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Drought In California January 2021 California Department of Water Resources | Natural Resources Agency | State of California Major Water Facilities Tule Lake Clear LLaakke Reservoir Trinity Reservoir Shasta Lake Whiskeytown Redding State Water Project Lake Antelope Federal Water Project Corning Canal Lake Tehama-ColuColussa Local Water Project Canal Frenchmmaan BlackBlack ButteButte LaLakke Lake Lake Lake Oroville Davis Stony GoGorgege Reservvoioir New BullBullaards East PaParrk Reservoivoir Bar Reservoir Lake Mennddoocincino Englebrightight Reservoivoir Indian Vaalleylley Reservoivoir Glenn-Colusa Canal Lake Sonoma Folsom Lake Lake Sacramento Auburn FolFolsom Sooututhh CCananaal Berryessa Putah S. CanaCanal Camanche Reservvoioir North Bay Aqueduct Mokelkeluummnne New Hogan Reservoir AqAquedueducuct New Meloelonnees LaLakke Contra Costa CCananal Stockton Los Vaqueros Reservoir Hetch Hetchyetchy Reservoir Don Pedro Lake San Francisco Lake McClure Lake Crowley Lake Hetch Hetchy Aqueduct Del Vaalllle South Bay Aqueduceduct Delta-Meendotandota Pachechecoo Conduit Canal Madera CaCanal Tinemaha Santa Clara CondConduiuit Millerton Lake Reservoir Hollister Condduuiit Pine Flat Reservoir San Luis Reeservvoioir Fresno San Luis Los Banos Reservoir Canal Lake Friant-Kern Kaweah Coalinga Canal Canal Haiwee Reservoir Lake Calif Success San Antonio Reservvoioir or Nacimientnto ni Isabella Reservoiir a Lake Los Angeles Cross Valley Aqueduct Canal California Aqueduct Twitchelwitchell Coastal Branch Reservoir Quail Lake Aq ued Pyramid LaLakke u ct Colorado River Lake Cachuma Castaic Lake Silverwood LLaakke Aqueduct Bouquet Santa Barbara Lake California Aququeeduct CaCassitaitas Reservoir East Branch Extensiioon Los Angeles Crafton Hills Reservoir Lake Perris Lake Mathews Diamond Valley Lake Coachella San Diego Canal Aqueducts San Vincenteincente Reservvoioir All American Canal San Diego Lower Otay Reservvoioir Miles 0 25 50 100 200 2 DROUGHT IN CALIFORNIA DEFINING DROUGHT respond to drought impacts, but such a proclamation is not California’s annual water supply conditions are highly itself a definition of drought. variable, and droughts are a recurring feature in the Drought is a gradual phenomenon. Impacts of drought state’s water budget. There are many ways that drought are typically felt first by those most dependent on annual can be defined. Some ways can be quantified, such rainfall, such as ranchers engaged in dryland grazing or as meteorological drought (a period of below-normal rural residents relying on wells in low-yield rock precipitation) or hydrologic drought (a period of below- formations. Drought impacts increase with the length of a average runoff), others are more qualitative in nature drought, as carry-over supplies in reservoirs are depleted (shortage of water for a particular purpose). There is no and water levels in ground water basins decline. Hydrologic universal definition of when a drought begins or ends, nor impacts of drought to any individual water supplier may be is there a State statutory process for defining or declaring exacerbated by other factors such as regulatory drought. A proclamation of emergency conditions pursuant requirements to satisfy the rights of senior water right to the California Emergency Services Act may be used to holders or to protect environmental resources. Calculated Statewide Runoff Data: U.S. Geological Survey 3 2021 DROUGHT BROCHURE DROUGHTS IN CALIFORNIA Drought played a role in shaping California’s early history, as the so-called Great Drought in 1863–1864 contributed to the demise of the cattle rancho system, especially in Southern California. Subsequently, a notable period of extended dry conditions was experienced during most of the 1920s and well into the 1930s, with the latter time including the Dustbowl drought that gripped much of the United States. Three 20th century droughts were of particular importance from a water supply standpoint—the droughts of 1929–1934, 1976–1977, and 1987–1992. More An aerial view of Lake Powell, with Glen Canyon Dam in the foreground. The recent multiyear droughts occurred in 2007–2009 and Colorado River Basin has been experiencing long-term drought conditions 2012–2016. since 2000, resulting in lowered water levels at Lake Powell (shown here) and Lake Mead. The Colorado River has historically been a highly reliable The 1929–1934 drought was notable not only for its water supply for Southern California, despite prolonged drought, thanks to duration but also for its occurrence within a longer period the basin’s reservoir storage capacity. Interim guidelines adopted in 2007 for Lower Basin shortages and coordinated operations of Lakes Mead and Powell of very dry hydrology. This drought’s hydrology was have helped reduce the risk of shortages to California. The existing guidelines subsequently widely used in evaluating and designing expire at the end of 2025. Photo credit: Getty Images storage capacity and yield of large Northern California From a water use perspective, drought is best defined reservoirs. The 1976–1977 drought, when statewide runoff by its impacts on a particular class of water users in a in 1977 hit an all-time low, served as a wake-up call for particular location. In this sense, drought is a very local California water agencies that were unprepared for major circumstance. Hydrologic conditions constituting a drought cutbacks in their supplies. Forty-seven of the state’s 58 counties declared local drought-related emergencies at for water users in one location may not constitute a that time. Probably the most iconic symbol of the 1976– drought for water users in a different part of the state or 1977 drought was construction of an emergency pipeline with a different water supply. California’s extensive system of water supply infrastructure—reservoirs, managed groundwater basins, and interregional conveyance facilities—mitigates the effect of short-term (single-year) dry periods for most water users. Individual water suppliers may use criteria such as rainfall or runoff, amount of water in storage, decline in groundwater levels, or expected supply from a water wholesaler to define their water supply conditions. Criteria used to identify statewide drought conditions—such as statewide runoff and reservoir storage— do not address these localized circumstances. And although California’s water supply infrastructure provides a means to mitigate impacts for most water users, other types of impacts (such as increased wildfire risk or stress Collecting a tree-ring sample near Ebbetts Pass. Data from multiple trees at on vegetation and wildlife) remain. one site are combined into a single record representative of the site. 4 DROUGHT IN CALIFORNIA Klamath River at Keno Running mean 2 1 0 Million Acre-feet 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 Sacramento River Runoff 35 30 25 20 15 Million Acre-feet 10 5 0 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 San Joaquin River Runoff 15 10 5 Million Acre-feet 0 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Reconstructed Flows In Major Rivers Colorado River at Lee’s Ferry Running mean 25 20 15 10 Klamath River at Keno Running mean Million Acre-feet 2 5 1 0 0 Million Acre-feet 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Sacramento River Runoff 35 30 25 20 15 Million Acre-feet 10 5 0 Assuming you can edit the picture, here are the edits: 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 San Joaquin River Runoff 15 Change y-axis to TAF to make less crowded 10 Driest 10-Year5 Periods in Reconstructed Records Million Acre-feet thousand0 acre feet900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Replace picture title with gure title in subject line 1,600 Klamath River at Keno, 1507-2003 1,400 Data courtesy of Dave Meko, University of Arizona Colorado River at Lee’s Ferry 1,200 annual averageRunning mean 25 “Klamath” should read Klamath River at Keno 1000 20 800 15 Driest600 10-Year Periods in Reconstructed Records 10 400 “Sacramento River” should read Sacramento River Runoff Million Acre-feet Sacramento River Runoff, 900-2012 5 21,000 0 annual average 800 17,000900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 “San Joaquin” should read San Joaquin River Runoff 13,000 9,000 San Joaquin River Runoff, 900-2012 7,000 annual average 6,000 5,000 4,000 3,000 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Sacramento River runoff is the sum of the unimpaired flow at the Sacramento River above Bend Bridge, Feather River at Oroville, Yuba River near Smartville, and American River below Folsom Lake. San Joaquin River runoff is the sum of the unimpaired flow at the Stanislaus River below Goodwin Reservoir, Tuolumne River below La Grange, Merced River below Merced Falls, and San Joaquin River inflow to Millerton Lake. Figure provided courtesy of Connie Woodhouse, University of Arizona 5 2021 DROUGHT BROCHURE across the San Rafael Bridge to bring water obtained Year 2017, localized drought conditions persisted in the through a complex system of exchanges to Marin Central Coast region and were not ended until a wet Municipal Water District in southern Marin County. The Water Year 2019. 1987–1992 drought stands out because of its six-year A period of historically recorded hydrology of little more duration. Twenty-three counties declared local drought than a century does not represent the full range of the emergencies during that period. Santa Barbara climate system’s natural variability. Paleoclimate experienced the greatest water supply reductions among information, such as streamflow reconstructions based on the larger urban areas. In addition to adoption of measures tree-ring data, shows that natural variability can be far such as a 14-month ban on all lawn watering, the city greater than that observed in the historical record.

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