Lessons from California’s 2012–2016 Drought

American Society of Civil Engineers (ASCE) | October 1st, 2018

California’s 5-year drought has ended, even as its aftermath lingers. From 2012–2016 much or all of California was under severe drought conditions, with gre

California’s 5-year drought has ended, even as its aftermath lingers. From 2012–2016 much or all of California was under severe drought conditions, with greatly diminished precipitation, snowpack, and streamflow and higher temperatures. Water shortages to forests, aquatic ecosystems, hydroelectric power plants, rural drinking water supplies, agriculture, and cities caused billions of dollars in economic losses, killed millions of forest trees, brought several fish species closer to extinction, and caused inconvenience and some expense to millions of households and businesses. The drought also brought innovations and improvements in water management, some of which will better prepare California for future droughts. This paper summarizes the magnitude and impacts of the 2012–2016 California drought. The paper then reviews innovations arising from the drought in the larger historical context of water management in California. Lessons for California and for modern drought management are then discussed. Droughts in modern, well-managed water systems serving globalized economies need not be economically catastrophic, but will always have impacts and challenges, particularly for native ecosystems. In California and every other water system, droughts usefully expose weaknesses and inadequate preparation in water management. In this regard for California, managers of ecosystems and small rural water supplies had the most to learn.

Letter from John J. Entsminger, General Manager, Southern Nevada Water Authority, to Debra Haland, Secretary, U.S. Department of Interior

Southern Nevada Water Authority (SNWA) | August 15th, 2022

Long-term climate and competition explain forest mortality patterns under extreme drought

Ecology Letters (Wiley) | December 20th, 2016

Rising temperatures are amplifying drought‐induced stress and mortality in forests globally. It remains uncertain, however, whether tree mortality across drought‐stri

Rising temperatures are amplifying drought‐induced stress and mortality in forests globally. It remains uncertain, however, whether tree mortality across drought‐stricken landscapes will be concentrated in particular climatic and competitive environments. We investigated the effects of long‐term average climate [i.e. 35‐year mean annual climatic water deficit (CWD)] and competition (i.e. tree basal area) on tree mortality patterns, using extensive aerial mortality surveys conducted throughout the forests of California during a 4‐year statewide extreme drought lasting from 2012 to 2015. During this period, tree mortality increased by an order of magnitude, typically from tens to hundreds of dead trees per km2, rising dramatically during the fourth year of drought. Mortality rates increased independently with average CWD and with basal area, and they increased disproportionately in areas that were both dry and dense. These results can assist forest managers and policy‐makers in identifying the most drought‐vulnerable forests across broad geographic areas.

Lower Colorado River Basin Plan letter to the U.S. Bureau of Reclamation, 5/22/23

U.S. Bureau of Reclamation (USBR) | May 22nd, 2023

Lower Colorado River Mainstream Evaporation and Riparian Evapotranspiration Losses Report

U.S. Department of the Interior (DOI) | February 8th, 2024

On August 16, 2022, the Bureau of Reclamation (Reclamation) and Department of the Interior announced several administrative actions for consideration to improve and prote

On August 16, 2022, the Bureau of Reclamation (Reclamation) and Department of the Interior announced several administrative actions for consideration to improve and protect the long-term sustainability of the Colorado River System. The System is currently experiencing prolonged drought and low runoff conditions accelerated by climate change that have led to historically low water levels in Lakes Powell and Mead (Reclamation, 2021). One of the actions included reviewing and prioritizing additional administrative initiatives to address system losses in the lower Colorado River mainstream. As part of that action, this report provides an overview of historical mainstream evaporation and riparian evapotranspiration (ET) losses along the lower Colorado River and presents methodologies used to develop those datasets. This report does not make recommendations on how to account for system losses in the lower Colorado River mainstream. Supplemental documents: Appendix 1 – Reaches Identified in the Lower Colorado River Mainstream Evaporation and Riparian Evapotranspiration Losses Report Appendix 2 – LCRAS Open Water Monthly Evaporative Losses Appendix 3 – Lake Mead, Lake Mohave, and Lake Havasu Evaporation from Reclamation’s Hydrologic Database (HDB) Appendix 4 – LCRAS Riparian Monthly Evapotranspiration Losses by Vegetation Appendix 5 – Evaporation and Riparian Evapotranspiration (ET) Coefficients Appendix 6 – Evaporation and Riparian Evapotranspiration (ET) Rates

Maladaptation to drought: a case report from California, USA

Sustainability Science (Springer) | October 15th, 2015

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capaci

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capacity of social and environmental systems to climate stresses, we provide an assessment of responses to water scarcity during a multi-year drought in California. In particular, we use Barnett and O’Neill’s (Global Environ Change 20:211–213, 2010) criteria for maladaptation to examine responses in the agricultural and energy sectors to a multi-year (2007–2009) California drought. We conclude that despite evidence in both sectors of resiliency to the impacts of the drought, some of the coping strategies adopted increased the vulnerability of other systems. These other systems include California’s aquatic ecosystems and social groups that rely on those ecosystems for their health or employment; future generations whose resources were drawn down in the near-term, where otherwise those resources would have been available at a later time; and current and future generations who were, or will be, exposed to the effects of increased greenhouse gas emissions. This case study demonstrates that California’s current strategies for dealing with long or severe droughts are less successful than previously thought when short- and long-term impacts are evaluated together. This finding is particularly relevant given projections of more frequent and severe water shortages in the future due to climate change. This study recommends a shift from crisis-driven responses to the development and enactment of long-term mitigation measures that are anticipatory and focus on comprehensive risk reduction.

Management of the Colorado River: Water Allocations, Drought, and the Federal Role

Congressional Research Service (CRS) | August 4th, 2022

Management of the Colorado River: Water Allocations, Drought, and the Federal Role

Congressional Research Service (CRS) | September 7th, 2022

Managing California’s Freshwater Ecosystems: Lessons from the 2012–16 Drought

Public Policy Institute of California (PPIC) | November 9th, 2017

The 2012–16 drought caused unprecedented stress to California’s ecosystems and pushed many native species to the brink of extinction. It also tested the laws, policie

The 2012–16 drought caused unprecedented stress to California’s ecosystems and pushed many native species to the brink of extinction. It also tested the laws, policies, and institutions charged with protecting the environment. Eight case studies on environmental water management during the drought reveal both strengths and weaknesses in federal, state, and local response that can inform how California addresses future droughts.

Managing Drought in a Changing Climate: Four Essential Reforms

Public Policy Institute of California (PPIC) | September 12th, 2018

California’s climate is changing. Hotter temperatures, a shrinking snowpack, shorter and more intense wet seasons, rising sea level, and more volatile precipita

California’s climate is changing. Hotter temperatures, a shrinking snowpack, shorter and more intense wet seasons, rising sea level, and more volatile precipitation—with wetter wet years and drier dry years—are stressing the state’s water management system. Recent climate projections indicate that the pace of change will increase. To avoid unwanted social, economic, and environmental consequences, the water system will need to adapt to greater climate extremes and growing water scarcity. While California is making good progress in some areas of drought management, a more focused plan of action is needed. Successful adaptation will require strong leadership at the state and local levels, and cooperation on all fronts. The 2012–16 drought—the hottest in the state’s recorded history and one of the driest—offered a window into the future under a warming climate and lessons for managing future droughts. Using these lessons as a starting point, this report offers a road map of essential reforms to prepare for and respond to droughts in California’s changing climate. Key reforms include: Plan ahead. Stronger drought planning is critically important for urban water management, groundwater sustainability, safe drinking water in rural communities, and freshwater ecosystems. Upgrade the water grid. California needs a comprehensive program to address above- and below-ground storage, conveyance, and operational challenges by mid-century, including repairing facilities that are broken, expanding conveyance and storage capacity, and modernizing and integrating operations. Update water allocation rules. California should comprehensively update its water allocation governance. The goals should be to find equitable and efficient ways to allocate limited supplies among competing demands during dry times while promoting efforts to capture and store water during wet times. Find the money. Reliable funding is crucial for adapting to climate change. New sources are needed to pay for necessary water-management investments and to fill funding gaps in the state’s water system. The focus of this reform agenda is on drought, because drought―more than any other aspect of California’s climate―reveals the vulnerabilities of watermanagement systems. Importantly, these reforms will improve drought resilience for today’s conditions, not just for the future.