Sacramento River

Effects of high temperatures on threatened estuarine fishes during periods of extreme drought

Journal of Experimental Biology (The Company of Biologists) | March 1st, 2016

Climate change and associated increases in water temperatures may impact physiological performance in ectotherms and exacerbate endangered species declines. We used an in

Climate change and associated increases in water temperatures may impact physiological performance in ectotherms and exacerbate endangered species declines. We used an integrative approach to assess the impact of elevated water temperature on two fishes of immediate conservation concern in a large estuary system, the threatened longfin smelt (Spirinchus thaleichthys) and endangered delta smelt (Hypomesus transpacificus). Abundances have reached record lows in California, USA, and these populations are at imminent risk of extirpation. California is currently impacted by a severe drought, resulting in high water temperatures, conditions that will become more common as a result of climate change. We exposed fish to environmentally relevant temperatures (14°C and 20°C) and used RNA sequencing to examine the transcriptome-wide responses to elevated water temperature in both species. Consistent with having a lower temperature tolerance, longfin smelt exhibited a pronounced cellular stress response, with an upregulation of heat shock proteins, after exposure to 20°C that was not observed in delta smelt. We detected an increase in metabolic rate in delta smelt at 20°C and increased expression of genes involved in metabolic processes and protein synthesis, patterns not observed in longfin smelt. Through examination of responses across multiple levels of biological organization, and by linking these responses to habitat distributions in the wild, we demonstrate that longfin smelt may be more susceptible than delta smelt to increases in temperatures, and they have little room to tolerate future warming in California. Understanding the species-specific physiological responses of sensitive species to environmental stressors is crucial for conservation efforts and managing aquatic systems globally.

Effects of Hydraulic Conditions on Salvage Efficiency of Adult Delta Smelt at the Tracy Fish Collection Facility

U.S. Bureau of Reclamation (USBR) | February 29th, 2016

Effects of montane watershed development on vulnerability of domestic groundwater supply during drought

Journal of Hydrology (Elsevier) | April 1st, 2020

Climate change is expected to reduce recharge to montane aquifers in the western United States, but it is unclear how this will impact groundwater resources in waters

Climate change is expected to reduce recharge to montane aquifers in the western United States, but it is unclear how this will impact groundwater resources in watersheds where intensive surface-water development has disrupted the natural hydrologic regime. To better understand sources of recharge and associated vulnerabilities of groundwater supply in this setting, we made a detailed geochemical survey of domestic wells finished in fractured bedrock throughout the Yuba and Bear River watersheds (Sierra Nevada foothills, northern California) during historic drought (2015–2016). Stable isotopes of water and noble gas recharge temperatures closely tracked atmospheric lapse rates across a broad elevation gradient (100–2000 m), indicating groundwater inputs are dominated by local precipitation that rapidly recharges fractured bedrock during the winter wet-season. However, nearly one-quarter of wells had water isotopes that were fractionated by evaporation and warm recharge temperatures, indicative of mixing with dry-season recharge by surface water. Monte Carlo mixing models suggest evaporation-impacted groundwater samples are mixtures of local rain with an average of 28% ± 13% from diverted surface water that can recharge bedrock aquifers during the dry-season by either irrigation return flow or seepage from extensive distribution infrastructure. Wells that received recharge subsidies from diverted surface water had elevated levels of nitrate and coliform bacteria compared to those replenished exclusively by local precipitation, which are more vulnerable to supply shortage during drought. It is important to consider the impacts of increased surface-water development on the quantity and quality of groundwater recharge in rapidly developing montane watersheds.

Effects of more extreme precipitation regimes on maximum seasonal snow water equivalent

American Geophysical Union (AGU) | October 31st, 2012

This study demonstrates how more extreme precipitation regimes (MEPR) under a changed climate might affect seasonal snow water resources.

This study demonstrates how more extreme precipitation regimes (MEPR) under a changed climate might affect seasonal snow water resources.

Effects of salinity on olfactory toxicity and behavioral responses of juvenile salmonids from copper

Aquatic Toxicology (Elsevier) | April 4th, 2016

Dissolved copper is one of the more pervasive and toxic constituents of stormwater runoff and is commonly found in stream, estuary, and coastal marine habitats of juvenil

Dissolved copper is one of the more pervasive and toxic constituents of stormwater runoff and is commonly found in stream, estuary, and coastal marine habitats of juvenile salmon. While stormwater runoff does not usually carry copper concentrations high enough to result in acute lethality, they are of concern because sublethal concentrations of copper exposure have been shown to both impair olfactory function and alter behavior in various species in freshwater. To compare these results to other environments that salmon are likely to encounter, experiments were conducted to evaluate the effects of salinity on the impairment of olfactory function and avoidance of copper. Copper concentrations well within the range of those found in urban watersheds, have been shown to diminish or eliminate the olfactory response to the amino acid, l-serine in freshwater using electro-olfactogram (EOG) techniques. The olfactory responses of both freshwater-phase and seawater-phase coho and seawater-phase Chinook salmon, were tested in freshwater or seawater, depending on phase, and freshwater-phase coho at an intermediate salinity of 10‰. Both 10‰ salinity and full strength seawater protected against the effects of 50 μg copper/L. In addition to impairing olfactory response, copper has also been shown to alter salmon behavior by causing an avoidance response. To determine whether copper will cause avoidance behavior at different salinities, experiments were conducted using a multi-chambered experimental tank. The circular tank was divided into six segments by water currents so that copper could be contained within one segment yet fish could move freely between them. The presence of individual fish in each of the segments was counted before and after introduction of dissolved copper (<20 μg/L) to one of the segments in both freshwater and seawater. To address whether use of preferred habitat is altered by the presence of copper, experiments were also conducted with a submerged structural element. The presence of sub-lethal levels of dissolved copper altered the behavior of juvenile Chinook salmon by inducing an avoidance response in both freshwater and seawater. While increased salinity is protective against loss of olfactory function from dissolved copper, avoidance could potentially affect behaviors beneficial to growth, survival and reproductive success.

Effects of Snow Water Storage on Hydrologic Partitioning Across the Mountainous, Western United States

American Geophysical Union (AGU) | July 12th, 2023

The retention of snow water storage and subsequent release of stored water in summer months resulted in increased hydrologic partitioning to streamflow. If the Snow Stora

The retention of snow water storage and subsequent release of stored water in summer months resulted in increased hydrologic partitioning to streamflow. If the Snow Storage Index (SSI) decreases with future warming, the volume of water partitioned streamflow will decrease non-uniformly across the western U.S. with substantial implications for ecosystemsand agricultural, industrial, and domestic water supplies.

Effects of structure and volcanic stratigraphy on groundwater and surface water flow: Hat Creek basin, California, USA

Hydrogeology Journal (Springer) | January 16th, 2022

Hydrogeologic systems in the southern Cascade Range in California (USA) develop in volcanic rocks where morphology, stratigraphy, extensional structures, and attendant ba

Hydrogeologic systems in the southern Cascade Range in California (USA) develop in volcanic rocks where morphology, stratigraphy, extensional structures, and attendant basin geometry play a central role in groundwater flow paths, groundwater/surface-water interactions, and spring discharge locations. High-volume springs (greater than 3 m3/s) flow from basin-filling (

Effects of Surface-Water Use on Domestic Groundwater Availability and Quality During Drought in the Sierra Nevada Foothills, California

U.S. Geological Survey (USGS) | January 13th, 2020

Approximately 2 million California residents rely on privately owned domestic wells for drinking water. During the California drought of 2012−16 groundwater lev

Approximately 2 million California residents rely on privately owned domestic wells for drinking water. During the California drought of 2012−16 groundwater levels declined in many parts of the state and wells were deepened in response. Most of the wells deepened during this time were domestic wells that were drilled into fractured bedrock throughout the Sierra Nevada foothills region of northern California (California Department of Water Resources, 2014). To understand the impacts of extreme drought on groundwater supply availability and quality in this setting, the United States Geological Survey (USGS) completed a geochemical survey of domestic wells throughout the Yuba and Bear River watersheds during 2015–16 (fig. 1) as part of the State Water Board’s Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP). This fact sheet highlights key findings from the GAMA-PBP assessment (Levy and others, 2020).

Effects of the South Delta Agricultural Barriers on Emigrating Juvenile Salmonids

California Department of Water Resources (DWR) | November 28th, 2018

The TBP is implemented in compliance with the terms and conditions of two NMFS Biological Opinions (BiOp) (NMFS 2008, 2009). To comply with the requirements of the NMFS

The TBP is implemented in compliance with the terms and conditions of two NMFS Biological Opinions (BiOp) (NMFS 2008, 2009). To comply with the requirements of the NMFS BiOps, a study of the effects of the three SDABs (i.e., ORTB, MRB, and GLCB) on emigrating (i.e., out-migrating) juvenile salmonids was conducted (2010–2011) and the results are reported in this document. There were four effects considered in this study: 1) survival of juvenile salmonids (Ŝ); 2) juvenile salmonid time-in-vicinity (TIV) of a barrier; 3) predation on juvenile salmonids; and 4) predatory fish density evaluations near the barriers before-, during-, and after- construction during each study year. For one barrier, the ORTB, two-dimensional (2D) acoustic fish tracks for juvenile salmonids were used to evaluate: 1) the rates of successful passage through the barrier; and 2) route selection through the barrier. In addition, utilizing the ORTB 2D fish tracks for both juvenile salmonids and predatory fish, a mixture model (Romine et al. 2014) approach was employed to determine the probability that a juvenile salmonid had been eaten by a predatory fish in the vicinity of the ORTB.

Effects of Tidal Wetland Restoration on Fish: A Suite of Conceptual Models

California Department of Water Resources (DWR) | November 2nd, 2017

Fishes native to the Sacramento-San Joaquin Delta and Suisun Marsh have historically had access to a complex mosaic of dendritic channels, large tule marshes, floodplain

Fishes native to the Sacramento-San Joaquin Delta and Suisun Marsh have historically had access to a complex mosaic of dendritic channels, large tule marshes, floodplains, and riparian woodlands. After the Gold Rush, that habitat was rapidly and drastically altered, and today several native fish species occur in record low numbers. Although many other stressors also contributed to population declines, habitat restoration is a major component of strategies to reverse the trend. Programs such as the Fish Restoration Program particularly emphasize restoration of tidal wetlands and associated shallow subtidal habitat and strive to restore and learn in an adaptive management context. Conceptual models, therefore, are necessary to plan both the restoration and the monitoring and evaluation of restoration actions.