San Joaquin River

Land subsidence in the San Joaquin Valley, California, as of 1972

U.S. Geological Survey (USGS) | July 10th, 1975

Land subsidence which began in the mid-1920's due to groundwater overdraft in the San Joaquin Valley has caused widespread concern for the past two decades. Withdrawals

Land subsidence which began in the mid-1920's due to groundwater overdraft in the San Joaquin Valley has caused widespread concern for the past two decades. Withdrawals for irrigation increased from 3 million acre-feet in 1942 to 10 million acre-feet in 1966. Water levels declined at unprecedented rates during the 1950's and early 1960's. Pumping lifts became inordinately high, well casings failed at alarming rates, and differential settlement caused numerous farming and engineering problems. By 1970,5,200 square miles of valley land had been affected, and maximum subsidence exceeded 28 feet. The valley-wide volume of subsidence totaled 15.6 million acre-feet, one-half the initial storage capacity of Lake Mead. This subsidence represents one of the great environmental changes imposed by man. Importation of surface water to the northwestern and eastern areas of overdraft in the valley began in the 1950's and to the much larger western and southern areas in the late 1960's. Canal imports have largely replaced ground-water pumpage in these areas. As of 1973, after three decades of continued declining water levels, many hundreds of irrigation wells are idle and water levels are rising. Throughout much of the valley, artesian pressures are recovering toward their presubsidence levels, and elevations of the subsiding land surface are stabilizing. Basic-data graphs and computer-plotted stress-strain relationships constitute a major part of this report. They are based on 10-13 years of detailed field measurements of both water-level change and compaction collected by the U.S. Geological Survey at 20 selected locations in the San Joaquin Valley. The recharge characteristics of a ground-water reservoir are indicated roughly by the volume ratio, which is subsidence/pumpage. In the Los Banos-Kettleman City area, the values of this ratio range from less than 0.2 near the perimeter to more than 0.6 in the central part of the area. In the corresponding parts of the Arvin-Maricopa area, the ratio ranges from near 0 to more than 0.4.

Land subsidence in the San Joaquin Valley, California, as of 1980

U.S. Geological Survey (USGS) | July 1st, 1984

Land subsidence in the San Joaquin Valley, California, USA, 2007–2014

Copernicus Publications | November 12th, 2015

Land Transitions and Dust in the San Joaquin Valley

Public Policy Institute of California (PPIC) | July 24th, 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 mean taking more than 500,000 acres of agricultural land out of intensive irrigated production. Among other issues, this could potentially lead to air quality impacts if the lands become new sources of dust, especially windblown dust, which can have numerous negative short- and long-term health and environmental impacts. In addition, the changing climate may exacerbate risks as warmer temperatures can dry out soils and increase dust emissions. The overall air quality impact of transitioning agricultural land to new uses is nuanced, but proactive management can help to identify high-risk areas and at-risk communities, and direct effort and funding to the most cost-effective interventions.

Land use and land cover influence on water quality in the last free-flowing river draining the western Sierra Nevada, California

Journal of Hydrology (Elsevier) | November 10th, 2005

Land use and land cover across 28 sub-basins within the Cosumnes Watershed, CA (1989 km2) were correlated to nitrate-N and total suspended solids (TSS) loading between w

Land use and land cover across 28 sub-basins within the Cosumnes Watershed, CA (1989 km2) were correlated to nitrate-N and total suspended solids (TSS) loading between water years 1999 and 2001. The impact of human development on stream water quality was evident as both agricultural area and population density predicted TSS loading in a linear mixed effects model. In contrast to the TSS model, the nitrate-N loading model was more complex with agriculture, grassland, and the presence or absence of waste water treatment plants (WWTPs) all contributing. The lack of correlation between population density and nitrate-N loading indicates that human habitation of the landscape does not impact stream nitrate levels until a WWTP is built within the sub-basin. During dry water years the models predict a linear reduction in TSS loading but the correlations to agriculture and population density remain positive. In contrast, nitrate is positively correlated to grasslands during average water years and negatively correlated during dry water years. Analysis of constituent fluxes from the upper watershed versus the lower watershed indicates that silica is derived primarily from the uplands and that during dry water years the upper watershed is an important source of dissolved organic carbon (DOC) and nitrate. The lower watershed contributes the majority of the sediment and nutrients during both dry and average water years, the one caveat being that during dry years the lower basin becomes a nitrate sink.

LandFlex Grant Program Guidelines

California Department of Water Resources (DWR) | January 14th, 2023

The California Department of Water Resources (DWR) is administering the LandFlex Grant Program (LandFlex) through DWR’s Sustainable Groundwater Management (SGM) Grant P

The California Department of Water Resources (DWR) is administering the LandFlex Grant Program (LandFlex) through DWR’s Sustainable Groundwater Management (SGM) Grant Program. LandFlex (referred to as Ag Drought Relief) will award funds authorized by the California Budget Act of 2021 (Stats. 2021, ch. 44, § 25). This document contains DWR’s Guidelines and scoring criteria (Guidelines) for LandFlex. Climate change means that California needs to plan for a hotter, drier future. Long-term drought, fueled by climate change, has adversely affected the State’s water supplies, which includes groundwater availbility. In response to the Governor’s California’s Water Supply Strategy, Adapting to a Hotter, Drier Future, DWR will launch the LandFlex Program as a new and innovative tool to protect vulnerable drinking water wells. LandFlex will provide incentives to farmers to limit groundwater pumping in areas near communities reliant on vulnerable drinking water wells before they go dry. LandFlex combines traditional short-term fallowing incentives with the elimination of long-term unsustainable groundwater pumping, a unique approach to groundwater resilience. LandFlex is a program that will provide $25 million in block grants to local government agencies to grant to farmers who limit agricultural water use. Local government agencies will work directly with farmers in critically overdrafted (COD) basins (as identified in Bulletin 118) to identify lands that would reduce pumping impacts to nearby drinking water wells. Through financial incentives to farmers, LandFlex will provide multiple community benefits such as drinking water well relief, groundwater overdraft prevention, and climate resilience.

Landflex Grant Program Guidelines (revised)

California Department of Water Resources (DWR) | October 31st, 2024

LandFlex Program’s Guidelines

California Department of Water Resources (DWR) | December 8th, 2022

LandFlex is a program that will provide $25 million in block grants to local government agencies to grant to farmers who limit agricultural water use. Local government ag

LandFlex is a program that will provide $25 million in block grants to local government agencies to grant to farmers who limit agricultural water use. Local government agencies will work directly with farmers in critically overdrafted (COD) basins to identify lands that would reduce pumping impacts to nearby drinking water wells. Through financial incentives to farmers LandFlex will provide multiple community benefits such as drinking water well relief, groundwater overdraft prevention, and climate resilience. 

Landscape Patterns and Processes of the McCormack-Williamson Tract and Surrounding Area: A framework for restoring a resilient and functional landscape

San Francisco Estuary Institute (SFEI) | March 25th, 2013

This report uses a reconstruction of the historical (early 19th century) Sacramento-San Joaquin Delta landscape in concert with contemporary data to elucidate restoration

This report uses a reconstruction of the historical (early 19th century) Sacramento-San Joaquin Delta landscape in concert with contemporary data to elucidate restoration opportunities and constraints at the McCormack-Williamson Tract and within the surrounding Delta setting. Historical ecology encourages a landscape-level perspective of restoration through improved understanding of how physical processes created and maintained habitat mosaics in the recent past. This perception of landscapes can be used to evaluate current conditions and develop future restoration scenarios. We used the recently completed study of the historical Delta landscape (Whipple et al. 2012) to explore opportunities for the McCormack-Williamson Tract (MWT), a 1,645 acre (6.6 km2) tract along the Mokelumne River (Figure 1 and Figure 2). This site exemplifies the need to balance contemporary constraints to restoration (including existing infrastructure and flood protection concerns) with the goals of landscape-scale restoration. To explore some of the strategies and opportunities available to advance the landscape-scale restoration in the MWT area, three general concepts emerged: increasing landscape complexity, connectivity, and resilience. To understand how to interpret and improve these attributes, we developed conceptual models that placed the site within the larger landscapes of the historical Delta, relating local habitat features to regional controlling physical gradients. This aided interpretation of the contemporary physical landscape and allowed identification of opportunities and constraints to both short-term and long-term landscape-scale restoration. The historical record reveals features such as floodplain lakes, forests on natural river levees, and tidal channels in the study area. These and other features could be strategically incorporated into a restoration vision, or an “operational landscape unit” for this part of the Delta (Verhoeven et al. 2008). This type of perspective can help focus restoration targets, including the relative proportion and placement of different habitat types and landscape elements within project design constraints, maximizing the site’s ecological potential. The landscape-scale approach also identifies opportunities to improve ecological connectivity and long-term adaptability to sea level rise and other environmental changes. Some of these opportunities may be critical to the ecological function and resilience of the area, but may not be able to be addressed in the immediate MWT project design. Thus, a central component of translating a historical landscape perspective to site-scale design is envisioning an adaptable restoration process that spans short-term restoration actions that are possible within the site’s bounds, while maintaining a longer-term vision of what is needed at the landscape scale.

Left Out in Drought: California Fish Impacts of the California Drought on Freshwater Ecosystems

Pacific Institute | September 7th, 2022

California is deep into the third year of another major drought. Rural and urban areas again face water use restrictions and financial losses. Less water and hotter tempe

California is deep into the third year of another major drought. Rural and urban areas again face water use restrictions and financial losses. Less water and hotter temperatures also stress ecosystems, increasing the prevalence of wildfires, air pollution, dry streambeds, and loss of wildlife. Impacts to rural and urban areas frequently mask the disproportionate ecological impacts of the drought and the related policy and management responses that have exacerbated those impacts. The lack of acknowledgement and de- prioritization of ecosystem water needs during drought has led to insufficient actions taken to protect the natural systems on which we all depend.