San Joaquin River

DRERIP Ecosystem Restoration Model: Tidal marsh

California Department of Fish and Wildlife (CDFW) | October 1st, 2008

Tidal marshes are a subset of estuarine wetlands defined by the presence of emergent vegetation types uniquely adapted to sheltered intertidal zones of temperate and subt

Tidal marshes are a subset of estuarine wetlands defined by the presence of emergent vegetation types uniquely adapted to sheltered intertidal zones of temperate and subtropical coastal plains (Chapman 1960, 1976, Mitsch & Gosselink 1993). They are found across a full range of salinity conditions from seawater on the immediate coast to freshwater tidal reaches of estuarine river systems. Marshes are transitional ecosystems that provide critical connections between adjacent subtidal and terrestrial ecosystems within the estuarine landscape (Simenstad et al. 2000; Levin et al. 2001). These “critical transition zones” often function as conduits for substantial fluxes of materials and energy (Ewel et al. 2001), and provide a variety of valuable ecosystems functions, goods and services related to the maintenance of biodiversity, fish and wildlife habitat, water quality, flood abatement and carbon sequestration (Rabenhorst 1995, Costanza et al. 1997, Weslawski et al. 2004, Zedler & Kercher 2005). However, estuarine marshes and the biotic communities that depend on them are vulnerable to both direct and indirect anthropogenic impacts (Holland et al. 2004, Snelgrove et al. 2004), and the functionality of these systems can be difficult to restore once severely impacted (Zedler & Kercher 2005). The San Francisco Bay and Sacramento-San Joaquin River Delta estuary is perhaps the most hydrologically-engineered estuarine wetland system in the United States, and an estimated 95% of the marsh area that existed there in 1850 has been altered or converted to other land uses (Josselyn 1983). The principal source of freshwater input to the estuary enters through the Sacramento and San Joaquin rivers; their inland delta (the Delta) is the terminus of a watershed that drains about 40% of California’s land area. Anthropogenic alterations of the estuary’s hydrologic characteristics have profoundly affected the extent and functioning of the tidal wetlands, particularly in the brackish and tidal fresh portions of the upper estuary associated with the Delta. Although the conceptual model presented in Figure 1 is intended to capture the features and dynamics of tidal marshes in the Delta (e.g., Suisun Bay to the upriver extent of the tides in the Delta), oligohaline and tidal freshwater marshes generally remain poorly understood. Recent texts (e.g., Sharitz & Pennings 2006) still consider the review by Odum (1988) as the best treatment of these low salinity tidal ecosystems. Consequently, development of the current conceptual biological model often required us to judiciously borrow from the more extensive literature on temperate salt marshes in diverse regions. Although one of our principal objectives in developing this model involves identifying the dominant processes and interactions that characterize restoring marshes at various stages of development, the model is intended to characterize the dynamics of “equilibrium” marshes at their mature state of geomorphic and ecological functioning (Pestrong 1972, Reed 2002, Williams et al. 2002). Our rationale is that restoring marshes are considerably variable and that trying to capture intermediate stages of development (e.g., positions along a development “trajectory”; Simenstad & Thom 1996 [however, see Zedler & Callaway 1999]) would introduce too much variability for a single model, and because the ultimate objective of restoration is the self-sustaining, equilibrium condition. However, we have sought were appropriate to describe important processes that influence restoration trajectories and affect the ecosystem functions, goods and services that marshes provide in various landscape settings that are found in the Sacramento-San Joaquin Delta.

Drift of Earth's Pole Confirms Groundwater Depletion as a Significant Contributor to Global Sea Level Rise 1993–2010

American Geophysical Union (AGU) | June 15th, 2023

Drinking Water and Exclusion: A Case Study from California's Central Valley

California Law Review | February 1st, 2012

The American West is notorious for its water wars, and California's complex water allocation and governance challenges serve as a bellwether for contemporary water gove

The American West is notorious for its water wars, and California's complex water allocation and governance challenges serve as a bellwether for contemporary water governance across western states, Policy makers and environmental advocates typically represent California's water woes as a regulatory problem - a failure to balance the needs of growing urban populations with ecological preservation and agricultural irrigation. These debates, however, often elide the issue of water deprivation, and they do not adequately address the concerns of an important constituency: low-income, rural communities. This Comment argues that a focus on regulation misses a fundamental feature of water inequality: the structure and design of local water districts. Utilizing a case study of California's Central Valley to illustrate how these structural barriers operate, I argue that Calfornia's complex system of local water districts fractures governance, limits electoral participation, and undermines the State's stated environmental, equity, and utilitarian water goals. I offer suggestions for alternative local water district organization in order to address the constraints of Calfornia's current water governance regime.

Drinking Water Notification Levels and Response Levels: An Overview

California State Water Resources Control Board (SWRCB) | February 6th, 2020

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of H

The Division of Drinking Water’s precursor, the Drinking Water Program of the California Department of Public Health (CDPH), and earlier, the California Department of Health Services, CDHS, established health-based advisory levels, called “notification levels” (referred to as “action levels" through 2004), as needed since the early 1980s. These have been used to provide information to public water systems and others about certain non-regulated chemicals in drinking water that lack maximum contaminant levels (MCLs).  When chemicals are found at concentrations greater than these levels, certain requirement and recommendations apply.  Generally, notification levels have been established in response to actual contamination of drinking water supplies, e.g., perchlorate, which now has an MCL. However, notification levels for a number of chemicals were established in anticipation of possible contamination, such as from a hazardous waste site containing many pesticides (in the 1980s), or from a Superfund site (in the 2000s).  Chemicals for which notification levels are established may eventually be regulated by MCLs (through a formal regulatory process), depending on the extent of contamination, the levels observed, and the risk to human health. Most, however, have not proceeded to MCLs. Once established, a notification level generally stays in place, unless it is replaced by an MCL.On occasion, though, we have revised the numeric value of an individualnotification level to reflect new risk assessment information on the particularchemical. For some of the chemicals that had advisory levels established early on, if noMCL was adopted and the need for the notification level had passed, the advisory levelwas archived. Archived advisory levels may nevertheless be updated to reflect any newrisk information that may become available, and may be used as notification levels ifneeded. To date, of the 93 chemicals for which notification levels have been established; 40 now have MCLs. Of the remaining 53 chemicals, 29 are chemicals with current notification levels. 24 are chemicals with archived advisory levels (AALs). Note that following adoption of an MCL, the notification level is no longer used. For more about AALs and notification levels, go to: http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NotificationLevels.shtml. 

Drought and Groundwater Sustainability in California’s Farming Regions

Public Policy Institute of California (PPIC) | June 25th, 2024

Drought and the California Delta—A Matter of Extremes

University of California, Davis (UC Davis) | July 14th, 2014

California is in an extreme drought as a result of low precipitation in water year 2012, record low precipitation in 2013, and the remarkably dry first few months of 2014

California is in an extreme drought as a result of low precipitation in water year 2012, record low precipitation in 2013, and the remarkably dry first few months of 2014. We typically receive our largest precipitation totals in Decembers and Januaries (which provide about 36% of the precipitation in the Delta’s catchment), and when those months are as dry as they were this year, subsequent months have to be unseasonably wet to avoid drought. Most of the current winter, especially December 2013–January 2014, was dry because a persistent ridge of high (atmospheric) pressures set up offshore, diverting storms away from California and into Alaska. That same diversion gave the Delta’s catchment its warmest winter in 120 years, as well as bringing all that cold weather to the eastern US. While the February 2014 storms provided minor relief and momentarily slowed the spiral into deeper drought, the drought continues apace. Nonetheless, as harsh as it is, the current drought is not unprecedented in the Delta’s history, and even less so in its prehistory. In this essay, we consider the ways that droughts in California arise from a few missing storms and from long-term variations and changes in climate, in order to identify drought-science needs for Delta management. 

Drought Contingency Planning (DCP) Negotiation #142, Attachment 1

California Department of Water Resources (DWR) | April 30th, 2020

This white paper describes current understanding of how the Department of Water Resources (DWR) would account for and administer the Delta Conveyance Facility (DCF) Bene

This white paper describes current understanding of how the Department of Water Resources (DWR) would account for and administer the Delta Conveyance Facility (DCF) Benefits. DWR will include information regarding the accounting and administration of water attributable to DCF in relevant Notice(s) to State Water Project Contractors consistent with prior practice. No legally binding obligations are created by this white paper. This white paper may be updated from time to time by DWR, in consultation with the Public Water Agencies (PWAs), in response to factors including, but not limited to, changes in laws, regulations or permits applicable to DWR and/or the State Water Project (SWP). Capitalized terms not defined herein shall have the meanings ascribed to them in the DCF Agreement in Principle (AIP).

Drought impacts to water footprints and virtual water transfers of the Central Valley of California

American Geophysical Union (AGU) | June 23rd, 2017

Drought less predictable under declining future snowpack

Nature Portfolio (Springer Nature) | April 20th, 2020

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical ear

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical early warning of hydrologic drought. This paradigm faces an impending challenge given consensus that a smaller fraction of future precipitation will fall as snow. Here, we apply downscaled hydrologic simulations from 28 climate model projections to show that by mid-century (2036–2065), 69% of historically snowmelt-dominated areas of the western United States see a decline in the ability of snow to predict seasonal drought, increasing to 83% by late century (2070–2099). Reduced predictability arises when peak snowpack approaches zero or because of decreased warm-season runoff efficiency. Changes in drought prediction skill show significant (P < 0.01) elevation dependence, with lower-elevation coastal areas most impacted by warming. Ancillary predictive information can only partially mitigate snow-based predictability losses to 65% of areas, underscoring the importance of declining future snowpack.

Drought Management and Climate Adaptation of Small, Self-Sufficient Drinking Water Systems in California

California Energy Commission (CEC) | August 15th, 2018

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This study focuses on the 2012-2016 Drought in California, documenting how small self-sufficient drinking water systems were affected and challenged by, and responded to the extreme event.