Denis R LeBlanc
Denis LeBlanc is a Scientist Emeritus with the New England Water Science Center.
Denis conducts research on the hydrology of shallow, unconfined groundwater/surface-water systems and the fate and transport of contaminants.
He joined the USGS in 1975 and, until 1983, participated in and led investigations of Cape Cod's hydrologic system.
From 1983 until his retirement in 2023, he conducted and coordinated multidisciplinary research at the USGS Cape Cod Toxic Substances Hydrology Research site at the Joint Base Cape Cod (JBCC) near Falmouth, Mass. He also led the team that provided technical support to Air Force and Army National Guard environmental restoration programs at JBCC and participated in several projects with the U.S Environmental Protection Agency on nitrogen and other wastewater contaminants in Cape Cod's groundwater.
Denis received his B.S. in Hydrology from the University of New Hampshire and his M.S. in Civil and Environmental Engineering from the Massachusetts Institute of Technology.
He is a member of the National Ground Water Association and the Geological Society of America.
Professional Experience
Scientist Emeritus, U.S. Geological Survey, New England Water Science Center, 2023 to Present
Research Hydrologist, U.S. Geological Survey, New England Water Science Center, Cape Cod Toxic Substances Hydrology projects, 1983 to 2023
Hydrologist, U.S. Geological Survey, New England Water Science Center, Cape Cod Hydrology projects, 1975 to 1983
Oceanographic Field Assistant, Normandeau Associates, 1973 to 1975
Education and Certifications
M.S. Civil and Environmental Engineering, Massachusetts Institute of Technology, 2001
B.S. Hydrology, University of New Hampshire, 1975
Affiliations and Memberships*
Geological Society of America 1997, to Present
National Groundwater Association, 1977 to Present
Honors and Awards
Eugene M. Shoemaker Award for Lifetime Achievement in Communications, U.S. Geological Survey, 2020
Distinguished Service Award, Dept. of the Interior, 2016
Fellow, Geological Society of America, 2013
Meritorious Service Award, Dept. of the Interior, 1995
Science and Products
Filter Total Items: 23
Concentrations of per- and polyfluoroalkyl substances (PFAS) and related chemical and physical data at and near surface-water/groundwater boundaries on Cape Cod, Massachusetts, 2016-19 Concentrations of per- and polyfluoroalkyl substances (PFAS) and related chemical and physical data at and near surface-water/groundwater boundaries on Cape Cod, Massachusetts, 2016-19
Groundwater, surface-water, sediment, and associated quality-control samples were collected downgradient from a former fire training area and wastewater infiltration beds on Cape Cod, Massachusetts and analyzed for per- and polyfluoroalkyl substances (PFAS). Samples were collected between July 2016 and February 2019 following U.S. Geological Survey protocols. Field parameters reported...
Microbial Community and N-cycling gene abundance from Ponds and Groundwater on Cape Cod, MA (2015 - 2018) Microbial Community and N-cycling gene abundance from Ponds and Groundwater on Cape Cod, MA (2015 - 2018)
Surface water, pore water, pond bottom sediments, and groundwater were sampled within and downgradient from five groundwater flow-through ponds that ranged from oligotrophic to eutrophic in Cape Cod, Massachusetts during different seasons from 2015 – 2018. The sampled ponds included Ashumet, Santuit, Snake, Shubael, and Longs. Pore water was collected between 15 to 100 cm below the pond...
Target-Chemical Concentration Results of Mixed-Organic/Inorganic Chemical Exposures in Cape Cod, Massachusetts Tapwater, 2018 Target-Chemical Concentration Results of Mixed-Organic/Inorganic Chemical Exposures in Cape Cod, Massachusetts Tapwater, 2018
This dataset provides the water-quality results for organic and inorganic concentrations analyzed from samples collected at residential tapwater faucets, sourced from private drinking water wells in Cape Cod, Massachusetts. Samples were collected in July and August, 2018 from 20 locations. Samples were analyzed at various U.S. Geological Survey laboratories: the National Water Quality...
Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts
Reserved for CDJ. Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts Johnson, White, Phillips, Pappas, Hull, LeBlanc, and Lane
Determination of the effect of temperature (Q10) on rates of oxygen consumption in surface sediments collected from Ashumet Pond on Cape Cod, MA (2016) Determination of the effect of temperature (Q10) on rates of oxygen consumption in surface sediments collected from Ashumet Pond on Cape Cod, MA (2016)
This data release presents results from a laboratory study designed to measure the effect of temperature on rates of oxygen consumption within lake-bottom surface sediments at 0- to 5-cm depth. Sediment and lake water samples were collected June 8, 2016 from the South site in Ashumet Pond, Cape Cod, MA, where lake water recharges to the aquifer. Samples were shipped to Boulder, CO for...
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
The U.S. Geological Survey Toxic Substances Hydrology Program at Cape Cod has been investigating the fate and transport of a treated-wastewater, groundwater contaminant plume. A portion of the contaminated groundwater discharges into Ashumet Pond, a kettle hole, freshwater lake. A study was conducted from June 2013 to June 2015 to document transport, transformation, and discharge of...
Data Release for Lake Shadow Seepage Calculations from Ashumet Pond, Cape Cod, MA, 2016 - 2018 Data Release for Lake Shadow Seepage Calculations from Ashumet Pond, Cape Cod, MA, 2016 - 2018
Hydrologic data were collected in the nearshore lake-bottom sediments of five lakes on western Cape Cod, Massachusetts: Ashumet (Falmouth), Long (Centerville), Santuit (Mashpee), Shubael (Barnstable), and Snake (Sandwich) Ponds. Water budgets of flow-through glacial kettle lakes are commonly dominated by groundwater flow into and surface-water seepage out of the lake, and inputs and...
Natural gradient, lakebed tracer tests using nitrite in a nitrate-contaminated groundwater discharge zone in Ashumet Pond, Massachusetts Natural gradient, lakebed tracer tests using nitrite in a nitrate-contaminated groundwater discharge zone in Ashumet Pond, Massachusetts
The U.S. Geological Survey Toxic Substances Hydrology Program at Cape Cod has been investigating the fate and transport of a treated-wastewater, groundwater contaminant plume. A portion of the contaminated groundwater discharges into Ashumet Pond, a kettle hole, freshwater lake. A study was conducted from June 2013 to June 2015 to document transport, transformation, and discharge of...
Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts
This data release provides analytical and other data in support of an analysis of nitrogen transport and transformation in groundwater and in a subterranean estuary in the Eel River and onshore locations on the Seacoast Shores peninsula, Falmouth, Massachusetts. The analysis is described in U.S. Geological Survey Scientific Investigations Report 2018-5095 by Colman and others (2018)...
Temperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015. Temperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015.
These data were collected to evaluate groundwater/surface-water exchange in the area of a lake-bottom permeable reactive barrier and to assess changes in groundwater seepage over the period between 2004 and 2015. This data release includes geospatial datasets, comma separated values (.csv) files, and associated FGDC-compliant metadata representing data collected between 2004 and 2015 as...
Poly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016 Poly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016
Drinking water health advisories for perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), were issued by the U.S. Environmental Protection Agency in 2016 in response to growing evidence associated with negative human health effects. PFOA and PFOS are often associated with other poly- and perfluorinated alkyl substances (PFAS). There has been increasing concern for groundwater...
40 Years Presenting Cape Cod Hydrology
USGS has studied the hydrology of Cape Cod and the Islands and demonstrated our science to the public for more than four decades. Many visitor groups from government agencies, universities, nonprofit organizations, and local communities have learned about our groundwater and surface water research in southeastern Massachusetts. USGS Research Hydrologist Emeritus Denis Leblanc has been a pillar in...
Filter Total Items: 67
Evaluating the effects of replacing septic systems with municipal sewers on groundwater quality in a densely developed coastal neighborhood, Falmouth, Massachusetts, 2016–19 Evaluating the effects of replacing septic systems with municipal sewers on groundwater quality in a densely developed coastal neighborhood, Falmouth, Massachusetts, 2016–19
Land disposal of sewage wastewater through septic systems and cesspools is a major cause of elevated concentrations of nitrogen in the shallow coastal aquifers of southern New England. The discharge of nitrogen from these sources at the coast is affecting the environmental health of coastal saltwater bodies. In response, local, State, and Federal agencies are considering expensive...
Authors
Timothy D. McCobb, Jeffrey R. Barbaro, Denis R. LeBlanc, Marcel Belaval
Characterizing the diverse hydrogeology underlying rivers and estuaries using new floating transient electromagnetic methodology Characterizing the diverse hydrogeology underlying rivers and estuaries using new floating transient electromagnetic methodology
The hydrogeology below large surface water features such as rivers and estuaries is universally under-informed at the long reach to basin scales (tens of km+). This challenge inhibits the accurate modeling of fresh/saline groundwater interfaces and groundwater/surface water exchange patterns at management-relevant spatial extents. Here we introduce a towed, floating transient...
Authors
John W. Lane, Martin A. Briggs, PK Maurya, Eric A. White, JB Pedersen, Esben Auken, Neil Terry, Burke J. Minsley, Wade Kress, Denis R. LeBlanc, Ryan F. Adams, Carole D. Johnson
Hillslope groundwater discharges provide localized ecosystem buffers from regional PFAS contamination in a gaining coastal stream Hillslope groundwater discharges provide localized ecosystem buffers from regional PFAS contamination in a gaining coastal stream
Emerging groundwater contaminants such as per- and polyfluoroalkyl substances (PFAS) may impact surface-water quality and groundwater-dependent ecosystems of gaining streams. Although complex near-surface hydrogeology of stream corridors challenges sampling efforts, recent advances in heat tracing of discharge zones enable efficient and informed data collection. For this study we used a
Authors
Martin A. Briggs, Andrea K. Tokranov, Robert B. Hull, Denis R. LeBlanc, A. Haynes, John W. Lane
Simulated water-table and pond-level responses to proposed public water-supply withdrawals in the Hyannis Ponds Wildlife Management Area, Barnstable, Massachusetts Simulated water-table and pond-level responses to proposed public water-supply withdrawals in the Hyannis Ponds Wildlife Management Area, Barnstable, Massachusetts
The glacial kettle ponds in the Hyannis Ponds Wildlife Management Area in Barnstable, Massachusetts, support a community of rare and endangered plants. The ponds are hydraulically connected to the unconfined aquifer that underlies Cape Cod. The plants are adapted to the rise and fall of water levels in the ponds as the water table fluctuates in response to seasonal and year-to-year...
Authors
Denis R. LeBlanc, Timothy D. McCobb, Jeffrey R. Barbaro
Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts
In spring 2016, a 310-foot-deep boring (named MA–FSW 750) was drilled by the U.S. Geological Survey near Nantucket Sound in East Falmouth, Massachusetts, to investigate the hydrogeology of the southern coast of western Cape Cod. Few borings that are drilled to bedrock exist in the area, and the study area was selected to fill a gap between comprehensive geologic datasets inland to the...
Authors
Robert B. Hull, Carole D. Johnson, Byron D. Stone, Denis R. LeBlanc, Timothy D. McCobb, Stephanie N. Phillips, Katherine L. Pappas, John W. Lane
Hydrologic site assessment for passive treatment of groundwater nitrogen with permeable reactive barriers, Cape Cod, Massachusetts Hydrologic site assessment for passive treatment of groundwater nitrogen with permeable reactive barriers, Cape Cod, Massachusetts
Wastewater disposal associated with rapid population growth and development on Cape Cod, Massachusetts, during the past several decades has resulted in widespread contamination of groundwater with nitrogen. As a result, water quality in many of the streams, lakes, and coastal embayments on Cape Cod is impaired by excess nitrogen. To reduce nitrogen loads to these impaired water bodies...
Authors
Jeffrey R. Barbaro, Marcel Belaval, Danna B. Truslow, Denis R. LeBlanc, Thomas C. Cambareri, Scott C. Michaud
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Groundwater discharge delivering anthropogenic N from surrounding watersheds can impact lake nutrient budgets. However, upgradient groundwater processes and changing dynamics in N biogeochemistry at the groundwater-lake interface are complex and difficult to resolve. In this study, hydrograph variations in a groundwater flow-through lake altered discharge patterns of a wastewater-derived
Authors
Richard L. Smith, Deborah A. Repert, Deborah Stoliker, Douglas B. Kent, Bongkeun Song, Denis R. LeBlanc, Timothy D. McCobb, J.K. Bohlke, Sung Pil Hyun, Hee Sun Moon
Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14 Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
Nitrogen transport and transformation were studied during 2013 to 2014 by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, in a subterranean estuary beneath onshore locations on the Seacoast Shores peninsula, a residential area in Falmouth, Massachusetts, served by septic systems and cesspools, and adjacent offshore locations in the Eel River, a...
Authors
John A. Colman, Denis R. LeBlanc, J.K. Bohlke, Timothy D. McCobb, Kevin D. Kroeger, Marcel Belaval, Thomas C. Cambareri, Gillian F. Pirolli, T. Wallace Brooks, Mary E. Garren, Tobias B. Stover, Ann Keeley
Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier
Identifying and quantifying groundwater exchange is critical when considering contaminant fate and transport at the groundwater/surface-water interface. In this paper, areally distributed temperature and point seepage measurements are used to efficiently assess spatial and temporal groundwater discharge patterns through a glacial-kettle lakebed area containing a zero-valent iron...
Authors
Timothy D. McCobb, Martin A. Briggs, Denis R. LeBlanc, Frederick D. Day-Lewis, Carole D. Johnson
Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts
Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of...
Authors
Andrea K. Weber, Larry B. Barber, Denis R. LeBlanc, Elsie M. Sunderland, Chad D. Vecitis
Microbial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview Microbial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview
Since 1986, fluorescent carboxylate-modified polystyrene/latex microspheres (FCM) have been co-injected into aquifers along with conservative tracers and viruses, bacteria, and (or) protozoa. Use of FCM has resulted in new information about subsurface transport behaviors of microorganisms in fractured crystalline rock, karst limestone, soils, and granular aquifers. FCM have been used as...
Authors
Ronald W. Harvey, David W. Metge, Denis R. LeBlanc
Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake
The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water...
Authors
Deborah L. Stoliker, Deborah A. Repert, Richard L. Smith, Bongkeun Song, Denis R. LeBlanc, Timothy D. McCobb, Christopher H. Conaway, Sung Pil Hyun, Dong-Chan Koh, Hee Sun Moon, Douglas B. Kent
Science and Products
Filter Total Items: 23
Concentrations of per- and polyfluoroalkyl substances (PFAS) and related chemical and physical data at and near surface-water/groundwater boundaries on Cape Cod, Massachusetts, 2016-19 Concentrations of per- and polyfluoroalkyl substances (PFAS) and related chemical and physical data at and near surface-water/groundwater boundaries on Cape Cod, Massachusetts, 2016-19
Groundwater, surface-water, sediment, and associated quality-control samples were collected downgradient from a former fire training area and wastewater infiltration beds on Cape Cod, Massachusetts and analyzed for per- and polyfluoroalkyl substances (PFAS). Samples were collected between July 2016 and February 2019 following U.S. Geological Survey protocols. Field parameters reported...
Microbial Community and N-cycling gene abundance from Ponds and Groundwater on Cape Cod, MA (2015 - 2018) Microbial Community and N-cycling gene abundance from Ponds and Groundwater on Cape Cod, MA (2015 - 2018)
Surface water, pore water, pond bottom sediments, and groundwater were sampled within and downgradient from five groundwater flow-through ponds that ranged from oligotrophic to eutrophic in Cape Cod, Massachusetts during different seasons from 2015 – 2018. The sampled ponds included Ashumet, Santuit, Snake, Shubael, and Longs. Pore water was collected between 15 to 100 cm below the pond...
Target-Chemical Concentration Results of Mixed-Organic/Inorganic Chemical Exposures in Cape Cod, Massachusetts Tapwater, 2018 Target-Chemical Concentration Results of Mixed-Organic/Inorganic Chemical Exposures in Cape Cod, Massachusetts Tapwater, 2018
This dataset provides the water-quality results for organic and inorganic concentrations analyzed from samples collected at residential tapwater faucets, sourced from private drinking water wells in Cape Cod, Massachusetts. Samples were collected in July and August, 2018 from 20 locations. Samples were analyzed at various U.S. Geological Survey laboratories: the National Water Quality...
Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts
Reserved for CDJ. Transient Electromagnetics, Passive Seismic, and Borehole Electromagnetics, Gamma, and Nuclear Magnetic Resonance Methods to Characterize an Unconsolidated Aquifer on Cape Cod, Massachusetts Johnson, White, Phillips, Pappas, Hull, LeBlanc, and Lane
Determination of the effect of temperature (Q10) on rates of oxygen consumption in surface sediments collected from Ashumet Pond on Cape Cod, MA (2016) Determination of the effect of temperature (Q10) on rates of oxygen consumption in surface sediments collected from Ashumet Pond on Cape Cod, MA (2016)
This data release presents results from a laboratory study designed to measure the effect of temperature on rates of oxygen consumption within lake-bottom surface sediments at 0- to 5-cm depth. Sediment and lake water samples were collected June 8, 2016 from the South site in Ashumet Pond, Cape Cod, MA, where lake water recharges to the aquifer. Samples were shipped to Boulder, CO for...
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
The U.S. Geological Survey Toxic Substances Hydrology Program at Cape Cod has been investigating the fate and transport of a treated-wastewater, groundwater contaminant plume. A portion of the contaminated groundwater discharges into Ashumet Pond, a kettle hole, freshwater lake. A study was conducted from June 2013 to June 2015 to document transport, transformation, and discharge of...
Data Release for Lake Shadow Seepage Calculations from Ashumet Pond, Cape Cod, MA, 2016 - 2018 Data Release for Lake Shadow Seepage Calculations from Ashumet Pond, Cape Cod, MA, 2016 - 2018
Hydrologic data were collected in the nearshore lake-bottom sediments of five lakes on western Cape Cod, Massachusetts: Ashumet (Falmouth), Long (Centerville), Santuit (Mashpee), Shubael (Barnstable), and Snake (Sandwich) Ponds. Water budgets of flow-through glacial kettle lakes are commonly dominated by groundwater flow into and surface-water seepage out of the lake, and inputs and...
Natural gradient, lakebed tracer tests using nitrite in a nitrate-contaminated groundwater discharge zone in Ashumet Pond, Massachusetts Natural gradient, lakebed tracer tests using nitrite in a nitrate-contaminated groundwater discharge zone in Ashumet Pond, Massachusetts
The U.S. Geological Survey Toxic Substances Hydrology Program at Cape Cod has been investigating the fate and transport of a treated-wastewater, groundwater contaminant plume. A portion of the contaminated groundwater discharges into Ashumet Pond, a kettle hole, freshwater lake. A study was conducted from June 2013 to June 2015 to document transport, transformation, and discharge of...
Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts
This data release provides analytical and other data in support of an analysis of nitrogen transport and transformation in groundwater and in a subterranean estuary in the Eel River and onshore locations on the Seacoast Shores peninsula, Falmouth, Massachusetts. The analysis is described in U.S. Geological Survey Scientific Investigations Report 2018-5095 by Colman and others (2018)...
Temperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015. Temperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015.
These data were collected to evaluate groundwater/surface-water exchange in the area of a lake-bottom permeable reactive barrier and to assess changes in groundwater seepage over the period between 2004 and 2015. This data release includes geospatial datasets, comma separated values (.csv) files, and associated FGDC-compliant metadata representing data collected between 2004 and 2015 as...
Poly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016 Poly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016
Drinking water health advisories for perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), were issued by the U.S. Environmental Protection Agency in 2016 in response to growing evidence associated with negative human health effects. PFOA and PFOS are often associated with other poly- and perfluorinated alkyl substances (PFAS). There has been increasing concern for groundwater...
40 Years Presenting Cape Cod Hydrology
USGS has studied the hydrology of Cape Cod and the Islands and demonstrated our science to the public for more than four decades. Many visitor groups from government agencies, universities, nonprofit organizations, and local communities have learned about our groundwater and surface water research in southeastern Massachusetts. USGS Research Hydrologist Emeritus Denis Leblanc has been a pillar in...
Filter Total Items: 67
Evaluating the effects of replacing septic systems with municipal sewers on groundwater quality in a densely developed coastal neighborhood, Falmouth, Massachusetts, 2016–19 Evaluating the effects of replacing septic systems with municipal sewers on groundwater quality in a densely developed coastal neighborhood, Falmouth, Massachusetts, 2016–19
Land disposal of sewage wastewater through septic systems and cesspools is a major cause of elevated concentrations of nitrogen in the shallow coastal aquifers of southern New England. The discharge of nitrogen from these sources at the coast is affecting the environmental health of coastal saltwater bodies. In response, local, State, and Federal agencies are considering expensive...
Authors
Timothy D. McCobb, Jeffrey R. Barbaro, Denis R. LeBlanc, Marcel Belaval
Characterizing the diverse hydrogeology underlying rivers and estuaries using new floating transient electromagnetic methodology Characterizing the diverse hydrogeology underlying rivers and estuaries using new floating transient electromagnetic methodology
The hydrogeology below large surface water features such as rivers and estuaries is universally under-informed at the long reach to basin scales (tens of km+). This challenge inhibits the accurate modeling of fresh/saline groundwater interfaces and groundwater/surface water exchange patterns at management-relevant spatial extents. Here we introduce a towed, floating transient...
Authors
John W. Lane, Martin A. Briggs, PK Maurya, Eric A. White, JB Pedersen, Esben Auken, Neil Terry, Burke J. Minsley, Wade Kress, Denis R. LeBlanc, Ryan F. Adams, Carole D. Johnson
Hillslope groundwater discharges provide localized ecosystem buffers from regional PFAS contamination in a gaining coastal stream Hillslope groundwater discharges provide localized ecosystem buffers from regional PFAS contamination in a gaining coastal stream
Emerging groundwater contaminants such as per- and polyfluoroalkyl substances (PFAS) may impact surface-water quality and groundwater-dependent ecosystems of gaining streams. Although complex near-surface hydrogeology of stream corridors challenges sampling efforts, recent advances in heat tracing of discharge zones enable efficient and informed data collection. For this study we used a
Authors
Martin A. Briggs, Andrea K. Tokranov, Robert B. Hull, Denis R. LeBlanc, A. Haynes, John W. Lane
Simulated water-table and pond-level responses to proposed public water-supply withdrawals in the Hyannis Ponds Wildlife Management Area, Barnstable, Massachusetts Simulated water-table and pond-level responses to proposed public water-supply withdrawals in the Hyannis Ponds Wildlife Management Area, Barnstable, Massachusetts
The glacial kettle ponds in the Hyannis Ponds Wildlife Management Area in Barnstable, Massachusetts, support a community of rare and endangered plants. The ponds are hydraulically connected to the unconfined aquifer that underlies Cape Cod. The plants are adapted to the rise and fall of water levels in the ponds as the water table fluctuates in response to seasonal and year-to-year...
Authors
Denis R. LeBlanc, Timothy D. McCobb, Jeffrey R. Barbaro
Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts Lithostratigraphic, geophysical, and hydrogeologic observations from a boring drilled to bedrock in glacial sediments near Nantucket Sound in East Falmouth, Massachusetts
In spring 2016, a 310-foot-deep boring (named MA–FSW 750) was drilled by the U.S. Geological Survey near Nantucket Sound in East Falmouth, Massachusetts, to investigate the hydrogeology of the southern coast of western Cape Cod. Few borings that are drilled to bedrock exist in the area, and the study area was selected to fill a gap between comprehensive geologic datasets inland to the...
Authors
Robert B. Hull, Carole D. Johnson, Byron D. Stone, Denis R. LeBlanc, Timothy D. McCobb, Stephanie N. Phillips, Katherine L. Pappas, John W. Lane
Hydrologic site assessment for passive treatment of groundwater nitrogen with permeable reactive barriers, Cape Cod, Massachusetts Hydrologic site assessment for passive treatment of groundwater nitrogen with permeable reactive barriers, Cape Cod, Massachusetts
Wastewater disposal associated with rapid population growth and development on Cape Cod, Massachusetts, during the past several decades has resulted in widespread contamination of groundwater with nitrogen. As a result, water quality in many of the streams, lakes, and coastal embayments on Cape Cod is impaired by excess nitrogen. To reduce nitrogen loads to these impaired water bodies...
Authors
Jeffrey R. Barbaro, Marcel Belaval, Danna B. Truslow, Denis R. LeBlanc, Thomas C. Cambareri, Scott C. Michaud
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Groundwater discharge delivering anthropogenic N from surrounding watersheds can impact lake nutrient budgets. However, upgradient groundwater processes and changing dynamics in N biogeochemistry at the groundwater-lake interface are complex and difficult to resolve. In this study, hydrograph variations in a groundwater flow-through lake altered discharge patterns of a wastewater-derived
Authors
Richard L. Smith, Deborah A. Repert, Deborah Stoliker, Douglas B. Kent, Bongkeun Song, Denis R. LeBlanc, Timothy D. McCobb, J.K. Bohlke, Sung Pil Hyun, Hee Sun Moon
Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14 Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
Nitrogen transport and transformation were studied during 2013 to 2014 by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, in a subterranean estuary beneath onshore locations on the Seacoast Shores peninsula, a residential area in Falmouth, Massachusetts, served by septic systems and cesspools, and adjacent offshore locations in the Eel River, a...
Authors
John A. Colman, Denis R. LeBlanc, J.K. Bohlke, Timothy D. McCobb, Kevin D. Kroeger, Marcel Belaval, Thomas C. Cambareri, Gillian F. Pirolli, T. Wallace Brooks, Mary E. Garren, Tobias B. Stover, Ann Keeley
Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier
Identifying and quantifying groundwater exchange is critical when considering contaminant fate and transport at the groundwater/surface-water interface. In this paper, areally distributed temperature and point seepage measurements are used to efficiently assess spatial and temporal groundwater discharge patterns through a glacial-kettle lakebed area containing a zero-valent iron...
Authors
Timothy D. McCobb, Martin A. Briggs, Denis R. LeBlanc, Frederick D. Day-Lewis, Carole D. Johnson
Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts
Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of...
Authors
Andrea K. Weber, Larry B. Barber, Denis R. LeBlanc, Elsie M. Sunderland, Chad D. Vecitis
Microbial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview Microbial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview
Since 1986, fluorescent carboxylate-modified polystyrene/latex microspheres (FCM) have been co-injected into aquifers along with conservative tracers and viruses, bacteria, and (or) protozoa. Use of FCM has resulted in new information about subsurface transport behaviors of microorganisms in fractured crystalline rock, karst limestone, soils, and granular aquifers. FCM have been used as...
Authors
Ronald W. Harvey, David W. Metge, Denis R. LeBlanc
Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake
The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water...
Authors
Deborah L. Stoliker, Deborah A. Repert, Richard L. Smith, Bongkeun Song, Denis R. LeBlanc, Timothy D. McCobb, Christopher H. Conaway, Sung Pil Hyun, Dong-Chan Koh, Hee Sun Moon, Douglas B. Kent
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