San Joaquin River

Losses of Sacramento River Chinook Salmon and Delta Smelt to Entrainment in Water Diversions in the Sacramento-San Joaquin Delta

University of California, Davis (UC Davis) | June 30th, 2008

Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of

Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of salvage counts with population indices have failed to provide quantitative estimates of the magnitude of this mortality. I estimated the proportional losses of Sacramento River Chinook salmon (Oncorhynchus tshawytscha) and delta smelt (Hypomesus transpacificus) to place these losses in a population context. The estimate for salmon was based on recoveries of tagged smolts released in the upper Sacramento River basin, and recovered at the fish-salvage facilities in the south Delta and in a trawling program in the western Delta. The proportion of fish salvaged increased with export flow, with a mean value around 10% at the highest export flows recorded. Mortality was around 10% if pre-salvage losses were about 80%, but this value is nearly unconstrained. Losses of adult delta smelt in winter and young delta smelt in spring were estimated from salvage data (adults) corrected for estimated pre-salvage survival, or from trawl data in the southern Delta (young). These losses were divided by population size and accumulated over the respective seasons. Losses of adult delta smelt were 1–50% (median 15%) although the highest value may have been biased upward. Daily losses of larvae and juveniles were 0–8%, and seasonal losses accumulated were 0–25% (median 13%). The effect of these losses on population abundance was obscured by subsequent 50-fold variability in survival from summer to fall.

Machine learning based downscaling of GRACE-estimated groundwater in Central Valley, California

Science of the Total Environment (Elsevier) | January 9th, 2023

California's Central Valley, one of the most agriculturally productive regions, is also one of the most stressed aquifers in the world due to anthropogenic groundwater ov

California's Central Valley, one of the most agriculturally productive regions, is also one of the most stressed aquifers in the world due to anthropogenic groundwater over-extraction primarily for irrigation. Groundwater depletion is further exacerbated by climate-driven droughts. Gravity Recovery and Climate Experiment (GRACE) satellite gravimetry has demonstrated the feasibility of quantifying global groundwater storage changes at uniform monthly sampling, though at a coarse resolution and is thus impractical for effective water resources management. Here, we employ the Random Forest machine learning algorithm to establish empirical relationships between GRACE-derived groundwater storage and in situ groundwater level variations over the Central Valley during 2002–2016 and achieved spatial downscaling of GRACE-observed groundwater storage changes from a few hundred km to 5 km. Validations of our modeled groundwater level with in situ groundwater level indicate excellent Nash-Sutcliffe Efficiency coefficients ranging from 0.94 to 0.97. In addition, the secular components of modeled groundwater show good agreements with those of vertical displacements observed by GPS, and CryoSat-2 radar altimetry measurements and is perfectly consistent with findings from previous studies. Our estimated groundwater loss is about 30 km3 from 2002 to 2016, which also agrees well with previous studies in Central Valley. We find the maximum groundwater storage loss rates of −5.7 ± 1.2 km3 yr−1 and -9.8 ± 1.7 km3 yr−1 occurred during the extended drought periods of January 2007–December 2009, and October 2011–September 2015, respectively while Central Valley also experienced groundwater recharges during prolonged flood episodes. The 5-km resolution Central Valley-wide groundwater storage trends reveal that groundwater depletion occurs mostly in southern San Joaquin Valley collocated with severe land subsidence due to aquifer compaction from excessive groundwater over withdrawal.

Madera Subbasin Joint Groundwater Sustainability Plan

Madera Subbasin Coordination Committee | January 31st, 2022

The Madera Subbasin is identified by California Department of Water Resources (DWR) as a critically overdrafted basin. Therefore, the Madera Subbasin GSAs must develop,

The Madera Subbasin is identified by California Department of Water Resources (DWR) as a critically overdrafted basin. Therefore, the Madera Subbasin GSAs must develop, adopt, and submit a GSP (or GSPs) to DWR for the entire Madera Subbasin by January 31, 2020. The Madera Subbasin is managed by seven GSAs, of which four (City of Madera GSA, Madera Irrigation District GSA, Madera County GSA, and Madera Water District GSA) have developed a joint GSP (attached here) and three (Gravelly Ford Water District GSA, New Stone Water District GSA, and Root Creek Water District GSA) have developed individual GSPs.

Making Conservation a California Way of Life - Revised

California State Water Resources Control Board (SWRCB) | March 12th, 2024

Making Nature's City: A science-based framework for building urban biodiversity

San Francisco Estuary Institute (SFEI) | July 1st, 2019

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges th

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges threatens global biodiversity, and many species face potential extinction. While urban planners and conservationists have long treated these issues as distinct, there is growing evidence that cities not only harbor a significant fraction of the world’s biodiversity, but that they can also be made more livable and resilient for people, plants, and animals through nature-friendly urban design. Urban ecological science can provide a powerful tool to guide cities towards more biodiversity-friendly design. However, current research remains scattered across thousands of journal articles and largely inaccessible to practitioners. Making Nature’s City fills this gap, synthesizing global research to develop a science-based approach for supporting nature in cities. We identify seven key elements of urban form and function that work together to maximize biodiversity, and we illustrate these elements through a case study in California’s Silicon Valley. Using the framework developed in this report, urban designers and local residents can work together to link local parks, greenways, green roofs, street trees, stormwater basins, commercial landscaping, and backyards to support biodiversity while making cities better places to live. As we envision the healthier, and more resilient cities, Making Nature’s City provides practical guidance for the many actors who together will shape the nature of cities.

Making the Delta a Better Place for Native Fishes

Orange County Coastkeeper | March 1st, 2018

The Sacramento-San Joaquin Delta is the heart of California’s water delivery system, connecting the precipitation-rich regions of the north with the dry farmlands and

The Sacramento-San Joaquin Delta is the heart of California’s water delivery system, connecting the precipitation-rich regions of the north with the dry farmlands and demanding urban areas of the south and coast, including the Bay Area. Scarce water resources create conflicts between people and fishes; as demand by people for water grows, less water is available for the environment. This white paper explores the ways to keep the native fishes, and the functional ecosystems they require, from disappearing. Our analysis is fish-oriented because salmon, smelt, and other declining fishes are major drivers of decisions on where to focus aquatic restoration efforts.  The goals of this white paper are to first provide a brief introduction to the Delta and then to describe why restoration of native fishes and natural processes is such a challenge in this system. We follow this with some general guidelines for restoration projects in the Delta and apply those guidelines with a project evaluation tool. We used this tool to evaluate 26 projects, mostly part of EcoRestore, to provide insights to help determine action items. We then present 17 action items, listed below, some of which can be accomplished fairly quickly, some that will take longer, and few that will have to be continuous. But taken together, our recommended actions could significantly improve the welfare of native fishes and help to create a novel aquatic ecosystem with many desirable features.

Making the Most of Water for the Environment: A Functional Flows Approach for California’s Rivers

Public Policy Institute of California (PPIC) | August 25th, 2020

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precip

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precipitous decline in native fish populations, including the collapse of valued salmon fisheries, and widespread imperilment of freshwater biodiversity. Environmental flows—flows in rivers and streams necessary to sustain ecosystem health—are essential to reversing these trends. Yet many rivers in California lack environmental flows. And for those rivers with such protections, environmental flows are typically established at static minimum levels, which fail to preserve the natural seasonal and interannual variability of flow that sustains healthy ecosystems. A new approach to managing environmental water is needed. 

Making Water Conservation a California Way of Life Proposed Regulation Review of the Water Board’s Standardized Regulatory Impact Analysis (SRIA)

Mesa Water District | September 28th, 2023

Making Water Conservation a California Way of Life: Primer of 2018 Legislation on Water Conservation and Drought Planning Senate Bill 606 (Hertzberg) and Assembly Bill 1668 (Friedman)

California State Water Resources Control Board (SWRCB) | November 30th, 2018

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish a new foundation for long-term improvements in water conservation and drought planning to adapt to climate change and the resulting longer and more intense droughts in California. These two bills amend existing law to provide expanded and new authorities and requirements to enable permanent changes and actions for those purposes, improving the state's water future for generations to come.

Maladaptation to drought: a case report from California, USA

Sustainability Science (Springer) | October 15th, 2015

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capaci

The interactions between natural water availability and societal water demand and management are complex. In response to gaps in empirical research of the adaptive capacity of social and environmental systems to climate stresses, we provide an assessment of responses to water scarcity during a multi-year drought in California. In particular, we use Barnett and O’Neill’s (Global Environ Change 20:211–213, 2010) criteria for maladaptation to examine responses in the agricultural and energy sectors to a multi-year (2007–2009) California drought. We conclude that despite evidence in both sectors of resiliency to the impacts of the drought, some of the coping strategies adopted increased the vulnerability of other systems. These other systems include California’s aquatic ecosystems and social groups that rely on those ecosystems for their health or employment; future generations whose resources were drawn down in the near-term, where otherwise those resources would have been available at a later time; and current and future generations who were, or will be, exposed to the effects of increased greenhouse gas emissions. This case study demonstrates that California’s current strategies for dealing with long or severe droughts are less successful than previously thought when short- and long-term impacts are evaluated together. This finding is particularly relevant given projections of more frequent and severe water shortages in the future due to climate change. This study recommends a shift from crisis-driven responses to the development and enactment of long-term mitigation measures that are anticipatory and focus on comprehensive risk reduction.