North Coast

Drought less predictable under declining future snowpack

Nature Portfolio (Springer Nature) | April 20th, 2020

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical ear

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical early warning of hydrologic drought. This paradigm faces an impending challenge given consensus that a smaller fraction of future precipitation will fall as snow. Here, we apply downscaled hydrologic simulations from 28 climate model projections to show that by mid-century (2036–2065), 69% of historically snowmelt-dominated areas of the western United States see a decline in the ability of snow to predict seasonal drought, increasing to 83% by late century (2070–2099). Reduced predictability arises when peak snowpack approaches zero or because of decreased warm-season runoff efficiency. Changes in drought prediction skill show significant (P < 0.01) elevation dependence, with lower-elevation coastal areas most impacted by warming. Ancillary predictive information can only partially mitigate snow-based predictability losses to 65% of areas, underscoring the importance of declining future snowpack.

Drought Management and Climate Adaptation of Small, Self-Sufficient Drinking Water Systems in California

California Energy Commission (CEC) | August 15th, 2018

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This study focuses on the 2012-2016 Drought in California, documenting how small self-sufficient drinking water systems were affected and challenged by, and responded to the extreme event.

Drought Resilience Interagency and Partners Collaborative Progress Report (2026)

California Department of Water Resources (DWR) | March 16th, 2026

This report summarizes the 2025 activities and progress of the Drought Resilience Interagency and Partners (DRIP) Collaborative.

This report summarizes the 2025 activities and progress of the Drought Resilience Interagency and Partners (DRIP) Collaborative.

Drought water right curtailment analysis for California’s Eel river

American Society of Civil Engineers (ASCE) | February 1st, 2018

Water users in California’s hybrid water rights system have different legal priorities to available surface water in times of water scarcity. A set of two linear progra

Water users in California’s hybrid water rights system have different legal priorities to available surface water in times of water scarcity. A set of two linear programming models was developed to determine curtailments of water use under drought conditions according to riparian and appropriative water right doctrines with spatially varying water availability and water rights within a basin. The models were implemented in spreadsheets and extended to estimate water right reliability and factors of safety in water rights administration. Alternate methods for calculating water use curtailments are discussed. Curtailments from the models are compared with actual water shortage notices issued by the state for the Eel River, California for June 30, 2014. Analyzing water use curtailments with an algorithm in spreadsheet software offers a mechanistic, transparent, accessible, and precise approach derived from legal doctrines to support water rights administration during drought.

Droughts in California

Public Policy Institute of California (PPIC) | April 1st, 2021

Dynamic flood modeling essential to assess the coastal impacts of climate change

Nature Portfolio (Springer Nature) | March 13th, 2019

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant eco

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant economic, humanitarian, and national-security challenges. However, the majority of previous efforts to characterize potential coastal impacts of climate change have focused primarily on long-term SLR with a static tide level, and have not comprehensively accounted for dynamic physical drivers such as tidal non-linearity, storms, short-term climate variability, erosion response and consequent flooding responses. Here we present a dynamic modeling approach that estimates climate-driven changes in flood-hazard exposure by integrating the effects of SLR, tides, waves, storms, and coastal change (i.e. beach erosion and cliff retreat). We show that for California, USA, the world’s 5th largest economy, over $150 billion of property equating to more than 6% of the state’s GDP and 600,000 people could be impacted by dynamic flooding by 2100; a three- fold increase in exposed population than if only SLR and a static coastline are considered. The potential for underestimating societal exposure to coastal flooding is greater for smaller SLR scenarios, up to a seven-fold increase in exposed population and economic interests when considering storm conditions in addition to SLR. These results highlight the importance of including climate-change driven dynamic coastal processes and impacts in both short-term hazard mitigation and long-term adaptation planning.

Ecological forecasts for marine resource management during climate extremes

Nature Portfolio (Springer Nature) | December 5th, 2023

Economic Impacts of the 2020–22 Drought on California Agriculture

University of California, Merced (UC Merced) | November 22nd, 2022

California just ended its third consecutive year of drought, resulting in the driest three-year period in the instrumental record. Multi-year deficits in precipitation in

California just ended its third consecutive year of drought, resulting in the driest three-year period in the instrumental record. Multi-year deficits in precipitation in the state’s usually wetter northern regions have been compounded by increased crop evaporative demands, leading to water scarcity impacts to agriculture across the state. Although 2020 was a dry year, water reserves stored during the wetter years of 2017 and 2019 greatly diminished drought impacts during that year. The water outlook changed rapidly in 2021—the third driest water year on record with the highest evaporative demand. The northern regions of the state—including the Sacramento Valley, the Scott and Shasta valleys, the Pit River valleys (northern intermountain valleys), and the Russian River—faced unusually dry conditions. Drought emergency conditions in 2021 were proclaimed first in the Russian River, Scott River and Shasta River basins, which faced subsequent curtailments. Water curtailments were extended to the Sacramento Valley later in the season. Water for local agriculture, ecosystems, exports, and water quality protection in the Sacramento-San Joaquin Delta were compromised by low water reserves. Atmospheric rivers in October and December 2021 provided temporary drought relief for a portion of the state, but record low precipitation from January-September allowed for extreme drought conditions to reign into the 2022 water year. To overcome persistent precipitation deficits and below-average storage in major reservoirs, the state again implemented water rights curtailments and low water deliveries from the State Water Project. The US Bureau of Reclamation announced reduced Central Valley Project deliveries—including unprecedented cutbacks to senior contractors in the Sacramento Valley—and local agencies implemented cutbacks as a first tier of drought response measures. Compared with the 2021 water year, however, 2022 brought less severe water cutbacks in the San Joaquin Valley. This report provides estimates of the economic impacts to agriculture for first three years of the current drought, which began in 2020. We use a combination of climate, hydrologic, agricultural and economic models, supplemented by informal surveys of irrigation districts and remote sensing data. The study includes nearly 88% of the 8.7 million acres of irrigated crop area in the state (LandIQ, 2019) excluding idle land. Our preliminary analysis for 2020–21 (Medellín-Azuara et al. 2022), focused on the Central Valley, and also examined the Russian River basin (North Coast), and northern intermountain valleys in Siskiyou, Shasta, and Modoc counties. Here, we expanded our spatial coverage to include the Central Coast, South Coast, and Colorado River.

Economics of a State Water Resources Program

Legislative Analyst's Office (LAO) | July 9th, 1957

Eel River Groundwater Sustainability Plan

Humboldt County Groundwater Sustainability Agency | January 29th, 2022

In 2015, Humboldt County received a planning grant from DWR for technical studies and planning which led to the submission in December 2016 of a Groundwater Sustainabili

In 2015, Humboldt County received a planning grant from DWR for technical studies and planning which led to the submission in December 2016 of a Groundwater Sustainability Plan (GSP) Alternative, a streamlined version of a GSP. The GSP Alternative was disapproved by DWR in 2019 primarily because objective management criteria had not been established for 10 years; a quantitative estimate of sustainable yield was not developed; and the GSP Alternative did not quantify the impacts of groundwater use on surface water systems and determine at what point they are significant and unreasonable. As a result of the GSP Alternative being disapproved, formation of a Groundwater Sustainability Agency (GSA) was required and development of a full GSP was required by January 31, 2022. This is that document. Due to file size, this document has been divided into sections. Part 1, Part 2, Part 3, Part 4, Part 5 Click here for the Eel River Valley GSP page at the California Department of Water Resources