Andrew Sekellick
Andrew has worked for the USGS since 2008, providing GIS, cartographic, and statistical support to a wide variety of projects. Experience and interests include GW modeling, watershed level sediment studies, and QW modeling.
Current work focuses the effects of BMPs in the Chesapeake Bay and predicting water quality in baseflow and total flow using time sensitive modeling techniques.
Professional Experience
Geographer - USGS MD-DE-DC Water Science Center, Catonsville, MD: 2008-present
Education and Certifications
M.P.S. Geographic Information Systems, University of Maryland, Baltimore County
B.S. Geography and Environmental Systems, University of Maryland, Baltimore County
Science and Products
Filter Total Items: 21
Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 5.0, June 2025) Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 5.0, June 2025)
This metadata record describes a series of data sets of natural and anthropogenic landscape features linked to NHDPlus Version 2.1’s (NHDPlusV2) approximately 2.7 million stream segments, their associated catchments, and their upstream watersheds within the conterminous United States. The data were linked to four spatial components of NHDPlusV2: individual reach catchments, riparian...
Discrete and high-frequency chloride (Cl) and specific conductance (SC) data sets and Cl-SC regression equations used for analysis of 93 USGS water quality monitoring stations in the eastern United States Discrete and high-frequency chloride (Cl) and specific conductance (SC) data sets and Cl-SC regression equations used for analysis of 93 USGS water quality monitoring stations in the eastern United States
High frequency estimated chloride (Cl) and observed specific conductance (SC) data sets, along with response variables derived from those data sets, were used in an analysis to quantify the extent to which deicer applications in winter affect water quality in 93 U.S. Geological Survey water quality monitoring stations across the eastern United States. The analysis was documented in the...
Input and predictions from a suspended-sediment SPARROW model CBSS_V2 in the Chesapeake Bay watershed Input and predictions from a suspended-sediment SPARROW model CBSS_V2 in the Chesapeake Bay watershed
These data represent input and estimates from a medium-resolution (1:100,000 scale) NHDPlus SPAtially Referenced Regression on Watershed attributes (SPARROW) model for the Chesapeake Bay watershed (CBSS_v2). The model spatially correlates long-term mean annual suspended-sediment flux in 113 non-tidal streams to likely upland and stream-corridor sources, landscape factors affecting upland...
Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed
The CBTN_v5 and CBTP_v5 SPARROW models were developed to support inferences about causes of observed changes in nitrogen and phosphorus (respectively) fluxes in Chesapeake Bay tributaries between 1992 and 2012. Model inputs and outputs are included in three files, which are described below. Detailed documentation of the SPARROW modeling technique is available at https://pubs.er.usgs.gov
Estimated effect of best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014 Estimated effect of best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014
This metadata record documents 3 sets of comma delimited tables representing the amount of reported best management practice (BMP) implementation within the Chesapeake Bay watershed as well as output data from scenarios of the Chesapeake Bay Program Phase 5.3.2 Watershed Model. The scenario data were used to estimate the effects of BMPs on water quality. The data are organized by three...
Implementation of conservation tillage and cover crops in the Chesapeake Bay watershed, 1985 to 2012 Implementation of conservation tillage and cover crops in the Chesapeake Bay watershed, 1985 to 2012
Conservation tillage practices and cover crops are used throughout the Chesapeake Bay watershed to reduce soil loss and improve water quality. Implementation of these Best Management Practices (BMPs) were reported to the Chesapeake Bay Program (CBP) by each state in the watershed (New York, Pennsylvania, Maryland, Delaware, West Virginia, and Virginia). Estimates of acres of...
itrogen and phosphorus from fertilizer and manure in the Chesapeake Bay watershed, 1950-2012 itrogen and phosphorus from fertilizer and manure in the Chesapeake Bay watershed, 1950-2012
This dataset contains four tables of estimates of the yearly sum of nitrogen and phosphorus inputs from fertilizer applications and from manure applications in selected watersheds in Chesapeake Bay drainage basin from 1950 to 2012. For the fertilizer data, county-level loads were used from three published sources. Data from 1950 to 1985 are from Alexander and Smith (1990). Data for the...
Animal Best Management Practice by Chesapeake Bay Watershed Region From 1985 to 2014 Animal Best Management Practice by Chesapeake Bay Watershed Region From 1985 to 2014
This metadata record covers 18 comma delimited files that support the USGS Scientific Investigations Report Manure and Fertilizer Inputs to Land in the Chesapeake Bay Watershed, 1950-2014 by Jennifer Keisman, Olivia Devereux, Andrew LaMotte, and Andrew Sekellick. The data were created by running scenarios through the Chesapeake Bay Program Partnership Phase 5.3.2 Watershed Model for...
Ancillary Data Related to Nutrients in the Chesapeake BayData Supporting Structural Equation Modeling of Nutrient Loads Ancillary Data Related to Nutrients in the Chesapeake BayData Supporting Structural Equation Modeling of Nutrient Loads
This data release provides total nitrogen (TN) and total phosphorus (TP) annual loads for sites within the Chesapeake Bay, as well as ancillary data that describe potential nutrient sources and processes. The purpose of the study for which these data were developed is to test causal hypotheses, using structural equation models, related to the drivers of TN and TP load in the Chesapeake...
Filter Total Items: 16
Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012 Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012
To assist in understanding sediment loadings and the management of water resources, a bathymetric survey was conducted in the part of Lake Linganore between Boyers Mill Road Bridge and Bens Branch in Frederick County, Maryland. The bathymetric survey was performed in January 2012 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County. A separate...
Authors
Andrew Sekellick, William Banks, Michael K. Myers
Statistical classification of hydrogeologic regions in the fractured rock area of Maryland and parts of the District of Columbia, Virginia, West Virginia, Pennsylvania, and Delaware Statistical classification of hydrogeologic regions in the fractured rock area of Maryland and parts of the District of Columbia, Virginia, West Virginia, Pennsylvania, and Delaware
Hydrogeologic regions in the fractured rock area of Maryland were classified using geographic information system tools with principal components and cluster analyses. A study area consisting of the 8-digit Hydrologic Unit Code (HUC) watersheds with rivers that flow through the fractured rock area of Maryland and bounded by the Fall Line was further subdivided into 21,431 catchments from...
Authors
Brandon Fleming, Andrew LaMotte, Andrew Sekellick
A regional classification of the effectiveness of depressional wetlands at mitigating nitrogen transport to surface waters in the Northern Atlantic Coastal Plain A regional classification of the effectiveness of depressional wetlands at mitigating nitrogen transport to surface waters in the Northern Atlantic Coastal Plain
Nitrogen from nonpoint sources contributes to eutrophication, hypoxia, and related ecological degradation in Atlantic Coastal Plain streams and adjacent coastal estuaries such as Chesapeake Bay and Pamlico Sound. Although denitrification in depressional (non-riparian) wetlands common to the Coastal Plain can be a significant landscape sink for nitrogen, the effectiveness of individual...
Authors
Scott Ator, Judith M. Denver, Andrew LaMotte, Andrew Sekellick
Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009 Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009
To assist in understanding sediment and phosphorus loadings and the management of water resources, a bathymetric survey was conducted at Lake Linganore in Frederick County, Maryland in June 2009 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County, Maryland. Position data and water-depth data were collected using a survey grade echo sounder and a
Authors
Andrew Sekellick, S.L. Banks
Science and Products
Filter Total Items: 21
Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 5.0, June 2025) Select Attributes for NHDPlus Version 2.1 Reach Catchments and Modified Network Routed Upstream Watersheds for the Conterminous United States (ver. 5.0, June 2025)
This metadata record describes a series of data sets of natural and anthropogenic landscape features linked to NHDPlus Version 2.1’s (NHDPlusV2) approximately 2.7 million stream segments, their associated catchments, and their upstream watersheds within the conterminous United States. The data were linked to four spatial components of NHDPlusV2: individual reach catchments, riparian...
Discrete and high-frequency chloride (Cl) and specific conductance (SC) data sets and Cl-SC regression equations used for analysis of 93 USGS water quality monitoring stations in the eastern United States Discrete and high-frequency chloride (Cl) and specific conductance (SC) data sets and Cl-SC regression equations used for analysis of 93 USGS water quality monitoring stations in the eastern United States
High frequency estimated chloride (Cl) and observed specific conductance (SC) data sets, along with response variables derived from those data sets, were used in an analysis to quantify the extent to which deicer applications in winter affect water quality in 93 U.S. Geological Survey water quality monitoring stations across the eastern United States. The analysis was documented in the...
Input and predictions from a suspended-sediment SPARROW model CBSS_V2 in the Chesapeake Bay watershed Input and predictions from a suspended-sediment SPARROW model CBSS_V2 in the Chesapeake Bay watershed
These data represent input and estimates from a medium-resolution (1:100,000 scale) NHDPlus SPAtially Referenced Regression on Watershed attributes (SPARROW) model for the Chesapeake Bay watershed (CBSS_v2). The model spatially correlates long-term mean annual suspended-sediment flux in 113 non-tidal streams to likely upland and stream-corridor sources, landscape factors affecting upland...
Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed Inputs and Selected Predictions of the CBTN_v5 and CBTP_v5 SPARROW Models for the Chesapeake Bay Watershed
The CBTN_v5 and CBTP_v5 SPARROW models were developed to support inferences about causes of observed changes in nitrogen and phosphorus (respectively) fluxes in Chesapeake Bay tributaries between 1992 and 2012. Model inputs and outputs are included in three files, which are described below. Detailed documentation of the SPARROW modeling technique is available at https://pubs.er.usgs.gov
Estimated effect of best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014 Estimated effect of best management practice implementation in the Chesapeake Bay watershed from 1985 to 2014
This metadata record documents 3 sets of comma delimited tables representing the amount of reported best management practice (BMP) implementation within the Chesapeake Bay watershed as well as output data from scenarios of the Chesapeake Bay Program Phase 5.3.2 Watershed Model. The scenario data were used to estimate the effects of BMPs on water quality. The data are organized by three...
Implementation of conservation tillage and cover crops in the Chesapeake Bay watershed, 1985 to 2012 Implementation of conservation tillage and cover crops in the Chesapeake Bay watershed, 1985 to 2012
Conservation tillage practices and cover crops are used throughout the Chesapeake Bay watershed to reduce soil loss and improve water quality. Implementation of these Best Management Practices (BMPs) were reported to the Chesapeake Bay Program (CBP) by each state in the watershed (New York, Pennsylvania, Maryland, Delaware, West Virginia, and Virginia). Estimates of acres of...
itrogen and phosphorus from fertilizer and manure in the Chesapeake Bay watershed, 1950-2012 itrogen and phosphorus from fertilizer and manure in the Chesapeake Bay watershed, 1950-2012
This dataset contains four tables of estimates of the yearly sum of nitrogen and phosphorus inputs from fertilizer applications and from manure applications in selected watersheds in Chesapeake Bay drainage basin from 1950 to 2012. For the fertilizer data, county-level loads were used from three published sources. Data from 1950 to 1985 are from Alexander and Smith (1990). Data for the...
Animal Best Management Practice by Chesapeake Bay Watershed Region From 1985 to 2014 Animal Best Management Practice by Chesapeake Bay Watershed Region From 1985 to 2014
This metadata record covers 18 comma delimited files that support the USGS Scientific Investigations Report Manure and Fertilizer Inputs to Land in the Chesapeake Bay Watershed, 1950-2014 by Jennifer Keisman, Olivia Devereux, Andrew LaMotte, and Andrew Sekellick. The data were created by running scenarios through the Chesapeake Bay Program Partnership Phase 5.3.2 Watershed Model for...
Ancillary Data Related to Nutrients in the Chesapeake BayData Supporting Structural Equation Modeling of Nutrient Loads Ancillary Data Related to Nutrients in the Chesapeake BayData Supporting Structural Equation Modeling of Nutrient Loads
This data release provides total nitrogen (TN) and total phosphorus (TP) annual loads for sites within the Chesapeake Bay, as well as ancillary data that describe potential nutrient sources and processes. The purpose of the study for which these data were developed is to test causal hypotheses, using structural equation models, related to the drivers of TN and TP load in the Chesapeake...
Filter Total Items: 16
Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012 Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012
To assist in understanding sediment loadings and the management of water resources, a bathymetric survey was conducted in the part of Lake Linganore between Boyers Mill Road Bridge and Bens Branch in Frederick County, Maryland. The bathymetric survey was performed in January 2012 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County. A separate...
Authors
Andrew Sekellick, William Banks, Michael K. Myers
Statistical classification of hydrogeologic regions in the fractured rock area of Maryland and parts of the District of Columbia, Virginia, West Virginia, Pennsylvania, and Delaware Statistical classification of hydrogeologic regions in the fractured rock area of Maryland and parts of the District of Columbia, Virginia, West Virginia, Pennsylvania, and Delaware
Hydrogeologic regions in the fractured rock area of Maryland were classified using geographic information system tools with principal components and cluster analyses. A study area consisting of the 8-digit Hydrologic Unit Code (HUC) watersheds with rivers that flow through the fractured rock area of Maryland and bounded by the Fall Line was further subdivided into 21,431 catchments from...
Authors
Brandon Fleming, Andrew LaMotte, Andrew Sekellick
A regional classification of the effectiveness of depressional wetlands at mitigating nitrogen transport to surface waters in the Northern Atlantic Coastal Plain A regional classification of the effectiveness of depressional wetlands at mitigating nitrogen transport to surface waters in the Northern Atlantic Coastal Plain
Nitrogen from nonpoint sources contributes to eutrophication, hypoxia, and related ecological degradation in Atlantic Coastal Plain streams and adjacent coastal estuaries such as Chesapeake Bay and Pamlico Sound. Although denitrification in depressional (non-riparian) wetlands common to the Coastal Plain can be a significant landscape sink for nitrogen, the effectiveness of individual...
Authors
Scott Ator, Judith M. Denver, Andrew LaMotte, Andrew Sekellick
Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009 Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009
To assist in understanding sediment and phosphorus loadings and the management of water resources, a bathymetric survey was conducted at Lake Linganore in Frederick County, Maryland in June 2009 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County, Maryland. Position data and water-depth data were collected using a survey grade echo sounder and a
Authors
Andrew Sekellick, S.L. Banks