Statement of Findings regarding the Periodic Review and Approval of the Coastal Plain of Orange County Basin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings regarding the Periodic Review and Approval of the Corralitos - Pajaro Valley Subbasin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings regarding the Periodic Review and Approval of the Gilroy-Hollister Valley - LLagas Area Subbasin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings regarding the Periodic Review and Approval of the Livermore Valley Basin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings Regarding the Periodic Review and Approval of the Santa Clara Valley – Santa Clara Subbasin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings regarding the Periodic Review and Approval of the Tahoe Valley - Tahoe South Subbasin Alternative Groundwater Sustainability Plan

California Department of Water Resources (DWR) | June 27th, 2024

Statement of Findings Regarding the Periodic Review of Alternative Groundwater Sustainability Plan Coachella Valley – Mission Creek Subbasin (No. 7-021.02)

California Department of Water Resources (DWR) | June 27th, 2024

Statewide Effects of Ending Long-Term Groundwater Overdraft in California

American Society of Civil Engineers (ASCE) | September 19th, 2019

Groundwater overdraft is a major problem globally and has been a growing problem for California for decades. This overdraft is predominantly driven by the economic value

Groundwater overdraft is a major problem globally and has been a growing problem for California for decades. This overdraft is predominantly driven by the economic value of water for agricultural production and cities. Spurred by the recent drought, California passed legislation requiring the elimination of groundwater overdraft by 2040. This paper employs a statewide hydroeconomic optimization model to explore potential water supply effects of ending long-term groundwater overdraft in California’s Central Valley for several general water policies with historical and warmer–drier climates. The model minimizes agricultural, urban scarcity, and operating costs over 82 years of historical hydrologic variability, given today’s infrastructure and environmental flow constraints. The model results assess effects of overdraft and Delta policies for different climates on water deliveries, economic costs, environmental flows, water market operations, and the economic value of expanding infrastructure capacities. Prohibiting long-term overdraft leads to reduced agricultural water use and reoperations, and reduced outflows to the sea from the Sacramento-San Joaquin Delta, where water availability policies become important. In combination with a warmer–drier climate, ending overdraft further exacerbates water scarcities, increases environmental and economic costs, and increases the marginal economic value of water exports from the Delta, which are likely to worsen water conflicts and illustrate connections of California’s groundwater and surface water problems. Economically useful adaptation actions include more water transfers involving the Delta, water markets, and trades; conjunctive use of surface water and groundwater; and recycled wastewater supplies for coastal urban users.

Statistical Clustering of Major Solutes: Use as a Tracer for Evaluating Interbasin Groundwater Flow into Indian Wells Valley, California

Geological Society of America (GSA) | February 9th, 2006

Many previous studies have demonstrated use of specific solutes or isotopes as tracers of groundwater flow. We present a technique that uses standard hydrochemical inform

Many previous studies have demonstrated use of specific solutes or isotopes as tracers of groundwater flow. We present a technique that uses standard hydrochemical information to create statistically based hydrochemical facies, which are then used as tracers of groundwater flow. This approach reduces potential subjective bias during interpretation of single tracer data in complex systems with multiple sources or conflicting multiple tracer data. Standard hydrochemical data from 1,368 water samples that spanned more than 80 years were analyzed using cluster analysis to decipher groundwater flow paths in Indian Wells Valley (IWV), California. The statistically derived hydrochemical facies form distinct spatial patterns in which all major-ion concentrations increase progressively from Sierra Nevada (recharge) to China Lake playa (discharge), consistent with the topographically driven flow of groundwater (the typical case for basin and range flow systems). However, once individual samples could be placed in the context of the normal hydrochemical evolution, anomalies are readily identifiable. The distribution of water chemistry in the southeastern part of the IWV does not conform to the regional trend. Groundwater from that part of the IWV is statistically more similar to waters from the Kern Plateau area (in the high Sierra Nevada outside the local watershed) than to waters from the local watershed. The groundwater is interpreted to originate from the fracture-directed interbasin flow from the Kern Plateau area that is directly recharging the alluvial aquifer in the subsurface. Inclusion of this flow could substantially alter current water budgets and water resources management approaches.

Status and Understanding of Groundwater Quality in the Klamath Mountains Study Unit, 2010: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | August 6th, 2014

Groundwater quality in the Klamath Mountains (KLAM) study unit was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and

Groundwater quality in the Klamath Mountains (KLAM) study unit was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in Del Norte, Humboldt, Shasta, Siskiyou, Tehama, and Trinity Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA Priority Basin Project was designed to provide a spatially unbiased, statistically robust assessment of the quality of untreated (raw) groundwater in the primary aquifer system. The assessment is based on water-quality data and explanatory factors for groundwater samples collected in 2010 by the USGS from 39 sites and on water-quality data from the California Department of Public Health (CDPH) water-quality database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH water-quality database for the KLAM study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. This study included two types of assessments: (1) a status assessment, which characterized the status of the current quality of the groundwater resource by using data from samples analyzed for volatile organic compounds, pesticides, and naturally occurring inorganic constituents, such as major ions and trace elements, and (2) an understanding assessment, which evaluated the natural and human factors potentially affecting the groundwater quality. The assessments were intended to characterize the quality of groundwater resources in the primary aquifer system of the KLAM study unit, not the quality of treated drinking water delivered to consumers by water purveyors.