Bulletin No. 69-72, California High Water 1971-1972

California Department of Water Resources (DWR) | November 15th, 1973

Bulletin No. 69-73, California High Water 1972-1973

California Department of Water Resources (DWR) | December 15th, 1974

Bulletin No. 69-74, California High Water 1973-1974

California Department of Water Resources (DWR) | November 15th, 1974

Bulletin No. 69-75, California High Water 1974-1975

California Department of Water Resources (DWR) | February 15th, 1976

Bullletin No. 69-64, California High Water 1963-1964

California Department of Water Resources (DWR) | September 15th, 1965

California Department of Water Plan 2023: Navigating Climate Challenges with Equity and Resilience

California Department of Water Resources (DWR) | September 20th, 2023

The California Water Plan (Water Plan), updated every five years, is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water

The California Water Plan (Water Plan), updated every five years, is the State’s strategic plan for sustainably and equitably managing, developing, and stewarding water resources. Required by Water Code Section 10005, the plan presents the status and trends of California’s water-dependent natural resources; water supplies; and agricultural, urban, and environmental water demands for a range of plausible future scenarios.

California Water Plan 2013: Sacramento River Hydrologic Region Report

California Department of Water Resources (DWR) | October 30th, 2014

The Sacramento River Hydrologic Region (see Figure SR-1 includes the entire California drainage area of the Sacramento River (the state’s largest river) and its tributa

The Sacramento River Hydrologic Region (see Figure SR-1 includes the entire California drainage area of the Sacramento River (the state’s largest river) and its tributaries. The region extends from Chipps Island in Solano County north to Goose Lake in Modoc County. It is bounded by the Sierra Nevada on the east, the Coast Ranges on the west, the Cascade and Trinity mountains on the north, and the Sacramento-San Joaquin River Delta (Delta) on the south.  The Sacramento River Basin actually begins in Oregon, north of Goose Lake, a near-sink that intercepts the Pit River drainage at the California-Oregon border. Some key issues for this region are summarized here and discussed further later in this report. Agriculture. Between 2005 and 2010, the region supported about 1.95 million acres of irrigated agriculture on average. Approximately 1.58 million acres is irrigated on the valley floor. The surrounding mountain valleys add about 370,000 irrigated acres to the region’s total — primarily as pasture and alfalfa. The gross value of agricultural production in the Sacramento Valley for 2011 was about $4.1 billion (California Department of Food and Agriculture 2013). Rice and walnuts are the highest grossing crops in the region followed by almonds and tomatoes. The direct, indirect, and induced effects of the agricultural industry to the regional economy are discussed in this report. Groundwater. With a 2005-2010 average annual extraction volume of 2.7 million acre-feet (maf), groundwater pumping in the Sacramento River Hydrologic Region accounts for 17 percent of all the groundwater extraction in California — the third highest among the 10 hydrologic regions in California, behind Tulare Lake Hydrologic Region with 38 percent and San Joaquin River Hydrologic Region with 19 percent of the total. Overall, groundwater contributes to about 31 percent of the total water supply. Most groundwater extraction in the region occurs for agricultural water use (2.4 maf), meeting about one-third of agricultural water demands. Groundwater extraction for urban water use is significantly less (465 thousand acre-feet [taf]), which meets about half of the urban water needs. Groundwater levels for much of the region have declined from 2005 to 2010. Groundwater level declines ranging from 20 to 30 feet are seen in the northwestern portion of the Sacramento Valley Groundwater Basin. Declines ranging from to 10 to 20 feet are seen in the northern, the mid- to south-western, and the southeastern portions of the valley. For the rest of the Sacramento Valley Groundwater Basin and the Redding Area Groundwater Basin, groundwater level declines have ranged from zero to 10 feet. Flood. Exposure to a 500-year flood event in the region threatens approximately one in three residents, almost $65 billion in assets (crops, buildings, and public infrastructure), 1.2 million acres of agricultural land, and over 340 sensitive species. Almost 95 percent of Sutter County residents, more than 55 percent of Yuba County and Yolo County residents, and more than 50 percent of agricultural land region-wide are exposed to the 500-year flood event. Climate Change. Several different climate regions overlie portions of the Sacramento River Hydrologic Region. Air temperature data collected for the past century has been summarized by the Western Regional Climate Center (WRCC) for the different regions which are outlined below. Within the WRCC North Central climate region, mean temperatures have increased by about 0.8 to 1.7 °F (0.4 to 0.9 °C) in the past century, with minimum and maximum temperatures increasing by about 1.2 to 2.1 °F (0.7 to 1.2 °C) and 0.1 to 1.5 °F (0.1 to 0.8 °C), respectively. Within the WRCC North East climate region, mean temperatures have increased by about 0.8 to 2.0 °F (0.5 to 1.1 °C) in the past century, with minimum and maximum temperatures increasing by about 0.9 to 2.2 °F (0.5 to 1.2 °C) and by 0.5 to 2.1 °F (0.3 to 1.2 °C), respectively. Within the WRCC Sierra climate region, mean temperatures have increased by about 0.8 to 2.0 °F (0.5 to 1.1 °C) in the past century, with minimum and maximum temperatures increasing and decreasing by about 1.7 to 2.8 °F (0.9 to 1.5 °C) and by -0.2 to 1.3 °F (-0.1 to 0.7 °C), respectively. Within the WRCC Sacramento-Delta climate region, mean temperatures have increased by about 1.5 to 2.4 °F (0.9 to 1.3 °C) in the past century, with minimum and maximum temperatures increasing by about 2.1 to 3.1 °F (1.2 to 1.7 °C) and by 0.8 to 2.0 °F (0.4 to 1.1 °C), respectively (Western Regional Climate Center 2013). The region also is currently experiencing impacts from climate change through changes in statewide precipitation and surface runoff volumes, which in turn affect availability of local and imported water supplies. During the last century, the average early snowpack in the Sierra Nevada decreased by about 10 percent, which equates to a loss of 1.5 maf of snowpack storage (California Department of Water Resources 2008). Projections and impacts based on modeling of climate change are included in this report.

California Winter Precipitation Change under Global Warming in the Coupled Model Intercomparison Project Phase 5 Ensemble

American Meteorological Society (AMS) | August 23rd, 2013

Projections of possible precipitation change in California under global warming have been subject to considerable uncertainty because California lies between the

Projections of possible precipitation change in California under global warming have been subject to considerable uncertainty because California lies between the region anticipated to undergo increases in precipitation at mid-to-high latitudes and regions of anticipated decrease in the subtropics. Evaluation of the large-scale model experiments for phase 5 of the Coupled Model Intercomparison Project (CMIP5) suggests a greater degree of agreement on the sign of the winter (December–February) precipitation change than in the previous such intercomparison, indicating a greater portion of California falling within the increased precipitation zone. While the resolution of global models should not be relied on for accurate depiction of topographic rainfall distribution within California, the precipitation changes depend substantially on large- scale shifts in the storm tracks arriving at the coast. Significant precipitation increases in the region arriving at the California coast are associated with an eastward extension of the region of strong Pacific jet stream, which appears to be a robust feature of the large-scale simulated changes. This suggests that effects of this jet extension in steering storm tracks toward the California coast constitute an important factor that should be assessed for impacts on incoming storm properties for high-resolution regional model assessments.

California's Flood Future: Recommendations for Managing the State's Flood Risk (Highlights)

California Department of Water Resources (DWR) | November 14th, 2013

California’s Coast and Ocean Summary Report

California Energy Commission (CEC) | August 27th, 2018

This report synthesizes current scientific understanding about the impacts of climate change on California’s coast and ocean and presents a forward-looking summary of

This report synthesizes current scientific understanding about the impacts of climate change on California’s coast and ocean and presents a forward-looking summary of challenges and opportunities for the future. It is one component of California’s Fourth Climate Change Assessment (Fourth Assessment). To prepare this report, the state called upon the California Ocean Protection Council (OPC) and California Ocean Science Trust (OST) to convene an Ocean Protection Council Science Advisory Team (OPC-SAT) working group composed of science and policy leaders. Similar to other components of the Fourth Assessment, the 12-member working group was guided by an Advisory Group of end users and high-level decision-makers. This report is intended to provide accessible scientific information that is relevant for policy and decision-makers, build a foundation for policy to address climate change impacts through adaptation and mitigation, highlight best practices and models for coastal adaptation to climate change along the coast, and inform interested members of the public on the impacts of climate change on California’s coast and ocean waters and potential approaches for adaptation and mitigation. It will also inform the next update of the Safeguarding California plan, a policy document serving as California’s climate adaptation strategy, by presenting a scientific grounding to help focus and prioritize future state adaptation efforts.