Solar Energy and Groundwater in the San Joaquin Valley

Public Policy Institute of California (PPIC) | October 26th, 2022

The Sustainable Groundwater Management Act (SGMA) requires groundwater users to bring their basins into balance over the next two decades. In the San Joaquin Valley, this

The Sustainable Groundwater Management Act (SGMA) requires groundwater users to bring their basins into balance over the next two decades. In the San Joaquin Valley, this will likely mean taking more than 500,000 acres of agricultural land out of intensive irrigated production. Local and regional economies could be stressed as a result, with some regular employment opportunities in agriculture disappearing and public revenues declining if lands are not put to new uses. As landowners and newly formed groundwater agencies tackle the groundwater deficits in their areas, utility-scale solar development—already an attractive option for landowners owning property with or without water rights—could offer an opportunity to keep lands that exit irrigated production economically productive. Moreover, development could provide multiple benefits by helping to supplement habitat and mitigate dust generation on transitioning lands. However, the expansion of solar hinges on whether state-level energy system planning processes—in conjunction with local land use planning—can address the transmission challenges that threaten the region’s promise as a solar power hub.

Solar-power replacement as a solution for hydropower foregone in US dam removals

Nature Portfolio (Springer Nature) | August 26th, 2019

There is a growing dam removal movement in the United States, driven in part by environmental, safety and cost considerations. These include electricity-producing hydro-d

There is a growing dam removal movement in the United States, driven in part by environmental, safety and cost considerations. These include electricity-producing hydro-dams, many of which are ageing and will require substantial maintenance or removal over the coming decades. However, hydropower has been and remains an important source of energy for the development of the United States, presently generating about 6% of the nation’s electricity while providing essential grid services. As a potential solution to the conflict between these imperatives, industrial-scale photovoltaics (PVs) could be used for replacement of the energy foregone from hydro-dam removals either by installing the PV infrastructure in the area formerly inundated by the dam reservoir or through offsite replacement. Presently, the total PV generation in the conterminous United States is 35,919 GWh yr−1, or approximately 13% of hydropower generation. On the basis of actual hydropower generation in the conterminous United States in 2016 (that is, 274,868 GWh yr−1), we estimated that 529,885 ha of PVs would be needed to replace the generation of all 2,603 hydro-dams—an area approximately equal to the land size of Delaware. PVs could replace the total annual energy produced from these dams while requiring only 13% of their existing reservoir area. If all the hydro-dams in the United States were removed and only 50% of the emergent land was used for PVs, 945,062 GWh yr−1 power could be generated, which is 3.44 times the current hydropower generation. These analyses are theoretical and do not consider costs, which would be highly site specific. Replacement by PVs without energy storage could not replicate the dispatchability and grid services provisions of existing hydropower facilities; however, improving battery storage capabilities may ameliorate this shortcoming. We suggest that PVs could replace much of the annual electricity output of hydro-dams in the United States while using substantially less land area and providing considerable environmental and ecological benefits.

Sonoma Creek Baylands Strategy

Sonoma Land Trust | May 1st, 2020

The purpose of the Strategy is to provide Sonoma Land Trust and partners with a clear and comprehensive plan that coordinates the protection, acquisition, restoration, an

The purpose of the Strategy is to provide Sonoma Land Trust and partners with a clear and comprehensive plan that coordinates the protection, acquisition, restoration, and enhancement of diverse baylands habitats (e.g., subtidal, mudflat, tidal marsh, brackish marsh, freshwater marsh, upland-wetland transition), integrates natural processes to increase climate resilience of the Sonoma Creek Baylands, identifies appropriate public access, and provides recommendations for the redesign of SR 37 and increased connectivity under and across the SMART rail line where they pass through the Sonoma Creek Baylands. 

Sonoma Valley Groundwater Sustainability Plan

Sonoma Water | January 29th, 2022

Source area management practices as remediation tool to address groundwater nitrate pollution in drinking supply wells

Journal of Contaminant Hydrology (Elsevier) | July 19th, 2019

Nitrate in drinking water may cause serious health problems for consumers. Agricultural activities are known to be the main source of groundwater nitrate contaminating ru

Nitrate in drinking water may cause serious health problems for consumers. Agricultural activities are known to be the main source of groundwater nitrate contaminating rural domestic and urban public water supply wells in farming regions. Management practices have been proposed to reduce the amount of nitrate in groundwater, including improved nutrient management practices and “pump and fertilize” with nitrate-affected irrigation wells. Here, we evaluate the feasibility and long-term impacts of agricultural managed aquifer recharge (Ag-MAR) in the source area of public water supply wells. A numerical model of nitrate fate and transport was developed for the Modesto basin, part of California's Central Valley aquifer system. The basin is representative of semi-arid agricultural regions around the world with a diversity of crop types, overlying an unconsolidated sedimentary aquifer system. A local public supply well in an economically disadvantaged community surrounded by farmland was the focus of this study. Model scenarios implemented include business as usual, alternative low-impact crops, and Ag-MAR in the source area of the public supply well. Alternative nutrient management and recharge practices act as remediation tools in the area between farmland and the public supply well. Improved agricultural source area management practices are shown to be an effective tool to maintain or even enhance groundwater quality in the targeted supply well while remediating ambient groundwater.

Source, distribution, and management of arsenic in water from wells, Eastern San Joaquin Ground-Water Subbasin, California

U.S. Geological Survey (USGS) | October 15th, 2008

Source, movement and age of groundwater in the upper part of the Mojave River Basin, California, USA

Proceedings of the 1994 International Symposium on Application of Tracers in Arid Zone Hydrology | August 22nd, 1996

Water samples from wells were collected and analysed for oxygen-18, deuterium, tritium, carbon-14, and carbon-13 to determine the source, movement and age of groundwate

Water samples from wells were collected and analysed for oxygen-18, deuterium, tritium, carbon-14, and carbon-13 to determine the source, movement and age of groundwater in the upper part of the Mojave River basin. Water in the alluvial aquifer has a median deuterium composition of — 66% and contains tritium, and was recently recharged by water from the Mojave River. Water in the regional aquifer near the Mojave River, near Summit Valley, and underlying several small washes has deuterium compositions heavier than — 60 %. Although some water in the regional aquifer near the Mojave River contains tritium, most of this water does not contain tritium. Carbon-14 data indicate that this water was recharged less than 2400 years ago. Water in the remainder of the regional aquifer has a median deuterium composition of — 84 %, which is as much as 20 % lighter than the volume-weighted deuterium composition of present-day precipitation. These data show that this water was recharged under climatic conditions different from average conditions today. Carbon-14 data indicate that some water in the regional aquifer was recharged more than 20,000 years ago.

Source, Movement, and Age of Ground Water in a Coastal California Aquifer

U.S. Geological Survey (USGS) | July 11th, 1996

Understanding the contribution of recharge from different sources is important to the management of ground-water supply in coastal aquifers in California especial

Understanding the contribution of recharge from different sources is important to the management of ground-water supply in coastal aquifers in California especially where water-supply or water-quality problems have developed as a result of ground-water pumping. In areas where water levels have changed greatly as a result of pumping and no longer reflect predevelopment conditions, an analysis of isotopic data can provide information about the source, movement, and age of ground water that is not readily obtained from a more traditional analysis of ground-water data This information can be used to develop management strategies that incorporate the availability of natural and artificial recharge to control water-level declines and water-quality degradation. In this study, the ratios of the stable isotopes of oxygen and hydrogen were used to determine the source and trace the movement of ground water in the Santa Clara-Calleguas basin, Ventura County, California Tritium and carbon-14 data were used to estimate the age (time since recharge) of ground water.

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

Hydrogeology Journal (Springer) | July 3rd, 2015

Sources, Pathways and Loadings: Multi-Year Synthesis with a Focus on PCBs and Hg

San Francisco Estuary Institute (SFEI) | December 15th, 2015

This report provides a synthesis of information gathered since 2000 on sources, pathways, and loadings of pollutants of concern in the San Francisco Bay Area with a focus

This report provides a synthesis of information gathered since 2000 on sources, pathways, and loadings of pollutants of concern in the San Francisco Bay Area with a focus on polychlorinated biphenyls (PCBs) and total mercury (Hg). Concentration and load estimates for other pollutants of concern (POC) are provided in the Appendix tables but not supported by any synthesis or discussion in the main body of the report. The PCB and Hg TMDLs for San Francisco Bay call for implementation of control measures to reduce stormwater PCB loads from 20 kg to 2 kg by 2030 and to reduce stormwater Hg loads from 160 kg to 80 kg by 2028 with an interim milestone of 120 kg by 2018. These are very challenging objectives given that the 2 kg PCB load allocation translates to a mean annual yield of 0.31 g/km2 for the free flowing areas downstream from reservoirs (6,650 km2), a mean annual concentration of 1.33 ng/L (assuming an annual average flow from small tributaries of 1.5 km3), and mean annual particle ratio of 1.4 ng/g of suspended sediment load (assuming an average annual suspended sediment load of 1.4 million metric t). Similarly for Hg, the 80 kg load allocation translates to a mean annual yield of 12 g/km2, a mean annual concentration of 53 ng/L, and mean annual particle ratio of 58 ng/g of suspended sediment load. Concentrations of these low magnitudes have been observed commonly in the Bay Area for Hg and yields of this low magnitude have been observed for PCBs and Hg. However, concentrations of PCBs at these magnitudes have only been observed in Marsh Creek (a more rural watershed) and particle ratios of PCBs and Hg as low as these have never been observed in the region.