Sacramento River

Development of Stage-Frequency Curves in the Sacramento-San Joaquin Delta for Climate Change and Sea Level Rise

California Energy Commission (CEC) | August 27th, 2018

Future changes in hydrologic patterns and sea level rise will impact water levels in the Sacramento-San Joaquin Delta (Delta), the hub of California’s water supply sys

Future changes in hydrologic patterns and sea level rise will impact water levels in the Sacramento-San Joaquin Delta (Delta), the hub of California’s water supply system and an important ecosystem and agricultural area. An important tool for flood management is stage frequency curves which indicate how often certain water levels (or stage) occur. The Delta poses inherent complexity in the determination of stage-frequency and requires a number of considerations. One needs to account for river flows coming into the Delta, as well as the effect of tides from the Delta’s connection to the ocean through San Francisco Bay. During storms, Delta water levels are also affected by storm surge from the advancing storm fronts coming from the Pacific Ocean. Under climate change, Delta water levels will also be affected by rising sea levels and expected changes in hydrology, such as shifts in timing and amount of precipitation and runoff and changes in how much of our precipitation falls as rain or snow (referred to as climate change hydrology in this paper). With these taken into consideration, this study lays out the assumption and method used to develop stage-frequency curves in the Delta for three different conditions: current hydrology conditions, current hydrology with sea level rise, and late-century climate change hydrology with sea level rise. In addition, water surface elevation profiles along the Sacramento and San Joaquin rivers for various magnitudes of flood events were compared to the top of levee elevations. Both the stage-frequency curves and the water surface elevation profiles comparisons to top of levee elevations provide valuable information to water resources planners and were applied to inform life and flood risk analysis for the Delta in the Central Valley Flood Protection Plan 2017 Update.

Development of the Lower Sacramento Valley Flood-Control System: Historical Perspective

American Society of Civil Engineers (ASCE) | July 1st, 2008

Natural physical conditions and the politics of flood management provide the historical context for structural flood control that underlies modern flood hazards in the S

Natural physical conditions and the politics of flood management provide the historical context for structural flood control that underlies modern flood hazards in the Sacramento Valley. The valley is a broad, low plain with backswamp basins that were frequently inundated prior to Anglo-American settlement, continuing until the modern flood-control system was established. Early attempts to emulate the Mississippi River single-channel levee strategy failed repeatedly in the Sacramento Valley due to high flow variability, mining sedimentation, lack of a coordinated levee system, and the inability of the main channels to carry most of the flood flows. Hydraulic mining caused massive sedimentation in major east-side tributaries, such as the Feather, Yuba, Bear, and American Rivers, and in the Sacramento River below the Feather River confluence. This sedimentation led to a flood-control design that relied on levees with narrow cross-channel spacings to promote channel scour and facilitate navigation. Even without sedimentation, floods were not contained within channels, but were largely conveyed through a system of low-land basins. In the early twentieth century, an innovative channel bypass system was adopted that emulates the natural system by routing excess flood waters over a series of weirs and through broad, channelized bypasses that cross the basins. This system has been successful in reducing the extent of frequent inundations of broad lowland areas of the valley. It is in need of maintenance and improvement, however, and cannot eliminate the risk of future flooding in low areas behind levees that are being rapidly developed.

Dimension reduction approach for understanding resource-flow resilience to climate change

Nature Portfolio (Springer Nature) | June 15th, 2024

DISB Review of the Final EIR/EIS for California WaterFix

Delta Stewardship Council (Delta Council) | June 19th, 2017

The Delta Reform Act of 2009 directs the Delta Independent Science Board to review environmental impact assessments of the Bay Delta Conservation Plan (now California Wat

The Delta Reform Act of 2009 directs the Delta Independent Science Board to review environmental impact assessments of the Bay Delta Conservation Plan (now California WaterFix). Here, in our fifth such review, we focus on the adequacy of the scientific information presented in the final Environmental Impact Report (EIR)/Environmental Impact Statement (EIS) for the California WaterFix by revisiting the six main concerns we raised in our September 2015 review of the Recirculated Draft EIR/Supplemental EIS. We discuss improvements and shortcomings. We also comment on the need to improve impact assessments for scientific evaluation and effective stakeholder engagement. The Final EIR/EIS contains a wealth of detail and considerable insight. This version improves on its predecessors but retains some persistent shortcomings. Improved content on adaptive management is still short on detail about how adaptive management would be implemented under changing and uncertain conditions. Summaries and comparisons, more abundant than before, lack insightful syntheses and graphics that ease comprehension of the vast amount of material presented. Expanded discussion of Delta levees stops short of evaluating interactions with water supply reliability and neglects changing views of earthquake hazards. Long-term effects are better addressed in several ways, but with insufficient attention to uncertainties in defining the No Action Alternative and to the interplay between California groundwater sustainability and Delta water supplies. Other content missing includes evaluation of environmental effects of water use south of the Delta. Evaluation of ecosystem impacts, though extensive, retains gaps on using restoration as mitigation. The completion of our reviews of the Final EIR/EIS and its predecessors prompt us to reflect more broadly on the use and communication of science in the Delta and more specifically on the false trade off between thoroughness and intelligibility that has become common in environmental impact assessments. Overwhelming readers with content that addresses the many scientific issues related to a proposed project and its alternatives, while neglecting the thoughtful presentation and synthesis of insights and performance trade offs among alternatives, diminishes the value of this important document as a comparative guide to the expected environmental effects of the alternatives considered.

Disentangling Stationary and Dynamic Estuarine Fish Habitat to Inform Conservation: Species-Specific Responses to Physical Habitat and Water Quality in San Francisco Estuary

American Fisheries Society (AFS) | October 12th, 2021

Estuaries represent critical aquatic habitat that connects surface water distributed between Earth’s landmasses and oceans. They are dynamic transitional ecosystems, wh

Estuaries represent critical aquatic habitat that connects surface water distributed between Earth’s landmasses and oceans. They are dynamic transitional ecosystems, which provide important habitat for fishes and other aquatic organisms. Effective conservation of species inhabiting estuaries requires knowledge of the habitat features that drive their abundance and distribution. We sought to elucidate how stationary (i.e., wetlands, shoals, and channels) and dynamic (i.e., salinity, temperature, turbidity, and chlorophyll concentration) habitat features interact to drive distributions of individual fish species. The Pacific coast of the conterminous United States has over 400 estuaries of various types. The largest (historical surface area) is San Francisco Estuary, California. We conducted extensive field observations of fishes in the central San Francisco Estuary among stationary habitat types (i.e., wetland, shoal, and channel) over a 19-month period encompassing substantial variability in dynamic water quality conditions. Most of the species observed, especially native species of special management interest, were associated with tidal wetland habitat. Few species exhibited associations with water quality conditions driven by seasonal (temperature) or a combination of broad- and fine-scale ecosystem processes (salinity and turbidity). Our study provides (1) an empirical demonstration of how researchers can deal with the complex and dynamic expressions of habitat in estuarine systems to address urgent natural resource problems and (2) a clear demonstration of the urgent need for habitat restoration and its likely outcome in systems such as San Francisco Estuary. Restoration of suitable tidal wetland habitat on the West Coast of the United States is likely to be an effective conservation tool to support estuarine fishes given that over 90% of historical tidal wetland habitat in San Francisco Estuary and 85% of vegetated wetland habitat along the Pacific coast of the United States has been lost due to human modification.

Dispersion and Stratification Dynamics in the Upper Sacramento River Deep Water Ship Channel

University of California, Davis (UC Davis) | December 1st, 2021

Hydrodynamics control the movement of water and material within and among habitats, where time-scales of mixing can exert bottom-up regulatory effects on aquatic ecosyste

Hydrodynamics control the movement of water and material within and among habitats, where time-scales of mixing can exert bottom-up regulatory effects on aquatic ecosystems through their influence on primary production. The San Francisco Estuary (estuary) is a low-productivity ecosystem, which is in part responsible for constraining higher trophic levels, including fishes. Many research and habitat-restoration efforts trying to increase primary production have been conducted, including, as described here, a whole-ecosystem nutrient addition experiment where calcium nitrate was applied in the Sacramento River Deep Water Ship Channel (DWSC) to see if phytoplankton production could be increased and exported out of the DWSC. As an integral part of this experiment, we investigated the physical mechanisms that control mixing, and how these mechanisms affect the strength and duration of thermal stratification, which we revealed as critical for controlling phytoplankton dynamics in the relatively turbid upper DWSC. Analysis of a suite of mixing mechanisms and time-scales show that both tidal currents and wind control mixing rates and stratification dynamics in the DWSC. Longitudinal and vertical dispersion increased during periods of high wind, during which wind speed influenced dispersion more than tidal currents. Thermal stratification developed most days, which slowed vertical mixing but was rapidly broken down by wind-induced mixing. Stratification rarely persisted for longer than 24 hours, limiting phytoplankton production in the study area. The interaction between physical mechanisms that control mixing rates, mediate stratification dynamics, and ultimately limit primary production in the DWSC may be useful in informing habitat restoration elsewhere in the Delta and in other turbid aquatic environments.

Dissolved Oxygen in South San Francisco Bay: Variability, Important Processes, and Implications for Understanding Fish Habitat

San Francisco Estuary Institute (SFEI) | October 30th, 2018

Dissolved oxygen (DO) is a key water quality parameter that is related to nutrient enrichment in estuaries around the world. In 2017-2018, the San Francisco Estuary Inst

Dissolved oxygen (DO) is a key water quality parameter that is related to nutrient enrichment in estuaries around the world. In 2017-2018, the San Francisco Estuary Institute (SFEI) launched a study to investigate the potential effects of low-DO on habitat quality in Lower South Bay (LSB) to inform decisions about nutrient regulation. The goal of the study was to understand where and when regions of LSB provide adequate DO to support resident fish species. The study approach involved convening a team of experts to advise on methods, analyzing high frequency DO measurements from seven mooring stations in LSB, and partnering with researchers from UC Davis to interpret several years of monthly fish abundance data in LSB relative to DO and other factors.

Distribution of Lakes in the United States

Scientific American | June 12th, 1880

There are numerous lacustrine basins to be found in the States bordering the Pacific Ocean. As in other regions of the globe, their distribution is determined by the co

There are numerous lacustrine basins to be found in the States bordering the Pacific Ocean. As in other regions of the globe, their distribution is determined by the configuration of land, or, more specifically, by the forms of the great hydrographic basins in the interior of the continent; hence some general idea of the topography of the western portions of the United States is an essential preliminary.

Ditching Our Innocence: The Clean Water Act in the Age of the Anthropocene

Lewis & Clark College | May 10th, 2018

Humanity has entered the Age of the Anthropocene, a geologic era marked by the emergence of human activity as the single most dominant influence on Earth’s environment.

Humanity has entered the Age of the Anthropocene, a geologic era marked by the emergence of human activity as the single most dominant influence on Earth’s environment. Every ecosystem shows signs of anthropogenic influence, and the environments we experience everyday are often shaped almost entirely by human actions and decisions. The new discipline of reconciliation ecology recognizes this reality and suggests that we must manage the new habitats we create in order to protect species diversity and ecosystem services. But the 2015 rule defining the jurisdiction of the Clean Water Act explicitly excludes many manmade environments, including many artificial lakes, farm ponds, reflecting pools, and most ditches, treating these landscape features as faux nature somehow unworthy of protection. This treatment is a marked departure from past Environmental Protection Agency and U.S. Army Corps of Engineers practices, which allowed for consideration of such places on a case-by-case basis. This departure finds no support in the Supreme Court precedent leading up to the new rule and seems to be based entirely on a shortsighted view of these places as somehow unimportant to protecting the waters of the United States. Based on the law and science surrounding ditches, we conclude that such places merit protection under the Clean Water Act.

Divergent effects of climate change on future groundwater availability in key mid-latitude aquifers

Nature Portfolio (Springer Nature) | July 24th, 2020

Groundwater provides critical freshwater supply, particularly in dry regions where surface water availability is limited. Climate change impacts on GWS (groundwater stora

Groundwater provides critical freshwater supply, particularly in dry regions where surface water availability is limited. Climate change impacts on GWS (groundwater storage) could affect the sustainability of freshwater resources. Here, we used a fully-coupled climate model to investigate GWS changes over seven critical aquifers identified as significantly distressed by satellite observations. We assessed the potential climate-driven impacts on GWS changes throughout the 21st century under the business-as-usual scenario (RCP8.5). Results show that the climate-driven impacts on GWS changes do not necessarily reflect the long-term trend in precipitation; instead, the trend may result from enhancement of evapotranspiration, and reduction in snowmelt, which collectively lead to divergent responses of GWS changes across different aquifers. Finally, we compare the climate-driven and anthropogenic pumping impacts. The reduction in GWS is mainly due to the combined impacts of over-pumping and climate effects; however, the contribution of pumping could easily far exceed the natural replenishment.