NATIONAL PARK Grand Canyon National Park U.S. Department of the Interior SERVICE Arizona National Park Service Initial Bison Herd Reduction ENVIRONMENTAL ASSESSMENT May 2017 NATIONAL PARK SERVICE U.S. DEPARTMENT OF THE INTERIOR Grand Canyon National Park Arizona Initial Bison Herd Reduction Environmental Assessment Grand Canyon National Park May 2017 This page intentionally left blank. TABLE OF CONTENTS CHAPTER 1: PURPOSE OF AND NEED FOR ACTION .................................................................... 1 INTRODUCTION .......................................................................................................................................... 1 PURPOSE OF AND NEED FOR ACTION ........................................................................................................ 1 BACKGROUND ........................................................................................................................................... 3 NPS AUTHORITY TO MANAGE WILDLIFE ................................................................................................. 4 COOPERATIVE MANAGEMENT OF THE HOUSE ROCK BISON HERD .......................................................... 4 ISSUES AND IMPACT TOPICS ...................................................................................................................... 6 Issues and Impact Topics Carried Forward for Additional Analysis .................................................... 7 House Rock Bison Herd .................................................................................................................... 7 Water Resources in the Karst Landscape .......................................................................................... 7 Bison-Affected Vegetation ............................................................................................................... 7 Soils .................................................................................................................................................. 8 Wildlife (Other than Bison) and Wildlife Habitat ............................................................................ 8 Special-Status Wildlife Species ........................................................................................................ 9 Wilderness Character ........................................................................................................................ 9 Cultural and Tribal Resources......................................................................................................... 10 Visitor Use and Experience............................................................................................................. 11 Issues and Impact Topics not Retained for Additional Analysis ........................................................ 12 House Rock Bison Herd Disease .................................................................................................... 12 House Rock Bison Herd Genetics ................................................................................................... 12 Other Vegetation ............................................................................................................................. 13 Other Special-Status Species .......................................................................................................... 13 Environmental Justice ..................................................................................................................... 13 Air Quality and Greenhouse Gas Emissions and Effects of Climate Change on Resources and Values ....................................................................................................................................... 14 Soundscapes/Acoustic Environment ............................................................................................... 15 Other Historic Districts, Buildings, Structures, and Cultural Landscapes ...................................... 15 Indian Trust Resources ................................................................................................................... 15 CHAPTER 2: ALTERNATIVES ............................................................................................................ 17 INTRODUCTION ........................................................................................................................................ 17 ALTERNATIVE 1: NO ACTION .................................................................................................................. 17 ALTERNATIVE 2: PROPOSED ACTION (PREFERRED ALTERNATIVE) ........................................................ 17 Overview ............................................................................................................................................. 17 Bison Removal Modeling ................................................................................................................... 19 Herd Reduction Tools ......................................................................................................................... 20 Nonlethal Culling ............................................................................................................................ 20 Lethal Culling ................................................................................................................................. 23 Other Considerations for Herd Reduction .......................................................................................... 30 Herd Composition ........................................................................................................................... 30 Genetic Considerations ................................................................................................................... 30 Additional Bison Reduction Tools ...................................................................................................... 30 Hazing and Herding ........................................................................................................................ 30 Initial Bison Herd Reduction EA i TABLE OF CONTENTS Use of Attractants ........................................................................................................................... 31 Local Exclusion Fencing ................................................................................................................. 31 Human Safety ..................................................................................................................................... 31 Public Outreach and Education ........................................................................................................... 33 Monitoring .......................................................................................................................................... 33 Reduction Tool Effectiveness ......................................................................................................... 33 Bison Response (Behavior and Population) .................................................................................... 33 Other Resources .............................................................................................................................. 33 MITIGATION MEASURES ......................................................................................................................... 34 Water Resources ................................................................................................................................. 34 Bison-Affected Vegetation ................................................................................................................. 34 Soils .................................................................................................................................................... 34 ALTERNATIVES CONSIDERED BUT DISMISSED FROM FURTHER DETAILED ANALYSIS ........................... 35 Complete Elimination of Bison from Grand Canyon National Park .................................................. 35 Managed Hunt/Public Hunting ........................................................................................................... 35 Fertility Control .................................................................................................................................. 35 Park Border Fence .............................................................................................................................. 36 Gray or Mexican Wolf Reintroduction ............................................................................................... 36 Use of Dogs to Haze or Herd the Bison .............................................................................................. 36 Stand-Alone Tools for Reduction (Nonlethal and Lethal Culling) ..................................................... 36 CHAPTER 3: AFFECTED ENVIRONMENT ...................................................................................... 39 HOUSE ROCK BISON HERD ..................................................................................................................... 39 WATER RESOURCES IN THE KARST LANDSCAPE .................................................................................... 42 BISON-AFFECTED VEGETATION .............................................................................................................. 46 SOILS ......................................................................................................................................................