Michelle Hornberger, PhD
(She/her)Michelle Hornberger is a research physical scientist at the U.S. Geological Survey, focusing on identifying the ecological consequence of chemical and physical disturbance in aquatic systems. Benthic macroinvertebrates are used as bioindicators of environmental condition in watersheds impacted by multiple stressors, including hard rock mining and wildfires.
Education and Certifications
PhD—Ecology (2006) University of California, Davis
MS—Marine Ecology (1990) Moss Landing Marine Laboratory
BA—Environmental Studies/Geology (1985) University of California, Santa Barbara
Science and Products
Filter Total Items: 64
A conceptual framework to assess post-wildfire water quality: State of the science and knowledge gaps
Wildfire substantially alters aquatic ecosystems by inducing moderate to catastrophic physical and chemical changes. However, the relations of environmental and watershed variables that drive those effects are complex. We present a Driver-Factor-Stressor-Effect (DFSE) conceptual framework to assess the current state of the science related to post-wildfire water-quality. We reviewed 64 peer-reviewe
Authors
Sarah M. Elliott, Michelle I. Hornberger, Donald O. Rosenberry, Rebecca Frus, Richard M. Webb
A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures
Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physi
Authors
Michelle I. Hornberger
Spatiotemporal variations in copper, arsenic, cadmium, and zinc concentrations in surface water, fine-grained bed sediment, and aquatic macroinvertebrates in the upper Clark Fork Basin, western Montana—A 20-year synthesis, 1996–2016
The legacy of mining-related contamination in the upper Clark Fork Basin created an extensive longitudinal gradient in metal concentrations, extending from Silver Bow Creek to Lake Pend Oreille, Idaho. Downstream metal concentrations continue to decline, but, despite such improvements, the ecological health of much of the river remains uncertain. Understanding the long-term consequences of the Cla
Authors
Sara L. Caldwell Eldridge, Michelle I. Hornberger
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2019–September 2020
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Eric J. Hepler, Terry L. Heinert
Long-term monitoring reveals convergent patterns of recovery from mining contamination across 4 western US watersheds
Long-term studies of stream ecosystems are essential for assessing restoration success because they allow researchers to quantify recovery trajectories, gauge the relative influence of episodic events, and determine the time required to achieve clean-up objectives. To quantify responses of benthic macroinvertebrate assemblages to stream remediation, we integrated results of 4 long-term (20–29 y) a
Authors
William H. Clements, David B. Herbst, Michelle I. Hornberger, Christopher A. Mebane, Terry M. Short
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2018–September 2019
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Eric J. Hepler, Thomas E. Cleasby, Terry L. Heinert
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2017–September 2018
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Thomas E. Cleasby, Terry L. Heinert, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2016 through September 2017) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and emphasize trace elements associated wi
Authors
Tom Cleasby, Michelle I. Hornberger, Terry L. Heinert, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2015 through September 2016) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements ass
Authors
Kent A. Dodge, Michelle I. Hornberger, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2014 through September 2015) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements ass
Authors
Kent A. Dodge, Michelle I. Hornberger, Matthew A. Turner
Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2015
Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, California. This report includes data collected by U.S
Authors
Daniel J. Cain, Janet K. Thompson, Jeffrey Crauder, Francis Parchaso, A. Robin Stewart, Matthew A. Turner, Michelle I. Hornberger, Samuel N. Luoma
Water-quality, bed-sediment, and biological data (October 2013 through September 2014) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements associated w
Authors
Kent A. Dodge, Michelle I. Hornberger
Metal concentrations in streambed sediment in the lower Klamath River basin, 2018-2022
The U.S. Geological Survey is monitoring metal concentrations in streambed sediment pre- and post-dam removal in the lower Klamath River basin. Concentrations of aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, nickel, lead, titanium, vanadium and zinc were sampled at 10 mainstem sites, four tributaries and two reservoirs. Mainstem and tributary collecti
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for the Clark Fork River and Tributaries in the Upper Clark Fork Basin, Montana, October 2020-September 2021
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana (MT), as part of a long-term monitoring program within the Upper Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Upper Clark Fork Basin and monitor trace e
Data for laboratory experiments conducted with the caddisflies Hydropsyche californica and Arctopsyche grandis to derive copper and cadmium bioaccumulation parameters
This USGS data release includes data from experiments conducted with two species of caddisflies (Hydropsyche californica and Arctopsyche grandis (Order: Trichoptera) to quantify copper and cadmium uptake and loss after dissolved and dietary exposures. Both Arctopsyche and Hydropsyche belong to the family Hydropsychidae (O: Trichoptera). They are relatively sessile, net-spinning filter feeders. Dat
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2019–September 2020
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Metal concentrations in seston and water in the Clark Fork River, MT
Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2018 - September 2019
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020
Long-term monitoring of stream-bed sediments reveals spatial and temporal trends in metal concentrations. Here we use concentration gradient "heat maps" as a visualization tool to report annual mean arsenic, cadmium and copper concentrations along a contamination gradient in the Clark Fork River (CFR) in Western Montana. The CFR has been heavily impacted by large-scale mining operations since the
Trace-element concentrations in water, streambed sediment, and aquatic invertebrates at select locations in the Klamath River and major tributaries, 2018-2019
The U.S. Geological Survey is monitoring concentrations of metals and other trace elements in water, streambed sediment, and aquatic invertebrates at 6 locations in the middle and lower portions of the mainstem Klamath River from below J.C. Boyle dam in Oregon to near the mouth on the northwestern coast of California. Included are 3 tributary monitoring sites, one each on the Scott, Salmon, and Tr
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2017 - September 2018
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Water-Quality, Bed-Sediment, and Biological Data (October 2016 through September 2017) and Statistical Summaries of Data for Streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Metal Concentrations of Sediment from 1993-2017 in San Francisco Bay-Delta Estuary (San Pablo Bay and Suisun Bay), CA
Surface sediment samples from the North San Francisco Bay-Delta Estuary were collected monthly at five stations located west of Rio Vista and east of Point Pinole. Sediment was collected near Montezuma Slough, Chips Island, the Concord Naval Weapons Station, Carquinez Strait near Martinez, and San Pablo Bay at water depths ranging from 6.5 to 14.3 meters. Samples were collected coincident with wat
Science and Products
Filter Total Items: 64
A conceptual framework to assess post-wildfire water quality: State of the science and knowledge gaps
Wildfire substantially alters aquatic ecosystems by inducing moderate to catastrophic physical and chemical changes. However, the relations of environmental and watershed variables that drive those effects are complex. We present a Driver-Factor-Stressor-Effect (DFSE) conceptual framework to assess the current state of the science related to post-wildfire water-quality. We reviewed 64 peer-reviewe
Authors
Sarah M. Elliott, Michelle I. Hornberger, Donald O. Rosenberry, Rebecca Frus, Richard M. Webb
A biodynamic model predicting copper and cadmium bioaccumulation in caddisflies: Linkages between field studies and laboratory exposures
Hydropsyche and Arctopsyche are filter-feeding caddisflies (Order: Trichoptera; Family: Hydropsychidae) that are commonly used to monitor metal exposures in rivers. While tissue residue concentrations provide important bioaccumulation data regarding metal bioavailability, they do not provide information regarding the mechanisms of uptake and loss, or exposure history. This study examined the physi
Authors
Michelle I. Hornberger
Spatiotemporal variations in copper, arsenic, cadmium, and zinc concentrations in surface water, fine-grained bed sediment, and aquatic macroinvertebrates in the upper Clark Fork Basin, western Montana—A 20-year synthesis, 1996–2016
The legacy of mining-related contamination in the upper Clark Fork Basin created an extensive longitudinal gradient in metal concentrations, extending from Silver Bow Creek to Lake Pend Oreille, Idaho. Downstream metal concentrations continue to decline, but, despite such improvements, the ecological health of much of the river remains uncertain. Understanding the long-term consequences of the Cla
Authors
Sara L. Caldwell Eldridge, Michelle I. Hornberger
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2019–September 2020
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Eric J. Hepler, Terry L. Heinert
Long-term monitoring reveals convergent patterns of recovery from mining contamination across 4 western US watersheds
Long-term studies of stream ecosystems are essential for assessing restoration success because they allow researchers to quantify recovery trajectories, gauge the relative influence of episodic events, and determine the time required to achieve clean-up objectives. To quantify responses of benthic macroinvertebrate assemblages to stream remediation, we integrated results of 4 long-term (20–29 y) a
Authors
William H. Clements, David B. Herbst, Michelle I. Hornberger, Christopher A. Mebane, Terry M. Short
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2018–September 2019
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Eric J. Hepler, Thomas E. Cleasby, Terry L. Heinert
Water-quality, bed-sediment, and invertebrate tissue trace-element concentrations for tributaries in the Clark Fork Basin, Montana, October 2017–September 2018
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Authors
Gregory D. Clark, Michelle I. Hornberger, Thomas E. Cleasby, Terry L. Heinert, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2016 through September 2017) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and emphasize trace elements associated wi
Authors
Tom Cleasby, Michelle I. Hornberger, Terry L. Heinert, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2015 through September 2016) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements ass
Authors
Kent A. Dodge, Michelle I. Hornberger, Matthew A. Turner
Water-quality, bed-sediment, and biological data (October 2014 through September 2015) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements ass
Authors
Kent A. Dodge, Michelle I. Hornberger, Matthew A. Turner
Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2015
Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, California. This report includes data collected by U.S
Authors
Daniel J. Cain, Janet K. Thompson, Jeffrey Crauder, Francis Parchaso, A. Robin Stewart, Matthew A. Turner, Michelle I. Hornberger, Samuel N. Luoma
Water-quality, bed-sediment, and biological data (October 2013 through September 2014) and statistical summaries of data for streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin, with emphasis on trace elements associated w
Authors
Kent A. Dodge, Michelle I. Hornberger
Metal concentrations in streambed sediment in the lower Klamath River basin, 2018-2022
The U.S. Geological Survey is monitoring metal concentrations in streambed sediment pre- and post-dam removal in the lower Klamath River basin. Concentrations of aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, nickel, lead, titanium, vanadium and zinc were sampled at 10 mainstem sites, four tributaries and two reservoirs. Mainstem and tributary collecti
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for the Clark Fork River and Tributaries in the Upper Clark Fork Basin, Montana, October 2020-September 2021
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana (MT), as part of a long-term monitoring program within the Upper Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Upper Clark Fork Basin and monitor trace e
Data for laboratory experiments conducted with the caddisflies Hydropsyche californica and Arctopsyche grandis to derive copper and cadmium bioaccumulation parameters
This USGS data release includes data from experiments conducted with two species of caddisflies (Hydropsyche californica and Arctopsyche grandis (Order: Trichoptera) to quantify copper and cadmium uptake and loss after dissolved and dietary exposures. Both Arctopsyche and Hydropsyche belong to the family Hydropsychidae (O: Trichoptera). They are relatively sessile, net-spinning filter feeders. Dat
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2019–September 2020
Water, bed sediment, and invertebrate tissue were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the Clark Fork Basin. The sampling program was completed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to characterize aquatic resources in the Clark Fork Basin and monitor trace elements associated with histori
Metal concentrations in seston and water in the Clark Fork River, MT
Legacy mine waste from the Clark Fork River in Western Montana has contributed 100 million tons of tailings into the watershed between 1880 and 1982 (E.D. Andrews, Longitudinal dispersion of metals in the Clark Fork River, Montana, Lewis Publishers, 1987). Tailings deposited along the floodplain, streambanks and river channel continue to contribute metal contaminated material into the river in the
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace-Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2018 - September 2019
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Heatmap visualizations of arsenic, cadmium, and copper concentrations in streambed sediment in the Clark Fork River, Montana, 1996-2020
Long-term monitoring of stream-bed sediments reveals spatial and temporal trends in metal concentrations. Here we use concentration gradient "heat maps" as a visualization tool to report annual mean arsenic, cadmium and copper concentrations along a contamination gradient in the Clark Fork River (CFR) in Western Montana. The CFR has been heavily impacted by large-scale mining operations since the
Trace-element concentrations in water, streambed sediment, and aquatic invertebrates at select locations in the Klamath River and major tributaries, 2018-2019
The U.S. Geological Survey is monitoring concentrations of metals and other trace elements in water, streambed sediment, and aquatic invertebrates at 6 locations in the middle and lower portions of the mainstem Klamath River from below J.C. Boyle dam in Oregon to near the mouth on the northwestern coast of California. Included are 3 tributary monitoring sites, one each on the Scott, Salmon, and Tr
Water-Quality, Bed-Sediment, and Invertebrate Tissue Trace Element Concentrations for Tributaries in the Clark Fork Basin, Montana, October 2017 - September 2018
Water, bed sediment, and biota were sampled in selected streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Water-Quality, Bed-Sediment, and Biological Data (October 2016 through September 2017) and Statistical Summaries of Data for Streams in the Clark Fork Basin, Montana
Water, bed sediment, and biota were sampled in streams from Butte to near Missoula, Montana, as part of a monitoring program in the upper Clark Fork Basin of western Montana. The sampling program was led by the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency.
Metal Concentrations of Sediment from 1993-2017 in San Francisco Bay-Delta Estuary (San Pablo Bay and Suisun Bay), CA
Surface sediment samples from the North San Francisco Bay-Delta Estuary were collected monthly at five stations located west of Rio Vista and east of Point Pinole. Sediment was collected near Montezuma Slough, Chips Island, the Concord Naval Weapons Station, Carquinez Strait near Martinez, and San Pablo Bay at water depths ranging from 6.5 to 14.3 meters. Samples were collected coincident with wat