Level for precipitation is 

0, indicating the component is of no concern.
222

Prevalence (locations) of Seeps and Springs

The Significance Level for prevalence of seeps and springs was a 2. Information regarding the 

locations of seeps and springs in the park is somewhat limited. The full extent of these features 

throughout the park may be difficult to determine, as the park’s geology allows seeps to develop 

across the landscape (C. Sexton, pers. comm., 2012). Since the data available for spring and seep 

locations are not conducive to an analysis of change in prevalence over time, a Condition Level

could not be assigned for this measure.

Flow Rates of Man-made Water Developments

The Significance Level for flow rates of man-made water developments was a 2. Flow rate data 

for the park is sporadic and recent measurements are not directly comparable to historic data 

since these developments are no longer maintained. Many developments, particularly those in 

wilderness areas, may be removed when they cease functioning. Therefore, a Condition Level

could not be assigned. 

Weighted Condition Score

Since Condition Levels could not be assigned for two of this component’s three measures, a 

Weighted Condition Score was not calculated. The overall condition of surface water availability 

is unknown.

4.16.6 Sources of Expertise

Chad Sexton, Geographic Information Systems Analyst, THRO

Jeff Hughes, Hydrologist, NPS

Eleanor Griffin, Hydrologist, USGS

Jonathan Friedman, Research Hydrologist, USGS
223

4.16.7 Literature Cited

Berkley, J., G. R. Reetz., and D. Vana-Miller. 1998. Water resources management plan. 

Theodore Roosevelt National Park. U.S. Environmental Protection Agency, Region VIII. 

National Park Service, Theodore Roosevelt National Park, North Dakota. 

Emerson, D. G., and K. M. Macek-Rowland. 1986. Flood analysis along the Little Missouri 

River within and adjacent to Theodore Roosevelt National Park, North Dakota. WaterResources Investigations Report 86-4090. U.S. Geological Survey, Bismarck, North Dakota. 

Everitt, B. L. 1968. Use of the cottonwood in an investigation of the recent history of a flood 

plain. American Journal of Science 266:417-439. 

Friedman, J. M., W. R. Osterkamp, M. L. Scott, and G. T. Auble. 1998. Downstream effects of 

dams on channel geometry and bottomland vegetation: regional patterns in the Great Plains. 

Wetlands 18(4):619-633.

Godfread, C. 1994. The vegetation of the Little Missouri Badlands of North Dakota. Pages 17-24 

in Proceedings: Leafy spurge strategic planning workshop, Dickinson, North Dakota. March 

29-30, 1994.

Harrison, S. S., and J. R. Reid. 1967. A flood-frequency graph based on tree-scar data: 

Proceedings of the North Dakota Academy of Science 21:23-33. 

High Plains Regional Climate-Center (HPRCC). 2011. Historical climate data 

summaries/precipitation/monthly totals. 

http://www.hprcc.unl.edu/data/historical/index.php?state=nd&action=select_state&submit=S

elect+State (accessed 19 October 2011). 

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. National Park Service, Denver, 

Colorado.

Macek-Rowland, K. M., and T. A. Gross. 2011. 2009 spring floods in North Dakota, Western 

Minnesota, and Northeastern South Dakota. Scientific Investigations Report 2010-5225. U.S. 

Geological Survey, Reston, Virginia.

Miller, J. R. 2005. Quantifying historical channel and floodplain change along the Little 

Missouri River in Theodore Roosevelt National Park, North Dakota. Thesis. Colorado State 

University, Fort Collins, Colorado. 

Miller, J. R., and J. M. Friedman. 2009. Influence of flow variability on floodplain formation and 

destruction, Little Missouri River, North Dakota. Geological Society of America 121:752-

759. 

National Park Service (NPS). 1994. Resource management plan. Theodore Roosevelt National 

Park. National Park Service, Theodore Roosevelt National Park, North Dakota. 
224

Oehler, M., and C. Sexton. 2010. Man-made water developments in the South Unit of Theodore 

Roosevelt National Park: Technical summary of research project and management 

recommendations. National Park Service, Theodore Roosevelt National Park, Medora, North 

Dakota. 

Scott, M. L., G. T. Auble, and J. M. Friedman. 1997. Flood dependency of cottonwood 

establishment along the Missouri River, Montana, USA. Ecological Applications 7(2):677-

690.

U.S. Geological Survey (USGS). 2011. USGS flood tracking 06336000 Little Missouri River at 

Medora, ND. http://nd.water.usgs.gov/floodtracking/charts/0633600.html (accessed 19 April 

2011).
225

Plate 23. Known spring and seep locations in the North Unit of THRO.
226

Plate 24. Known spring, seep, and well locations in the South Unit of THRO.
227

4.17 Paleontological Features

4.17.1 Description

Paleontological features (i.e., fossils) are “the remains, imprints and traces of once living 

organisms preserved in the earth’s crust” (DOI 2000, p. 13). These features are vital in providing 

insight to the history of life on earth (e.g., mass extinctions, genealogical relationships between 

species), and how life responds to changing conditions, including effects of anthropological 

caused changes, as well as effects on biological diversity and ecological structure due to 

environmental changes (DOI 2000). Fossils also provide evidence of physical changes to the 

earth over time such as changes in the positions of continents, climate change cycles, and 

mountain building (DOI 2000).

Fossils are found in both of THRO’s primary exposed 

rock formations: the Bullion Creek Formation and the 

overlying Sentinel Butte Formation (Hoganson and 

Campbell 1997). These formations were formed during 

the Paleocene Epoch (60-55 Ma), when sediments carried 

from the uplifting Rocky Mountains were deposited on the 

Central Plains by fluvial and lacustrine systems, forming 

generally flat beds (Figure 39). For example, the Bullion 

Creek Formation, only exposed in the South Unit of 

THRO, consists of poorly lithified claystones, mudstones, 

and siltstones, with minor amounts of fine-grained 

sandstone and lignite. The formation is yellow and tan in 

color and approximately 61 m (200 ft) thick (Hoganson 

and Campbell 1997). The Sentinel Butte Formation is 

found in both the South and North Units of the park. It is 

composed of similar lithologies as the Bullion Creek 

Formation; however, it is gray to brown in color. This 

formation can be greater than 213 m (700 ft) thick in the 

North Unit and 91 m (300 ft) thick in the South Unit. 

Generally, the contact between these two formations can 

be recognized by a pink rock layer identified as the HT 

Butte clinker (Hoganson and Campbell 1997).

The fossils in THRO indicate that the historical 

(Paleocene) climate was subtropical with hot and humid 

swampy lowlands. There were periods with wellestablished forests composed of ferns, cycads, figs (Ficus

spp.), bald cypress (Taxodium spp.), Ginkgo, katsura

(Cercidiphyllum spp.), Magnolia, sycamore (Platanus 

spp.), and dawn redwoods (Metasequoia spp.) (Hoganson and Campbell 1997). These forests 

provided an extensive habitat and food source for insects and birds. Rivers, streams, ponds, and 

swamps provided habitat for invertebrates such as pill clams, mussels, snails, insects, and minute 

crustaceans, as well as predators such as crocodiles (Borealosuchus), alligators (genus not 

identified), and Champsosaurus (crocodile-like creatures). The swampy lowland forests 

supported mammals similar to present-day lemurs (Hoganson and Campbell 1997).

Figure 39. Schematic stratigraphic 

column of rock formations in THRO 

(from Tweet et al. 2011).
228

The NPS recognizes paleontological sites as a sensitive resource in need of protection. On 30 

March 2009, the Omnibus Public Land Management Act of 2009 was passed into law. Subtitle 

D, the Paleontological Resources Preservation Act, mandates the Secretaries of the Interior and 

Agriculture to implement a paleontological resource management program on federal lands, with 

the requirements to increase protection, enhance management tools, and increase scientific and 

public understanding of fossil resources (Tweet et al. 2011). 

4.17.2 Measures

 Distribution and abundance of paleontological resources

 Protection of collections 

4.17.3 Reference Conditions/Values

A reference condition has not been determined for this component.

4.17.4 Data and Methods

Hoganson and Campbell (1997) conducted a detailed study of 25.9 km2(10 mi2) of THRO

(about 1/10 of the entire park area), and mapped 400 fossil sites. Fossils collected during this 

study are housed at the North Dakota Heritage Center in Bismarck and cataloged in their North 

Dakota State Fossil Collection (J. Hoganson, pers. comm., 2012).

The NPS Geologic Resource Evaluation (GRE) Program conducted scoping meetings with park 

staff and geologic experts, with the purpose of reviewing available geologic maps and discussing 

geologic issues, features, and processes. Then, using a GIS data model, the team converted 

geologic maps identified in the scoping meeting into digital data sets. Finally, a park specific 

report was produced (KellerLynn 2007) to provide the park with an overview of the geology and 

related resource management issues. 

Tweet et al. (2011) prepared a paleontological resource summary report for the parks of the 

NGPN, based on an extensive literature review and interviews with park staff and professional

geologists and paleontologists in the region.

4.17.5 Current Condition and Trend

Distribution and Abundance 

The presence of fossils in THRO has been known for many years; however, up until the 1990s, 

the documented diversity was limited to the abundant petrified wood. In 1994, the park entered 

into a cooperative agreement with the North Dakota Geological Survey “to identify, map and 

assess the significance of fossils and paleontological sites in the park, for the intent to use that 

information in overall resource management planning” (Hoganson and Campbell 1997, p. 1). 

This survey effort mapped 400 fossil sites in a 26 km2(10 mi2) study area of THRO, with an 

average of 40 fossil sites per 2.6 km2(1 mi2). They concluded that the Bullion Creek and 

Sentinel Butte Formations were relatively fossiliferous, predominantly consisting of freshwater 

mollusk fossils (Hoganson and Campbell 1997). Petrified wood, located at several levels within 

the Bullion Creek and Sentinel Butte formations, remains the most abundant fossil in the park, 

and has proven impractical to map completely. Poor preservation of these remains makes it 

difficult to determine the original tree taxa; however, it is thought that most trees were conifers

of the genus Metasequoia (Tweet et al. 2011). Vertebrate fossils are found throughout the park, 
229

located in both the Bullion Creek and Sentinel Butte Formations. The most abundant vertebrate 

fossil was the aquatic reptile Champsosaurus (Tweet et al. 2011). Table 35 contains a list of 

fossils documented in THRO, along with the formation in which they were found.

Table 35. Fossils at Theodore Roosevelt National Park (Hoganson and Campbell 1997, as cited in 

KellerLynn 2007).

Fossil type Formation

Petrified wood Bullion Creek and Sentinel Butte

Freshwater mollusks Bullion Creek and Sentinel Butte

Ostracods (small bivalved crustaceans) Sentinel Butte

Coleoptera (beetle) Sentinel Butte

Leaves (e.g., angiosperms and ferns) Bullion Creek and Sentinel Butte

Seeds (e.g., Cercidiphyllum [katsura tree]) Bullion Creek and Sentinel Butte

Twigs, roots, and branches Taylor bed of the Golden Valley Formation

Champsosaurs (crocodile- like creature), including common

Champsosaurus and extremely rare Simoedosaurus Bullion Creek and Sentinel Butte

Crocodiles (probably Borealosuchus) Bullion Creek and Sentinel Butte

Alligators Sentinel Butte

Turtles (Protochelydra - chelydrid [snapping turtle], and

Plastomenus - plastomenid [soft- shelled turtle]) Sentinel Butte

Fish (Amia [bowfin] and Lepisosteus gar.) Bullion Creek and Sentinel Butte

Giant salamander (Piceoerpeton) Sentinel Butte

Plesiadapis (lemur- like mammal) Sentinel Butte

Bison Quaternary alluvial and colluvial deposits

Photo 26. Fossils from the Sentinel Butte Formation (l-r): A leaf, a crocodile scute and tooth, and petrified 

wood (photos from Hoganson and Campbell 1997).

The Wannagan Creek Quarry (part of the Bullion Creek Formation), just west of the South Unit 

of the park, has a diverse fossil assemblage. The floral record is composed of spores, pollen 

(Melchior and Hall 1983, as cited in Tweet et al. 2011), and over 100 taxa including both aquatic 

and terrestrial plants (Erickson 1982, 1991, 1999, as cited in Tweet et al. 2011). Animal fossils 

include invertebrates (e.g., mollusks and insects), fish, amphibians, reptiles, and mammals (e.g., 

marsupials, early primate relatives) (Melchior and Hall 1983, Erickson 1991, as cited in Tweet et 

al. 2011).
230

Protection of Collections

NPS museums study, interpret, and provide visitors the opportunity to view natural and cultural 

resources that have been collected and preserved (Hitchcock and Floray 2006). The primary 

responsibility of a museum is to document the collection, and continue to collect according to its 

written “Scope of Collections” statement (required for each museum under Director’s Order #24 

– see Floray and Knapp 2003). Preservation of the collection is the second responsibility, as 

museum specimens lose their value if they are damaged or if their documentation is lost. The 

third responsibility of the museum is to provide access, use, and interpretation of the collection 

(Hitchcock and Floray 2006).

To meet these responsibilities, the park must consider many factors such as lighting, dust, 

storage, handling, fire security, and theft and/or vandalism. Light levels affect glues and 

preservatives; however, they do not adversely affect the fossil itself (McDonald et al. 2005).

Fossils with remaining organic constituents can also be vulnerable to high humidity or ultraviolet 

light. The leading source of degradation is improper storage and handling of a fossil (McDonald 

et al. 2005). Dust can be abrasive if it settles on specimens that are not stored properly. Fossils 

can be damaged with gentle cleaning, so it is recommended to eliminate dust by storing 

specimens in enclosed areas with filtered circulating air. If a closed area is not available, dust 

covers should be used on open rack shelving (McDonald et al. 2005). Fossils are particularly 

susceptible to improper handling because most fossils cannot sustain their own weight. To 

prevent damage, museum staff should practice good maintenance procedures and use methods 

outlined in its Museum Housekeeping Plan (see NPS 1998).

Fossils are susceptible to fire damage; it is important for the museum to practice and train staff in 

fire prevention. All NPS museums should have an up-to-date Emergency Operations Plan, which 

includes information about hazardous material, and special needs of the collection (McDonald et 

al. 2005). All structures containing the collection should have an appropriate level of fire 

protection. Security is also important as many of the specimens are very valuable. Fossils are 

very collectible, and there are opportunities to sell fossils in a black market (McDonald et al. 

2005). In particular, trilobites, dinosaur parts, amber, and shark’s teeth are very popular fossils. 

Petrified wood also is sought after as some specimens are considered to be of gemstone quality. 

It is important for museums to discuss security with the regional/SO curator, park protection 

staff, and/or regional law enforcement specialist. To protect the collection from theft or 

vandalism, doors, exhibit cases, and storage cabinets should remain locked (McDonald et al. 

2005).

THRO’s collection consists of 55 catalog numbers for fossil objects, representing approximately 

230 specimens (Tweet et al. 2011). The majority of the catalog numbers were from the Sentinel 

Butte Formation, with the remaining catalog numbers from the Bullion Creek Formation, the 

White River Formation, and Quaternary deposits. While plant fossils are most abundant in the 

collection, it also includes brachiopods, bivalves, gastropods, fish, reptiles, mammals, and some 

unknown fossils (Tweet et al. 2011).

Understanding the geology and geographic abundance, occurrence, and distribution of fossils as 

well as threats and stressors (e.g., erosion, human activity) is critical when managing and 

protecting paleontological resources (KellerLynn 2007). NPS paleontologists have established 

protocol to monitor baseline changes and to quantify resource loss. Park staff monitors locations 
231

of fossils through normal patrol activities. However, some areas of the park are more difficult to 

monitor, such as the backcountry and the Petrified Forest Plateau area, which is a particularly 

sensitive area (KellerLynn 2007). The locations of paleontological resources in the park differ 

extensively in terms of rock types, degree of preservation, geomorphic characteristics, and 

accessibility. A specific inventory may not be useful or appropriate at all fossil sites within the 

park. A combination of monitoring strategies (e.g., baseline inventory and patrols) provides a 

useful approach to assess or measure impacts to in situ resources in THRO (KellerLynn 2007).

Threats and Stressor Factors

Threats to paleontological features include any natural (physical, chemical, and biological) or 

human factor (theft or vandalism) that has the potential to cause degradation or loss (Santucci 

and Koch 2003). Erosion is an important natural process that aids in the discovery of 

paleontological resources. However, it is also a major threat because once a fossil is exposed, it 

can rapidly be destroyed (NPS 2004). Climatic factors such as precipitation and wind can 

influence weathering and erosion of paleontological resources (Santucci et al. 2009).

Precipitation (rain, snow, hail, etc.) can influence the stability of in situ paleontological resources 

(Santucci et al. 2009), and rainfall has been described as the initial and essential driving force for 

erosion variation (Wei et al. 2009). Erosion rates are directly proportional to precipitation levels 

and intensity. Areas with greater or intense seasonal periods of precipitation generally have 

higher rates of erosion (Santucci et al. 2009). Hydrologic factors such as flooding and droughts 

can significantly influence the stability of in situ paleontological features. Periods of flooding 

can increase erosion of resources located along riverbanks. Droughts may cause river levels to 

drop, exposing previously submerged fossils (Santucci et al. 2009). 

Wind has the potential to influence the stability of in situ resources in two ways. Abrasive wind 

transportation (eolian) of unconsolidated sediments can smooth exposed fossils at the surface. In 

contrast, winds can cause sediments to accumulate in the form of dunes. Degradation can occur 

as the dune migrates; resources may be buried, exposed, or destroyed (Santucci et al. 2009).

Theft and vandalism are of concern at THRO (Tweet et al. 2011). Data compiled by the NPS in 

1999 for 721 incidents of theft or vandalism indicate that humans pose a significant threat to 

paleontological resources (Santucci 1999, as cited in Santucci and Koch 2003). Fossils and

fragments can have high commercial value. Many people collect fossils with the purpose of 

selling them to museums or private collectors (DOI 2000). Park management and adequate 

baseline data is critical to prevent degradation due to human causes (Santucci and Koch 2003).

Development in THRO could also pose a threat to paleontological resources if projects are not 

managed properly. According to the NPS (2004) Paleontological Resources Management policy, 

any area with the potential for paleontological resources must receive a surface assessment prior 

to any disturbance or development. If paleontological resources are found, then the site will be 

avoided or, if necessary, the resources will be collected before development begins and properly 

cared for. These areas also must be monitored during development (NPS 2004).

Data Needs/Gaps

There is a need for a complete park paleontological survey to aid in resource management. Prior 

to the 1990s, little was known about the abundance of paleontological features; only 10% of the 
232

park was surveyed by Hoganson and Campbell (1997). It is also critical for sites to be resurveyed 

to monitor any changes in the condition of in situ fossils. 

Overall Condition

Distribution and Abundance

The measure of distribution and abundance was assigned a Significance Level of 3. Due to the 

limited amount of paleontological survey work that has been conducted in the park, a Condition 

Level cannot be assigned at this time. 

Protection of Collections

The protection of collections measure was assigned a Significance Level of 2. Because it is not 

clear if protection of collections at THRO meets NPS standards for preservation, Condition Level

for this measure cannot be assigned at this time.

Weighted Condition Score

A Weighted Condition Score (WCS) cannot be assigned at this time due to lack of data on 

component measures.

4.17.6 Sources of Expertise

John Hoganson, State Paleontologist, North Dakota Geological Survey.

Rachel Benton, Geologist, Badlands National Park.
233

4.17.7 Literature Cited

Department of the Interior (DOI). 2000. Fossils on Federal & Indian lands. Report of the 

Secretary of the Interior. Department of the Interior, Washington, D.C.

http://www.blm.gov/heritage/docum/fossilrpt.pdf (accessed 10 November 2011).

Erickson, B. R. 1982. The Wannagan Creek Quarry and its reptilian fauna (Bullion Creek 

Formation, Paleocene) in Billings County, North Dakota. Report of Investigation 72. North 

Dakota Geological Survey, Bismarck, North Dakota.

Erickson, B. R. 1991. Flora and fauna of the Wannagan Creek Quarry: Late Paleocene of North 

America. Scientific Publications of the Science Museum of Minnesota 7(3).

Erickson, B. R. 1999. Fossil Lake Wannagan (Paleocene: Tiffanian): Billings County, North 

Dakota. North Dakota Geological Survey, Bismarck, North Dakota.

Floray, S., and T. Knapp. 2003. Chapter 2: Scope of museum collections. In NPS museum 

handbook part I. http://www.nps.gov/museum/publications/MHI/mushbkI.html (accessed 19 

December 2011).

Gitzen, R. A., M. Wilson, J. Brumm, M. Bynum, J. Wrede, J. J. Millspaugh, and K. J. Paintner. 

2010. Northern Great Plains Network vital signs monitoring plan. Natural Resource Report 

NPS/NGPN/NRR—2010/186. National Park Service, Fort Collins, Colorado. 

Hitchcock, A., and S. Floray. 2006. Chapter 1: National Park Service museums and collections. 

In NPS museum handbook part I. http://www.nps.gov/museum/publications/

MHI/mushbkI.html (accessed 10 November 2011).

Hoganson, J. W., and J. Campbell. 1997. Paleontology of Theodore Roosevelt National Park. 

NDGS Newsletter 24(1):12–23.

KellerLynn, K. 2007. Theodore Roosevelt National Park geologic resource evaluation report. 

Natural Resource Report NPS/NRPC/GRD/NRR—2007/006. National Park Service, Denver, 

Colorado.

McDonald, G., A. Elder, and S. Shelton. 2005. Appendix U: Curatorial care of paleontological 

and geological collections. In NPS museum handbook part I. http://www.nps.gov/

museum/publications/MHI/mushbkI.html (accessed 19 December 2011).

Melchior, R. C., and J. W. Hall. 1983. Some megaspores and other small mammal fossils from 

the Wannagan Creek site (Paleocene) of North Dakota. Palynology 7:133-145.

National Park Service (NPS). 1994. Resource management plan, Theodore Roosevelt National 

Park. National Park Service, Rocky Mountain Region, Fort Collins, Colorado.

National Park Service (NPS). 1998. Chapter 13: Museum housekeeping. In NPS museum 

handbook part I. http://www.nps.gov/museum/publications/MHI/mushbkI.html (accessed 19 

December 2011). 
234

National Park Service (NPS). 2004. Paleontological resources management. 

http://www.nature.nps.gov/Rm77/paleo.cfm (accessed 1 November 2011).

National Park Service (NPS). 2010. New fossil preservation law. 

http://www.nature.nps.gov/geology/nationalfossilday/prpa.cfm (accessed 19 October 2011). 

Santucci, V. L. 1999. Paleontological resources protection survey report. National Park Service, 

Ranger Activities Division and Geologic Resources Division, Washington, D.C. and Denver, 

Colorado.

Santucci, V. L., J. P. Kenworthy, and A. L. Mims. 2009. Monitoring in situ paleontological 

resources. Pages 189-204 in Young, R., and L. Norby. Geological monitoring. Geological 

Society of America, Boulder, Colorado.

Santucci, V. L., and A. L. Koch. 2003. Paleontological resource monitoring strategies for the 

National Park Service. Park Science 22(1):22-25.

Tweet, J. S., V. L. Santucci, and J. P. Kenworthy. 2011. Paleontological resource inventory and 

monitoring: Northern Great Plains Network. Natural Resource Technical Report 

NPS/NRPC/NRTR—2011/437. National Park Service, Fort Collins, Colorado.

Wei, W., L. Chen, and B. Fu. 2009. Effects of rainfall change on water erosion processes in 

terrestrial ecosystems: a review. Progress in Physical Geography 33(3):307-318.

236

Chapter 5 Discussion

Chapter 5 provides an opportunity to summarize the assessment findings and discuss the 

overarching themes and common threads that have emerged for the featured components. 

Specifically, the data gaps and needs identified for each component are summarized and the role 

these play in the designation of current condition is discussed. Also discussed is how condition 

analysis relates to the overall natural resource management issues of the park.

5.1 Component Data Gaps

The identification of key data and information gaps is an important objective of NRCAs. Data 

gaps or needs are those pieces of information that are currently unavailable, but are needed to 

help inform the status or overall condition of a key resource component in the park. Data gaps 

and needs exist for most key resource components assessed in this NRCA. Table 36 provides a 

detailed list of the key data gaps by component. Each data gap or need is discussed in detail in 

the individual component assessments in Chapter 4. 

Some data gaps, if addressed, would provide managers with more information for resource 

protection and enhancement for multiple components in the project framework. Such is the case 

for the vegetation communities featured in this NRCA. For all vegetation components, carrying 

out updated surveys of species composition, capturing the extent/distribution of the communities, 

and assessing the prevalence of non-native species presence in these communities would help to 

fill data gaps and provide a more complete understanding of the current condition of each 

community. In addition, the condition of several other featured components and natural resources 

may be affected by the health and integrity of the native vegetation communities. These include

the frequency and behavior of fire on the landscape, rates of erosion by wind and water, and the 

health of animals such as breeding birds, prairie dogs, and grazing and browsing ungulates 

managed within the park (bison, elk, and feral horses, etc.). Filling in data gaps for each 

vegetation community would help managers determine an accurate current condition of these 

communities, as well as provide insight into how the health and diversity of these vegetative 

systems affect the organisms that depend on them for habitat. Data gaps for other featured biotic 

components, breeding birds and aquatic communities, include updated surveys of species 

diversity and abundance to understand population trends. 

Data gaps vary for the chemical and physical components in THRO, including water quality, air 

quality, and surface water availability. Since THRO is a Class I airshed, monitoring of air quality 

conditions in the park is quite thorough. However, identifying and monitoring sensitive plant and 

tree species that serve as bioindicators for air pollutants could help managers understand, at early 

stages, the degree of impact from air pollution on the landscape. The Little Missouri River is a 

major water feature in all three units of THRO. Though much data are available on water quality 

parameters courtesy of outside agency monitoring stations adjacent to the park’s North and 

South Units, very little monitoring is conducted within the park through an established NPS 

monitoring program. In addition, these monitoring stations do not survey the macroinvertebrate 

communities in the Little Missouri River within the park; macroinvertebrates can be important 

indicators of poor or good water quality. Any monitoring of water quality parameters that does 

occur within park boundaries is sporadic and does not allow for assessing long-term trends in 

water quality. To date, the largest data gap for water quality is a consistent survey of 

macroinvertebrate species diversity and abundance in the park. 
237

Components featuring natural disturbance regimes, including fire, erosion from wind and water, 

and flooding on the Little Missouri River, are important in shaping the landscape both 

ecologically and physically. Wind and water erosion are largely responsible for shaping the 

dramatic badlands formation that are characteristic of the park landscape. However, no research 

has been conducted on the rate at which these processes affect the landscape. Regular flooding of 

the Little Missouri River is essential for the proliferation and health of various floodplain 

woodlands, particularly the regeneration of cottonwood woodlands. Currently, it is unclear how 

development and the extent of water draw down activities upriver from THRO or on tributaries 

to the river may affect the rate and magnitude of flooding and availability of surface water within 

the park. Fire in THRO, almost exclusively occurring as prescription burns, is monitored 

regularly through data collected before, during, and after burn events. Managers could continue 

to benefit from continual, detailed monitoring of established vegetation plots to estimate the 

effects of fire on desired vegetation outcomes. These data would help managers further 

understand the condition of fire and its usefulness in meeting management objectives for the 

native plant communities in the park. 

Soundscape and dark night skies are components commonly thought of as “goods and services” 

for visitors; however, quantitative data related to these in THRO is very limited. National 

programs and sampling standards have been developed by NPS in order to monitor soundscape 

and dark night skies conditions in all parks. Currently, baseline data do not exist for dark night 

skies conditions or the levels of unnatural sounds in the park. Implementing the NPS protocol for 

these resources would provide a better understanding of the components’ conditions. 

Table 36. Identified data gaps or needs for the featured components.

Component Data Gaps/Needs

Fire  Continued and consistent monitoring of established vegetation plots to 

characterize the effects of fire and parameters that correlate with desired 

vegetation outcomes

 Record of burn severity and intensity and its correlative effects on native 

vegetation

Wind and water erosion  No research has been conducted on this component

Flooding (Little Missouri River)  Consistent monitoring of peak magnitude and peak gage height at Medora, 

ND

 Understanding of the amount and extent of water permits near the Little 

Missouri River to understand drawn down statistics

 Summary of the amount, location, and extent of stock dams in upstream 

tributaries of the Little Missouri River

Native grasslands  An updated vegetation mapping effort to characterize extent of juniper and 

other woody encroachment

 Updated survey of grassland composition

Juniper forests  Updated data on density and stand structure 

 Updated distribution and extent of juniper stands
238

Table 37. Identified data gaps or needs for the featured components. (continued)

Component Data Gaps/Needs

Floodplain forests  Specific information on the species composition and abundance of floodplain 

woodland alliances

 Cottonwood woodland stand age data to understand regeneration and 

mortality

 Updated extent and distribution data for floodplain woodlands

Woody draws  Prevalence of diseases affecting species in the woody draws

 Data representing changes in woody draw communities over time

 More detailed examination of non-native species prevalence/abundance

Upland shrublands  Updated information on plant species composition with an emphasis on the 

prevalence and impact of non-native species

 Updated extent and distribution of upland shrubland communities

Aquatic communities  Species surveys during normal and low flow periods to understand diversity 

and abundance

 Updated survey of species diversity

 Updated survey of macroinvertebrate diversity and abundance in the Little 

Missouri River

Prairie dogs  Continued monitoring efforts that include mapping of prairie dog town 

extents

Breeding birds  Greater frequency of surveys to understand population trends

 Increased sampling under the IMBCR spatially balanced land bird protocol

 Consistent monitoring of priority species populations

 Raptor specific monitoring

Air quality  Periodic monitoring of air pollutant sensitive plants that may act as 

bioindicators of declining air quality conditions

Water quality  Consistent monitoring of water quality parameters within THRO, including 

macroinvertebrate populations

Soundscape  Acoustic monitoring to quantify levels of ambient and unnatural sounds

Dark night skies  Baseline data on dark night skies

 Study of effects of oil and gas “flaring” activities on night skies 

Surface water availability  Park-wide inventory of springs and seeps and regular monitoring of these 

features

 Summary of the number, location, and extent of man-made developments in 

the tributaries of the Little Missouri River in and around THRO

Paleontological features  A complete park paleontological survey to aid resource management

 Resurvey of sites to monitor for changes in the condition of in situ fossils
239

5.2 Component Condition Designations

Table 38 displays the conditions assigned to each resource component presented in Chapter 4 

(definitions of condition graphics are located in Figure 40 following Table 38). It is important to 

remember that the graphics represented are simple symbols for the overall condition and trend 

assigned to each component. Because the assigned condition of a component (as represented by 

the symbols used in Table 38) is based on a number of factors and an assessment of multiple 

literature and data sources, it is strongly recommended that the reader refer back to each specific 

component assessment in Chapter 4 for a detailed explanation and justification of the assigned 

condition. Condition designations for some components are supported by existing or long-term 

datasets and monitoring information and expertise by NPS and other non-NPS scientists, while

other components lack historic data, a clear understanding of reference conditions (i.e., what is 

considered desirable or natural), or even current information. 

Data are unavailable or insufficient for many of the measures of the featured components and,

thus, it is not possible to define current condition for these components. In other instances, 

reference condition data were limited or unavailable for components, making comparisons 

inappropriate or invalid. Current condition was not able to be determined for 10 of the 17 

components (58%) due to these significant data gaps.

For featured components with available data and fewer data gaps, assigned conditions varied.

For some components, enough data exist to determine a trend in condition over time; however, 

for others the lack of long-term or comparable data prevented the determination of trends. 

Several components were determined to be in good condition with a stable trend, including air 

quality, water quality, fire, and the prairie dog population. Flooding on the Little Missouri River

in the park was determined to have a condition of moderate concern but with a stable trend, 

meaning the condition is not believed to be degrading or improving from past conditions. Native 

grasslands and woody draws were also determined to be of moderate concern, but a lack of 

historical data does not allow for designating a trend in condition over time. A discussion of 

these designations is presented in the following section. 

Table 38. Summary of current condition and condition trend for featured NRCA components.

Component WCS Condition

Ecosystem Extent and Function

Disturbance Regimes

Fire 0.333

Wind and water erosion N/A

Flooding (Little Missouri) 0.666

Biological Composition

Ecological communities

Native grasslands 0.500
240

Table 39. Summary of current condition and condition trend for featured NRCA components. (continued)

Component WCS Condition

Juniper forests N/A

Floodplain forests N/A

Woody draws 0.500

Upland shrubland communities N/A

Aquatic communities N/A

Grazing animals

Prairie dogs 0*

Birds

Breeding birds N/A

Environmental Quality

Air quality 0.333

Water quality 0.333

Soundscape N/A

Dark night skies N/A

Physical Characteristics

Hydrologic & Geologic

Surface water availability N/A

Paleontological features N/A
241

Figure 40. Symbols used for individual component assessments with condition or concern designations 

along the vertical axis and trend designations along the horizontal.

5.3 Park-wide Condition Observations

The landscape in THRO is rich in natural resources that are diverse and complex. As a result, a 

number of components featured in the NRCA are interrelated, with the condition of many being

dependent on the condition and healthy functioning of others. In particular, the native vegetation 

communities and the natural disturbance patterns in the park (i.e., fire and flooding along the 

Little Missouri River) seem to be an important influence on the condition of many other biotic 

components in the park. 

Native Vegetation Communities

THRO managers agree that the native vegetation communities within the park are integral to the 

healthy functioning of the overall ecological landscape and that the health of the vegetation 

communities can significantly influence the condition of many of the species that also reside in 

the park. For example, the condition of the vegetation communities in the park is an important

factor in the health of ungulate populations (such as bison, elk, and feral horses), as well as small 

mammals and breeding birds that utilize these communities for habitat. Thus, the health and 

composition of the native plant communities is important for many of the species present in the 

park. 

Data gaps for three of the five native vegetation communities featured in the NRCA prevent the 

determination of current condition or any trends that may be occurring over time. The juniper 

forests, floodplain woodlands, and upland shrublands components substantially lack data for 

most or all component measures to be able to determine current condition or any trends that may 

be occurring over time. Enough data were available to assign condition for the woody draws and 
242

native grasslands components, both of which were determined to be of moderate concern. Both 

native grasslands and woody draws were determined to be of moderate concern due to the 

presence of invasive non-native species that threaten to alter native species composition and 

abundance in these two communities. Particularly aggressive species, such as leafy spurge and 

Canada thistle, are treated actively in both native communities to limit spread and shift of native 

composition. Non-native grasses (e.g., field brome and cheatgrass) also threaten the composition 

of the native grasslands throughout the park. Unfortunately, the lack of long-term communityspecific monitoring data prevents the identification of any trends in condition over time for either 

woody draws or native grasslands in the park. 

Disturbance Regimes

Disturbance regimes (e.g., fire, flooding, or erosion) can play a signicant role in the evolution 

and adaptation of vegetation communities across a landscape, as well as influence the current 

condition of these communities. In THRO, frequent burning of the landscape, by either naturalcaused wildfires or prescribed fires, is an important factor in maintaining species composition in

native vegetation communities, for example, by limiting the encroachment of woody shrubs and 

junipers into open areas and regenerating native grasslands. However, fire suppression has 

significantly altered the rate at which fires historically occurred in and around THRO. As a 

result, in order to obtain the beneficial effects of wildfires throughout the park, fire is managed 

heavily, with nearly all fires occurring as prescribed burns. Because of the high degree of 

planning and control of location, time of year, intensity, and frequency for burning to occur in 

THRO, fire was determined to be in good condition with a stable trend. Although fires are not as 

frequent on the landscape as they once were, current prescribed burn efforts aim to distribute fire 

throughout the park to benefit native plant communities.

Regular flooding events on the Little Missouri River also are important, particularly for the 

floodplain forest communities, where regular flooding and extended periods of inundation of the 

floodplain are necessary for the regeneration of cottonwood stands along the Little Missouri 

River. Without this regeneration, the cottonwood woodlands would age and slowly die away. 

This would effectively contribute to a decrease in important habitat for various breeding birds 

and raptors, among other associated impacts. As a component, flooding events along the Little 

Missouri River in THRO were determined to be of moderate concern. Of particular concern is

the decreased frequency of periods of inundation in the floodplains, which are necessary for the 

regeneration of cottonwood stands in the floodplain woodlands along the river. In May 2011, the 

Little Missouri River experienced a 100-year flood event that left floodplains inundated for 

several weeks. This event and available data indicate that the trend for flooding is stable. 

Other Biotics

Animals featured as NRCA components included prairie dogs and breeding birds. Prairie dog 

colonies are allowed to expand and contract naturally within park boundaries and active 

management is required only when disease threatens individual populations or when prairie dogs 

move into non-tolerance areas such as leach fields and corrals. Plague has been found 

sporadically in the park over the last several years, however, managers have little concern about 

the rates of colony growth and spread of disease. To date, no action has been taken to reduce 

plague when it occurs. Thus, praire dogs were determined to be in good condition with a stable 

trend. Breeding birds are also an important resource in the park, but significant data gaps make it 

impossible to determine condition of populations at this time.
243

Environmental Quality

Environmental quality is important in maintaining healthy functioning ecosystems. The health of 

terrestrial and aquatic organisms in parks can be affected substantially by the condition of air and 

water quality. Designated as a Class I airshed, THRO closely monitors air quality in the park. 

Current data suggest air quality is in good condition with a stable trend; this is in part likely due 

to THRO’s location in rural North Dakota, away from any major population center. However, 

recent exponential growth in energy development around the park has the potential to impact air 

quality in the future through increased emissions and atmospheric deposition. 

With the exception of a few sporadic, short-term sampling studies conducted throughout the 

years, consistent monitoring of basic water quality parameters is not performed within park 

boundaries. To understand the state of water quality in the park, managers must rely on 

monitoring stations established and maintained by other agencies. Historic and current data 

indicate that, in the stretches of the Little Missouri River that flow through the park, water 

quality is in good condition with a stable trend. However, certain elements of water quality are of 

particular concern, such as the high concentration of fecal coliform bacteria, which have 

warranted EPA 303[d] impaired waters listing for large sections of the Little Missouri River 

flowing through the park. Also of slight concern are higher measures of specific conductance, 

indicating high levels of dissolved solids in the Little Missouri River. Higher specific 

conductance in a waterway can occur naturally as a result of geology (such as a stream running 

through a highly erodible landscape) and water temperature (warmer water has higher 

conductivity than cold water). However, it is not clear how much natural variability contributes 

to specific conductance measures in the Little Missouri River in THRO and what may be 

contributed by development, agriculture, or other activities upriver from the park. 

Park-wide Threats and Stressors

Several park-wide threats and stressors will continue to influence the condition of resources in 

THRO. Those of primary concern include establishment of non-native and invasive species, 

increased oil and gas industry development, and air pollution, especially increased emissions 

from nearby oil, gas, and powerplant development. 

The presence of non-native and invasive species, especially plants, poses a significant threat for 

the native vegetation communities in THRO. Some invasive plant species present in THRO, such 

as leafy spurge and Canada thistle, have the ability to overtake native plant communities if left 

unchecked. Major changes in vegetation communities, from native to more non-native species, 

could have a significant impact on the animal species that use these communities for habitat. A 

more complete understanding of the prevalence of non-natives in the different vegetation 

communities throughout the park would help managers strategize about potential management 

actions. 

Land development around THRO is mainly associated with the growth and expansion of the oil 

and gas industry. This development has increased exponentially in western North Dakota and 

around THRO over the last decade. Such development affects different aspects of park resources

including impacts to viewscapes with the building of new structures that can be seen from 

various points in the park, impacts to soundscapes with increased industrial activity and vehicle 

traffic at development sites, and greater stresses to air quality from increased vehicle and 

industrial emissions. 
244

Overall Conclusions

This assessment serves as a review and summary of available data and literature for featured 

natural resources in the park. The information presented here may serve as a baseline against 

which any changes in condition of components in coming years may be compared. Establishing a 

number of monitoring programs would begin to fill in data gaps for the resources viewed as 

important by THRO managers and would help managers better understand the current state of 

these resources throughout the park. Of those components that had sufficient available 

information, current condition was determined to be either good or of moderate concern. 

Understanding this can help managers prioritize management objectives and better focus 

conservation strategies. 

246

Appendices

Page

Appendix A: Fire History in THRO, 1946 to 2010 .................................................................... 241

Appendix B: Peak Flow Data for the Little Missouri River at Medora, ND.............................. 245

Appendix C. Peak Flow Data for the Little Missouri River at Watford City, ND ..................... 248

Appendix D: Non-native Plant Species Documented in THRO................................................. 251

248

Appendix A: Fire History in THRO, 1946 to 2010

Area

Fire Year Fire Name Fire Cause Start Date

Park 

Unita ac ha

1946 EAST_ENTRANCE HUMAN 3/28/1946 SU 14.0 5.7

1949 EAST_ENTRANCE HUMAN 4/22/1949 SU 11.0 4.5

1949 EAST_ENTRANCE_#2 LIGHTNING 7/16/1949 SU 200.0 80.9

1951 BUCK_HILL_#3 LIGHTNING 8/17/1951 SU 38.0 15.4

1951 COOPER_PASTURE LIGHTNING 8/17/1951 SU 1.0 0.4

1951 EAST_BORDER LIGHTNING 8/17/1951 SU 19.0 7.7

1952 PAINTED_CANYON HUMAN 10/16/1952 SU 1.0 0.4

1954 DEDICATION_HILL HUMAN 8/14/1954 SU 3.0 1.2

1954 HEADQUARTERS_DUMP HUMAN 7/26/1954 SU 1.0 0.4

1955 BUCK_HILL COAL_SEAM 4/10/1955 SU 36.0 14.6

1955 NORTH_PADDOCK_CREEK LIGHTNING 8/23/1955 SU 37.0 15.0

1955 SQUAW_CREEK HUMAN 9/30/1955 NU 110.0 44.5

1956 CEDAR_CANYON HUMAN 5/19/1956 SU 1.0 0.4

1957 CORRAL_CREEK LIGHTNING 7/27/1957 NU 35.0 14.2

1958 NORTH_RIM LIGHTNING NU 5.0 2.0

1958 RIDGELINE HUMAN 9/21/1958 SU 17.0 6.9

1959 BIG_PLATEAU_#1 LIGHTNING 6/7/1959 SU 2.0 0.8

1959 TWO UNKNOWN 6/7/1959 SU 2.0 0.8

1962 APPLE_BOTTOM LIGHTNING 8/21/1962 NU 1.0 0.4

1963 BOICOURT_SPRING LIGHTNING 7/26/1963 SU 1.0 0.4

1963 GARLAND_BOTTOM LIGHTNING 9/10/1963 NU 1.0 0.4

1963 MILLER_BOTTOM UNKNOWN 5/21/1963 NU 1.0 0.4

1963 PAINTED_CANYON_OVERLOOK HUMAN 10/25/1963 SU 1.0 0.4

1966 CORRAL_CREEK_PRAIRIE_DOG_TOWN LIGHTNING 7/8/1966 NU 1.0 0.4

1966 JOHNSON'S_PLATEAU HUMAN 5/30/1966 SU 1.0 0.4

1966 SHEEP_BUTTE LIGHTNING 9/12/1966 SU 15.0 6.1

1967 PEACEFUL_VALLEY_PICNIC_AREA HUMAN 10/22/1967 SU 1.0 0.4

1967 SHEEP_CREEK_#1 HUMAN 8/1/1967 SU 1.0 0.4

1967 SHEEP_CREEK_#2 HUMAN 8/17/1967 SU 1.0 0.4

1967 SHEEP_CREEK_#3 HUMAN 8/19/1967 SU 2.0 0.8

1967 SHEEP_CREEK_#4 HUMAN 8/31/1967 SU 1.0 0.4

1967 SQUAW_CREEK_CAMPGROUND HUMAN 8/14/1967 NU 3.0 1.2

1968 STONE_HILLS LIGHTNING 9/14/1968 NU 14.0 5.7

1974 RIDGELINE HUMAN 7/14/1974 SU 2.0 0.8

1976 FIREWORKS HUMAN 7/4/1976 SU 1.0 0.4

1976 GLACIAL_NORTH HUMAN 7/26/1976 NU 1.0 0.4

1976 GLACIAL_SOUTH HUMAN 7/27/1976 NU 1.0 0.4

1976 OVER_SPRING HUMAN 7/24/1976 NU 2.0 0.8
249

Area

Fire Year Fire Name Fire Cause Start Date

Park 

Unita ac ha

1976 SPERATI_POINT LIGHTNING 8/18/1976 NU 30.0 12.1

1977 HIGHWAY 85 WEST HUMAN 5/13/1977 NU 1.0 0.4

1978 BUFFALO_CORRAL HUMAN 5/22/1978 NU 9.0 3.6

1978 PLATEAU LIGHTNING 8/22/1978 SU 275.0 111.3

1979 KNUTSON_CREEK LIGHTNING 7/8/1979 SU 1.0 0.4

1979 TOWER_FIRE LIGHTNING 6/30/1979 SU 80.0 32.4

1980 MAN_AND_GRASS LIGHTNING 6/3/1980 NU 84.0 34.0

1980 PAINTED_CANYON LIGHTNING 8/22/1980 SU 1.0 0.4

1981 PAINTED_CANYON HUMAN 3/23/1981 SU 13.0 5.3

1981 ROUGHRIDER HUMAN 3/13/1981 SU 8.0 3.2

1983 JOHNSON HUMAN 8/25/1983 SU 100.0 40.5

1983 SQUAW_CREEK HUMAN 4/24/1983 NU 1.0 0.4

1983 SQUAW_CREEK_DOG LIGHTNING 8/28/1983 NU 1.0 0.4

1984 SQUAW_CREEK HUMAN 8/8/1984 NU 3.0 1.2

1984 SU_ENTRANCE PRESCRIBED SU 0.0 0.0

1984 TUESDAY LIGHTNING 8/14/1984 NU 10.0 4.0

1985 FATHERS_DAY HUMAN 6/16/1985 SU 27.0 10.9

1985 NORTH_UNIT_CORRAL PRESCRIBED 4/11/1985 NU 250.0 101.2

1988 BUCK_HILL LIGHTNING 7/27/1988 SU 197.0 79.7

1988 SOUTH_UNIT_HEADQUARTERS PRESCRIBED 4/19/1988 SU 2.0 0.8

1988 TR_CABIN HUMAN 3/26/1988 SU 1.0 0.4

1989 PADDOCK_CREEK LIGHTNING 8/30/1989 SU 1.0 0.4

1991 CHIP LIGHTNING 6/29/1991 NU 1.0 0.4

1992 MAINTENANCE HUMAN 7/5/1992 SU 1.0 0.4

1992 MEDIAN HUMAN 2/25/1992 SU 1.0 0.4

1992 MEDIAN HUMAN 2/25/1992 SU 1.0 0.4

1992 NORTH_UNIT_SLASH PRESCRIBED 4/10/1992 NU 0.0 0.0

1992 TIMBERS PRESCRIBED 2/14/1992 SU 0.0 0.0

1993 CORRAL HUMAN 3/22/1993 SU 25.0 10.1

1993 RAMIREZ HUMAN 4/17/1993 NU 1.0 0.4

1993 RESIDENCE 188C HUMAN 12/22/1993 NU 1.0 0.4

1993 TRAP LIGHTNING 3/3/1993 NU 6.0 2.4

1993 TRAP LIGHTNING 3/3/1993 SU 6.0 2.4

1994 COTTON_#1 HUMAN 5/29/1994 SU 1.0 0.4

1994 COTTON_#2 HUMAN 5/29/1994 SU 1.0 0.4

1994 COTTON_#3 HUMAN 6/5/1994 SU 1.0 0.4

1994 HAYSTACK HUMAN 4/21/1994 NU 1.0 0.4

1995 LEAVES HUMAN 2/7/1995 SU 1.0 0.4

1995 LEAVES HUMAN 2/7/1995 SU 1.0 0.4

1995 RESIDENCE_101 HUMAN 12/30/1995 SU 1.0 0.4
250

Area

Fire Year Fire Name Fire Cause Start Date

Park 

Unita ac ha

1996 INTERSTATE LIGHTNING 6/8/1996 SU 6.0 2.4

1996 INTERSTATE LIGHTNING 6/8/1996 SU 6.0 2.4

1996 SHUT_DOWN HUMAN 1/13/1996 NU 1.0 0.4

1997 COTTON_#3 HUMAN 6/1/1997 SU 1.0 0.4

1997 RIVER_BEND LIGHTNING 6/22/1997 NU 1.0 0.4

1997 RIVER_BEND LIGHTNING 6/22/1997 NU 1.0 0.4

1997 UNKNOWN_2 HUMAN 6/20/1997 NU 1.0 0.4

1998 BOICOURT LIGHTNING 8/10/1998 SU 15.1 6.1

1998 CHALKCLIFF UNKNOWN 5/31/1998 NU 18.0 7.3

1998 CHASER LIGHTNING 8/10/1998 SU 1.0 0.4

1998 NORTH_UNIT_HOUSING LIGHTNING 8/14/1998 NU 1.0 0.4

1998 VOLUNTEER LIGHTNING 8/10/1998 SU 2.0 0.8

1999 BURN_HILLS HUMAN 7/30/1999 SU 1.0 0.4

1999 JOHNSON'S_PLATEAU LIGHTNING 6/25/1999 SU 1.0 0.4

1999 LITTLE_MISSOURI PRESCRIBED 9/21/1999 NU 504.3 204.1

1999 LITTLE_MISSOURI PRESCRIBED 9/21/1999 NU 100.6 40.7

1999 PUMPKIN UNKNOWN 10/23/1999 NU 1.0 0.4

1999 RAIL_CAR LIGHTNING 6/25/1999 SU 1.0 0.4

1999 SE_CORNER PRESCRIBED 4/19/1999 SU 304.8 123.3

1999 SE_CORNER PRESCRIBED 4/19/1999 SU 167.6 67.8

1999 SOUTH_UNIT_HEADQUARTERS PRESCRIBED 4/14/1999 SU 0.0 0.0

2000 BURLINGTON HUMAN 10/10/2000 SU 2.0 0.8

2000 BURNT_TREE LIGHTNING 9/19/2000 SU 1.0 0.4

2000 PAINTED_CANYON LIGHTNING 8/28/2000 SU 277.6 112.3

2000 PETRIFIED LIGHTNING 8/26/2000 SU 2.0 0.8

2000 SE_CORNER PRESCRIBED 4/11/2000 SU 331.0 133.9

2000 WIND_CANYON HUMAN 7/29/2000 SU 1.0 0.4

2001 ELKHORN_FIRE LIGHTNING 8/31/2001 EHR 158.0 63.9

2001 NOTHWEST_CORNER PRESCRIBED NU 827.2 334.7

2002 INTERSTATE_94 PRESCRIBED 10/10/2002 SU 227.5 92.1

2002 INTERSTATE_94 PRESCRIBED 5/2/2003 SU 306.6 124.1

2002 KNUTSON_CREEK_RESEARCH PRESCRIBED 4/24/2002 SU 0.0 0.0

2002 LITTLE_MISSOURI PRESCRIBED 5/13/2002 NU 540.5 218.7

2002 MIX_PIT UNKNOWN 8/16/2002 SU 1.0 0.4

2002 NORTHWEST_CORNER PRESCRIBED NU 160.0 64.7

2002 OLSEN_WELL_RESEARCH PRESCRIBED 10/17/2002 SU 0.0 0.0

2002 PEACEFUL_VALLEY PRESCRIBED 5/29/2002 SU 625.9 253.3

2002 SKYLINE_VISTA PRESCRIBED 10/9/2002 SU 588.9 238.3

2002 SPAGHETTI HUMAN 8/15/2002 SU 2.0 0.8

2003 BIGHORN LIGHTNING 9/14/2003 NU 2.0 0.8
251

Area

Fire Year Fire Name Fire Cause Start Date

Park 

Unita ac ha

2003 COTTONWOOD_CAMPGROUND PRESCRIBED 4/24/2003 SU 155.5 62.9

2003 FA #1 UNKNOWN 9/5/2003 SU 1.0 0.4

2003 LOST_BISON LIGHTNING 9/9/2003 NU 50.0 20.2

2003 SMOOTH_BROME_RESEARCH PRESCRIBED 10/22/2003 SU 0.0 0.0

2003 WIND_CANYON HUMAN 7/22/2003 SU 1.0 0.4

2004 JULES_CREEK LIGHTNING 7/9/2004 SU 8.0 3.2

2004 SE_CORNER PRESCRIBED 4/22/2004 SU 910.0 368.3

2006 MILE_36 LIGHTNING 8/10/2006 SU 1.0 0.4

2007 HORSECAMP PRESCRIBED 4/24/2007 SU 92.1 37.3

2007 LOOP_1 PRESCRIBED 4/17/2007 SU 17.2 6.9

2007 LOOP_2 PRESCRIBED 4/17/2007 SU 24.5 9.9

2007 LOOP_3 PRESCRIBED 4/17/2007 SU 5.7 2.3

2007 LOOP_4 PRESCRIBED 4/17/2007 SU 43.9 17.7

2007 LOOP_5 PRESCRIBED 4/24/2007 SU 40.3 16.3

2007 RADIOTOWER PRESCRIBED 10/4/2007 SU 94.9 38.4

2008 CORRAL_FIRE LIGHTNING 6/23/2008 NU 3.5 1.4

2008 LOOP_6 PRESCRIBED 4/13/2008 SU 38.8 15.7

2008 LOOP_7 PRESCRIBED 4/13/2008 SU 92.9 37.6

2008 LOOP_8 PRESCRIBED 4/13/2008 SU 19.7 8.0

2008 LOOP_9 PRESCRIBED 4/13/2008 SU 70.0 28.3

2008 NORTHWEST_CORNER_1 PRESCRIBED 10/9/2008 NU 68.9 27.9

2008 NORTHWEST_CORNER_2 PRESCRIBED 10/9/2008 NU 326.8 132.3

2008 NORTHWEST_CORNER_3 PRESCRIBED 10/9/2008 NU 296.8 120.1

2009 CAR 1 HUMAN 7/13/2009 SU 0.0 0.0

2009 ELKHORN_RANCH_1 PRESCRIBED 5/7/2009 EHR 2.9 1.2

2009 ELKHORN_RANCH_2 PRESCRIBED 5/7/2009 EHR 11.1 4.5

2009 ELKHORN_RANCH_3 PRESCRIBED 5/7/2009 EHR 4.1 1.6

2009 JUNIPER CAMPGROUND PRESCRIBED NU 150.0 60.7

2009 LOOP UNIT 1 PRESCRIBED NU 10.8 4.4

2009 MUD FIRE LIGHTNING 5/12/2009 NU 1.0 0.4

2009 NORTH_LOOP_BURN PRESCRIBED 5/3/2009 NU 149.6 60.5

2010 SE_CORNER_6 PRESCRIBED 4/22/2010 SU 250.1 101.2

2011 SHEEP PRESCRIBED 9/14/2011 NU 3641 1474

2011 LONGHORN FLATS PRESCRIBED 9/16/2011 NU 460 186

a NU=North Unit, SU=South Unit, EHR=Elkhorn Ranch Unit
252

Appendix B: Peak Flow Data for the Little Missouri River at Medora, ND

Water Year Gage Height (ft) Streamflow (cfs) Date of Peak Flow

1904 11.2 11,600 9-Jun-04

1905 10.2 8,500 2-Jul-05

1906 12 13,900 8-Jun-06

1907 16 29,000 24-Jun-07

1908 10.7 10,800 6-Jun-08

1909 11.5 12,400 31-May-09

1910 9.5 7,550 16-Mar-10

1911 8.6 5,540 17-May-11

1912 8.7 5,750 8-Jul-12

1913 n.d. n.d. n.d.

1914 6.3 1,850 3-Apr-14

1915 14.1 24,700 16-Jun-15

1916 9.1 6,630 16-Mar-16

1917 n.d. n.d. n.d.

1918 n.d. n.d. n.d.

1919 n.d. n.d. n.d.

1920 n.d. n.d. n.d.

1921 n.d. n.d. n.d.

1922 n.d. n.d. n.d.

1923 n.d. n.d. n.d.

1924 13.8 18,500 4-Apr-24

1925 n.d. n.d. n.d.

1926 n.d. n.d. n.d.

1927 n.d. n.d. n.d.

1928 n.d. n.d. n.d.

1929 17.2 38,700 7-Jun-29

1930 7 4,700 13-Sep-30

1931 4.52 1,610 22-Jun-31

1932 9.66 12,500 28-Apr-32

1933 12.44 20,800 24-May-33

1934 4.5 1,850 12-Jun-34

1935 n.d. n.d. n.d.

1936 n.d. n.d. n.d.

1937 n.d. n.d. n.d.

1938 n.d. n.d. n.d.

1939 n.d. n.d. n.d.

1940 n.d. n.d. n.d.

1941 n.d. n.d. n.d.
253

Water Year Gage Height (ft) Streamflow (cfs) Date of Peak Flow

1942 n.d. n.d. n.d.

1943 n.d. n.d. n.d.

1944 n.d. n.d. n.d.

1945 n.d. n.d. n.d.

1946 8.75 9,310 24-Jun-46

1947 20.5 65,000 23-Mar-47

1948 13.5 24,100 23-Mar-48

1949 11.2 14,600 27-Mar-49

1950 13 25,600 8-Apr-50

1951 8.5 5,200 22-Mar-51

1952 17.32 42,500 8-Apr-52

1953 8.21 8,820 21-Jun-53

1954 5.99 4,320 7-Apr-54

1955 13.9 25,600 27-Jun-55

1956 4.05 2,030 27-Mar-56

1957 7.45 7,900 22-Jun-57

1958 5.9 5,050 4-Jul-58

1959 7.47 6,650 20-Mar-59

1960 8.72 8,100 22-Mar-60

1961 5.22 3,540 24-May-61

1962 9.85 10,800 30-May-62

1963 n.d. 11,000 3-Mar-63

1964 9.11 9,170 10-Jun-64

1965 n.d. 15,000 3-Apr-65

1966 7.98 6,800 14-Mar-66

1967 11.73 15,700 11-May-67

1968 5.35 3,000 7-Mar-68

1969 10 11,200 23-Mar-69

1970 7.31 6,550 9-May-70

1971 12.82 21,200 6-Jun-71

1972 18 40,000 11-Mar-72

1973 5.72 3,820 20-Jun-73

1974 6.9 5,230 21-May-74

1975 14 22,800 9-May-75

1976 n.d. 6,000 21-Jun-76

1977 n.d. n.d. n.d.

1978 n.d. n.d. n.d.

1979 n.d. n.d. n.d.

1980 n.d. n.d. n.d.

1981 n.d. n.d. n.d.
254

Water Year Gage Height (ft) Streamflow (cfs) Date of Peak Flow

1984 n.d. n.d. n.d.

1985 n.d. n.d. n.d.

1986 n.d. n.d. n.d.

1987 n.d. n.d. n.d.

1988 n.d. n.d. n.d.

1989 n.d. n.d. n.d.

1990 n.d. n.d. n.d.

1991 n.d. n.d. n.d.

1992 n.d. n.d. n.d.

1993 n.d. n.d. n.d.

1994 n.d. n.d. n.d.

1995 n.d. n.d. n.d.

1996 n.d. n.d. n.d.

1997 n.d. n.d. n.d.

1998 n.d. n.d. n.d.

1999 n.d. n.d. n.d.

2000 n.d. n.d. n.d.

2001 n.d. 7,840 12-Mar-01

2002 5.62 1,680 11-Jun-02

2003 7.46 2,500 18-Mar-03

2004 9.51 5,500 10-Mar-04

2005 11.41 7,680 30-Jun-05

2006 13.61 12,700 25-Apr-06

2007 11.77 9,110 9-Jun-07

2008 11.9 8,810 10-May-08

2009 16.43 20,800 19-Apr-09

2010 8.69 4,330 24-Mar-10

2011 20.39 35,100 25-May-11
255

Appendix C. Peak Flow Data for the Little Missouri River at Watford City, ND

Water Year Gage Height (ft) Streamflow (cfs) Date of Peak Flow

1935 10.6 20,500 11-Jul-35

1936 8 8,800 10-Mar-36

1937 7.85 8,990 15-Jun-37

1938 9.4 14,600 15-Mar-38

1939 13.05 26,500 22-Mar-39

1940 6.83 4,270 23-Sep-11

1941 9 13,000 11-Jun-41

1942 9.59 12,600 11-Mar-42

1943 n.d. 25,000 22-Feb-43

1944 14.4 32,600 8-Apr-44

1945 14.4 30,000 14-Mar-45

1946 8.75 8,000 24-Feb-46

1947 24 110,000 25-Mar-11

1948 11.56 16,000 24-Mar-11

1949 13.7 26,000 28-Mar-49

1950 21.42 60,000 9-Apr-50

1951 13.82 18,000 27-Mar-51

1952 15.53 42,200 10-Apr-52

1953 7.68 7,650 22-Jun-53

1954 8.37 10,200 14-Jun-54

1955 9.96 17,600 28-Jun-55

1956 6 2,770 30-Jul-56

1957 7.8 6,890 23-Jun-57

1958 9.94 12,000 25-Mar-58

1959 10.13 12,800 20-Mar-59

1960 9.83 18,900 22-Mar-60

1961 3.76 2,920 25-May-61

1962 6.71 12,100 31-May-62

1963 n.d. 10,000 5-Mar-63

1964 7.82 12,000 5-Jul-64

1965 n.d. 20,000 10-Apr-65

1966 7.06 12,000 12-Mar-66

1967 16.07 30,000 22-Mar-67

1968 6.38 7,900 1-Mar-68

1969 8.04 15,300 23-Mar-69

1970 7.3 13,400 9-May-70

1971 15.27 31,000 28-Mar-71

1972 14.68 52,800 13-Mar-72

1973 6.42 7,500 28-Feb-73

1974 5.45 6,750 21-May-74
256

Water Year Gage Height (ft) Streamflow (cfs) Date of Peak Flow

1975 8.4 17,500 11-May-75

1976 6 7,600 24-Jun-76

1977 5.4 6,430 17-Jun-77

1978 11.08 31,500 30-Mar-78

1979 6.45 10,000 17-Apr-79

1980 3.09 865 14-Jun-80

1981 3.54 1,390 23-Oct-81

1982 n.d. 11,000 21-Feb-82

1983 8.41 13,500 23-Feb-83

1984 5.77 6,200 24-Jun-84

1985 5.1 4,540 24-Mar-85

1986 7.9 14,500 28-Feb-86

1987 5.47 6,740 1-Apr-87

1988 2.18 400 24-Mar-88

1989 7.44 5,000 11-Mar-89

1990 6.81 6,000 5-Mar-90

1991 8.15 8,900 15-Sep-91

1992 4.7 1,000 28-Feb-92

1993 n.d. 12,000 27-Jul-93

1994 11.79 10,000 6-Mar-94

1995 11.6 15,300 15-May-95

1996 17.23 10,000 15-Mar-96

1997 n.d. 20,500 22-Mar-97

1998 5.55 3,520 2-Apr-98

1999 6.31 4,960 16-Mar-99

2000 4.46 1,400 26-Feb-00

2001 n.d. 12,000 13-Mar-01

2002 4.91 2,360 23-Jun-02

2003 n.d. 8,000 17-Mar-03

2004 6.99 5,900 14-Mar-04

2005 8.01 6,770 2-Jul-05

2006 10.61 12,770 27-Apr-06

2007 8.21 8,710 10-Jun-07

2008 8.38 7,110 12-May-08

2009 13.68 20,800 21-Apr-09

2010 5.16 4,550 26-Mar-10

2011 16.70 34,000 27-May-11
257

Appendix D: Non-native Plant Species Documented in THRO

Non-native plant species documented in THRO through May 2011. A number of additional species are classified as 

“probably present” in the park or “unconfirmed” and are therefore not listed here. The full list can be found at 

http://science.nature.nps.gov/im/units/ngpn/monitor/exoticplant/docs/THRO_Park_Exotics.pdf.

Scientific Name Common Name Life cycle1 Growth form2 High priority?

Acroptilon repens Russian knapweed P F x

Agropyron cristatum Crested wheatgrass P G

Artemisia absinthium Absinth wormwood P F-SS x

Asparagus officinalis Garden asparagus P F

Asperugo procumbens German-madwort A F

Bassia scoparia Burning bush A F

Bromus inermis Smooth brome P G

Bromus arvensis Field brome A G

Bromus tectorum Cheatgrass A G x

Camelina microcarpa Littlepod false flax A-B F

Capsella bursa-pastoris Shepherd's purse A F

Cardaria draba Whitetop P F x

Carduus nutans Musk thistle B-P F x

Centaurea stoebe ssp. micranthos Spotted knapweed B-P F x

Ceratocephala testiculata Bur buttercup A F

Chenopodium album Lambsquarters A F

Chenopodium glaucum Oakleaf goosefoot A F

Cirsium arvense Canada thistle P F x

Cirsium vulgare Bull thistle B F x

Conringia orientalis Hare's ear mustard A F

Convolvulus arvensis Field bindweed P F-V x

Cynoglossum officinale Houndstongue B F x

Descurainia sophia Flixweed A-B F

Echinochloa crus-galli Barnyard grass A G

Elaeagnus angustifolia Russian olive P S-T x

Eragrostis cilianensis Stinkgrass A G

Erysimum cheiranthoides Wormseed wallflower A-B F

Euphorbia esula Leafy spurge P F x

Hyoscyamus niger Black henbane A-B F x

Lactuca serriola Prickly lettuce A-B F

Lappula squarrosa European stickseed A-B F

Lepidium perfoliatum Clasping pepperweed A-B F

Linaria vulgaris Yellow toadflax P F

Malva rotundifolia Low mallow A-B F

Medicago lupulina Black medick A-P F

Medicago sativa Alfalfa A-P F

Melilotus alba White sweetclover A-B-P F

Melilotus officinalis Yellow sweetclover A-B-P F

Nepeta cataria Catnip P F

Pennisetum glaucum Pearl millet A-P G

Poa compressa Canada bluegrass P G

Poa pratensis Kentucky bluegrass P G

Polygonum arenastrum Oval-leaf knotweed A-P F

Polygonum aviculare Prostrate knotweed A-P F

Polygonum convolvulus Black bindweed A F-V

Polygonum persicaria Spotted ladysthumb A-P F
258

Scientific Name Common Name Life cycle1 Growth form2 High priority?

Rumex crispus Curly dock P F

Rumex stenophyllus Narrowleaf dock P F

Salsola kali Russian thistle A F

Salsola tragus Prickly Russian thistle A F

Schedonorus pratensis Meadow fescue P G

Setaria viridis Green foxtail A G

Silene cserei Balkan catchfly B-P F

Silene latifolia ssp. alba Bladder campion B-P F

Sisymbrium altissimum Tumbling mustard A-B F

Sonchus arvensis Perennial sowthistle P F

Tamarix ramosissima Saltcedar P S-T x

Taraxacum officinale Common dandelion P F

Thlaspi arvense Field pennycress A F

Tragopogon dubius Yellow salsify A-B F

Trifolium repens White clover P F

Typha angustifolia Narrowleaf cattail P F

Ulmus pumila Siberian elm P S-T

Verbascum thapsus Common mullein B F x

Vicia sativa ssp. nigra Garden vetch A F-V

1 A = Annual, B = Biennial, P = Perennial

2 F = Forb, G = Graminoid, S = Shrub, SS = Subshrub, T = Tree, V = Vine
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific 

and other information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and 

affiliated Island Communities.

NPS387/123911, February 2014
National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

1201 Oakridge Drive, Suite 150

Fort Collins, CO 80525

www.nature.nps.gov

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