Sacramento River

Economic and Water Supply Effects of Ending Groundwater Overdraft in California's Central Valley

University of California, Davis (UC Davis) | March 1st, 2016

Surface water and groundwater management are often tightly linked, even when linkage is not intended or expected. This link is especially common in semi-arid regions, suc

Surface water and groundwater management are often tightly linked, even when linkage is not intended or expected. This link is especially common in semi-arid regions, such as California. This paper summarizes a modeling study on the effects of ending long-term overdraft in California’s Central Valley, the state’s largest aquifer system. The study focuses on economic and operational aspects, such as surface water pumping and diversions, groundwater recharge, water scarcity, and the associated operating and water scarcity costs. This analysis uses CALVIN, a hydro-economic optimization model for California’s water resource system that suggests operational changes to minimize net system costs for a given set of conditions, such as ending long-term overdraft. Based on model results, ending overdraft might induce some major statewide operational changes, including large increases to Delta exports, more intensive conjunctive-use operations with increasing artificial and in-lieu recharge, and greater water scarcity for Central Valley agriculture. The statewide costs of ending roughly 1.2 maf yr of groundwater overdraft are at least $50 million per year from additional direct water shortage and additional operating costs. At its worst, the costs of ending Central Valley overdraft could be much higher, perhaps comparable to the recent economic effects of drought. Driven by recent state legislation to improve groundwater sustainability, ending groundwater overdraft has important implications statewide for water use and management, particularly in the Sacramento–San Joaquin Delta. Ending Central Valley overdraft will amplify economic pressure to increase Delta water exports rather than reduce them, tying together two of California’s largest water management problems.

Economic and water supply effects of ending groundwater overdraft in California’s Central Valley

University of California, Davis (UC Davis) | March 1st, 2016

Surface water and groundwater management are often tightly linked, even when linkage is not intended or expected. This link is especially common in semi-arid regions,

Surface water and groundwater management are often tightly linked, even when linkage is not intended or expected. This link is especially common in semi-arid regions, such as California. This paper summarizes a modeling study on the effects of ending long-term overdraft in California’s Central Valley, the state’s largest aquifer system. The study focuses on economic and operational aspects, such as surface water pumping and diversions, groundwater recharge, water scarcity, and the associated operating and water scarcity costs. This analysis uses CALVIN, a hydro-economic optimization model for California’s water resource system that suggests operational changes to minimize net system costs for a given set of conditions, such as ending long-term overdraft. Based on model results, ending overdraft might induce some major statewide operational changes, including large increases to Delta exports, more intensive conjunctive-use operations with increasing artificial and in-lieu recharge, and greater water scarcity for Central Valley agriculture. The statewide costs of ending roughly 1.2 maf yr-1  of groundwater overdraft are at least $50 million per year from additional direct water shortage and additional operating costs. At its worst, the costs of ending Central Valley overdraft could be much higher, perhaps comparable to the recent economic effects of drought. Driven by recent state legislation to improve groundwater sustainability, ending groundwater overdraft has important implications statewide for water use and management, particularly in the Sacramento–San Joaquin Delta. Ending Central Valley overdraft will amplify economic pressure to increase Delta water exports rather than reduce them, tying together two of California’s largest water management problems.

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.

Economic-engineering optimization for California water management

American Society of Civil Engineers (ASCE) | May 15th, 2003

An economic-engineering optimization model of California’s major water supply system is presented. The model’s development, calibration, limitations, and resu

An economic-engineering optimization model of California’s major water supply system is presented. The model’s development, calibration, limitations, and results are reviewed. The major methodological conclusions are that large-scale water resources optimization models driven by economic objective functions are both possible and practical; deterministic models are useful despite their limitations; and data management, reconciliation, and documentation are important benefits of large-scale system modeling. Specific results for California indicate a great potential for water markets and conjunctive use to improve economic performance and significant economic value for expanding some conveyance facilities. Overall, economic-engineering optimization even if deterministic can suggest a variety of promising approaches for managing large systems. These approaches can then be refined and tested using more detailed simulation models. The process of developing large-scale models also motivates the systematic and integrated treatment of surface water, groundwater, facility, and water demand data, and identification of particularly important data problems, something of long-term value for all types of water resources analysis.

Economics of a State Water Resources Program

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

Ecosystem variability along the estuarine salinity gradient: Examples from long-term study of San Francisco Bay

Limnology and Oceanography (Wiley) | March 25th, 2017

The salinity gradient of estuaries plays a unique and fundamental role in structuring spatial patterns of physical properties, biota, and biogeochemical processes. We use

The salinity gradient of estuaries plays a unique and fundamental role in structuring spatial patterns of physical properties, biota, and biogeochemical processes. We use variability along the salinity gradient of San Francisco Bay to illustrate some lessons about the diversity of spatial structures in estuaries and their variability over time. Spatial patterns of dissolved constituents (e.g., silicate) can be linear or nonlinear, depending on the relative importance of river-ocean mixing and internal sinks (diatom uptake). Particles have different spatial patterns because they accumulate in estuarine turbidity maxima formed by the combination of sinking and estuarine circulation. Some constituents have weak or no mean spatial structure along the salinity gradient, reflecting spatially distributed sources along the estuary (nitrate) or atmospheric exchanges that buffer spatial variability of ecosystem metabolism (dissolved oxygen). The density difference between freshwater and seawater establishes stratification in estuaries stronger than the thermal stratification of lakes and oceans. Stratification is strongest around the center of the salinity gradient and when river discharge is high. Spatial distributions of motile organisms are shaped by species-specific adaptations to different salinity ranges (shrimp) and by behavioral responses to environmental variability (northern anchovy). Estuarine spatial patterns change over time scales of events (intrusions of upwelled ocean water), seasons (river inflow), years (annual weather anomalies), and between eras separated by ecosystem disturbances (a species introduction). Each of these lessons is a piece in the puzzle of how estuarine ecosystems are structured and how they differ from the river and ocean ecosystems they bridge.

Effect of the South Delta Agricultural Barriers on Emigrating Juvenile Salmonids

California Department of Water Resources (DWR) | November 15th, 2018

The California Department of Water Resources’ (DWR) Temporary Barriers Project (TBP) is an ongoing project that installs, operates, and monitors up to four temporary ro

The California Department of Water Resources’ (DWR) Temporary Barriers Project (TBP) is an ongoing project that installs, operates, and monitors up to four temporary rock-fill barriers constructed in waterways located in the southern portion of the Sacramento-San Joaquin Delta (Delta) near the cities of Tracy and Lathrop in San Joaquin County, California (Figure 1-1). Three of the temporary barriers—Old River at Tracy (ORTB), Middle River (MRB), and Grant Line Canal (GLCB), collectively, the south Delta agricultural barriers (SDABs)—are constructed and operated during the agricultural irrigation season, usually April through November. The SDABs are designed to act as flow control structures, retaining tidal fresh water behind each barrier following a flood tide. The fourth barrier, Head of Old River Barrier (HORB), is installed during the spring and fall as a fish guidance barrier. The HORB is normally installed in the spring to prevent juvenile fall-run San Joaquin River Chinook Salmon (Oncorhynchus tshawytscha) and juvenile Central Valley steelhead (Oncorhynchus mykiss) 2 from emigrating through Old River toward the south Delta water export facilities at the intakes of the State Water Project (SWP) and federal Central Valley Project (CVP). In the fall, the HORB helps to guide adult San Joaquin River Chinook Salmon to spawning locations in the upper watershed. Installation, operation, and removal of the SDABs has the potential to harm, harass, or cause mortality to fish species of management concern to the National Marine Fisheries Service (NMFS), specifically, juvenile fall-run Chinook Salmon which are NMFS Species of Concern (NMFS 2010), juvenile Central Valley steelhead which is a threatened species, an Endangered Species Act (ESA) Section 10j experimental population (63 Federal Register [FR] 13347), and juvenile Green Sturgeon (Acipenser medirostris), also a federally listed threatened species (71 FR 17757). The TBP is implemented in compliance with the terms and conditions of two NMFS Biological Opinions (BiOp) (NMFS 2008, 2009).

Effective at Any Scale: Watershed-based Decision Support Tools

San Francisco Estuary Institute (SFEI) | July 1st, 2016

EcoAtlas  tools apply the USEPA’s three-level wetland monitoring and assessment framework for wetland and stream protection in a variety of California watersheds, an

EcoAtlas  tools apply the USEPA’s three-level wetland monitoring and assessment framework for wetland and stream protection in a variety of California watersheds, and it can be adjusted to more generally support natural resource planning, assessment, monitoring, and reporting. EcoAtlas operationalizes the Wetland and Riparian Area Monitoring Plan (WRAMP) by enabling users to assess the abundance, distribution, diversity, and condition of wetlands in the landscape or watershed context.

Effects Analysis for the Delta Smelt Fall Habitat Action in 2019

U.S. Bureau of Reclamation (USBR) | August 1st, 2019

Effects of ferric sulfate and polyaluminum chloride coagulation enhanced treatment wetlands on Typha growth, soil and water chemistry

Science of the Total Environment (Elsevier) | January 15th, 2019

Land surface subsidence is a concern in many deltas worldwide as it contributes to water quality degradation, loss of fertile land and increased potential for levee f

Land surface subsidence is a concern in many deltas worldwide as it contributes to water quality degradation, loss of fertile land and increased potential for levee failure. As a possible solution to these concerns, on-site coagulation enhanced treatment wetlands (CETWs), coagulation water treatment followed by wetland passage serving as a settling basin, were implemented in a field-scale study located on a subsided island of the Sacramento-San Joaquin Delta in northern California under three treatments; coagulation with polyaluminum chloride (PAC), coagulation with ferric sulfate and an untreated control. Because CETWs offer a relatively novel solution for water quality improvement and subsidence reversal due to its low-infrastructure requirements and in-situ nature, effects from these systems remain uncharted and they may have adverse effects on plant biomass production that also contribute to sediment accretion. This study focuses on the effect CETWs had on the growth of Typha spp.; the dominant vegetation in the wetlands. Plant growth parameters and nutrient content were measured in conjunction with soil, pore water and surface water chemistry. Soil analysis indicated there was no intermixing of newly formed flocs and original soil material. Where there was significant deposition of floc, PAC treatment reduced phosphateconcentrations and ferric sulfate treatment increased total Fe concentrations in surrounding water compared to the control. Results indicated coagulation treatments had no negative effects on Typha leaf nutrient content, Typha growth or allometric parameters. Additionally, no signs of plant toxicity such as necrosis, wilting or chlorosis were observed in any of the treatments. Overall, this study suggests that CETWs are viable treatment option for water quality improvement and sediment accretion while having no negative impact on the growth of Typha plants.