2010s Californian droughts

2010s Californian droughts
Name	2010s Californian droughts
Location	California, United States
Dates	2011–2017 (major episode), related events through 2019
Causes	Persistent precipitation deficits, enhanced evapotranspiration, Pacific sea surface temperature anomalies
Consequences	Water shortages, reservoir declines, agricultural losses, ecological stress, wildfire expansion, policy reforms

Contents

2010s Californian droughts The 2010s Californian droughts were a prolonged series of precipitation deficits and hydrologic extremes affecting California and adjoining regions in the United States during the 2010s. The events involved interactions among atmospheric circulation patterns such as the Pacific Decadal Oscillation, El Niño–Southern Oscillation, and a persistent Ridiculously Resilient Ridge-like ridge pattern, producing major socioeconomic impacts across Los Angeles County, San Francisco Bay Area, the Central Valley, and the Sierra Nevada. Responses involved federal, state, and local actors including California Department of Water Resources, United States Bureau of Reclamation, and municipal utilities like Metropolitan Water District of Southern California.

Background and climatology

Climatic drivers included variations in El Niño–Southern Oscillation phases, shifts of the Pacific Decadal Oscillation, and anomalous sea surface temperatures in the Northeast Pacific that reinforced a high-amplitude atmospheric ridge similar to patterns documented in the Ridiculously Resilient Ridge literature. Snowpack behavior in the Sierra Nevada tracked with wintertime precipitation deficits measured by the California Department of Water Resources snow surveys and affected storage at reservoirs such as Shasta Lake, Lake Oroville, and Folsom Lake. Paleoclimate comparisons invoked tree-ring records from researchers affiliated with University of California, Berkeley, Stanford University, and California State University, Sacramento to place 2010s dryness relative to historical megadroughts found in Western North America studies by teams from Princeton University and the Lamont–Doherty Earth Observatory.

The drought chronology features a pronounced onset in 2011 with escalation through 2014–2016. Key milestones included emergency declarations by Governor of California Jerry Brown, federal drought disaster declarations by the United States Department of Agriculture, and operational changes by the United States Bureau of Reclamation for Central Valley Project allocations. The winter of 2016–2017 produced an episodic recovery influenced by a strong El Niño and atmospheric river events tracked by the National Oceanic and Atmospheric Administration, but residual deficits persisted into 2019 in some basins monitored by the United States Geological Survey and California Water Science Center.

Reservoir storages fell to historically low levels at systems managed by the California State Water Project and Metropolitan Water District of Southern California, prompting curtailments in water transfers overseen by the California State Water Resources Control Board. Groundwater withdrawals increased, triggering expanded use of the Sustainable Groundwater Management Act framework and adjudications in basins like the San Joaquin Valley and Santa Clara Valley. Urban utilities including the San Francisco Public Utilities Commission and Los Angeles Department of Water and Power implemented conservation measures; desalination projects such as the Carlsbad Desalination Plant and intertie projects like the Delta Conveyance Project were discussed or advanced. Aging conveyance infrastructure and levee systems maintained by California Department of Water Resources and the U.S. Army Corps of Engineers faced altered operation schedules and risk profiles.

Irrigated agriculture in the Central Valley experienced fallowed acreage and crop shifts affecting producers represented by the California Farm Bureau Federation and University of California, Davis extension programs. Reduced instream flows altered habitat for species protected under the Endangered Species Act, including Chinook salmon and Delta smelt, invoking regulatory actions by the National Marine Fisheries Service and U.S. Fish and Wildlife Service. Vegetation stress increased susceptibility to pests documented by the California Department of Food and Agriculture, while forest dieback in the Sierra Nevada and the Klamath Mountains contributed to enhanced wildfire risk as observed in perimeters recorded by the California Department of Forestry and Fire Protection (Cal Fire). Major conflagrations during the decade involved coordination with the Federal Emergency Management Agency and state emergency systems.

Economic losses included revenue declines reported by United States Department of Agriculture crop reports and employment impacts in agricultural counties represented by Fresno County, Kern County, and Stanislaus County. Urban water restrictions affected consumers served by agencies such as the East Bay Municipal Utility District and Santa Clara Valley Water District, while public health concerns raised by the California Department of Public Health included increased dust exposure from dry lakebeds and groundwater subsidence in communities like Corcoran, California. Equity issues invoked advocacy by organizations including the Leadership Counsel for Justice and Accountability and legal actions reviewed in courts such as the California Supreme Court on water rights disputes.

State responses included emergency conservation regulations promulgated by the California State Water Resources Control Board, the governor's drought proclamations by Jerry Brown, and investments in water recycling led by entities such as the Orange County Water District. Legislative actions included passage of the Sustainable Groundwater Management Act and funding measures administered through the California Department of Water Resources and the California Natural Resources Agency. Federal-state coordination involved the United States Bureau of Reclamation and United States Environmental Protection Agency on water quality rules, while regional initiatives by groups like the Association of California Water Agencies advanced integrated resource portfolios.

Attribution studies published by researchers at Scripps Institution of Oceanography, NASA, NOAA, and university consortia examined the roles of anthropogenic warming, increased vapor pressure deficit, and decadal sea surface temperature variability. Climate model projections from intercomparison projects used by IPCC assessments suggested elevated drought risk for parts of California under higher greenhouse gas trajectories evaluated by Intergovernmental Panel on Climate Change. Stakeholders including California Energy Commission and California Air Resources Board incorporated drought risk into planning for energy-water nexus resilience, while water managers at Metropolitan Water District of Southern California and Santa Ana Watershed Project Authority pursued adaptation measures such as conjunctive use and expanded recycled water capacity.

Category:Water scarcity in California