1 Climate Change Vulnerability and Adaptation 2 for Infrastructure and Recreation in the Sierra 3 Nevada 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Editors 32 J.E. Halofsky is a research ecologist, U.S. Department of Agriculture, Forest Service, Pacific 33 Northwest Research Station, 3625 93rd Ave. SW, Olympia, WA 98512; D.L. Peterson is a 34 professor, University of Washington, College of the Environment, School of Environmental and 35 Forest Sciences, Box 352100, Seattle, WA 98195-2100; L. Buluç is the climate change co- 36 coordinator, U.S. Department of Agriculture, Forest Service, Pacific Southwest Region, 1323 37 Club Dr., Vallejo, CA 94592; J. Ko is the climate change co-coordinator, U.S. Department of 38 Agriculture, Forest Service, State and Private Forestry, Pacific Southwest Region, 1323 Club 39 Dr., Vallejo, CA 94592. 1 40 Climate Change Vulnerability and Adaptation 41 for Infrastructure and Recreation in the Sierra 42 Nevada 43 44 Jessica E. Halofsky, David L. Peterson, Lara Buluç, and Jason Ko 45 46 47 Editors 48 49 50 51 52 53 U.S. Department of Agriculture, Forest Service 54 Pacific Southwest Research Station 55 Albany, CA 56 General Technical Report PSW-GTR-xxx 57 Month year 2 58 Abstract 59 Halofsky, J.E.; Peterson, D.L.; Buluç, L.; Ko, J., eds. 202X. Climate change vulnerability and 60 adaptation for infrastructure and recreation in the Sierra Nevada. Gen. Tech. Rep. PSW-GTR- 61 xxx. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research 62 Station. xxx p. 63 64 Keywords: Adaptation, climate change, disturbances, drought, extreme weather, infrastructure, 65 recreation, resilience, roads, Sierra Nevada, wildfire. 66 67 68 The Sierra Nevada Infrastructure and Recreation Vulnerability Assessment and Adaptation 69 Partnership identified climate change issues relevant for resource management on national forest 70 units in the Sierra Nevada region of the U.S. Department of Agriculture, Forest Service (USFS) 71 Pacific Southwest Region. This partnership assessed the vulnerability of infrastructure and 72 outdoor recreation to climate change, and developed adaptation options that minimize negative 73 impacts of climate change and facilitate transition to a warmer climate. 74 Increasing use and aging infrastructure are increasing the vulnerability of infrastructure to 75 the effects of climate change. Altered timing, type (rain versus snow), and amount of 76 precipitation will create challenges when storing and allocating water for irrigation, flood 77 prevention, and energy production. The Sierra Nevada is already experiencing temperature 78 increases as a result of human-caused climate change. Higher winter temperatures have resulted 79 in more precipitation falling as rain rather than snow and reduced snowpack, which in turn have 80 led to earlier timing of streamflow; peak flows are projected to occur 1–2 months earlier by the 81 end of the 21st century. 82 Roads, bridges, and culverts are susceptible to increased runoff during storm events, 83 causing failures due to washouts, plugging, overtopping, stream diversion, and scour. Long-term 84 climatic patterns that affect infrastructure over multiple decades—altered freeze-thaw cycle, 85 snowmelt, and stream hydrology—can also affect the sustainability of transportation and water 86 resource infrastructure. Increased magnitude of peak streamflows in winter is expected to 87 damage roads near perennial streams, ranging from minor erosion to complete loss of the road. 88 Associated infrastructure such as bridges, culverts, campgrounds, and facilities near streams and 89 floodplains will be especially vulnerable. 90 At vulnerable or flood-prone sites, resilience near stream crossings and in floodplains can 91 be enhanced by designing future infrastructure to withstand more frequent and severe flood 92 events, and by upsizing or upgrading existing infrastructure to withstand future flooding. Some 93 roads and other infrastructure can be decommissioned or moved to mitigate risks. Improving 94 streamflow forecasting and expanding streamflow and snowpack monitoring networks will help 95 managers respond to extreme events and ensure water allocation downstream. 96 To prevent wildfire damage to infrastructure, vegetation can be managed to reduce fuel 97 loads and increase defensible space around facilities and transportation corridors in the wildland- 98 urban interface. Following wildfires, managers can prioritize slope stabilization projects for 99 infrastructure near unstable slopes and river banks, increase monitoring of soil and slope 100 conditions, and restrict public access to sites where unstable soils create safety hazards. In 101 general, using best management practices while employing a “climate change lens” will facilitate 102 long-term resilience of infrastructure. 103 Outdoor recreation is a huge enterprise in the Sierra Nevada, providing diverse 3 104 experiences and health benefits to residents of California and beyond. Nearly all recreation is 105 affected by weather conditions, affecting decisions about if, when, and where to recreate. 106 Summer recreation will benefit from a longer period of suitable weather without snow, especially 107 during the spring and autumn shoulder seasons. Winter recreation (skiing, snowmobiling) will be 108 negatively affected by a warmer climate because of less and more transient snow. Ski areas and 109 other facilities at lower elevations will be especially vulnerable. The effects of higher 110 temperatures on hunting, fishing, water-based recreation, and gathering forest products will be 111 variable and less certain. 112 Nearly all recreation activities will be negatively affected by projected increases in 113 extreme weather and disturbance events. Wildfire creates short-term (weeks to months) impacts 114 by reducing visitor access to roads, trails, and recreation facilities; pervasive smoke reduces air 115 quality over large areas within and outside national forests. Severe wildfires often kill trees 116 across tens of thousands of acres, altering the aesthetic quality of recreation sites and vistas, and 117 in some cases affecting plants and animals that are valued by recreationists. Dead and damaged 118 trees, as well as postfire soil erosion, create significant hazards for recreationists that may last for 119 decades. 120 Increased recreation is projected for the Sierra Nevada, so adequate staffing and 121 resources will be needed to aid delivery of recreation opportunities and to maintain visitor safety. 122 Limits on visitation through determination of carrying and social capacity may be increasingly 123 necessary, as will communication about alternative recreation areas, alternative activities, and 124 warnings about potential crowding (through websites and social media). Partnerships can 125 supplement management for diverse recreation opportunities and settings, supporting 126 information needs and informing adaptive responses. 127 Specific adaptation strategies for recreation include: (1) increase resilience of 128 recreation infrastructure to increasing disturbances, (2) adjust staffing and management during 129 variable shoulder seasons to accommodate changes in seasonal access and recreation locations, 130 (3) adjust visitor management policies and practices to increase management flexibility and 131 facilitate transitions to meet user demands and expectations, (4) increase resilience of recreation 132 sites to changing conditions and/or increased demand, and (5) increase capacity to accommodate 133 shifting seasonal recreation patterns. Many on-the-ground management actions are available to 134 implement these strategies. 135 Collaborative adaptation efforts are essential for effective responses to the effects of 136 climate change on infrastructure and recreation. Expanding partnerships among federal, state, 137 and local agencies will increase the capacity of the USFS and other organizations to maintain 138 functional ecosystems, water resources, and recreation and transportation infrastructure. The 139 Sierra Nevada Partnership achieved specific elements of national and regional climate change 140 strategies for federal agencies, providing a scientific foundation for resource management and 141 planning in national forests and beyond. Timely implementation of adaptation will help prevent 142 the deterioration of infrastructure and the huge costs of repairs and replacement, and will ensure 143 the sustainability of facilities, access, and opportunities for recreation. Long-term monitoring 144 will help detect potential climate change effects, as well as evaluate the effectiveness of 145 adaptation options. 146 147 4 148 Summary 149 150 The Sierra Nevada Infrastructure and Recreation Vulnerability Assessment and Adaptation 151 Partnership (hereafter Sierra Nevada Partnership) was developed to identify climate change 152 issues relevant for resource management on national forest units in the Sierra Nevada region of 153 the U.S. Department of Agriculture, Forest Service (USFS) Pacific Southwest Region (Eldorado 154 National Forest [NF], Inyo NF, Lake Tahoe Management Unit, Lassen NF, Modoc NF, Plumas 155 NF, Sequoia NF, Sierra NF, Stanislaus NF, and Tahoe NF). 156 The 10 national forest units in the Sierra Nevada contain a combined 26,500 mi of roads, 157 9,300 mi of trails, 684 bridges, 169 dams, over 4,100 buildings and administrative sites, and over 158 50 campgrounds. Total infrastructure investments for facilities alone have an