Salinas Valley – Upper Valley Aquifer

Statistics

Basin Notes

2003: Bulletin 118 basin description

2007: “Steelhead use of upper Salinas River tributaries is dependent upon the presence of a migration corridor in the main stem Salinas River. One of the main limitations to migration within the Salinas River Basin is the limited availability of adequate flows … The number of days within the migration period where flows are adequate for migration is highly variable from year to year, and groundwater pumping has shortened this window … Spring flows declined substantially following increased pumping of groundwater for agricultural production.” Source: Biological Opinion, Salinas Valley Water Project, National Marine Fisheries Service, June 21, 2007

2014: CASGEM Basin Prioritization: medium “Upper Valley Aquifer groundwater recharge uniquely linked to reservoir releases. The pattern of storage change is similar to that of the Forebay Subarea, with a similar apparent reliance on reservoir releases … If reservoir releases are severely curtailed, storage losses on the order of 50,000 to 70,000 afy, or about 30-50% of annual pumping would occur.” Source: State of the Salinas River Groundwater Basin Report, 10 December 2014

2015: Monterey County Water Resources Agency SGMA timeline

2018: Draft priority: High. Comment – Declining groundwater levels. See State of the Salinas River Groundwater Basin, Monterey County Water Agency,  January 16, 2015 Basin boundary request with Paso Robles Area subbasin 3-004.06 pending.

2019: Basin boundary modification approved. Extended the shared boundary of the Upper Valley Aquifer and Paso Robles Area subbasins to coincide with the Monterey and San Luis Obispo county line. Expansion changed basin priority from High to Medium.

2022: January 24 – GSP submitted to DWR

2023: April 27 – DWR approved GSP

At-A-Glance

Source: CA DWR
Source: CA DWR

California Water Library Documents About This Basin

A joint Gaussian process model of geochemistry, geophysics, and temperature for groundwater TDS in the San Ardo Oil Field, California, USA

Journal of Hydrology (Elsevier) | May 27th, 2025

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Application of Hydrologic Simulation Program—FORTRAN (HSPF) as Part of an Integrated Hydrologic Model for the Salinas Valley, California

U.S. Geological Survey (USGS) | April 8th, 2025

The U.S. Geological Survey (USGS), in cooperation with the Monterey County Water Resources Agency, conducted studies to help evaluate the surface-water and grou

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Salinas Valley Integrated Hydrologic and Reservoir Operations Models, Monterey and San Luis Obispo Counties, California

Monterey County Resources Agency (MCRA) | April 5th, 2025

To evaluate the challenging water management issues in the Salinas Valley, the U.S. Geological Survey, Monterey County Water Resource Agency, and the Salina

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Establishing ecological thresholds and targets for groundwater management

Nature Portfolio (Springer Nature) | April 3rd, 2024

Groundwater is critical for many ecosystems, yet groundwater requirements for dependent ecosystems are rarely accounted for during water and conservation planning. Here w

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Statement of Findings regarding the Approval of the Salinas Valley -- Upper Valley Aquifer Subbasin Groundwater Sustainability Plan

California Department of Water Resources (DWR) | March 27th, 2023

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Linkages between land-use change and groundwater management foster long-term resilience of water supply in California

Journal of Hydrology: Regional Studies (Elsevier) | March 9th, 2022

Study Region: We created a 270-m coupled model of land-use and groundwater conditions, LUCAS-W[ater], for California’s Central Coast. This groundwater-dependent region

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Upper Valley Aquifer Subbasin Groundwater Sustainability Plan

Salinas Valley Basin Groundwater Sustainability Agency | January 13th, 2022

The 2014 California Sustainable Groundwater Management Act (SGMA) requires that medium- and high-priority groundwater basins and subbasins develop Groundwater Sustainabil

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The Economic Impact on the Local Economy of Irrigated Agriculture in the Paso Robles Area and Potential Impacts of the Sustainable Groundwater Management Act

California Polytechnic State University, San Luis Obispo (CSU) | August 26th, 2020

The purpose of this study is to analyze the economic impact of the agricultural and wine industry within the Paso Robles Subbasin and AVA and San Luis Obispo County and t

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Salinas Valley Groundwater Basin 180/400-Foot Aquifer Subbasin Groundwater Sustainability Plan

Salinas Valley Basin Groundwater Sustainability Agency | January 3rd, 2020

The 2014 California Sustainable Groundwater Management Act (SGMA) requires that medium and high-priority groundwater basins and subbasins develop Groundwater Sustainabil

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A multi-isotope (B, Sr, O, H, and C) and age dating (3H–3He and14C) study of groundwater from Salinas Valley, California: Hydrochemistry, dynamics, and contamination processes

American Geophysical Union (AGU) | January 31st, 2002

The chemical and isotope (11B/10B, 87Sr/86Sr, 18O/16O, 2H/H, 13C/12C, 14C, and 3He/3H) compositions of groundwater from the upper aquifer system of the Salinas Valley in

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A Water Resources Data Network Evaluation for Monterey County, California; Phase 3, Northern Salinas River Drainage Basin

U.S. Geological Survey (USGS) | December 13th, 1990

Continuing data collection and analysis are vital to efficient development and management of water resources. To insure that water managers have adequate information on c

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Bulletin 118: California's Groundwater (1980)

California Department of Water Resources (DWR) | January 1st, 1980

Ground water management is a major issue in California.  The Governor's Commission to Review California Water Rights Law, in its December 1978 report, recommends a new g

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GSA Information