Night Sky & Dark Environments

BUREAU OF LAND MANAGEMENT Night Sky and Dark Environments: Best Management Practices for Artificial Light at Night on BLM-Managed Lands Technical Note 457 APRIL 2023

Suggested citation: Sullivan, R., N. Glines-Bovio, K.N. Rogers, J.H. McCarty, D. Korzilius, and H. Hartmann. 2023. Night Sky and Dark Environments: Best Management Practices for Artificial Light at Night on BLM-Managed Lands. Tech Note 457. U.S. Department of the Interior, Bureau of Land Management, National Operations Center, Denver, CO. Disclaimer: The mention of company names, trade names, or commercial products does not constitute endorsement or recommendation for use by the Federal Government. Production services provided by: Bureau of Land Management National Operations Center Information and Publishing Services Section P.O. Box 25047 Denver, CO 80225 BLM/OC/ST-23/001+8430

Night Sky and Dark Environments: Best Management Practices for Artificial Light at Night on BLM-Managed Lands Technical Note 457 Authors: Robert Sullivan (retired) Landscape Architect Argonne National Laboratory Noelle Glines-Bovio Manager, Mojave Trails National Monument Bureau of Land Management Karla N. Rogers Landscape Architect Bureau of Land Management John H. McCarty (former position) Chief Landscape Architect Bureau of Land Management David Korzilius Training Coordinator Bureau of Land Management Heidi Hartmann Environmental Scientist Argonne National Laboratory U.S. Department of the Interior Bureau of Land Management April 2023

ii NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 Acknowledgments The Bureau of Land Management (BLM) appreciates the many professionals whose comments improved this technical note. This technical note is a product of many different BLM programs and perspectives from field, state, and national levels. It reflects the input of dozens of program staff and many others. In addition to Argonne National Laboratory, the BLM thanks the following government agencies and nongovernmental organizations for providing extensive review and technical expertise: • AE Design • Clanton & Associates, Inc. • Colorado Department of Transportation • Colorado Plateau Dark Sky Cooperative • Colorado State University • Consortium for Dark Sky Studies at the University of Utah • Federal Communications Commission • Institute of the Environment and Sustainability at UCLA (University of California, Los Angeles) • International Dark-Sky Association • Kaibab Paiute Tribe • Leibniz-Institute of Freshwater Ecology and Inland Fisheries • National Park Service • Night Sky Metrics LLC • Sierra Club, Grand Canyon Chapter • Space Art Travel Bureau • Stantec • Starry Skies Lake Superior IDA • The Nature Conservancy • University of Utah • U.S. Fish and Wildlife Service • U.S. Forest Service The authors thank Paul Doshkov, Tamara Faust, Joelle Gehring, Ram Hari, David Korzilius, Kristen Lalumiere, P. Evan Myers, Jesse Pluim, Karla Rogers, Greg Shine, Kyle Sullivan, Robert Sullivan, David Walker, Haley Webster, and Bob Wick for providing photos into the public domain for use in this publication. A special thanks goes to those who gave extra effort to acquire photos to illustrate specific concepts in this publication.

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 iii List of Acronyms ADLS...........................aircraft detection lighting system ALAN..................................................artificial light at night BLM ....................................Bureau of Land Management BMP.........................................best management practice BUG.......................................backlight, uplight, and glare CCT.......................................correlated color temperature CRI......................................................color rendering index DOE...................................................Department of Energy DOI...........................................Department of the Interior EA..............................................environmental assessment EERE.................................Office of Energy Efficiency and Renewable Energy EIS................................environmental impact statement ESPC....................energy savings performance contract FAA.................................Federal Aviation Administration FCC..............................................Federal Communications Commission FLPMA...........................................Federal Land Policy and Management Act of 1976 GIS...................................geographic information system IDA.............................International Dark-Sky Association IDSP......................................International Dark Sky Places IES.................................Illuminating Engineering Society K. ........................................................................................ Kelvin LCS...................................Luminaire Classification System LED........................................................light-emitting diode LZ.........................................................................lighting zone MLO...........................................Model Lighting Ordinance M/P....................................................... melanopic/photopic MSHA..............................................Mine Safety and Health Administration NPS......................................................National Park Service OSHA.............................Occupational Safety and Health Administration ROW......................................................................right-of-way USFS..........................................................U.S. Forest Service

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 iv Contents Abstract �� viii 1. Introduction ��1 1.1 Why Attention to Outdoor Lighting is Important ��1 1.2 How to Use This Technical Note �� 3 2. Night Sky and Darkness Values �� 5 2.1 Aesthetic, Spiritual, and Wilderness Values of Night Skies �� 6 2.2 Historic and Cultural Values of Night Skies �� 6 2.3 Recreation Values of Night Skies �� 8 2.4 Astronomical and Scientific Values of Night Skies �� 9 2.5 Biological Values of Natural Darkness and Night Skies �� 9 2.6 Night Sky and Darkness Values in Relation to BLM-Managed Lands ��10 3. Light Pollution: Exposure Mechanisms and Effects ��12 3.1 Basics of Light and Light Pollution ��13 3.1.1 Light Qualities �� 13 3.1.2 Types of Light Pollution ��14 3.1.3 How Distance Affects Light Pollution ��17 3.2 Exposure Mechanisms: How Artificial Light at Night Affects Humans ��18 3.2.1 Increase in Brightness of the Night Sky ��18 3.2.2 Effects on Visibility of Objects in Dark or Near-Dark Conditions ��19 3.2.3 Too Little or Too Much Light ��20 3.2.4 Light Trespassing Where It Is Not Wanted ��20 3.3 Effects of Artificial Light at Night on Humans ��20 3.3.1 Aesthetic, Spiritual, and Recreational Effects ��20 3.3.2 Historic and Cultural Effects ��21 3.3.3 Astronomical and Scientific Effects ��22 3.3.4 Nuisance Effects �� 22 3.3.5 Human Health Effects ��23 3.3.6 Economic Effects �� 23 3.4 Exposure Mechanisms: How Artificial Light at Night Affects Animals and Plants ��24

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 v 3.4.1 Temporal Niche Partitioning in Animals ��25 3.4.2 Role of Darkness in Biological Repair and Recovery ��26 3.4.3 Photoperiodism and Circadian Rhythms in Animals and Plants ��26 3.4.4 Visual Perception in Animals ��26 3.4.5 Spatial Orientation and Navigation in Animals ��27 3.4.6 Photosynthesis in Plants ��27 3.5 Effects of Artificial Light at Night on Animals and Plants ��27 3.5.1 Effects of Artificial Light at Night on Animals ��27 3.5.1.1 Effects on Insects and Other Arthropods ��28 3.5.1.2 Effects on Mammals ��29 3.5.1.3 Effects on Birds ��30 3.5.1.4 Effects on Reptiles ��31 3.5.1.5 Effects on Fish ��32 3.5.1.6 Effects on Amphibians ��32 3.5.2 Effects of Artificial Light at Night on Plants ��33 4. Principles of Artificial Light at Night to Avoid Light Pollution ��34 4.1 Light Only If Needed: Use Alternatives to Permanent Lighting ��35 4.2 Light Only When Needed: Use Lighting Control Technologies ��35 4.3 Light Only Where Needed: Shield Lights and Direct Them Properly ��36 4.4 Light Color Matters: Select Amber, Orange, or Red Whenever Possible ��36 4.5 Use the Minimum Level of Illumination Necessary: Avoid Over-Illumination ��37 4.6 Use Energy-Efficient Lights and Advanced Lighting Controls: Save Energy While Adding Useful Lighting Capabilities ��37 5. BMPs for Artificial Light at Night on BLM-Managed Lands ��38 5.1 Planning and Design BMPs ��40 5.1.1 Have a Lighting Plan Prepared by a Qualified Lighting Designer ��40 5.1.2 Select Outdoor Luminaires Certified to Minimize Light Pollution ��41 5.1.3 Consider Using an Energy Savings Performance Contract (ESPC) for Lighting ��45 5.1.4 Take Advantage of DOE Assistance for Outdoor Lighting ��45 5.1.5 Consider Nearby Astronomical Observatories before Installing Lighting Systems ��46 5.1.6 Educate Stakeholders Concerning Night Sky and Darkness Resources ��46 5.1.7 Keep Informed about Lighting Best Practices ��47 5.1.8 Identify Light-Sensitive Receptors ��47

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 vi 5.1.9 Conduct a Baseline Study of Existing Light Pollution and Night Sky Conditions ��47 5.1.10 Conduct an Inventory of Existing Lighting When Retrofitting ��49 5.1.11 Establish a Lighting and Light Pollution Monitoring Program ��50 5.2 BMPs for Lighting Only If Needed ��50 5.2.1 Critique New or Evaluate Existing Lighting Systems ��50 5.2.1.1 Consider Essential Light Sources Associated with a Built Environment ��51 5.2.1.2 Consider Nonessential Light Sources Associated with a Built Environment ��51 5.2.2 Consider Dark Adaptation Needs of People and Wildlife ��51 5.2.3 Encourage Alternatives to Permanent Lighting for Infrequent Lighting Needs ��52 5.3 BMPs for Lighting Only When Needed ��53 5.3.1 Use Lighting Controls to Limit Lighting to Specified Periods ��53 5.3.2 Switch Off or Dim Lighting during Times of Critical Biological Activity ��54 5.3.3 Include Lighting Season/Date Restrictions in Operations Permits ��54 5.3.4 Use Aircraft Detection Lighting System (ADLS) Technology for Hazard Navigation Lighting ��55 5.4 BMPs for Lighting Only Where Needed ��55 5.4.1 Direct Light Only Where It Is Needed ��55 5.4.2 Do Not Aim Lights Upward, Horizontally, or at Large Angles from the Ground ��56 5.4.3 Re-Aim Existing Lights to Illuminate Task Targets ��56 5.4.4 Use Dark Sky-Compliant Luminaires ��56 5.4.5 Use Luminaires with an IES TM-15-20 BUG Rating System Uplight (U0) Rating ��57 5.4.6 Retrofit Existing Poorly Shielded Lights with Luminaires with a BUG U0 Rating ��57 5.4.7 Where Necessary, Install Customized Shielding ��57 5.4.8 Use Low-Height, Fully Shielded Step or Path Lights ��58 5.4.9 Install Window Coverings Inside Buildings ��58 5.4.10 Mount Lights at the Proper Height ��58 5.4.11 Install Lights at the Tops of Signs and Buildings, Pointing Downward ��58 5.4.12 Avoid the Use of Swivel-Mounted Floodlights ��59 5.4.13 Avoid Uplighting Where Possible ��59 5.4.14 Screen Lighting Where Possible ��60 5.4.15 Use Pole-Mounted Lights with Low BUG Ratings for Backlight Close to Property Boundaries ��60 5.4.16 Use Forward Throw Asymmetric Luminaires Where Appropriate ��60 5.4.17 Choose Roadway Luminaires to Maximize Lighting the Road and Minimize Lighting Away from the Road ��61

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 vii 5.4.18 Use Lighting Transition Zones between Brightly Lit and Unlit Areas ��61 5.4.19 Leave Gaps in Long Linear Arrangements of Lights ��61 5.4.20 Provide Dark Corridors to Facilitate Animal Movement ��61 5.5 BMPs for Light Color Matters: Select Amber, Orange, or Red When Possible ��61 5.5.1 Use “Night Sky Friendly” Narrow-Spectrum Amber, Orange, or Red Light Sources ��62 5.5.2 Use Tunable CCT Lighting to Adjust Color of Light Sources ��62 5.5.3 Consider Melanopic/Photopic Ratio When Selecting Light Sources ��63 5.5.4 If Necessary, Remove UV Light Content with Filters or Housings ��63 5.5.5 Use Consistently Colored Light Sources ��63 5.6 BMPs for Minimizing the Level of Illumination ��63 5.6.1 Use the Lowest Possible Level of Illumination that Meets the Lighting Needs ��63 5.6.2 Reduce Light Levels of Security Cameras to the Minimum Required for Proper Functioning ��64 5.6.3 Replace Existing Lights with Lower-Output Light Sources ��64 5.6.4 Use Dimming Lighting Controls to Reduce Over-Illumination ��64 5.6.5 Dim Lighting by 30 to 50 Percent after High Traffic Hours in Public Spaces that Must Stay Illuminated �� 65 5.6.6 For Tall Structures, Use Flashing Warning Lights at Night, and Replace Nonflashing with Flashing Lights ��65 5.6.7 Where ADLS Technology Is Not Used, Use the Minimum Amount of Hazard Navigation Lighting Specified by the FAA ��66 5.6.8 Use Reduced Intensity Lights with Short Flash Durations for Hazard Navigation Lighting ��66 5.6.9 Use Enclosed Flare Systems for Gas Flaring Associated with Oil and Gas and Similar Operations ��67 5.6.10 Where Decreased Visibility Is Desired, Reduce Reflectivity of Illuminated Surfaces ��67 5.7 BMPs for Energy-Efficient Lights and Advanced Lighting Technology ��68 5.7.1 Use Energy-Efficient Lights with Advanced Lighting Technology ��68 5.7.2 Consider the Total Life Cycle Cost When Selecting New Lighting Systems or Retrofitting Existing Systems ��68 5.7.3 Inspect and Clean Luminaires Regularly ��68 6. Summary ��69 7. Glossary ��70 8. References ��76

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 viii Abstract Outdoor lighting at night is considered essential to modern human life. It allows us to safely extend our daytime activities into the night hours. Without proper precautions, the addition of artificial light at night can change the natural night sky conditions and affect scenic, historic, cultural, scientific, recreational, and ecological values that depend on darkness and dark night skies. The mission of the Bureau of Land Management (BLM) is to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations. BLM-managed lands provide differing types of activities, developments, and visitor services that include outdoor lighting where appropriate to provide for worker and visitor safety, security, and enjoyment. Due to growing public concern and research available about light pollution, this technical note provides a set of best practices for outdoor lighting. The information comes from research and practical experience published by industry and other sources and provides knowledge on the relationships between dark night skies and scenic, historic, cultural, scientific, recreational, and ecological values. This technical note provides an easy reference for a variety of ways the BLM can protect night skies and dark environments by reducing or avoiding sources of light pollution from BLM-managed lands to maintain visible clarity of night skies and ensure a healthful dark environment for wildlife and people.

NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 1 1. Introduction 1 Glossary terms are sometimes highlighted in bold throughout this technical note, and definitions appear in the glossary. 1.1 Why Attention to Outdoor Lighting is Important Outdoor lighting at night is considered essential to modern human life. It allows us to safely extend our daytime activities into the night hours—everything from work activities to high-speed travel to leisure and recreation. Yet outdoor lighting can have many negative consequences if not used responsibly. Outdoor lighting can interfere with our enjoyment of the night sky and negatively impact the many ecological processes that depend on darkness. Without proper precautions, the addition of artificial light at night1, commonly known as ALAN, can change the natural night sky conditions and affect scenic, historic, cultural, scientific, recreational, and ecological values that depend on darkness and dark night skies. The mission of the Bureau of Land Management (BLM) is to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations. The BLM is responsible for more land than any other federal agency, approximately 245 million acres Piper Mountain Wilderness in California.

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