Sacramento River

The Relationship between California Rainfall and ENSO Events

American Meteorological Society (AMS) | November 1st, 1989

This paper examines the annual rainfall over California during 11 ENSO events within the period 1950 to 1982. During six of these, unusually wet conditions prevailed thro

This paper examines the annual rainfall over California during 11 ENSO events within the period 1950 to 1982. During six of these, unusually wet conditions prevailed throughout California; conditions were near normal during five events; and in one extreme drought occurred statewide. A comparison with the ENSO classification scheme of Fu et al, based on SST patterns in the Pacific, shows an excellent correspondence. Type 1 years, with large positive temperature anomalies east of the date line and lasting well into winter, are invariably events that enhance California rainfall. Normal years coincide with Type 2 ENSO events (moderate warming over a broad sector); the dry year is the sole Type 3 year, with weak anomalies confined to the eastern Pacific. This study also shows that the response to ENSO is regionally specific. Although throughout the state most years with extremely wet conditions are ENSO years, the tendency for an ENSO event to increase rainfall is greatest in Southern California, where 9 of 11 events produced above-normal rainfall and 8 of the 10 wettest years was an ENSO year. The pattern is more complex in central California; there ENSO years are almost invariably ones with highly abnormal rainfall, but they may be either wet or dry. The areas least influenced by ENSO are the Sierra Nevada and Northern California. The reasons for the geographical pattern of response become apparent when the seasonality and causes of rainfall in the various regions are evaluated.

The Role of Tidal Marsh Restoration in Fish Management in the San Francisco Estuary

University of California, Davis (UC Davis) | March 1st, 2014

Tidal marsh restoration is an important management issue in the San Francisco Estuary (estuary). Restoration of large areas of tidal marsh is ongoing or planned in the lo

Tidal marsh restoration is an important management issue in the San Francisco Estuary (estuary). Restoration of large areas of tidal marsh is ongoing or planned in the lower estuary (up to 6,000 ha, Callaway et al. 2011). Large areas are proposed for restoration in the upper estuary under the Endangered Species Act biological opinions (3,237 ha) and the Bay Delta Conservation Plan (26,305 ha). In the lower estuary, tidal marsh has proven its value to a wide array of species that live within it (Palaima 2012). In the Sacramento–San Joaquin Delta (Delta), one important function ascribed to restoration of freshwater tidal marshes is that they make large contributions to the food web of fish in open waters (BDCP 2013). The Ecosystem Restoration Program ascribed a suite of ecological functions to tidal marsh restoration, including habitat and food web benefits to native fish (CDFW 2010). This background was the basis for a symposium (Tidal Marshes and Native Fishes in the Delta: Will Restoration Make a Difference?) held at the University of California, Davis, on June 10, 2013. This paper summarizes conclusions the authors drew from the symposium.

The Sacramento-San Joaquin Delta: The Evolution and Implementation of Water Policy: An Historical Perspective

University of California, Davis (UC Davis) | June 1st, 1977

This report is a history of the attempts to control the encroachment of salinity from San Francisco Bay into the Delta of the Sacramento and San Joaquin rivers from 1920

This report is a history of the attempts to control the encroachment of salinity from San Francisco Bay into the Delta of the Sacramento and San Joaquin rivers from 1920 to the present. Two basic solutions to the problem present themselves: the physical separation of salt water from fresh water by means of a barrier at some point downstream from the Delta, or the release of sufficient water from upstream storage reservoirs to drive back tidal salinity.

The San Francisco Bay-Delta Agreement: Principles for Agreement on Bay-Delta Standards Between the State of California and the Federal Government

California State Water Resources Control Board (SWRCB) | December 15th, 1994

The San Francisco Bay-Delta: A failure of decision-making capacity

Environmental Science & Policy (Elsevier) | August 12th, 2009

The paper reviews the history of Bay-Delta decision-making in California in order to highlight the continuity between what happened with CALFED and what happened in the

The paper reviews the history of Bay-Delta decision-making in California in order to highlight the continuity between what happened with CALFED and what happened in the preceding decades since water project deliveries began in 1949. Throughout this period, there has been intense conflict about whether and how to transfer water from the Bay-Delta to users elsewhere—a conflict marked by a fundamental opposition of interests among stakeholders. We document how the State of California has failed to organize itself effectively to resolve this conflict and make a decision on how to manage the Delta. The strategy consistently adopted by the State was to encourage the main parties – agricultural and urban water diverters, and fisheries and other instream-protection interests – to work out a solution among themselves, rather than imposing one externally. However, economic theory suggests that a bargaining solution is unlikely to exist because of the extreme opposition of interest among the parties. The Bay-Delta history amply confirms this theoretical prediction. Thus, the State’s strategy of relying on voluntary agreement to resolve the issue is fundamentally misconceived and is, at some level, an abdication of its responsibility.

The Science of Non-native Species in a Dynamic Delta

Delta Stewardship Council (Delta Council) | May 21st, 2022

Invasion of non-native species is one of the greatest global threats to the integrity of ecosystems and one of the five main drivers of ecosystem change. When a new speci

Invasion of non-native species is one of the greatest global threats to the integrity of ecosystems and one of the five main drivers of ecosystem change. When a new species becomes part of the ecosystem, it can alter the food web, nutrient and contaminant cycling, abundances of other species, and habitat structure. The resultant changes in ecosystem services (e.g. water quality, water flow, fisheries, endangered species) and even ecosystem stability can impact a broad range of stakeholders and impinge on the responsibilities of many government agencies. The California San Francisco Bay-Delta ecosystem is one of the world’s most invaded estuaries. Indeed, non-native species comprise much of today’s Delta ecosystem. Non-native species threaten the Delta Plan’s coequal goals of “protecting, restoring, and enhancing the Delta ecosystem,“ and “providing a more reliable water supply for California” as well as state and federal objectives for preserving native species and ecosystems. The Delta Reform Act of 2009 recognized the importance of this issue and stipulated that the Delta Plan should restore a healthy ecosystem by promoting “self-sustaining, diverse populations of native and valued species by reducing the risk of take and harm from invasive species.” Reducing the impact of non-native species is also a core strategy highlighted in the Ecosystem Amendment to California’s Delta Plan.

The State Water Project’s Strategic Plan

California Department of Water Resources (DWR) | February 22nd, 2024

The strategic plan, Elevate to ’28, projects the trajectory for the SWP for the next five years.

The strategic plan, Elevate to ’28, projects the trajectory for the SWP for the next five years.

The Struggle for Water Justice in California’s San Joaquin Valley: A Focus on Disadvantaged Unincorporated Communities

University of California, Davis (UC Davis) | February 1st, 2018

In California, lack of access to clean, safe, and affordable water is a threat to public health and well-being, and violates the state’s newly codified Human Ri

In California, lack of access to clean, safe, and affordable water is a threat to public health and well-being, and violates the state’s newly codified Human Right to Water (HRTW). In low-income communities located outside city boundaries (otherwise known as disadvantaged unincorporated communities or DUCs), drinking water is often unsafe to drink. In many such localities, drinking water is contaminated by industrial by-products (usually associated with agriculture, oil and gas production, transportation, and manufacturing) and compromised by inadequate wastewater treatment and disposal systems, as well as naturally occurring toxic substances like arsenic and uranium. Many DUC residents in the San Joaquin Valley pay a triple penalty to obtain safe water: they bear the health costs of unsafe drinking water; they purchase that unsafe water at high costs; and they must also purchase “substitute” water—typically expensive bottled water—for drinking and cooking purposes. Lack of access to clean, safe and affordable drinking water has a racial and ethnic component: the vast majority of the valley’s DUC residents are people of color who also face cumulative impacts from environmental contamination brought on by proximity to air pollution, pesticides, toxic facilities and waste disposal. Without city governments to directly represent their interests and provide essential services, residents of these DUCs have been systematically deprived of access to important means of democratic governance (Anderson 2008). California’s San Joaquin Valley is the source of much of the state and the nation’s agricultural wealth. Yet it is also a region where poverty persists amidst prosperity (Taylor and Mar n 1998). Many of the region’s DUC residents hold low-wage and dangerous jobs, and confront severe and cumulative environmental contamination of their air, water, and land (London, Huang, Zagofsky 2011). The well-being of the nearly 350,000 residents living in 450 DUCs throughout San Joaquin Valley is therefore an important environmental health, and social justice issue that demands urgent attention by policy makers, public agencies and advocates. Over the past two decades, community leaders, advocates, and policymakers have pursued a range of strategies to address unsafe drinking water in the valley’s DUCs and elsewhere in California. For example, in 2004, resident advocates won a case against the City of Modesto in 2003 for its systematic exclusion from city services of communities of color living in nearby DUCs (Molina 2014). In 2011, Senate Bill (SB) 244 required cities and counties to address the infrastructure needs of California DUCs in land use and municipal service plans, and in annexation decisions. In 2012, an HRTW policy was passed in response to massive community mobilization. Known as Assembly Bill (AB) 685, and signed by Governor Jerry Brown, it codified that every human being has a right to safe, clean, affordable, and accessible water to meet basic human needs, and required state agencies to consider this right when establishing policies and regulations. A 2013 report by the Community Equity Initiative (led by PolicyLink, California Rural Legal Assistance Inc., and California Rural Legal Assistance Foundation) developed a sophisticated analysis of the conditions of DUCs in the San Joaquin Valley. California Unincorporated: Mapping Disadvantaged Communities in the San Joaquin Valley (Flegal et al. 2013) put DUCs on the map by using a new methodology to identify these communities, and to highlight the need for new policies and funding mechanisms to address the significant challenges they face. This report, and the dedicated work of water justice advocates, have greatly increased public awareness of water inequality in DUCs. This has helped direct new public funding to improve water infrastructure, and encouraged collaborative solutions among interest groups that historically have been in conflict with each other. However, all parties agree that much more needs to be done to understand the complex issues facing DUCs, and to provide their residents with safe and affordable drinking water. Our report analyzes this situation in detail, and offers several recommendations to inform policy and advocacy on how to improve water access to these communities. To do so, we have used maps of DUCs, CWSs, and State Small Water Systems (SSWSs), as well as water quality reports, demographic data, and expert interviews. Together, these sources have helped us highlight gaps in the provision of safe and a ordable drinking water. Our main conclusion is that California’s legislature, regulatory agencies, and water suppliers need to undertake more concerted and well-resourced efforts to ensure that the HRTW is ensured for all of the San Joaquin Valley’s residents.

The Sustainable Groundwater Management Act challenges the diversity of California farms

California Agriculture (UCANR) | November 16th, 2016

California’s agricultural sector, a major groundwater user, finds itself in the midst of the implementation of the Sustainable Groundwater Management Act (SGMA). The la

California’s agricultural sector, a major groundwater user, finds itself in the midst of the implementation of the Sustainable Groundwater Management Act (SGMA). The law mandates the formation of local groundwater sustainability agencies (GSAs) and adoption of groundwater sustainability plans (GSPs) for all overdrafted groundwater basins across the state by 2020. Each GSA will be unique, with its own governance structures and rules, including the size and composition of the governing board, mechanisms for representing different interests, opportunities for stakeholders to participate, and rules concerning the allocation of pumping “rights” and the use of economic instruments, such as pumping permits, pumping taxes or tiered pricing, to incentivize pumping curtailments (DWR 2016). This new water management landscape may threaten the diversity of the state’s farming operations.

The tradeoff between water savings and salinization prevention in dryland irrigation

Advances in Water Resources (Elsevier) | December 7th, 2023

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in

Soil salinization is a global phenomenon that affects large tracts of arid farmland worldwide. It contributes to the loss of soil fertility, declining yields, and – in the most severe cases – land unsuitability for cultivation. Irrigation water applications are both the main cause of and the solution to, anthropogenic (or ‘secondary’) salinization because salt typically enters the soil column as dissolved in irrigation water and leaves it through excess water applications (e.g., leaching). Excess leaching, which places additional water costs in areas affected by water scarcity, can be achieved with different irrigation techniques and practices. Here, by complementing a process-based crop water model with a salt balance of the shallow soil, we investigate the tradeoff between root zone salinization and water conservation to limit withdrawals from the water source. We evaluate how such a tradeoff is achieved under different irrigation technology and excess leaching practices. Considering as a case study the cultivation of tomatoes in Egypt, we find that drip and furrow irrigation allows for better control of salt accumulation, thus preventing crop exposure to salt stress. Drip irrigation achieves this goal with minimal water applications because it maintains the soil wetter. Thus, the (rare) rainfall events find more suitable conditions to drain the excess moisture. Conversely, by using more irrigation water (and ‘less efficiently’), furrow irrigation allows for higher rates of soil drainage and salt leaching. The irrigation schedule typically adopted with sprinkler irrigation allows for soil drying, thus limiting the ability of rainfall events to drain the soil and leach its salts. Collectively, these results highlight the key role of irrigation technology and practices in the management of secondary salinity in dryland agriculture. Specifically, there is a tradeoff between minimizing water use and preventing salt accumulation in the root zone. Drip irrigation exhibits the co-benefit of achieving both goals, while furrow irrigation limits soil salinity at the cost of requiring greater volumes of applied irrigation water.