On-farm flood capture could reduce groundwater overdraft in Kings River Basin

California Agriculture (UCANR) | November 16th, 2016

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater rechar

Chronic groundwater overdraft threatens agricultural sustainability in California’s Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.

Paso Robles vineyard irrigation study provides benchmark data to assist future area groundwater management

California Agriculture (UCANR) | March 13th, 2018

Accurate information on irrigation water usage does not exist in many areas where groundwater is the primary water source. This lack of information will hinder

Accurate information on irrigation water usage does not exist in many areas where groundwater is the primary water source. This lack of information will hinder efforts to manage these groundwater basins sustainably according to current and future water regulations and policies. Using a low-cost methodology of irrigation-line pressure sensors connected to data loggers, we estimated irrigation applications at 84 vineyard sites in the Paso Robles Groundwater Basin over 4 years (2010–2013). We compared irrigation amounts with the preceding winter’s rainfall and with the growing season reference evapotranspiration (ETo). Over the study period, the average annual irrigation application was 11.46 inches (291 millimeters). The average annual application correlated inversely to the preceding winter’s rainfall, while the irrigation over the growing season (April–October) correlated directly with the ETo over this same period. This study provides an initial data framework that can be used by groundwater sustainability agencies to help manage groundwater in the Paso Robles area. The methodology also could be utilized in other regions to estimate regional irrigation usage while maintaining anonymity for participants.

Priorities for California’s Water

Public Policy Institute of California (PPIC) | November 14th, 2022

This report considers the state of water in California: What changes are we seeing now, and what should we expect in the near future? Then it examines how these climate s

This report considers the state of water in California: What changes are we seeing now, and what should we expect in the near future? Then it examines how these climate shifts will impact urban and rural communities, agriculture, and the environment. Finally, it explores wet-year strategies that will help Californians get through the dry years.

Refinement of Rice Water Consumptive Use During the Growing Season — Sacramento Valley

University of California, Davis (UC Davis) | June 6th, 2018

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected from 2007 through 2009, and from 2011 through 2013. M206 was identified by the University of California (UC) Cooperative Extension Farm Advisors as the most commonly grown rice variety in the study area. Phase I of this study was conducted by the University of California, Davis (UC Davis), under contract with DWR. A brief description of both Phase I and Phase II have been included here to provide orientation as the progression of the work and linkages between each phase regarding the study results. 

Refinement of Rice Water Consumptive Use During the Growing Season — Sacramento Valley Phase II — Cal-SIMETAW Model Study

California Department of Water Resources (DWR) | June 6th, 2018

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected from 2007 through 2009, and from 2011 through 2013. M206 was identified by the University of California (UC) Cooperative Extension Farm Advisors as the most commonly grown rice variety in the study area. Phase I of this study was conducted by the University of California, Davis (UC Davis), under contract with DWR. A brief description of both Phase I and Phase II have been included here to provide orientation as the progression of the work and linkages between each phase regarding the study results. 

Reimagining Water Infrastructure in a Changing California

American Water Resources Association (AWRA) | April 15th, 2023

For much of the 20th century, California’s water supply strategy has relied on building large reservoirs and conveyance systems to store and divert surface water and dr

For much of the 20th century, California’s water supply strategy has relied on building large reservoirs and conveyance systems to store and divert surface water and drilling ever deeper wells to tap declining aquifers. This approach has brought many benefits but has also come at great social, economic, and environmental costs. Moreover, these traditional water supplies are tapped out. Even in wet years, the state’s major rivers are overallocated and major aquifers severely overdrafted. Dry years intensify these issues. Persistent water challenges, the severe drought, and the intensifying effects of climate change highlight the vulnerability of California’s water systems and the need for new approaches.

Review of CDFW Recommendations for the 2022 Readoption of Drought Emergency Regulations on the Scott River and Recommendations for Future Management During Extreme Drought Conditions

Siskiyou Farm Bureau | August 31st, 2022

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

To evaluate the challenging water management issues in the Salinas Valley, the U.S. Geological Survey, Monterey County Water Resource Agency, and the Salinas Valley Basin Groundwater Sustainability Agency developed a comprehensive suite of models that represent the Salinas Valley Hydrogeologic system called the Salinas Valley System Model. The Salinas Valley Geologic Framework was developed to characterize the subsurface using various topographic and geologic data sources, including information on hydrogeologic units, their surfaces and extents, geologic structures, lithology, and elevations from borehole data and cross sections, as well as details on faults and existing models. The Salinas Valley Watershed Model simulates the entire Salinas River watershed. Monthly surface water inflows into the integrated hydrologic model domain were simulated using the Salinas Valley Watershed Model. The historical model uses historical climate data, water and land use data, and reservoir releases to simulate agricultural operations, including landscape water demands, diversions, and reclaimed wastewater. The operational model adds an embedded reservoir operations framework to the simulation of the historical model that allows specified operational rules to simulate reservoir releases and changes in reservoir storage. The operational model assumes current reservoir operations and constant land use, which differs from historical conditions. Thus, the operational model is a hypothetical baseline model that can be used by local water managers to evaluate and quantify potential benefits of water supply projects. Together, the geologic framework, watershed, historical, and operational models form a tool that can be used to simulate irrigated agriculture and associated reservoir operations of the integrated hydrologic system of the Salinas Valley.

Satellite observations indicate that chia uses less water than other crops in warm climates

Nature Portfolio (Springer Nature) | September 30th, 2024

Siskiyou County Agricultural Economics Analysis Considering Groundwater Regulation

University of California, Merced | September 2nd, 2021

This economic analysis estimates potential impacts in gross revenues from changing cropping patterns in Siskiyou County’s three agricultural valleys namely Butte Valle

This economic analysis estimates potential impacts in gross revenues from changing cropping patterns in Siskiyou County’s three agricultural valleys namely Butte Valley (Butte), Scott River Valley (Scott), and Shasta Valley (Shasta). This analysis provides insight on economic costs of benefits of land and water use decisions, while identifying areas that may benefit from intervention and stakeholder processes.