California's Water Supply Strategy: Adapting to a Hotter, Drier Future

California Department of Water Resources (DWR) | August 16th, 2022

California's Water Supply Strategy: Adapting to a Hotter, Drier Future

Office of Governor Gavin Newsom | August 11th, 2022

California’s Central Valley Groundwater Study: A Powerful New Tool to Assess Water Resources in California’s Central Valley

U.S. Geological Survey (USGS) | June 16th, 2009

Competition for water resources is growing throughout California, particularly in the Central Valley. Since 1980, the Central Valley’s population has nearly

Competition for water resources is growing throughout California, particularly in the Central Valley. Since 1980, the Central Valley’s population has nearly doubled to 3.8 million people. It is expected to increase to 6 million by 2020. Statewide population growth, anticipated reductions in Colorado River water deliveries, drought, and the ecological crisis in the Sacramento–San Joaquin Delta have created an intense demand for water. Tools and information can be used to help manage the Central Valley aquifer system, an important State and national resource. The U.S. Geological Survey (USGS) has released results from a study on the largest water reservoir in the State of California, the Central Valley groundwater system. The findings show continued loss of stored groundwater in the southern part of the valley (see figure below). Since about 1960, groundwater has been depleted by almost 60 million acre-feet, which is, on average, enough to supply every resident of California with water for 8 years. In order to complete the study, the USGS developed an extensive, detailed three-dimensional (3D) computer model of the hydrologic system of the Central Valley (Faunt, 2009). The Central Valley Hydrologic Model (CVHM) simultaneously accounts for changing water supply and demand across the landscape, and simulates surface water and groundwater flow across the entire Central Valley. This new hydrologic modeling tool can be used by water managers to understand how water moves through the aquifer system, predict water-supply scenarios, and address issues related to water competition in California and the Central Valley including: Conjunctive water use (interdependent use of surface water and groundwater); Conservation of agricultural land; Land-use change, including environmental concerns and urbanization, and its effects on water resources; and Effects of climate change.

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.

California’s Flood Future: Recommendations for Managing the State’s Flood Risk

California Department of Water Resources (DWR) | November 1st, 2013

California is at risk for catastrophic flooding that could have wide-ranging impacts due to the size of its economy and the number of people residing in the state. The St

California is at risk for catastrophic flooding that could have wide-ranging impacts due to the size of its economy and the number of people residing in the state. The State’s economy ranks ninth globally; therefore, the consequences associated with its potential exposure to property damage, economic harm, and loss of life are great. California is the nation’s most populous state, ranks third largest in land size, and has widely varying climates and topographies, all of which make developing one-size-fits-all solutions to flood risk management impracticable. In California, 20 percent of the almost 38 million residents live within 500-year floodplains (i.e., have a 0.2 percent chance of flooding in a given year). Four of the nation’s 15 largest cities are in California (Los Angeles, San Diego, San Jose, and San Francisco), and all are at risk for some type of flooding. These factors make decisions regarding California’s flood risk management policies and financial investments vital to the State and the nation. This report, California’s Flood Future: Recommendations for Managing the State’s Flood Risk (Flood Future Report) presents an overview of the flood threats facing the state, approaches for reducing flood risk, and recommendations for managing California’s flood risk. The Flood Future Report is the first statewide report to be developed through collaboration between the California Department of Water Resources (DWR) and the United States Army Corps of Engineers (USACE). As a joint report by the State and Federal governments, the document represents an unprecedented level of intergovernmental cooperation, including tribal entities.1 Additionally, this report would not have been possible without the participation of and information shared by more than 140 local flood management agencies. The Flood Future Report represents the first characterization of flood management activities and exposure to flood hazard throughout each county and hydrologic region of the state. This statewide assessment is intended to provide valuable information for local, State, and Federal decision makers as they chart California’s complex flood management future.

California’s Most Significant Droughts: Comparing Historical and Recent Conditions

California Department of Water Resources (DWR) | February 2nd, 2015

This report was prepared in response to the dry conditions of 2012-14 (Figure 1.1) and particularly in response to the very dry hydrology of water year 2014. Water year 2

This report was prepared in response to the dry conditions of 2012-14 (Figure 1.1) and particularly in response to the very dry hydrology of water year 2014. Water year 2014 ranked as the third driest on record in terms of statewide precipitation, with the three-year period of water years 2012-14 ranking as the driest consecutive three-year period on record in terms of statewide precipitation. Continuing dry hydrology in 2015 raises questions about the similarity of present conditions to those of prior droughts and changes in observed impacts as California’s population increases and new institutional requirements are put in place. The purpose of this report is to compare present conditions with California’s most significant droughts of statewide scope, to help answer questions about the comparative severity of drought hydrology and drought impacts. The report also summarizes lessons learned and commonalities seen in the state’s most severe historical droughts.

California’s Severe Drought Has Only Marginal Impacts on Food Prices

University of California Giannini Foundation of Agricultural Economics | May 14th, 2015

The extreme drought that has gripped California over the past several years is causing onerous adjustments in the natural and human environments. Agriculture, which uses

The extreme drought that has gripped California over the past several years is causing onerous adjustments in the natural and human environments. Agriculture, which uses much of the state’s water, is at the center of many of these arduous responses. The 2015 impacts of the continuing drought are still underway, but in this special Agriculture and Resource Economics Update issue, we project responses and consequences within agriculture and more broadly. In this issue, Hanak and Mount put this drought in the context of California’s history and put agriculture in the context of water institutions, management, and distribution throughout the state. Next, Medellin-Azuara and co-authors develop detailed, and albeit preliminary, assessments of 2015 irrigation water distribution. They estimate a cut to agriculture of about 8.8 million acre-feet, or about 30% of what might be available in a normal year. (This number may be an underestimate given recent events.) During droughts, farms increase groundwater pumping. The authors estimate that farmers and ranchers will replace about 6.2 million acre-feet of lost surface water deliveries with costly increases in groundwater pumping, where possible in 2015. Another painful response to drought is to leave land idle. The authors estimate about 564,000 more acres, mostly field crop land in the Central Valley (including irrigated pastures), will be idled in 2015. This too may be an underestimate. USDA reported on June 30, that 2015 California acreage of “principal crops,” (defined as field crops such as hay, grains, oilseeds, cotton and potatoes) is about 900,000 acres below the 2013 total of about four million acres. Over this period, tree nut and tomato acreage increased by about 180,000 acres. So, even accounting for the steady shift to tree nuts and some other higher revenue per acre (and per acre-foot) crops, there is a strong indication of severely accelerated reductions in field crop acreage in California. The economic toll of the drought is fewer jobs and smaller value of output and economic contribution that would have otherwise occurred. Based on 564,000 idled acres, Howitt et al. estimates farm revenue losses of $1.8 billion, economy-wide revenue losses of $2.7 billion, and 18,600 fewer jobs due to the agricultural drought. That these economic impacts are not even larger is a testament to the extraordinary efforts and innovations by farmers, and others in California agriculture. Idling land, shifting water across crops, and using each acre-foot more economically all have led to smaller losses of revenue and jobs, and only very small price increases for consumers.

California’s Stream Flow Monitoring System Is Essential for Water Decision Making

University of California, Berkeley (UC Berkeley) | April 1st, 2018

With California’s drought risk, flood risk, and demand for water all increasing, effective monitoring is more important than ever to water decision making. Str

With California’s drought risk, flood risk, and demand for water all increasing, effective monitoring is more important than ever to water decision making. Stream gages monitor the most basic vital sign of California’s waterways—stream flow.1 Stream flow data support day-to-day decisions about how to manage water and operate water infrastructure. In turn, those decisions have important implications for flood control and the water supplies upon which residential, industrial, agricultural, and environmental water users depend. Stream flow information also provides technical insights into basin hydrology, and those insights aid long-term water planning. As pressures on the state’s water systems intensify, the need for accurate and timely stream flow information will continue to grow. Opportunities for better water management created by groundbreaking legislation such as the Sustainable Groundwater Management Act (SGMA), the Open and Transparent Water Data Act, and Proposition 1 will be severely limited without an effective network of continuous stream gaging.

California’s Sustainable Groundwater Management Act and the Half-Exemption of Owens Valley Groundwater Basin

University of California, Los Angeles (UCLA) | May 1st, 2024

This Comment first uses historical accounts and secondary sources to describe the history of Owens Valley groundwater. It next describes the Governing Documents that curr

This Comment first uses historical accounts and secondary sources to describe the history of Owens Valley groundwater. It next describes the Governing Documents that currently manage this groundwater. It ends its history by relying on the content of OVGA meetings to tell the recent story of SGMA’s implementation in Owens Valley.

California’s Water: Climate Change and Water

Public Policy Institute of California (PPIC) | October 1st, 2016

California’s climate is warming and becoming more variable. While the state is a leader in reducing greenhouse gas emissions, its water system was designed for a 20th c

California’s climate is warming and becoming more variable. While the state is a leader in reducing greenhouse gas emissions, its water system was designed for a 20th century climate. All facets of water management must be updated to adapt to changing conditions. This brief summarizes strategies to help the state prepare for a changing climate and rising sea level. This publication is part of a briefing kit that summarizes a dozen of the state’s most pressing water management issues.