San Joaquin River

Estuary News, September 2020

San Francisco Estuary Partnership (SFEP) | September 15th, 2020

Estuary-wide Data Repository for Delta Environmental Data to Understand a California Estuary Poster (2017)

San Francisco Estuary Institute (SFEI) | July 1st, 2017

The Sacramento-San Joaquin Delta (Delta) has some of the most pressing water supply and natural resource management issues facing California. The Delta Environmental Da

The Sacramento-San Joaquin Delta (Delta) has some of the most pressing water supply and natural resource management issues facing California. The Delta Environmental Data for the Understanding a California Estuary (DEDUCE), a collaborative project building upon the 2014 Environmental Data Summit vision, initiated a forum to integrate disparate data from multiple sources along with legacy data not uploaded to any of the State’s data-sharing systems. DEDUCE collected legacy toxic contaminant data from the Delta according to rigorous business rules, uploaded the data to the expanded estuary-wide data repository, and established design standards to exchange datasets with the California Environmental Data Exchange Network (CEDEN), a contributor to the US Environmental Protection Agency’s Water Quality Exchange (WQX). This data integration effort liberated accurate, accessible, and synthesized data for scientists and decision-makers as a foundation to inform management actions with the best available science

Estuary-Wide Data Repository for the Delta Environmental Data to Understand a California Estuary

San Francisco Estuary Institute (SFEI) | July 1st, 2017

The Sacramento-San Joaquin Delta (Delta) is the backdrop for some of the most pressing water supply and natural resource management issues facing California. To navigate

The Sacramento-San Joaquin Delta (Delta) is the backdrop for some of the most pressing water supply and natural resource management issues facing California. To navigate such matters comprehensively with transparency, and rigor, it is important to ensure broad dissemination of data. An Environmental Data Summit held in 2014 created a new era in information management and knowledge discoveries, and shed light on challenges associated with the use of disparate datasets. The Delta Environmental Data for the Understanding a California Estuary (DEDUCE), a collaborative project, builds upon the Data Summit vision and initiated a forum to integrate disparate data from multiple sources and legacy data that are currently not in any of the State’s data sharing systems. DEDUCE expanded the existing infrastructure to house water quality data from the Delta to address management questions by identifying and collecting high priority data according to rigorous business rules and mapping these data to a central system. This important step of harmonizing the data improves its interoperability and increases the access to and exchange of high-quality environmental data. DEDUCE facilitates the upload, aggregation and display of data in tools such as those created under the auspices of the California Water Quality Monitoring Council, including EcoAtlas and My Water Quality Portals, and CD3: Contaminant Data Display and Download tool for accessing and visualizing data comparable to State standards. DEDUCE achieved collecting and uploading the legacy and toxic contaminant data, and established design standards to exchange future datasets from the initial data storage or database to California Environmental Data Exchange Network (CEDEN). This data integration effort created accurate, accessible, and synthesized data for scientists and decision-makers as a foundation to inform management actions with the best available science.

Evaluation and Synthesis of the Yolo Bypass Fish Monitoring Program

U.S. Geological Survey (USGS) | August 18th, 2026

The Yolo Bypass is the largest functional remnant floodplain of the Sacramento River, providing benefits to aquatic taxa of the San Francisco Bay and Sacram

The Yolo Bypass is the largest functional remnant floodplain of the Sacramento River, providing benefits to aquatic taxa of the San Francisco Bay and Sacramento–San Joaquin Delta (hereafter, Bay-Delta). Because of the Yolo Bypass’s vital role in flood control and its ecological effects, the California Department of Water Resources started the Yolo Bypass Fish Monitoring Program (YBFMP) to monitor the aquatic ecology of the floodplain. Here, we present a scientific evaluation of the monitoring program to assess the efficacy and efficiency of the program in meeting its objective of collecting biological data to understand the ecological role the Yolo Bypass plays in the larger Bay-Delta. We used a multivariate assessment of floodplain flow to classify flood events (no flood, intense, early, late) and water years (low, average, high). To assess efficacy, we used a null hypothesis approach to determine if the YBFMP could distinguish variability in measured constituents (water quality and nutrient concentrations; phytoplankton, zooplankton, drift invertebrates, and fish communities; and densities of Chinook salmon [Oncorhynchus tshawytscha], Sacramento splittail [Pogonichthys macrolepidotus], and prickly sculpin [Cottus asper]) across different flood regime classifications. To assess efficiency, we used a data subsampling approach to quantify the amount of data needed to reach similar conclusions to analyses that used the entire dataset. Regarding efficacy, we concluded that the YBFMP is generally effective at identifying variability across various spatial and temporal scales (including flood regimes). Regarding efficiency, we concluded that reduced sampling effort would likely result in similar conclusions, enabling program managers to identify sites or periods that do not provide data essential to meeting program objectives. Our evaluation of the YBFMP indicated where data variability might limit mechanistic inference (particularly for phytoplankton and zooplankton), thus indicating that a series of targeted studies may be a prerequisite for further analysis. This evaluation has also identified areas where existing sampling may not be providing additional informational value, allowing for reallocation of effort to address management concerns.

Evaluation of Salinity Patterns and Effects of Tidal Flows and Temporary Barriers in South Delta Channels

California Department of Water Resources (DWR) | September 15th, 2016

There are several important water issues in the south Delta related to the San Joaquin River (SJR) inflow, Central Valley Project (CVP) and State Water Project (SWP) expo

There are several important water issues in the south Delta related to the San Joaquin River (SJR) inflow, Central Valley Project (CVP) and State Water Project (SWP) export pumping, reverse flows in Old and Middle Rivers, tidal water elevations and corresponding tidal flows in south Delta channels, effects of the temporary rock barriers that are installed seasonally by DWR in various south Delta channels, as well as the sources and longitudinal patterns of salinity caused by the net inflows, outflows, and tidal movement of water in south Delta channels. This study investigated the likely inflow locations of higher salinity water (i.e., sources) measured in Old River between the head of Old River and the Delta-Mendota Canal (DMC); the electrical conductivity (EC) at the Old River at Tracy Boulevard EC monitoring station was often the highest EC measured in the south Delta channels and has frequently exceeded the D-1641 EC objectives.

Evaluation of the Subseasonal Forecast Skill of Floods Associated with Atmospheric Rivers in Coastal Western U.S. Watersheds

American Meteorological Society (AMS) | May 27th, 2021

Atmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The time scale of subseasonal forecasting (from 2 weeks to 1 month

Atmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The time scale of subseasonal forecasting (from 2 weeks to 1 month) is a critical lead time for proactive mitigation of flood disasters. The NOAA Climate Testbed Subseasonal Experiment (SubX) is a research-to-operations project with almost immediate availability of forecasts. It has produced a reforecast database that facilitates evaluation of flood forecasts at these subseasonal lead times. Here, we examine the SubX-driven forecast skill of AR-related flooding out to 4-week lead using the Distributed Hydrology Soil Vegetation Model (DHSVM), with particular attention to the role of antecedent soil moisture (ASM), which modulates the relationship between meteorological and hydrological forecast skill. We study three watersheds along a transect of the U.S. West Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We find that the SubX-driven flood forecast skill drops quickly after week 1, during which there is relatively high deterministic forecast skill. We find some probabilistic forecast skill relative to climatology as well as ensemble streamflow prediction (ESP) in week 2, but minimal skill in weeks 3–4, especially for annual maximum floods, notwithstanding some probabilistic skill for smaller floods in week 3. Using ESP and reverse-ESP experiments to consider the relative influence of ASM and SubX reforecast skill, we find that ASM dominates probabilistic forecast skill only for small flood events at week 1, while SubX reforecast skill dominates for large flood events at all lead times.

Evapotranspiration frequently increases during droughts

Nature Portfolio (Springer Nature) | October 27th, 2022

Changes in evapotranspiration (ET) affect water availability and ecosystem health. Higher evaporative demand during drought acts to increase ET, but droughts also reduce

Changes in evapotranspiration (ET) affect water availability and ecosystem health. Higher evaporative demand during drought acts to increase ET, but droughts also reduce the moisture supply necessary for ET, limiting predictions of even the sign of ET anomalies. Drought-driven increases in ET (ET+drought) are of particular concern because they quickly deplete water resources, causing flash droughts and acute stress on ecosystems. Here, using a water balance approach, we show that ET+drought is globally widespread, occurring in 44.4% of drought months. The sign of ET’s drought response depends most on the magnitude of precipitation and total water storage anomalies, rather than its location. The Coupled Model Intercomparison Project Phase 6 Earth system models underestimate the ET+drought probability by nearly one-half, and more so in drier regions, primarily due to missing representations of soil structure effects on soil evaporation, as well as incorrectly parameterized plant and soil traits. These processes should be prioritized to reduce model uncertainties in the water–energy–food nexus.

Evidence of Landlocked Chinook Salmon Populations in California

North American Journal of Fisheries Management (Taylor & Francis) | November 10th, 2015

Natural reproduction of adfluvial Chinook Salmon Oncorhynchus tshawytscha has been documented in their native and introduced range but not in California, the southern end

Natural reproduction of adfluvial Chinook Salmon Oncorhynchus tshawytscha has been documented in their native and introduced range but not in California, the southern end of their native range. A combination of anecdotal evidence and survey data suggests that successful spawning by Chinook Salmon reared in California reservoirs could be common. The planted juveniles are often from different basins and are genetically distinguishable from local salmon populations below reservoirs. Consequently, the possibility of behavioral and genetic interactions may lead to complications of restoration efforts via trap and haul programs. The full extent of this phenomenon needs to be documented before trap and haul programs are initiated to reintroduce salmon above reservoirs.

Evolution of global snow drought characteristics from 1850 to 2100

Environmental Research Letters (IOP) | June 6th, 2023

Examining the causes and consequences of hybridization during Chinook salmon reintroductions: using the San Joaquin River as a restoration case study of management options

University of California, Davis (UC Davis) | June 15th, 2014

Successful salmonid restoration efforts depend upon an understanding of the evolutionary processes that historically shaped population diversity, as well as the realities

Successful salmonid restoration efforts depend upon an understanding of the evolutionary processes that historically shaped population diversity, as well as the realities of currently available, altered river systems. Habitat alterations over the past century have dramatically changed the ecological forces that shaped salmonid speciation and evolution, bringing formerly separate and distinct populations into contact and in some cases leading to hybridization. Hybridization can threaten the genetic diversity within salmonid species and may affect the outcomes of restoration efforts. Here we use the San Joaquin River Restoration as a case study to discuss some of the genetic challenges of Chinook salmon restoration in a newly reopened habitat. We discuss a range of genetic management strategies—from passive reintroduction to tightly managed, active reintroduction—and the strengths and weaknesses of each approach.