Salinas Valley Groundwater Basin Monterey Subbasin Groundwater Sustainability Plan

Salinas Valley Basin Groundwater Sustainability Agency | January 28th, 2022

On September 16, 2014, the California legislature enacted the Sustainable Groundwater Management Act (SGMA) whose primary purpose is to achieve and/or maintain sustainabi

On September 16, 2014, the California legislature enacted the Sustainable Groundwater Management Act (SGMA) whose primary purpose is to achieve and/or maintain sustainability within the state’s high and medium priority groundwater basins. Key tenets of SGMA are the concept of local control, use of best available data and science, and active engagement and consideration of all beneficial uses and users of groundwater. As such, SGMA empowers certain local agencies to form Groundwater Sustainability Agencies (GSAs) whose purpose is to manage basins sustainably through the development and implementation of Groundwater Sustainability Plans (GSPs). Under SGMA, GSPs are required to contain certain elements, the most significant of which include: a Sustainability Goal; a description of the area covered by the GSP (“Plan Area”); a description of the Basin Setting, including the hydrogeologic conceptual model, historical and current groundwater conditions, and a water budget; locally-defined sustainability criteria; networks and protocols for monitoring sustainability indicators; and a description of projects and/or management actions that will be implemented to achieve or maintain sustainability. SGMA also requires a significant element of stakeholder outreach to ensure that beneficial uses and users of groundwater are given the opportunity to provide input into the GSP development and implementation process. This GSP covers the entire Monterey Subbasin (Department of Water Resources [DWR] Basin 3-004.10), which encompasses 30,850 acres (or 48.2 square miles) in the northwestern Salinas Valley Groundwater Basin in the Central Coast region of California (Figure ES-1). The Monterey Subbasin (Subbasin) has been designated by the California Department of Water Resources (DWR) as medium priority. As such, the Subbasin is required to develop a GSP by January 2022 and achieve sustainability by 2042. The GSP has been co-developed by the Marina Coast Water District Groundwater Sustainability Agency (MCWD GSA) and the Salinas Valley Basin Groundwater Sustainability Agency (SVBGSA) pursuant to a Framework Agreement. The Framework Agreement outlines the Management Areas to be established within the Subbasin, which are later formalized in this GSP. The Framework Agreement further establishes a basis for information developed by the two agencies to be integrated into a single GSP for the Monterey Subbasin. Plan approved by DWR 4/27/23.

Salinity distribution in heterogeneous coastal aquifers mapped by airborne electromagnetics

Soil Science Society of America (SSSA) | February 8th, 2011

Understanding the hydrologic setting of any given area is a challenging task, especially considering that the amount of available informaon is ofen very sparse re

Understanding the hydrologic setting of any given area is a challenging task, especially considering that the amount of available informaon is ofen very sparse relative to the size of the area and the complexity of the problem. We used geophysical transient electromagnetic (TEM) data from an airborne SkyTEM instrument to investigate discharge of freshwater from a river catchment into a coastal lagoon area, in support of large-scale hydrologic mapping of the HOBE hydrology research center. Existing hydrologic data indicate possible outflow from the catchment underneath the survey area, a hypothesis that was indeed backed up by our geophysical results. The results revealed a stratified geologic setting frequently incised by buried valleys beneath the lagoon. They also showed that the valleys are saturated with sea water, unlike the layers at the same depth that are probably saturated with brackish water. The salinity decreases with depth in large parts of the lagoon. The salinity distribution in the setting indicates the presence of intricate flow systems beneath the coastal area and the lagoon, and we propose that it is governed by the heterogeneity in the geologic setting. We also demonstrated how water depth as well as salinity can be accurately mapped using SkyTEM in combination with a robust and flexible inversion scheme.

Salinity Effects on Agricultural Irrigation‐related Uses

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | December 1st, 2016

Purpose: Summarize current state of knowledge regarding the effects of elevated EC (TDS) concentrations on crop yields with specific attention to seasonal tolerance

Purpose: Summarize current state of knowledge regarding the effects of elevated EC (TDS) concentrations on crop yields with specific attention to seasonal tolerances. Additional information provided regarding federal, state, international regulations and guidelines and effects of elevated EC on turfgrass, landscape plants and wetland plants.

Salinity Effects on MUN‐Related Uses of Water

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | December 1st, 2016

Purpose: Summarize current state of knowledge regarding the effects of elevated conductivity, salinity or TDS and hardness on drinking water supply

Purpose: Summarize current state of knowledge regarding the effects of elevated conductivity, salinity or TDS and hardness on drinking water supply and other domestic purposes for water use. Identify/summarize unique concerns related to specific ions (e.g. sodium, chloride, boron, etc.).

Salinity of deep groundwater in California: Water quantity, quality, and protection

National Academy of Sciences (NAS) | July 12th, 2016

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and g

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.

Salinity Trends in a Groundwater System Supplemented by 50 Years of Imported Colorado River Water

American Chemical Society (ACS) | September 21st, 2023

The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultur

The Indio subbasin of the Coachella Valley is a desert area of southern California where a growing population depends primarily on groundwater for drinking and agricultural uses. The aquifer system has been supplemented with Colorado River water through managed recharge and widespread irrigation since the mid-20th century. We use a combination of geochemical modeling and trend analysis to identify changes in total dissolved solids through time, elucidate the sources of dissolved solids, and quantify the extent of contributions from those sources throughout the Indio subbasin. We conclude that recharged Colorado River water is the primary source and driver of increasing salinity, particularly in areas immediately downgradient from the recharge locations and in the eastern part of the subbasin away from the recharge ponds due to irrigation using imported water. Other contributions of dissolved solids to groundwater resources include geothermal waters, wastewater effluent, and agricultural return flow, although their effects are more localized. This study presents a broadly applicable framework for identifying sources of dissolved solids in groundwater wells and salinity trends at a regional scale in a large data set.

Salt and Nutrient Management Plan Santa Clara River Valley East Subbasin

California State Water Resources Control Board (SWRCB) | October 25th, 2016

In accordance with the State Water Resources Control Board’s (SWRCB’s) Recycled Water Policy, the Upper Santa Clara River Integrated Regional Water Management Group

In accordance with the State Water Resources Control Board’s (SWRCB’s) Recycled Water Policy, the Upper Santa Clara River Integrated Regional Water Management Group (IRWMG), which is comprised of Castaic Lake Water Agency (CLWA), City of Santa Clarita, CLWA Santa Clarita Water Division (SCWD), Los Angeles County Flood Control District (LACFCD), Newhall County Water District (NCWD), San Gabriel & Lower Los Angeles Rivers and Mountains Conservancy, Santa Clarita Valley Sanitation District (SCVSD) and Valencia Water Company (VWC), have entered into a Memorandum of Understanding (MOU) to prepare a Salt and Nutrient Management Plan (SNMP) for the Santa Clara River Valley East Groundwater Subbasin (East Subbasin). This group of agencies, collectively known as the SNMP Task Force (Task Force) and facilitated by the CLWA, have directed the preparation of this SNMP, which was prepared using guidance set forth by the Los Angeles Regional Water Quality Control Board (LARWQCB). The purpose of this SNMP is to determine the current (ambient) water quality conditions in the East Subbasin and to ensure that all water management practices, including the use of recycled water, are consistent with water quality objectives. This SNMP is intended to provide the framework for water management practices to ensure protection of beneficial uses, and allow for the sustainability of groundwater resources consistent with the Water Quality Control Plan Los Angeles Region (Basin Plan). Additionally, compliance with the California Environmental Quality Act (CEQA) and approval by LARWQCB staff is required. As part of the SNMP, a monitoring plan has been developed for the East Subbasin which identifies key monitoring locations within each subunit for both surface water and groundwater.

Saltwater Intrusion in Los Angeles Area Coastal Aquifers— the Marine Connection

U.S. Geological Survey (USGS) | August 14th, 2002

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform t

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform to drinking-water or agricultural standards. This problem is significant because much of the water used by the nearly 10 million residents of Los Angeles County comes from ground-water sources. Although not all coastal aquifers in the region are at risk, the existing resources are vital and must be protected to maintain adequate supplies of potable water. In the 1950’s, construction began on the first of three “barriers” in an attempt to halt saltwater intrusion. Each barrier consists of a series of injection wells that essentially form a subsurface wall of freshwater designed to keep saltwater from penetrating further into aquifers. The barriers are only partly effective; saltwater continues to infiltrate in some areas. New studies show that the ground-water geohydrology of the coastal aquifers is more complex than previously imagined. U.S. Geological Survey (USGS) scientists, working in cooperation with the Water Replenishment District of Southern California and the Los Angeles County Department of Public Works, are expanding efforts to understand the geologic processes and fluid pathways that control saltwater intrusion.

Sampling for Per- and Polyfluoroalkyl Substances (PFAS) by the Groundwater Ambient Monitoring and Assessment Priority Basin Project

Publisher not available | May 25th, 2021

San Andreas Fault Stress Change Due To Groundwater Withdrawal in California's Central Valley, 1860-2010

American Geophysical Union (AGU) | December 28th, 2021

We investigate the spatial and temporal effects of groundwater removal in California's Central Valley on ground surface deformation and on stress changes on the nearby ce

We investigate the spatial and temporal effects of groundwater removal in California's Central Valley on ground surface deformation and on stress changes on the nearby central San Andreas fault (CSAF). In particular, we focus on two outstanding questions: (a) What are the spatial distributions of Coulomb failure stress (ΔCFS) on the CSAF? (b) What are the effects of viscoelasticity on uplift and ΔCSF over time? We focus on the well studied 2006–2010 drought, estimating the change in groundwater storage and the resulting uplift and stress change through a numerical model for the Earth. Viscoelastic effects are examined through an estimate of historical groundwater change from 1860-1961 and a hydrological model from 1961-2003 added to the 2006–2010 drought estimates. Here we find that lower crust or upper mantle viscosity variations enhance uplift and stress changes and that CSAF stress changes may accumulate with time, especially with droughts and groundwater consumption.