2021 Emergency Drought Salinity Barrier Project Water Quality Certification

California State Water Resources Control Board (SWRCB) | May 28th, 2021

The California Department of Water Resources (DWR) is proposing to implement the 2021 Emergency Drought Salinity Barrier Project (Project). The Project consists of instal

The California Department of Water Resources (DWR) is proposing to implement the 2021 Emergency Drought Salinity Barrier Project (Project). The Project consists of installation of a temporary emergency drought salinity barrier across West False River in the Sacramento-San Joaquin Delta (Delta). The barrier will be constructed of embankment rock (riprap). The purpose of the Project is to control saltwater intrusion into the Central and south Delta and conserve water in upstream reservoirs for other uses. Pursuant to Clean Water Act section 401, the State Water Resources Control Board (State Water Board) has authority to consider whether a proposed activity involving a discharge to navigable waters complies with applicable water quality standards and other appropriate requirements of state law and to issue a water quality certification if those requirements will be met. The State Water Board concludes that, as conditioned herein, water quality certification may be issued.  During drought conditions, the release of water stored in upstream reservoirs may be insufficient to repel salinity moving upstream from San Francisco Bay. According to DWR’s analyses, without the protection of the drought salinity barrier, saltwater intrusions could render Delta water unusable for agricultural needs, reduce habitat value for aquatic species, and affect roughly 25 million Californians who rely on the export of this water for personal use. Installation of the temporary rock barrier at West False River would limit salinity intrusion into the Central and south Delta and would potentially conserve water for a variety of uses system-wide.  On May 10, 2021, California Governor Gavin Newsom issued a Proclamation of State of Emergency (May 2021 Proclamation) due to drought conditions and directed DWR, among other things, to implement plans that address potential Delta salinity issues, including installation and removal of emergency drought salinity barriers as needed. The May 2021 Proclamation mandates that such emergency barriers be designed to conserve water for use later in the year to meet state and federal Endangered Species Act requirements, preserve to the extent possible water quality in the Delta, and retain water supply for human health and safety uses. The State Water Board and the California Department of Fish and Wildlife (CDFW) are also directed to immediately consider any necessary regulatory approvals needed to install emergency drought salinity barriers. Additionally, the May 2021 Proclamation suspends Water Code section 13247, which requires state agencies to comply with water quality control plans approved by the State Water Board, and suspends the California Environmental Quality Act (CEQA) for purpose of implementing actions such as the Project.  Installation and removal of the Project will require a permit from the United States Army Corps of Engineers (USACE) pursuant to Section 404 of the Clean Water Act. DWR is seeking emergency authorization under USACE’s Regional General Permit (RGP) 8 – Emergency Repair and Protection Activities. 

2021-2022 Comprehensive Emergency Drought Barrier Effectiveness Report

California Department of Water Resources (DWR) | June 19th, 2024

This report summarizes the construction, monitoring, effectiveness, and impacts of the 2021–2022 West False River Emergency Drought Salinity Barrier (2021–2022 EDB).

This report summarizes the construction, monitoring, effectiveness, and impacts of the 2021–2022 West False River Emergency Drought Salinity Barrier (2021–2022 EDB). The purpose of this report is to meet the reporting requirements in the State Water Resources Control Board’s (State Water Board) May 2021 Water Quality Certification (Section 8.0, Condition 1: Monitoring, Analysis, and Reporting) and the commitment detailed in the California Department of Water Resources’ (DWR) Monitoring Plan (updated in January 2022).

2022 Annual Water Supply and Demand Assessment Summary Report

California Department of Water Resources (DWR) | November 22nd, 2022

This summary report contains projected water shortage information at the urban water supplier level as well as regional and statewide analyses of water supply conditions

This summary report contains projected water shortage information at the urban water supplier level as well as regional and statewide analyses of water supply conditions and is intended to inform the State Water Resources Control Board (State Water Board). Additionally, the report includes information on water shortage response actions taken by urban water suppliers as a result of their Annual Water Supply and Demand Assessments (Annual Assessments), and urban water suppliers’ compliance statistics with respect to their Annual Water Shortage Assessment Report (Annual Shortage Report) submittals. The purpose of this Annual Water Supply and Demand Assessment Summary Report (Summary Report) is to fulfill the California Water Code (CWC) §10644(c)(1)(B) requirements and it is due on or before September 30, 2022, and every year thereafter. The full text of the CWC section regarding the Department of Water Resources’ (DWR) Summary Report to the State Water Board is presented below for reference.

2022 Drought Plan Klamath Project, Oregon-California Interior Region 10, California-Great Basin

U.S. Bureau of Reclamation (USBR) | April 29th, 2022

The Klamath Project (Project) delivers water for irrigation purposes to up to approximately 230,000 acres in southern Oregon and northern California when water is availab

The Klamath Project (Project) delivers water for irrigation purposes to up to approximately 230,000 acres in southern Oregon and northern California when water is available. The Project relies upon several primary water sources to meet irrigation demands including water from Upper Klamath Lake (UKL), Clear Lake Reservoir, and Gerber Reservoir, and from the Klamath and Lost rivers. The Project’s water supplies (Project Supply or Supplies) have been impacted by the severe drought conditions currently affecting the Klamath Basin in southern Oregon and northern California. This 2022 Drought Plan describes the background for and the process of allocating the available Project Supply during the 2022 spring/summer irrigation season (April 15 through September 30, 20222), consistent with the contract priorities that exist within the Project.

2022 Drought Response Operations Plan

U.S. Bureau of Reclamation (USBR) | April 20th, 2022

A 1,200-year perspective of 21st century drought in southwestern North America

National Academy of Sciences (NAS) | December 11th, 2009

A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and

A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, ∼AD 900–1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.

A global transition to flash droughts under climate change

American Association for the Advancement of Science (AAAS) | April 13th, 2023

Flash droughts have occurred frequently worldwide, with a rapid onset that challenges drought monitoring and forecasting capabilities. However, there is no consensus on w

Flash droughts have occurred frequently worldwide, with a rapid onset that challenges drought monitoring and forecasting capabilities. However, there is no consensus on whether flash droughts have become the new normal because slow droughts may also increase. In this study, we show that drought intensification rates have sped up over subseasonal time scales and that there has been a transition toward more flash droughts over 74% of the global regions identified by the Intergovernmental Panel on Climate Change Special Report on Extreme Events during the past 64 years. The transition is associated with amplified anomalies of evapotranspiration and precipitation deficit caused by anthropogenic climate change. In the future, the transition is projected to expand to most land areas, with larger increases under higher-emission scenarios. These findings underscore the urgency for adapting to faster-onset droughts in a warmer future.

A Multidataset Assessment of Climatic Drivers and Uncertainties of Recent Trends in Evaporative Demand across the Continental United States

American Meteorological Society (AMS) | April 1st, 2022

Increased atmospheric evaporative demand has important implications for humans and ecosystems in water-scarce lands. While temperature plays a significant role in drivin

Increased atmospheric evaporative demand has important implications for humans and ecosystems in water-scarce lands. While temperature plays a significant role in driving evaporative demand and its trend, other climate variables are also influential and their contributions to recent trends in evaporative demand are unknown. We address this gap with an assessment of recent (1980–2020) trends in annual reference evapotranspiration (ETo) and its drivers across the continental United States based on five gridded datasets. In doing so, we characterize the structural uncertainty of ETo trends and decompose the relative influences of temperature, wind speed, solar radiation, and humidity. Results highlight large and robust changes in ETo across much of the western United States, centered on the Rio Grande region where ETo increased 135–235 mm during 1980–2020. The largest uncertainties in ETo trends are in the central and eastern United States and surrounding the Upper Colorado River. Trend decomposition highlights the strong and widespread influence of temperature, which contributes to 57% of observed ETo trends, on average. ETo increases are mitigated by increases in specific humidity in non-water-limited regions, while small decreases in specific humidity and increases in wind speed and solar radiation magnify ETo increases across the West. Our results show increases in ETo across the West that are already emerging outside the range of variability observed 20–40 years ago. Our results suggest that twenty-first-century land and water managers need to plan for an already increasing influence of evaporative demand on water availability and wildfire risks. SIGNIFICANCE STATEMENT: Increased atmospheric thirst due to climate warming has the potential to decrease water availability and increase wildfire risks in water-scarce regions. Here, we identified how much atmospheric thirst has changed across the continental United States over the past 40 years, what climate variables are driving the change, and how consistent these changes are among five data sources. We found that atmospheric thirst is consistently emerging outside the range experienced in the late twentieth century in some western regions with 57% of the change driven by temperature. Importantly, we demonstrate that increased atmospheric thirst has already become a persistent forcing of western landscapes and water supplies toward drought and will be an essential consideration for land and water management planning going forward.

A Perspective on the Drought in California

Legislative Analyst's Office (LAO) | November 21st, 1991

Despite heavy rains in March 1991, California continues to face a serious near-term water problem resulting from five years of drought. In fact, the amount of water in st

Despite heavy rains in March 1991, California continues to face a serious near-term water problem resulting from five years of drought. In fact, the amount of water in storage on October 1, 1991 was about equal to the amount in storage one year ago—a year in which strict conservation measures were imposed in some areas and there were significant reductions in water supplies for many agricultural users. In this paper, we provide background information on California's water system, the impact of the drought, water needs in the future, and legislative options for coping with water supply limitations.

A tale of two California droughts: Lessons amidst record warmth and dryness in a region of complex physical and human geography

American Geophysical Union (AGU) | November 19th, 2015

The state of California has experienced the worst drought in its historical record during 2012–2015. Adverse effects of this multi year event have been far from unifor

The state of California has experienced the worst drought in its historical record during 2012–2015. Adverse effects of this multi year event have been far from uniformly distributed across the region, ranging from remarkably mild in most of California’s densely populated coastal cities to very severe in more rural, agricultural, and wildfire-prone regions. This duality of impacts has created a tale of two very different California droughts—highlighting enhanced susceptibility to climate stresses at the environmental andsocioeconomic margins of California. From a geophysical perspective, the persistence of related atmospheric anomalies has raised a number of questions regarding the drought’s origins—including the role of anthropogenic climate change. Recent investigations underscore the importance of understanding the underlying physical causes of extremes in the climate system, and the present California drought represents an excellent case study for such endeavors. Meanwhile, a powerful El Niño event in the Pacific Ocean offers the simultaneous prospect of partial drought relief but also an increased risk of flooding during the 2015–2016 winter—a situation illustrative of the complex hydroclimatic risks California and other regions are likely to face in a warming world.