2008–2009 California drought

2008–2009 California drought
Name	2008–2009 California drought
Start	2008
End	2009
Places	California, United States, Sierra Nevada, Central Valley, Los Angeles, Sacramento
Causes	below-average precipitation, warm temperatures, Pacific circulation anomalies
Impacts	reservoir declines, groundwater depletion, agricultural losses, ecosystem stress

Contents

2008–2009 California drought The 2008–2009 California drought was a multiyear hydrological deficit that affected the State of California and adjacent regions, producing record low snowpack in the Sierra Nevada, critically low reservoirs such as Shasta Lake and Lake Oroville, and intense water restrictions across the Central Valley and Los Angeles County. The event intersected with policy debates involving the California Department of Water Resources, the United States Geological Survey, the Metropolitan Water District of Southern California, and the United States Bureau of Reclamation while prompting scientific studies from institutions like Stanford University, the Scripps Institution of Oceanography, and the National Oceanic and Atmospheric Administration.

Background and climatic context

The drought followed a sequence of anomalous atmospheric patterns including weak El Niño signals, shifting phases of the Pacific Decadal Oscillation and a northward-displaced Aleutian Low, which together altered storm tracks impacting California and the Great Basin. Observational records from the National Weather Service and analyses by the California Climate Change Center placed the event within a longer-term trend noted by the Intergovernmental Panel on Climate Change and researchers at University of California, Berkeley and NASA of increasing warm-season evaporative demand and altered snow-to-rain ratios in the Sierra Nevada. Paleoclimate reconstructions led by teams at the Tree-Ring Laboratory (University of Arizona) and the Lamont–Doherty Earth Observatory contextualized the 2008–2009 deficit against historical megadroughts recorded in Western North America.

Seasonal precipitation deficits began in late 2007 and intensified through 2008 into 2009, with the California Department of Water Resources reporting record-low snow water equivalent in early 2009 and the United States Bureau of Reclamation declaring critical reservoir operations for Central Valley Project facilities. Emergency declarations and drought advisories were issued by the Governor of California in coordination with the Federal Emergency Management Agency and state emergency services. Key hydrological benchmarks included Shasta Dam and Oroville Dam pool elevations falling below historical averages, and major river flow reductions in the Sacramento River and San Joaquin River watersheds affecting the Sacramento–San Joaquin River Delta.

Hydrological impacts included multi-season reductions in runoff documented by the United States Geological Survey streamflow gaging network and accelerated groundwater extraction reported by the California Department of Water Resources and local water districts like the Tulare County agencies. Environmental consequences affected habitats managed by the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service, with stress on species such as the Central Valley steelhead, Chinook salmon, and riparian communities in the San Joaquin Valley. Agricultural losses in the Central Valley and Imperial Valley were quantified by the United States Department of Agriculture and led to fallowing of cropland grown for almonds, rice, and orchards supplying firms linked to Blue Diamond Growers and J.G. Boswell Company. Economic impacts rippled through municipal utilities like the Metropolitan Water District of Southern California and regional economies including San Francisco, Los Angeles, and Fresno County, with reported reductions in hydroelectric generation at Pacific Gas and Electric Company facilities and increased reliance on interbasin transfers administered through the State Water Project.

State responses included emergency water conservation measures led by the California Governor's office and operational adjustments by the California Department of Water Resources for the State Water Project, while federal actions involved reallocations under the Central Valley Project overseen by the United States Bureau of Reclamation and regulatory exemptions coordinated with the U.S. Fish and Wildlife Service and the Environmental Protection Agency. Funding for drought relief and infrastructure was mobilized through legislative instruments debated in the California State Legislature and appropriations coordinated with offices of the United States Congress and the United States Department of Agriculture to support farmers, small water suppliers, and habitat restoration projects with involvement from NGOs such as the Nature Conservancy and the California Farm Bureau Federation.

The crisis accelerated policy discussions about allocation priorities administered through legal frameworks including the California Water Code and water rights adjudications in courts such as the United States District Court for the Eastern District of California. Agencies like the State Water Resources Control Board and regional entities including the San Francisco Public Utilities Commission revised contingency planning, demand management, and groundwater monitoring, anticipating amendments later incorporated into statewide reforms such as the Sustainable Groundwater Management Act deliberations. Municipal utilities expanded conservation programs, reuse projects, and infrastructure investments in collaboration with engineering firms and research centers at University of California, Davis.

Peer-reviewed studies conducted by researchers at Stanford University, the Scripps Institution of Oceanography, Lawrence Berkeley National Laboratory, and the USGS evaluated contributions from reduced precipitation, higher temperatures, and anthropogenic climate forcing consistent with findings from the Intergovernmental Panel on Climate Change. Analyses used climate models developed at institutions like the National Center for Atmospheric Research and NOAA to attribute portions of drought severity to long-term warming trends versus internal variability associated with the El Niño–Southern Oscillation and the Pacific Decadal Oscillation, informing subsequent risk assessments by the California Climate Change Center and planners in the California Natural Resources Agency.

The event influenced later policy and infrastructure investments across agencies including the California Department of Water Resources, the State Water Resources Control Board, and the Metropolitan Water District of Southern California, and it informed adaptation planning by local governments such as the City of San Diego and counties in the San Joaquin Valley. Scientific lessons contributed to improved snowpack monitoring by the California Cooperative Snow Survey and integration of climate projections from NASA and NOAA into water resource planning, shaping responses to subsequent droughts and the statewide dialogue involving stakeholders like the California Farm Bureau Federation, the Environmental Defense Fund, and tribal governments including representatives from the California Tribal Water Coalition.

Category:Droughts in California