Brent Topping
Brent is the Quality Management System (QMS) Manager for the Southwest Region. He, and the USGS QMS Team, lead USGS laboratories through implementation of a new Bureau-wide QMS. Brent works closely with Southwest Region laboratories and their staff on the implementation of 10 Core Elements, including documentation, procedures, methods, quality controls, sample management and quality assessments.
Science and Products
Dissolved arsenic, copper, and lead concentrations in surface water within the Klamath Basin (ver. 3.0, October 2022)
Arsenic (As) toxicity is a global environmental and health problem. There are both natural (eg volcanic activity) and anthropogenic sources of As (eg lead arsenate and copper arsenate were commonly used pesticides in the 1900's). Aqueous levels of arsenic in the Klamath Basin (CA, OR), which has a volcanic origin, can exceed at some locations both the Oregon Department of Environmental Quality hum
MODFLOW, MT3D-USGS and VS2DH simulations used to estimate groundwater and nutrient inflow to Upper Klamath Lake, Oregon
One-dimensional vertical models of GW flow (MODFLOW-2005) and solute transport (MT3D-USGS) were calibrated (UCODE) to 2014 observed dissolved silica (Si, 0.2-micron filtered) porewater concentrations in the upper 0.1 m of lakebed sediment to estimate GW flow and Si exchange across the lakebed interface. The Si-based calibrated GW flow rates were then used in conjunction with observed dissolved pho
Filter Total Items: 25
Dissolved arsenic concentrations in surface waters within the upper portions of the Klamath River Basin, Oregon and California
Arsenic toxicity is an environmental health problem. Levels of arsenic in surface waters at some locations in the Klamath River Basin in southern Oregon and northern California can exceed the U.S. Environmental Protection Agency (EPA) standard for drinking water. There are both anthropogenic and natural sources of arsenic. The Klamath River Basin consists primarily of volcanic deposits and contain
Authors
Marie Noële Croteau, Brent R. Topping, Rick A. Carlson
Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA
Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesiz
Authors
Hedeff I. Essaid, James S. Kuwabara, Nicholas Corson-Dosch, James L. Carter, Brent R. Topping
Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon
Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invert
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Rick A Carlson, Francis Parchaso, Steven V. Fend, Natalie Stauffer-Olsen, Andrew J. Manning, Jennie M. Land
Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column
Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for mo
Authors
Brent R. Topping, James S. Kuwabara, James L. Carter, Krista K. Garrettt, Eric Mruz, Sarah Piotter, John Y. Takekawa
Unintended consequences of management actions in salt pond restoration: cascading effects in trophic interactions
Salt evaporation ponds have played an important role as habitat for migratory waterbirds across the world, however, efforts to restore and manage these habitats to maximize their conservation value has proven to be challenging. For example, salinity reduction has been a goal for restoring and managing former salt evaporation ponds to support waterbirds in the South Bay Salt Pond Restoration Projec
Authors
John Y. Takekawa, Joshua T. Ackerman, Arriana Brand, Tanya R. Graham, Collin A. Eagles-Smith, Mark P. Herzog, Brent R. Topping, Gregory Shellenbarger, James S. Kuwabara, Eric Mruz, Sara L. Piotter, Nicole D. Athearn
Internal nutrient sources and nutrient distributions in Alviso Pond A3W, California
Within the Alviso Salt Pond complex, California, currently undergoing avian-habitat restoration, pore-water profilers (U.S. Patent 8,051,727 B1) were deployed in triplicate at two contrasting sites in Pond A3W (“Inlet”, near the inflow, and “Deep”, near the middle of the pond; figs. 1 and 2; table 1, note that tables in this report are provided online only as a .xlsx workbook at http://pubs.usgs.g
Authors
Brent R. Topping, James S. Kuwabara, Krista K. Garrett, John Y. Takekawa, Francis Parcheso, Sara Piotter, Iris Clearwater, Gregory Shellenbarger
Time scales of change in chemical and biological parameters after engineered levee breaches adjacent to Upper Klamath and Agency Lakes, Oregon
Eight sampling trips were coordinated after engineered levee breaches hydrologically reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. The reconnection, by a series of explosive blasts, was coordinated by The Nature Conservancy to reclaim wetlands that had for approximately seven decades been leveed for crop production. Sets of nonmetallic porewater profilers (U.S.
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Tamara M. Wood, Francis Parcheso, Jason M. Cameron, Jessica R. Asbill, Rick A. Carlson, Steven V. Fend
The transition of benthic nutrient sources after planned levee breaches adjacent to upper Klamath and Agency Lakes, Oregon
Four sampling trips were coordinated after planned levee breaches that hydrologically reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. Sets of nonmetallic pore-water profilers were deployed during these trips in November 2007, June 2008, May 2009, and July 2009. Deployments temporally spanned the annual cyanophyte bloom of Aphanizomenon flos-aquae (AFA) and spatia
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Francis Parchaso, Jason M. Cameron, Jessica R. Asbill, Steven V. Fend, John H. Duff, Anita C. Engelstad
Benthic oxygen demand in three former salt ponds adjacent to south San Francisco Bay, California
Sampling trips were coordinated in the second half of 2008 to examine the interstitial water in the sediment and the overlying bottom waters of three shallow (average depth 2 meters). The water column at all deployment sites was monitored with dataloggers for ancillary water-quality parameters (including dissolved oxygen, salinity, specific conductance, temperature, and pH) to facilitate the inte
Authors
Brent R. Topping, James S. Kuwabara, Nicole D. Athearn, John Y. Takekawa, Francis Parcheso, Kathleen D. Henderson, Sara Piotter
Benthic flux of nutrients and trace metals in the northern component of San Francisco Bay, California
Two sets of sampling trips were coordinated in late summer 2008 (weeks of July 8 and August 6) to sample the interstitial and overlying bottom waters at 10 shallow locations (9 sites
Authors
James S. Kuwabara, Brent R. Topping, Francis Parcheso, Anita C. Engelstad, Valerie E. Greene
Benthic nutrient sources to hypereutrophic Upper Klamath Lake, Oregon, USA
Three collecting trips were coordinated in April, May, and August 2006 to sample the water column and benthos of hypereutrophic Upper Klamath Lake (OR, USA) through the annual cyanophyte bloom of Aphanizomenon flos‐aquae. A pore‐water profiler was designed and fabricated to obtain the first high‐resolution (centimeter‐scale) estimates of the vertical concentration gradients of macro‐ and micronutr
Authors
J.S. Kuwabara, B.R. Topping, D. D. Lynch, J.L. Carter, H.I. Essaid
Environmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03
This report documents water quality in Camp Far West Reservoir from October 2001 through August 2003. The reservoir, located at approximately 300 feet above sea level in the foothills of the northwestern Sierra Nevada, California, is a monomictic lake characterized by extreme drawdown in the late summer and fall. Thermal stratification in summer and fall is coupled with anoxic conditions in the hy
Authors
Charles N. Alpers, A. Robin Stewart, Michael K. Saiki, Mark C. Marvin-DiPasquale, Brent R. Topping, Kelly M. Rider, Steven K. Gallanthine, Cynthia A. Kester, Robert O. Rye, Ronald C. Antweiler, John F. De Wild
Science and Products
Dissolved arsenic, copper, and lead concentrations in surface water within the Klamath Basin (ver. 3.0, October 2022)
Arsenic (As) toxicity is a global environmental and health problem. There are both natural (eg volcanic activity) and anthropogenic sources of As (eg lead arsenate and copper arsenate were commonly used pesticides in the 1900's). Aqueous levels of arsenic in the Klamath Basin (CA, OR), which has a volcanic origin, can exceed at some locations both the Oregon Department of Environmental Quality hum
MODFLOW, MT3D-USGS and VS2DH simulations used to estimate groundwater and nutrient inflow to Upper Klamath Lake, Oregon
One-dimensional vertical models of GW flow (MODFLOW-2005) and solute transport (MT3D-USGS) were calibrated (UCODE) to 2014 observed dissolved silica (Si, 0.2-micron filtered) porewater concentrations in the upper 0.1 m of lakebed sediment to estimate GW flow and Si exchange across the lakebed interface. The Si-based calibrated GW flow rates were then used in conjunction with observed dissolved pho
Filter Total Items: 25
Dissolved arsenic concentrations in surface waters within the upper portions of the Klamath River Basin, Oregon and California
Arsenic toxicity is an environmental health problem. Levels of arsenic in surface waters at some locations in the Klamath River Basin in southern Oregon and northern California can exceed the U.S. Environmental Protection Agency (EPA) standard for drinking water. There are both anthropogenic and natural sources of arsenic. The Klamath River Basin consists primarily of volcanic deposits and contain
Authors
Marie Noële Croteau, Brent R. Topping, Rick A. Carlson
Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA
Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesiz
Authors
Hedeff I. Essaid, James S. Kuwabara, Nicholas Corson-Dosch, James L. Carter, Brent R. Topping
Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon
Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invert
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Rick A Carlson, Francis Parchaso, Steven V. Fend, Natalie Stauffer-Olsen, Andrew J. Manning, Jennie M. Land
Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column
Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for mo
Authors
Brent R. Topping, James S. Kuwabara, James L. Carter, Krista K. Garrettt, Eric Mruz, Sarah Piotter, John Y. Takekawa
Unintended consequences of management actions in salt pond restoration: cascading effects in trophic interactions
Salt evaporation ponds have played an important role as habitat for migratory waterbirds across the world, however, efforts to restore and manage these habitats to maximize their conservation value has proven to be challenging. For example, salinity reduction has been a goal for restoring and managing former salt evaporation ponds to support waterbirds in the South Bay Salt Pond Restoration Projec
Authors
John Y. Takekawa, Joshua T. Ackerman, Arriana Brand, Tanya R. Graham, Collin A. Eagles-Smith, Mark P. Herzog, Brent R. Topping, Gregory Shellenbarger, James S. Kuwabara, Eric Mruz, Sara L. Piotter, Nicole D. Athearn
Internal nutrient sources and nutrient distributions in Alviso Pond A3W, California
Within the Alviso Salt Pond complex, California, currently undergoing avian-habitat restoration, pore-water profilers (U.S. Patent 8,051,727 B1) were deployed in triplicate at two contrasting sites in Pond A3W (“Inlet”, near the inflow, and “Deep”, near the middle of the pond; figs. 1 and 2; table 1, note that tables in this report are provided online only as a .xlsx workbook at http://pubs.usgs.g
Authors
Brent R. Topping, James S. Kuwabara, Krista K. Garrett, John Y. Takekawa, Francis Parcheso, Sara Piotter, Iris Clearwater, Gregory Shellenbarger
Time scales of change in chemical and biological parameters after engineered levee breaches adjacent to Upper Klamath and Agency Lakes, Oregon
Eight sampling trips were coordinated after engineered levee breaches hydrologically reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. The reconnection, by a series of explosive blasts, was coordinated by The Nature Conservancy to reclaim wetlands that had for approximately seven decades been leveed for crop production. Sets of nonmetallic porewater profilers (U.S.
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Tamara M. Wood, Francis Parcheso, Jason M. Cameron, Jessica R. Asbill, Rick A. Carlson, Steven V. Fend
The transition of benthic nutrient sources after planned levee breaches adjacent to upper Klamath and Agency Lakes, Oregon
Four sampling trips were coordinated after planned levee breaches that hydrologically reconnected both Upper Klamath Lake and Agency Lake, Oregon, to adjacent wetlands. Sets of nonmetallic pore-water profilers were deployed during these trips in November 2007, June 2008, May 2009, and July 2009. Deployments temporally spanned the annual cyanophyte bloom of Aphanizomenon flos-aquae (AFA) and spatia
Authors
James S. Kuwabara, Brent R. Topping, James L. Carter, Francis Parchaso, Jason M. Cameron, Jessica R. Asbill, Steven V. Fend, John H. Duff, Anita C. Engelstad
Benthic oxygen demand in three former salt ponds adjacent to south San Francisco Bay, California
Sampling trips were coordinated in the second half of 2008 to examine the interstitial water in the sediment and the overlying bottom waters of three shallow (average depth 2 meters). The water column at all deployment sites was monitored with dataloggers for ancillary water-quality parameters (including dissolved oxygen, salinity, specific conductance, temperature, and pH) to facilitate the inte
Authors
Brent R. Topping, James S. Kuwabara, Nicole D. Athearn, John Y. Takekawa, Francis Parcheso, Kathleen D. Henderson, Sara Piotter
Benthic flux of nutrients and trace metals in the northern component of San Francisco Bay, California
Two sets of sampling trips were coordinated in late summer 2008 (weeks of July 8 and August 6) to sample the interstitial and overlying bottom waters at 10 shallow locations (9 sites
Authors
James S. Kuwabara, Brent R. Topping, Francis Parcheso, Anita C. Engelstad, Valerie E. Greene
Benthic nutrient sources to hypereutrophic Upper Klamath Lake, Oregon, USA
Three collecting trips were coordinated in April, May, and August 2006 to sample the water column and benthos of hypereutrophic Upper Klamath Lake (OR, USA) through the annual cyanophyte bloom of Aphanizomenon flos‐aquae. A pore‐water profiler was designed and fabricated to obtain the first high‐resolution (centimeter‐scale) estimates of the vertical concentration gradients of macro‐ and micronutr
Authors
J.S. Kuwabara, B.R. Topping, D. D. Lynch, J.L. Carter, H.I. Essaid
Environmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03
This report documents water quality in Camp Far West Reservoir from October 2001 through August 2003. The reservoir, located at approximately 300 feet above sea level in the foothills of the northwestern Sierra Nevada, California, is a monomictic lake characterized by extreme drawdown in the late summer and fall. Thermal stratification in summer and fall is coupled with anoxic conditions in the hy
Authors
Charles N. Alpers, A. Robin Stewart, Michael K. Saiki, Mark C. Marvin-DiPasquale, Brent R. Topping, Kelly M. Rider, Steven K. Gallanthine, Cynthia A. Kester, Robert O. Rye, Ronald C. Antweiler, John F. De Wild