Projected responses of the coastal water table for California using present-day and future sea-level rise scenarios

U.S. Geological Survey (USGS) | August 11th, 2020

Coastal groundwater levels (heads) can increase with sea level rise (SLR) where shallow groundwater floats on underlying seawater. In some areas coastal groundwater could

Coastal groundwater levels (heads) can increase with sea level rise (SLR) where shallow groundwater floats on underlying seawater. In some areas coastal groundwater could rise almost as much as SLR, but where rising groundwater intersects surface drainage features, the increase will be less. Numerical modeling can provide insight into coastal areas that may be more or less vulnerable to hazards associated with SLR-driven groundwater shoaling (moving closer to the ground surface) and emergence (flooding the ground surface), providing coastal planners with critical information that can be used to increase public safety, mitigate physical damages, and more effectively manage and allocate resources in complex coastal settings. Seamless unconfined groundwater heads for coastal California groundwater systems were modeled with homogeneous, steady-state MODFLOW simulations. The geographic extent examined was limited primarily to low-elevation (land surface less than approximately 10 m above mean sea level) areas. In areas where coastal elevations increase rapidly (e.g., bluff stretches), the model boundary was set approximately 1 kilometer inland of the present-day shoreline. Steady-state MODFLOW groundwater flow models were used to obtain detailed (10-meter-scale) predictions over large geographic scales (100s of kilometers) of groundwater heads for both current and future sea-level rise (SLR) scenarios (0 to 2 meters (m) in 0.25 m increments, 2.5 m, 3 m, and 5 m) using a range of horizontal hydraulic conductivity (Kh) scenarios (0.1, 1, and 10 m/day). For each SLR/Kh combination, results are provided for two marine boundary conditions; local mean sea level (LMSL) and mean higher-high water (MHHW), and for two model versions. In the first model version, groundwater reaching the land surface is removed from the model, simulating loss via natural drainage. In the second model version, SLR impacts are modeled by simply raising the present-day (SLR 0m) modeled groundwater head by the amount of sea-level rise, simulating the worst-case "linear" response to sea-level rise. Modeled groundwater heads were then subtracted from high-resolution topographic digital elevation model (DEM) data to obtain water table depths. Groundwater head and water table depths are presented in raster GeoTIFF format. Polygon shapefiles also present water table depths by depth range (emergent, 0 to 1, 1 to 2, 2 to 5, and greater than 5 meters depth). All results are presented by County.

Projecting groundwater storage changes in California’s Central Valley

Nature Portfolio (Springer Nature) | August 27th, 2018

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a

Accurate and detailed knowledge of California’s groundwater is of paramount importance for statewide water resources planning and management, and to sustain a multi-billion-dollar agriculture industry during prolonged droughts. In this study, we use water supply and demand information from California’s Department of Water Resources to develop an aggregate groundwater storage model for California’s Central Valley. The model is evaluated against 34 years of historic estimates of changes in groundwater storage derived from the United States Geological Survey’s Central Valley Hydrologic Model (USGS CVHM) and NASA’s Gravity Recovery and Climate Experiment (NASA GRACE) satellites. The calibrated model is then applied to predict future changes in groundwater storage for the years 2015–2050 under various precipitation scenarios from downscaled climate projections. We also discuss and project potential management strategies across different annual supply and demand variables and how they affect changes in groundwater storage. All simulations support the need for collective statewide management intervention to prevent continued depletion of groundwater availability.

Protecting Groundwater Quality in California: Management Considerations for Avoiding Naturally Occurring and Emerging Contaminants

Environmental Defense Fund (EDF) | September 20th, 2019

Public Draft Groundwater Sustainability Plan for the Santa Ynez River Valley Groundwater Basin, Western Management Area

Western Management Area Groundwater Sustainability Agency | September 1st, 2021

This Groundwater Sustainability Plan (GSP) is prepared in accordance with the 2014 Sustainable Groundwater Management Act (SGMA) and covers the Western Management Area (W

This Groundwater Sustainability Plan (GSP) is prepared in accordance with the 2014 Sustainable Groundwater Management Act (SGMA) and covers the Western Management Area (WMA) of the Santa Ynez River Valley Groundwater Basin (Basin or SYRVGB) located in coastal central California. There are two principal aquifers within the WMA: an Upper Aquifer, consisting of younger alluvial sediments that are primarily associated with river and surface water geomorphic processes, and a Lower Aquifer, which is more extensive throughout the Basin and consists of older geologic depositions. Marginal geologic formations containing perched water-bearing soils are also identified within the Basin but are not principal aquifers managed under SGMA. The Santa Ynez River is the primary surface water source within the Basin. The subflow of the Santa Ynez River is considered part of the river flow and is managed as surface water pursuant to the administrative authority and jurisdiction of the State Water Resources Control Board (SWRCB) over waters flowing in known and definite channels. The analyses conducted for this GSP indicate that current Basin conditions are generally sustainable. Potential undesirable results (defined as significant and unreasonable impacts to sustainability indicators) have been identified and specific minimum thresholds have been developed to help ensure that undesirable results do not occur under future conditions. Potential project operations and management actions designed to maintain and improve groundwater conditions and sustainability have been identified and are described within this GSP.

Public Update for Drought Response Groundwater Basins with Potential Water Shortages and Gaps in Groundwater Monitoring

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

Year 2013 closed as the driest in recorded history for many areas of California. On January 17, 2014, Governor Brown signed a Proclamation of a State of Emergency in resp

Year 2013 closed as the driest in recorded history for many areas of California. On January 17, 2014, Governor Brown signed a Proclamation of a State of Emergency in response to the drought. This Public Update addresses Order #11 of the Governor’s Proclamation and provides information regarding groundwater basins with potential water shortages and gaps in groundwater monitoring. Groundwater is a vital resource in California providing close to 60 percent of the state’s water supply in a dry year. Drought conditions typically result in an increase of groundwater well activity and pumping to compensate for water supply shortages. Increased groundwater pumping can lead to adverse conditions including dry wells, subsidence, decreased water quality, saline intrusion, and stream depletion. Evaluation of available data produced the following: Groundwater levels have decreased in nearly all areas of the state since spring 2013, and more notably since spring 2010. Since spring 2008, groundwater levels have experienced all-time historical lows (for period of record) in most areas of the state and especially in the northern portion of the San Francisco Bay Hydrologic Region, the southern San Joaquin Valley, and also for the South Lahontan and South Coast hydrologic regions. In many areas of the San Joaquin Valley, recent groundwater levels are more than 100 feet below previous historical lows. The greatest concentration of recently deepened wells is in the fractured bedrock foothill areas of Nevada, Placer, and El Dorado counties. The Kaweah and Kings subbasins have the greatest numbers of deepened wells in an alluvial groundwater basin. Thirty-six alluvial groundwater basins that have a high degree of groundwater use and reliance may possess greater potential to incur water shortages as a result of drought. The basins exist in the North Coast, Central Coast, Sacramento River, Tulare Lake, and South Coast hydrologic regions. Of California’s 515 alluvial groundwater basins, 169 are fully or partially monitored under the California Statewide Groundwater Elevation Monitoring (CASGEM) Program. Forty of the 126 High and Medium priority basins are not monitored under CASGEM. There are significant CASGEM groundwater monitoring data gaps in the Sacramento, San Joaquin River, Tulare Lake, Central Coast, and South Lahontan hydrologic regions. Although there are 4,122 CASGEM wells and 39,429 Voluntary wells in the Water Data Library groundwater level database, gaps in groundwater monitoring persist. Several areas of the state lack a current groundwater management plan that addresses all related requirements of the California Water Code. DWR is contracting with National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory for use of satellite-based radar data to measure subsidence in the Sacramento and San Joaquin valleys. NASA, the U.S. Geological Survey, and U.S. Department of Agriculture are developing an automated system for estimating fallowed agricultural acreage.

Public Update for Drought Response: Groundwater Basins with Potential Water Shortages, Gaps in Groundwater Monitoring, Monitoring of Land Subsidence, and Agricultural Land Fallowing

California Department of Water Resources (DWR) | November 25th, 2014

California’s Water Year 2014 (October 1, 2013 through September 30, 2014) was one of the driest in decades and followed two consecutive dry years throughout the state.

California’s Water Year 2014 (October 1, 2013 through September 30, 2014) was one of the driest in decades and followed two consecutive dry years throughout the state. Water year 2014 was the fourth driest year on record after 1924, 1931, and 1977, based on the Sacramento Valley water year index, and the second driest year on record after 1977, based on the San Joaquin Valley water year index. On January 17, 2014, Governor Brown signed a Proclamation of a State of Emergency in response to the drought. In accordance with the proclamation, the Department of Water Resources (DWR) prepared Public Update for Drought Response, Groundwater Basins with Potential Water Shortages and Gaps in Groundwater Monitoring, dated April 30, 2014. On April 25, 2014, the governor issued a second emergency proclamation to strengthen the state’s ability to manage water and habitat effectively in drought conditions and called on all Californians to redouble their efforts to conserve water. In accordance with Order #11 of the April proclamation, this report provides additional and expanded information on groundwater basins with potential water shortages, gaps in groundwater monitoring, monitoring of land subsidence, and agricultural land fallowing.

Pulse Flows Component of the Water Storage Investment Program Groundwater Projects Supplemental Environmental Impact Report

California Department of Water Resources (DWR) | July 30th, 2024

This final supplemental environmental impact report (Final SEIR) has been prepared for the Pulse Flows Component of the Water Storage Investment Program (WSIP) Groundwate

This final supplemental environmental impact report (Final SEIR) has been prepared for the Pulse Flows Component of the Water Storage Investment Program (WSIP) Groundwater Projects (Pulse Flows Component). The Final SEIR is a supplement to three certified environmental impact reports (EIRs) prepared pursuant to the California Environmental Quality Act (CEQA) for three independent WSIP projects (referred to herein as the “WSIP Groundwater Projects”): (1) the Chino Basin Program, (2) the Kern Fan Groundwater Storage Project (Kern Fan), and (3) the Willow Springs Water Bank Project (Willow Springs).

Pumping and Ground-Water Storage Depletion in Las Vegas Valley, Nevada, 1955-1974

U.S. Geological Survey (USGS) | July 1st, 1976

Pumping for the masses: evolution of groundwater management in metropolitan Los Angeles

Geo Journal (Springer) | August 7th, 2015

Groundwater supports many aspects of human life. In cities, groundwater can provide a cost-effective source of water for drinking and industrial uses, while groundwater b

Groundwater supports many aspects of human life. In cities, groundwater can provide a cost-effective source of water for drinking and industrial uses, while groundwater basins provide storage. The role of groundwater in a city’s water supply tends to change over time. In the Los Angeles metropolitan area, groundwater is critical. Over decades, users in the region’s many basins allocated annual pumping rights to groundwater among users through adjudications. These rights were determined through collective processes over decades, which contributed to the complex array of public and private organizations involved in water management. The rights also continue to evolve. We analyzed changes in the distribution of groundwater rights over time for adjudicated basins in Southern Los Angeles County. Results indicate that groundwater rights are increasingly: (1) controlled or regulated by public institutions and municipalities, and (2) consolidated among larger users. Yet, both the percentage of total supplies provided by groundwater, as well as the distribution of groundwater rights, varies widely among cities and communities throughout Los Angeles. As metropolitan Los Angeles faces reduced water imports and emphasizes local water reliance, access to pumping rights and storage capacity in groundwater basins will become even more vital. We discuss implications of our results for future urban water management.

Pure Water Soquel Groundwater Model Simulation Results

Soquel Creek Water District | June 22nd, 2018

This technical memorandum discusses model simulation groundwater levels, groundwater budget, and particle tracking results to support the Environmental Impact Rep

This technical memorandum discusses model simulation groundwater levels, groundwater budget, and particle tracking results to support the Environmental Impact Report of the Pure Water Soquel project involving replenishment of advanced purified recycled water within Soquel Creek Water District’s (SqCWD’s) service area. Six model simulations have been run using the calibrated GSFLOW model for the Santa Cruz Mid- County Basin (the Basin) where SqCWD’s service area is located. These simulations have different pumping and active replenishment distributions, as follows: Two Projected Existing Conditions (No Project) simulations with SqCWD’spumping distribution reflecting future demand without additional replenishment at proposed recharge wells. Two Project simulations with SqCWD’s pumping distribution reflecting future demand and pumping re-distribution with the addition of replenishment at the Monterey and Cabrillo College Dr. sites (referred to as the Cabrillo-Monterey simulations). These simulations also represent potential replenishment at the Twin Lakes Church site instead of one of the two Cabrillo College Dr. sites. The Twin Lakes Church site is approximately 500-750 feet to the west of the Cabrillo College Dr. sites. Two Project simulations with the same pumping distribution as the Cabrillo- Monterey simulations, but with replenishment at the Monterey and Willowbrook sites (referred to as the Monterey-Willowbrook simulations).Simulation groundwater levels are evaluated for the following effects: Comparison of groundwater levels at coastal monitoring wells to protective elevations estimated to prevent seawater intrusion from further occurring in groundwater supply aquifers. Groundwater levels in the recharge wells to assess whether model results are consistent with estimated capacities for the well, recognizing that site specific testing will be needed to confirm recharge well capacities. Groundwater levels at nearby wells to evaluate effects on operation of those municipal, private, and institutional wells.Simulation groundwater budgets are evaluated for following effects: • Flows entering and leaving the Basin, including flows to and from groundwater in storage and flows offshore to prevent seawater intrusion. • Flows between groundwater and surface water. This memo does not include results for a Cumulative simulation. Information from the City of Santa Cruz to define its Aquifer Storage and Recovery project to be cumulative with Pure Water Soquel is not available or developed at this time. This memo includes results from particle tracking based on the above simulations performed to support the Salt and Nutrient Anti-degradation Study and permitting of the recharge wells. This involves particle tracking of simulated purified, replenishment water to evaluate the fate of the water as it travels in subsurface aquifers. Particle tracking is also used to evaluate travel times of purified, replenishment water, which requires refined analysis near the recharge wells. A scope to superimpose analytic element solutions for recharge and nearby extraction wells onto GSFLOW results to facilitate travel time calculations was approved by SqCWD Board December 18, 2017 and results should be forthcoming in July 2018.