Tamara Kraus is a Research Soil Scientist at the California Water Science Center.
Tamara Kraus received a master's degree in Agronomy and a doctoral degree in Soils and Biogeochemistry from the University of California, Davis. She has been working at the USGS California Water Science Center (CAWSC) in Sacramento since 2004, where she does research on the cycling of carbon and nutrients, and the linkages between terrestrial and aquatic systems. Her projects span a range of topics from identifying sources of dissolved organic carbon and to inform drinking water quality management, to using constructed wetlands to reverse subsidence, to the application of in situ coagulation to remove mercury from surface waters, to understanding the links between nutrients and phytoplankton.
Professional Experience
2010-present Soil Scientist, US Geological Survey, Sacramento, CA
2006-2009 Post Doctoral Researcher, US Geological Survey through UC Davis, Sacramento, CA
2004-2005 National Research Council Post Doctoral Fellow with US Geological Survey, Sacramento, CA
1996-2003 Research Assistant: Soil Chemistry Lab, , University of California, Davis, CA
1996-2003 Teaching Assistant: Soils and Biogeochemistry, , University of California, Davis, CA
1995-1996 Post-Graduate Researcher/Project Manager, University of California, Davis, CA
1992-1994 Research Assistant: Agronomy, University of California, Davis, CA
Education and Certifications
Ph.D., Soils and Biogeochemistry, 2002, University of California, Davis , CA Dissertation: Tannins and Nutrient Dynamics in Forest Soils: Plant-Litter-Soil Interactions
M.S., Agronomy and Range Science, 1994, University of California, Davis, CAThesis: Weed Abundance and Competition in Water-Seeded versus Drill-Seeded Rice in California
B.A., Biology and Society: Agriculture and the Environment, 1989, College of Arts and Sciences Cornell University, Ithaca, NY
Science and Products
Biogeochemistry Group
Assessing Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta
Evaluating the effects of wastewater-derived nutrients on phytoplankton abundance and community structure in the San Francisco Estuary and Delta
Modeling Nitrogen Reduction Benefit to Invasive Aquatic Vegetation vs. Native Phytoplankton
Monitoring Cyanotoxins in California's Sacramento-San Joaquin Delta: Fixed Stations and High-Resolution Mapping Surveys
Trends in Dissolved Organic Carbon (DOC) in the Sacramento-San Joaquin Delta
Subsidence in the Sacramento-San Joaquin Delta
Nitrogen Dynamics Along the Sacramento River and Links to Phytoplankton Dynamics: Resolving Spatial and Temporal Variability Using In-Situ, High-Frequency Measurements and Other Tools
Causes and Relevance of Phytoplankton Blooms in the Northern Sacramento-San Joaquin Delta
Decomposition of Organic Soils in the Sacramento-San Joaquin Delta
Low Intensity Chemical Dosing (LICD)
Effects of Aquatic Vegetation on Water Quality and Residence Time in the Bay-Delta
Absorbance and fluorescence measurements and concentrations of disinfection by-products in source water and finished water in the McKenzie River Basin, Oregon: 2012-2014
Produced water chemistry data for the Lost Hills, Fruitvale, and North and South Belridge study areas, Southern San Joaquin Valley, California (version 1.1, September 2020)
Characterization of water residence time, nutrients, phytoplankton and related water quality constituents in the Cache Slough Complex of the California Sacramento-San Joaquin Delta in 2017 and 2018
Spatial assessment of nutrients and water-quality constituents in Suisun Marsh with the salinity control gate reoperation experiment; a Delta Smelt Resiliency Strategy experiment 2018
Assessment of water-quality in the California Sacramento-San Joaquin Delta during a North Delta directed flow action: August - October 2018
Assessment of nutrients and water-quality constituents in the North Delta during Yolo Bypass flooding events in March 2017
Assessment of nutrients and water-quality constituents at the Sacramento-San Joaquin River Confluence during a phytoplankton bloom in July 2017
High-Resolution Measurements to Identify Effects of Aquatic Vegetation on Water Quality and Stratification
Chemical and Stable Isotope Data for Discrete Water Samples Collected in the Northern Sacramento-San Joaquin Delta, 2011-2012
Sources and characteristics of dissolved organic carbon in the McKenzie River, Oregon, related to the formation of disinfection by-products in treated drinking water
Stable isotopes provide insight into sources and cycling of N compounds in the Sacramento-San Joaquin Delta, California, USA
Ocean connectivity drives trophic support for consumers in an intermittently closed coastal lagoon
Lateral carbon exports from drained peatlands: An understudied carbon pathway in the Sacramento-San Joaquin Delta, California
Spatial variability of phytoplankton in a shallow tidal freshwater system reveals complex controls on abundance and community structure
Chemically enhanced treatment wetland to improve water quality and mitigate land subsidence in the Sacramento-San Joaquin Delta: Cost and design considerations
Sequestration and transformation in chemically enhanced treatment wetlands: DOC, DBPPs and Nutrients
Aluminum- and iron-based coagulation for in-situ removal of dissolved organic carbon, disinfection byproducts, mercury and other constituents from agricultural drain water
Effects of ferric sulfate and polyaluminum chloride coagulation enhanced treatment wetlands on Typha growth, soil and water chemistry
Procedures for using the Horiba Scientific Aqualog® fluorometer to measure absorbance and fluorescence from dissolved organic matter
Sediment accretion and carbon storage in constructed wetlands receiving water treated with metal-based coagulants
Wetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors
Science and Products
- Science
Biogeochemistry Group
The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.Assessing Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta
Sediments represent an important pool of nutrients in the Sacramento-San Joaquin Delta (Delta). The exchange of nutrients between the water column and the benthos impacts water quality and effects phytoplankton, harmful algal blooms, aquatic vegetation, and drinking water quality. To date, there is very limited information about nutrient pools in Delta sediments, nor how these nutrients are...Evaluating the effects of wastewater-derived nutrients on phytoplankton abundance and community structure in the San Francisco Estuary and Delta
Planned upgrades to the Sacramento Regional wastewater treatment plant (SRWTP) will substantially reduce nutrient discharge and also alter the types and amounts of nutrients being distributed across the San Francisco Delta and Estuary (Delta). One highly anticipated outcome of lower nutrients is improved productivity in the phytoplankton communities that supply aquatic food webs, which should...Modeling Nitrogen Reduction Benefit to Invasive Aquatic Vegetation vs. Native Phytoplankton
Phytoplankton comprise the bottom of the aquatic food web and the abundance of phytoplankton serves as an indicator of healthy aquatic habitats. In the Sacramento-San Joaquin River Delta (Delta), competing with phytoplankton for required nitrogen, invasive aquatic vegetation (IAV) has increased exponentially in recent years. Once established, IAV can negatively impact local ecosystems and...Monitoring Cyanotoxins in California's Sacramento-San Joaquin Delta: Fixed Stations and High-Resolution Mapping Surveys
California’s Sacramento-San Joaquin River Delta (Delta) provides drinking water to about 30 million people and irrigation water to the agriculturally rich Central Valley. The Delta is also home to numerous threatened and endangered native species. The health of the Delta's aquatic ecosystems, and fish in particular, have long been in a state of decline. This is associated with decreasing...Trends in Dissolved Organic Carbon (DOC) in the Sacramento-San Joaquin Delta
Water from the Sacramento-San Joaquin Delta contains high concentrations of disinfection byproduct-forming (DBP-forming) materials when treated for potable use. DBPs form when dissolved organic compounds (DOC) in water react with disinfectants such as chlorine and ozone during the water treatment process. The amount of DBPs that form is a function of both the amount and source of the DOC, both of...Subsidence in the Sacramento-San Joaquin Delta
The Sacramento-San Joaquin Delta is part of the San Francisco Estuary, home to a diverse flora and fauna, including several threatened and endangered species, has a large area of prime farmland, and serves as the hub of California's freshwater-delivery system that moves water from the wet north to the dry southern part of the State.Nitrogen Dynamics Along the Sacramento River and Links to Phytoplankton Dynamics: Resolving Spatial and Temporal Variability Using In-Situ, High-Frequency Measurements and Other Tools
The overall project objective is to further our understanding of the link between nitrogen and phytoplankton dynamics in the Sacramento River and to elucidate effects of wastewater treatment plant effluent on food web dynamics.Causes and Relevance of Phytoplankton Blooms in the Northern Sacramento-San Joaquin Delta
Phytoplankton are an important part of aquatic food webs and ecosystems. These single-celled plants grow faster in the stronger light of spring or summer, resulting in population explosions called phytoplankton blooms. These blooms in turn feed zooplankton (free-floating aquatic microorganisms), providing food for many aquatic species, including fish, shrimp, crabs, and other invertebrates.Decomposition of Organic Soils in the Sacramento-San Joaquin Delta
The Sacramento-San Joaquin Delta of California was once a great tidal freshwater marsh. It is blanketed by peat and peaty alluvium deposited where streams originating in the Sierra Nevada, Coast Ranges, and South Cascade Range enter San Francisco Bay. In the late 1800s, levees were built along the stream channels, and the land thus protected from flooding was drained, cleared, and planted (...Low Intensity Chemical Dosing (LICD)
Rivers, wetlands, and agricultural operations supply natural organic material to the Sacramento-San Joaquin Delta (Delta) and the San Francisco Estuary. This natural organic matter provides many ecosystem benefits, but it also adversely affects drinking water. During drinking water treatment, chlorine added for purposes of pathogen control reacts with dissolved organic carbon (DOC) in the water to...Effects of Aquatic Vegetation on Water Quality and Residence Time in the Bay-Delta
The spread of invasive aquatic vegetation in the Sacramento-San Joaquin Delta is having a profound impact on the Delta’s natural habitat. The presence of these “aquatic weeds” has been shown to alter water velocity and increase water clarity, posing threats to native fish species, specifically the threatened Delta Smelt. These aquatic plants can also affect the foodweb by altering nutrient... - Data
Absorbance and fluorescence measurements and concentrations of disinfection by-products in source water and finished water in the McKenzie River Basin, Oregon: 2012-2014
This data release contains the results from a study that characterized the concentration and quality of dissolved organic carbon (DOC) in the McKenzie River, a relatively pristine watershed in western Oregon, and its link to forming disinfection by-products (DBPs) in treated drinking water. The study aimed to identify the primary source(s) of DOC in source water for the Eugene Water and Electric BProduced water chemistry data for the Lost Hills, Fruitvale, and North and South Belridge study areas, Southern San Joaquin Valley, California (version 1.1, September 2020)
The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (Water Board) collected produced water and casing gas samples from petroleum wells and other oil-field sites in selected oil fields in the southern San Joaquin Valley in Kern County in 2016 and 2017. The samples were collected as part of the Water Boards Regional Groundwater Monitoring ProgramCharacterization of water residence time, nutrients, phytoplankton and related water quality constituents in the Cache Slough Complex of the California Sacramento-San Joaquin Delta in 2017 and 2018
Data was collected in the Cache Slough Complex located in the northern San Francisco Estuary to characterize water quality parameters at high spatial resolution. Data collection was conducted on three separate occasions: October 2017, May 2018, and October 2018. Data set includes nitrate, ammonium, ortho-phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, cSpatial assessment of nutrients and water-quality constituents in Suisun Marsh with the salinity control gate reoperation experiment; a Delta Smelt Resiliency Strategy experiment 2018
This data release documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in Suisun Marsh and Suisun Bay in the San Francisco Estuary of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, chlorophyll, blue-green algal pigments, andAssessment of water-quality in the California Sacramento-San Joaquin Delta during a North Delta directed flow action: August - October 2018
This report documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta in the Sacramento-San Joaquin River Delta of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll . Data-collection cruises were coAssessment of nutrients and water-quality constituents in the North Delta during Yolo Bypass flooding events in March 2017
The data release contains data for the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta in the Sacramento-San Joaquin River Delta of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll. Data-collection cruAssessment of nutrients and water-quality constituents at the Sacramento-San Joaquin River Confluence during a phytoplankton bloom in July 2017
This report documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta in the Sacramento-San Joaquin River Delta of California, USA. The data set includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll. Data-collection were conducted oHigh-Resolution Measurements to Identify Effects of Aquatic Vegetation on Water Quality and Stratification
The dataset documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta of the Sacramento-San Joaquin River Delta of California, USA. The dataset includes surface mapping, depth profile, and discrete data for nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, and chlChemical and Stable Isotope Data for Discrete Water Samples Collected in the Northern Sacramento-San Joaquin Delta, 2011-2012
This data set consists of chemical and stable isotope data obtained through the analysis of discrete water samples collected from 14 fixed sampling locations in the northern Sacramento-San Joaquin Delta at roughly monthly intervals between April 2011 and November 2012. - Publications
Filter Total Items: 34
Sources and characteristics of dissolved organic carbon in the McKenzie River, Oregon, related to the formation of disinfection by-products in treated drinking water
Executive SummaryThis study characterized the concentration and quality of dissolved organic carbon (DOC) in the McKenzie River, a relatively undeveloped watershed in western Oregon, and its link to forming disinfection by-products (DBPs) in treated drinking water. The study aimed to identify the primary source(s) of DOC in source water for the Eugene Water & Electric Board’s (EWEB) conventional tStable isotopes provide insight into sources and cycling of N compounds in the Sacramento-San Joaquin Delta, California, USA
River deltas and their diverse array of aquatic environments are increasingly impacted by anthropogenic inputs of nitrogen (N). These inputs can alter the N biogeochemistry of these systems and promote undesirable phenomena including harmful algae blooms and invasive aquatic macrophytes. To examine N sources and biogeochemical processes in the Sacramento-San Joaquin Delta, a river delta located inOcean connectivity drives trophic support for consumers in an intermittently closed coastal lagoon
Estuarine food webs are complex, as marine, freshwater, and terrestrial inputs combine and contribute variable amounts of organic material. Seasonal fluctuations in precipitation amplify the dynamism inherent to estuarine food webs, particularly in lagoonal estuaries, which can be seasonally closed and disconnected from the ocean in low-runoff periods (bar-built lagoons). Despite their abundance aLateral carbon exports from drained peatlands: An understudied carbon pathway in the Sacramento-San Joaquin Delta, California
Degradation of peatlands via drainage is increasing globally and destabilizing peat carbon (C) stores. The effects of drainage on the timing and magnitude of lateral C losses from degraded peatlands remains understudied. We measured spatial and temporal variability in lateral C exports from three drained peat islands in the Sacramento‐San Joaquin Delta in California across the 2017 and 2018 waterSpatial variability of phytoplankton in a shallow tidal freshwater system reveals complex controls on abundance and community structure
Estuaries worldwide are undergoing changes to patterns of aquatic productivity because of human activities that alter flow, impact sediment delivery and thus the light field, and contribute nutrients and contaminants like pesticides and metals. These changes can influence phytoplankton communities, which in turn can alter estuarine food webs. We used multiple approaches-including high-resolution wChemically enhanced treatment wetland to improve water quality and mitigate land subsidence in the Sacramento-San Joaquin Delta: Cost and design considerations
Water quality impairment and land surface subsidence threaten the viability of the Sacramento-San Joaquin Delta (Delta), a critical component of California’s water conveyance system. Current day irrigation drainage through Delta island peat soils impacts drinking water treatment and is linked to mercury transport, potentially posing both ecological and public health concerns. Hybrid coagulation-trSequestration and transformation in chemically enhanced treatment wetlands: DOC, DBPPs and Nutrients
We examined the effectiveness of chemically enhanced treatment wetlands (CETWs), wetlands that received water treated with coagulants, to remove dissolved organic carbon (DOC), disinfection byproduct precursors (DBPPs), nutrients and metals from agricultural drain water. Wetlands consisted of controls with no coagulant addition, ferric sulfate dosed and polyaluminum chloride dosed treatments. CETWAluminum- and iron-based coagulation for in-situ removal of dissolved organic carbon, disinfection byproducts, mercury and other constituents from agricultural drain water
Agricultural production on wetland soils can be significant sources of dissolved organic carbon (DOC), disinfection byproduct precursors, mercury and nutrients to downstream water bodies and accelerate land subsidence. Presented as a potential solution for in-situ water quality improvement and land subsidence mitigation, chemically enhanced treatment wetlands (CETWs) were used to leverage both coaEffects of ferric sulfate and polyaluminum chloride coagulation enhanced treatment wetlands on Typha growth, soil and water chemistry
Land surface subsidence is a concern in many deltas worldwide as it contributes to water quality degradation, loss of fertile land and increased potential for levee failure. As a possible solution to these concerns, on-site coagulation enhanced treatment wetlands(CETWs), coagulation water treatment followed by wetland passage serving as a settling basin, were implemented in a field-scale study locProcedures for using the Horiba Scientific Aqualog® fluorometer to measure absorbance and fluorescence from dissolved organic matter
Advances in spectroscopic techniques have led to an increase in the use of optical measurements (absorbance and fluorescence) to assess dissolved organic matter composition and infer sources and processing. Although optical measurements are easy to make, they can be affected by many variables rendering them less comparable, including by inconsistencies in sample collection (for example, filter porSediment accretion and carbon storage in constructed wetlands receiving water treated with metal-based coagulants
In many regions of the world, subsidence of organic rich soils threatens levee stability and freshwater supply, and continued oxidative loss of organic matter contributes to greenhouse gas production. To counter subsidence in the Sacramento-San Joaquin Delta of northern California, we examined the feasibility of using constructed wetlands receiving drainage water treated with metal-based coagulantWetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors
Constructed wetlands are used worldwide to improve water quality while also providing critical wetland habitat. However, wetlands have the potential to negatively impact drinking water quality by exporting dissolved organic carbon (DOC) that upon disinfection can form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs). We used a replicated field-scale study loca - News