Better Assessment Science Integrating Point and Nonpoint Sources BASINS Version 4.5


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Better Assessment Science
Integrating point and
Nonpoint Sources
BASINS
Version 4.S
User's Manual
January 2019

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Disclaimer
Production of this document has been funded wholly or in part by the U.S. Environmental Protection
Agency. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use by the U.S. Environmental Protection Agency. The Better Assessment Science
Integrating Point and Nonpoint Sources (BASINS) system described in this manual is applied at the user's
own risk. Neither the U.S. Environmental Protection Agency nor the system authors can assume
responsibility for system operation, output, interpretation, or use.

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Contents
Contents	3
Acknowledgments	5
User Assistance and Technical Support	8
Introduction	9
System Overview and What's New	14
Databases	18
Environmental Assessment Tools	23
Utilities	25
Analysis Tools and Postprocessors	26
Hardware and Software Requirements	27
Installation	28
Finding Functionality from Earlier Versions	30
BASINS Details	33
User Interface	34
Project Creation and Management	50
Plug-ins	84
Watershed Delineation	112
Analysis	124
Compute	159
Tutorial	222
Building a BASINS Project	223
Downloading Additional Data	229
Reclassifying Land Use	240
Manual Delineation	246
Automatic Delineation	259
Frequently Asked Questions	279

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References	284
Appendix A - GIS Data Dictionary	287
Appendix B - Weather Data Files (WDM) Distributed Prior to Version 4.0	317
Appendix C - BASINS 4.0 Meteorological Data (Version 2009)	345
Appendix D - Cligen Meteorological Data Use in BASINS 4	353
Appendix E - NLDAS Meteorological Data in BASINS	355
Appendix F - Watershed and Instream Models	357

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Acknowledgments
BASINS 4.5 Core is the first full BASINS release to be produced jointly by U.S. EPA National Exposure
Research Laboratory (Computational Exposure Division) in Athens, Georgia and U.S. EPA Region 4
(Water Protection Division) in Atlanta, Georgia. Steve Kraemer, Rajbir Parmar, Yusuf Mohamoud, John
Johnston, Michelle Simon and the U.S. EPA Region 4 Modeling Team (Glenn Fernandez, Tim Wool,
Amanda Howell and John Davis) are acknowledged for their technical direction, guidance and testing in
advancing BASINS through this release. AQUA TERRA Consultants (a Division of RESPEC, Inc.) provided
software development services for this release. Paul Duda, Paul Hummel, and Tong Zhai made up the
RESPEC team for this effort. RESPEC intern Lucy Bricker assisted with documentation and testing.
Version 4.5 Core of the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS)
system is a maintenance release that builds on Version 4.1 and earlier versions of the system. See the
User's Manuals for the earlier versions for the team involved in the production of those versions of the
system.
Technical direction and guidance for the development of BASINS 4.1 was provided by Marjorie Wellman
and Lisa Larimer of EPA's Office of Science and Technology, Standards and Health Protection Division.
For the development of version 4.0, technical direction and guidance was provided by Russell Kinerson,
Jim Carleton, Ed Partington, Marjorie Wellman and David Wells of the same office and division.
The GIS foundation for BASINS 4.0 and subsequent versions is provided by the open-source MapWindow
GIS. MapWindow was originally developed by the Utah Water Research Laboratory at Utah State
University and benefits from continuing development and support at Idaho State University and Utah
State University, along with a community of users around the world. Dan Ames at Idaho State University
and David Stevens and Jeff Horsburgh at Utah State University are particularly acknowledged for their
contributions to this effort.
David Tarboton at Utah State University is acknowledged for his contribution to the automatic
watershed delineation tools of BASINS 4.0 and subsequent versions. The automatic delineator is based
upon TauDEM (Terrain Analysis Using Digital Elevation Models), a set of tools for the analysis of terrain
using digital elevation models developed at Utah State University. TauDEM incorporates programs and
digital elevation model (DEM) analysis functions developed over several years of research.
The OpenSWAT plug-in included in BASINS 4.0 and subsequent versions was developed by Jeyakanthan
Veluppillai and Daniel P. Ames at Idaho State University. The SWAT Editor for SWAT 2005 is included in
the installation package in cooperation with R. Srinivasan at the Texas Agricultural Experiment Station.
Lew Rossman of the US EPA is acknowledged for his contributions and support for the inclusion of
SWMM in BASINS. Tim Wool at EPA Region 4 is acknowledged for his contributions and support for the
inclusion of WASP in BASINS, as well as the Watershed Characterization System (WCS). Chris Wilson of
Wilson Engineering was responsible for much of the development of the WCS plug-in.
The GWLF-E plug-in for BASINS was developed by Barry Evans and Ken Corradini of Penn State
University. The watershed simulation tools used in the GWLF-E plug-in are based on the GWLF
(Generalized Watershed Loading Function) model developed by Haith and Shoemaker (1987). The

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original DOS-compatible version of GWLF was re-written in Visual Basic by Evans et al. (2002) to
facilitate integration with various GIS software packages.
The BASINS 3.1 system, upon which version 4.0 is based, was developed for EPA by AQUA TERRA
Consultants under EPA contract number 68-C-01-037. USDA-ARS Southwest Watershed Research
Center and the US-EPA National Research Exposure Lab in Las Vegas, NV are acknowledged for their
contribution of the Automated Geospatial Watershed Assessment (AGWA) tool as an extension for
BASINS 3.1.
The BASINS 3.0 system, upon which version 3.1 is based, was developed for EPA by AQUA TERRA
Consultants under EPA contract number 68-C-98-010. This system was developed by AQUA TERRA in
cooperation with the following three groups outside of EPA:
Tetra Tech, Inc., Fairfax, Virginia, provided conceptual design, core system implementation, extension
implementation, database update, documentation, testing, and production services as a subcontractor
under EPA contract number 68-C-98-010. Henry Manguerra, Dan Sandhaus, Matt Meyers, Haihong Yang,
Qin Li, Ansu John, Jian Ouyang, Mustafa Faizullabhoy, Jim Callahan and Alex Trounov made up the Tetra
Tech team.
Texas A & M University and the Blacklands Research Center of the Texas Agricultural Experiment Station
provided an enhanced version of the SWAT model for BASINS 3.0, along with extensions linking BASINS
to SWAT, a watershed delineation extension, testing and documentation to the BASINS system under
EPA InterAgency Agreement number DW12938632. Jeff Arnold, Mauro Di Luzio and R. Srinivasan are
recognized for their efforts.
CH2M HILL, Herndon, Virginia provided the PLOAD extension to BASINS 3.0 under EPA contract number
OW1435NTLX. Sayedul Choudhury, John Tully and Tim Hare made up the CH2M HILL team which made
the enhancements which integrated PLOAD into BASINS 3.0. CH2M HILL also supported the
development of the BMP and REPORT modules in the HSPF model. Avinash Patwardhan is recognized for
his efforts on that effort.
The Hydrologic Analysis Software Support Program of the United States Geological Survey, Water
Resources Division is acknowledged for its support of the development of GenScn version 1.0 and some
of the extensions found in GenScn 2.0. Their support of the development of the MetComp software
which provided algorithms for the WDMUtil tool is also acknowledged. Kate Flynn and Alan Lumb are
particularly recognized.
EPA acknowledges the support of Earthlnfo, Inc., which granted permission to import selected hourly
precipitation data into BASINS from its CD-ROMs. Earthlnfo, Inc., 5541 Central Avenue, Boulder,
Colorado, (303) 938-1788.
Dr. Dennis C. Flanagan of the USDA - ARS NSERL in West Lafayette, IN provided the WEPP model code
used to disaggregate Cligen daily precipitation events into breakpoint data.
The development of the HSPFParm database was made possible by the support of a number of
individuals and organizations. At EPA's Office of Science and Technology Russell Kinerson was the Work

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Assignment Manager for the original development effort. In this capacity he provided focus and
guidance that assured a successful product.
Equally important to the successful development of the HSPFParm database were the contributions of
parameter data sets by modelers across the nation. Contributors to this first version of the database
included David Chen (Chinese University of Hong Kong), James Sams (USGS, Pittsburgh), Larry Moore
(University of Memphis), Thomas Fontaine (South Dakota School of Mines & Technology) and Scott
Wells (Portland State University).
For the original HSPFParm development effort, AQUA TERRA Consultants was responsible for the
collection of parameter values for HSPF applications, assimilation of the data into a unified database,
and development of a user interface. For AQUA TERRA, Tony Donigian, Jr. was the Project Manager. In
addition he developed the coarse characterization data for many of AQUA TERRA's HSPF applications
that were included in the database. He provided guidance throughout the planning and development of
the database and the database interface. John Imhoff was the Project Engineer and was responsible for
establishing database and interface requirements, acquiring data from modelers, and coordinating
documentation of the final product. John Kittle, Jr. was responsible for designing the data model for
the parameter database, designing the user interface, and automating the extraction of parameter
values from HSPF User Control Input files. Thomas Jobes and Paul Duda provided assistance in
assembling the database; in addition Paul Duda prepared the documentation related to the data model
and operational aspects of the database interface. Paul Hummel assisted in developing the initial list of
requirements for the user interface, and Mark Gray provided assistance in implementing the interface.
The Minnesota Pollution Control Agency (MPCA) funded an update to HSPFParm in 2012. Under
contract to the MPCA, AQUA TERRA Consultants ported the original stand-alone HSPFParm software to
this BASINS plug-in. As part of that project, many recent Minnesota HSPF applications were added to
the HSPFParm database. For AQUA TERRA, Paul Duda was the Project Manager. Tong Zhai of AQUA
TERRA revised the documentation following the HSPFParm software's inclusion as a BASINS Plug-in.
Timothy Larson and Charles Regan of MPCA are particularly acknowledged for their support.
The Minnesota Pollution Control Agency is also acknowledged for funding enhancements to the model
setup tool for HSPF. These enhancements facilitate HSPF model setup for snow simulation. Timothy
Larson and Charles Regan are again acknowledged for their support of these enhancements that benefit
the entire BASINS/HSPF modeling community.

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User Assistance and Technical Support
BASINS was developed to promote better assessment and integration of point and nonpoint sources in
watershed and water quality management. It integrates several key environmental data sets with
improved analysis techniques. Several types of environmental programs can benefit from the use and
application of such an integrated system in various stages of environmental management planning and
decision making.
EPA's Center for Exposure Assessment Modeling (CEAM) provides assistance and technical support to
users of the BASINS system to facilitate its effective application. Technical support can be obtained at
the BASINS Home Page: http://www2.epa.eov/exposure-assessment-models/basins-user-information"
arid-guidance

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Introduction
Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) is a multipurpose
environmental analysis system for use by regional, state, and local agencies in performing watershed-
and water-quality-based studies. It was developed by the U.S. Environmental Protection Agency's
(EPA's) Office of Water to address three objectives:
• To facilitate examination of environmental information
• To support analysis of environmental systems
• To provide a framework for examining management alternatives
Because many states and local agencies are moving toward a watershed-based approach, the BASINS
system is configured to support environmental and ecological studies in a watershed context. The
system is designed to be flexible. It can support analysis at a variety of scales using tools that range from
simple to sophisticated.
BASINS was also conceived as a system for supporting the development of Total Maximum Daily Loads
(TMDLs). Section 303(d) of the Clean Water Act requires states to develop TMDLs for water bodies that
are not meeting applicable water quality standards by using technology-based controls. Developing
TMDLs requires a watershed-based approach that integrates both point and nonpoint sources. BASINS
can support this type of watershed-based point and nonpoint source analysis for a variety of pollutants.
It also lets the user test different management options.
Traditional approaches to watershed-based assessments typically involve many separate steps preparing
data, summarizing information, developing maps and tables, and applying and interpreting models. Each
individual step is performed using a variety of tools and computer systems. The isolated implementation
of steps can result in a lack of integration, limited coordination, and time-intensive execution. BASINS
makes watershed and water quality studies easier by bringing key data and analytical components
"under one roof". Using the familiar Windows environment, analysts can efficiently access national
environmental information, apply assessment and planning tools, and run a variety of proven, robust
nonpoint loading and water quality models. With many of the necessary components together in one
system, the analysis time is significantly reduced, a greater variety of questions can be answered, and
data and management needs can be more efficiently identified. BASINS takes advantage of recent
developments in software, data management technologies, and computer capabilities to provide the
user with a fully comprehensive watershed management tool.
A geographic information system (GIS) provides the integrating framework for BASINS. GIS organizes
spatial information so it can be displayed as maps, tables, or graphics. GIS provides techniques for
analyzing landscape information and displaying relationships. Through the use of GIS, BASINS has the
flexibility to display and integrate a wide range of information (e.g., land use, point source discharges,
water supply withdrawals) at a scale chosen by the user. For example, some users will need to examine
data at a multistate scale to determine problem areas, compare watersheds, or investigate gaps in data.
Others will want to work at a much smaller scale, perhaps investigating a particular river segment

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impaired by multiple point source discharges. This "zooming" capability of BASINS makes it a unique and
powerful environmental analysis tool.
Some agencies might wish to perform analyses at a variety of scales, in a nested fashion, to meet several
objectives at once. BASINS is designed to facilitate all of these scenarios because it incorporates tools
that operate on both large and small watersheds. Adding locally developed, high-resolution data sources
to existing data layers is an additional option that expands the local-scale evaluation capabilities.
BASINS comprises a suite of interrelated components for performing the various aspects of
environmental analysis. The components include (1) nationally derived databases with tools to Build
New Projects; (2) Watershed Characterization Reports that address large- and small-scale
characterization needs; (3) utilities to facilitate organizing and evaluating data; (4) tools for Watershed
Delineation; (5) infrastructure to include watershed loading and transport models such as Hydrological
Simulation Program - Fortran (HSPF) and Soil and Water Assessment Tool (SWAT).
The watershed characterization component, working under the GIS umbrella, allows users to quickly
evaluate selected areas, organize information, and display results. The model inclusion capability allows
users to examine the impacts of pollutant loadings from point and nonpoint sources. Working together,
these modules support several specific aspects of watershed-based analysis by
• Identifying and prioritizing water-quality-limited waters.
• Supplying data characterizing point and nonpoint sources and evaluating their magnitudes and
potential significance.
• Integrating point source and nonpoint source loadings and fate and transport processes.
• Evaluating and comparing the relative value of potential control strategies.
• Visualizing and communicating environmental conditions to the public through tables, graphs, and
maps.
This user's guide provides information on the systems and procedures in BASINS Version 4.5 Core. This
version provides some significant enhancements and functions beyond those provided by the earlier
releases of BASINS, Versions 1.0 through 4.1. The modification and enhancement of the program reflect
the extensive comments and input provided by the user community regarding earlier versions. The
significant changes between BASINS versions include the following:
BASINS 4.5 Core
• Complete replacement of all the data download libraries with the D4EM version of these libraries.
Data for Environmental Modeling, or D4EM, is a comprehensive set of tools that obtains and
processes data to be used in mathematical environmental models. See
http://www.epa.gov/athens/research/d4em.html for more information.
• Updates the HUC8 layer of the 'Build New Project' national map to use the March 2017 update of
the Watershed Boundary Dataset (WBD).

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• Provides access to both National Hydrography Dataset Plus (NHDPIus) version 1.0 and 2.1 through
the data download tool.
• Updates the National Land Cover Database (NLCD) data download options to include 2011 land use
and impervious area data
• Updates the North American Land Data Assimilation System (NLDAS) download to allow access to
the full suite of meteorological constituents needed for watershed and in-stream models, as well as
a new option to adjust time from UTC to the project time zone.
• In BASINS 4.5 Core, all model plugins are installed separately from the BASINS 4.5 Core install.
BASINS 4.1
• This release of BASINS is built upon the latest stable release of the non-proprietary, open-source GIS
MapWindow GIS (MapWindow web site). Along with the update to the underlying GIS platform, the
BASINS automatic watershed delineation tools have been updated to use TauDEM version 5 from
Utah State University.
• Ensured 64-bit compatibility and compatibility with Windows 8.
BASINS 4.0
• The first version of BASINS to be primarily based on a non-proprietary, open-source GIS foundation.
MapWindow GIS (MapWindow web site) is the lightweight open-source GIS upon which BASINS 4.0
is built. While not being dependent upon any proprietary GIS platform, the core of BASINS 4.0 is
designed to complement and interoperate with enterprise and full-featured GIS systems. BASINS
4.0 can import and export projects from ArcView 3.x and ArcGIS 9.x. This interoperability allows
users access to features available in these systems but not BASINS 4.0. Along with the change to
the underlying GIS platform, the BASINS extensions were refactored as they were ported to the new
system.
• New plug-ins were developed to support several additional models, including SWMM, WASP and
GWLF-E. DFLOW was added as an analysis tool, and NHDPIus and NLDAS Precipitation were added
as available download types.
BASINS 3.1
• Entirely web-based data extraction. CD sets are no longer released by EPA region, but as only one
master CD for the BASINS system and tutorial data. All other data is downloaded from the web as
needed.

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• A new Data Download tool that manages the downloading of data from the web.
• A Build New Project tool that provides an interface for selecting the geographic area of interest from
among the entire 48 contiguous United States.
• Refined BASINS web data holdings.
• 30-meter DEMs, from the National Elevation Dataset (NED).
• A new Archive and Restore tool, to assist with storage and retrieval of BASINS projects, with the
ability to compare two BASINS projects.
• New extensions for the AQUATOX model and the AGWA GIS-based modeling tool.
• A new report tool based on the Watershed Characterization System (WCS)
BASINS 3.0
• Addition of grid data sets including USGS DEM elevations grids (1:250,000 scale).
• Additional flexibility for users to import their own data layers including elevation, landuse soils,
streams and point sources layers in shapefile and/or grid file formats.
• New utility to perform automatic watershed delineations based on DEM data. The new watershed
delineation tool is used to generate and define the watershed boundary, stream network, and point
source discharge layers to be used for watershed modeling using HSPF or SWAT. The stream
network can be generated based on the DEM or defined by an existing stream layer such as USEPA
Reach File, Version 1 or National Hydrography Dataset (NHD). Point source locations can be
selected from the permit compliance system layer or manually added. The tool also generates many
of the watershed and stream characteristics needed for modeling including slopes, elevations, and
stream widths and depths.
• A significantly enhanced manual delineation tool that provides users additional flexibility in editing
shapes and attributes of manually delineated watersheds.
• A grid projector that extends the ArcView projection tool to also project grid data. This component
requires Spatial Analyst.
• An NHD download tool that allows users to download NHD data layers from the USGS web site and
import them directly into a BASINS project window using the correct projection.
• Incorporation of the Soil and Water Assessment Tool (SWAT) developed by the USDA Agriculture
Research Service (ARS). SWAT is a physical based, watershed scale model that was developed to
predict the impacts of land management practices on water, sediment and agricultural chemical
yields in large complex watersheds with varying soils, land uses and management conditions over

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long periods of time. SWAT2000 is the underlying model that is run from the BASINS ArcView
interface. SWAT requires the Spatial Analyst extension.
• A new interface to the Hydrological Simulation Program - Fortran (HSPF), called WinHSPF. In earlier
versions of BASINS, the interface to HSPF was known as the Nonpoint Source Model (NPSM).
WinHSPF builds upon the successes of NPSM, but adds enhanced graphical displays and editing
capabilities such that all features of HSPF are available in WinHSPF. WinHSPF fully supports the
MASS-LINK, SCHEMATIC and SPECIAL ACTIONS blocks of the UCI File. This interface also directly
reads HSPF UCI file.
• A postprocessor known as GenScn. GenScn works with data in a variety of formats including
Watershed Data Management (WDM) files, SWAT output files, and BASINS observed water quality
files.
• A utility program for managing WDM files known as WDMUtil. WDM files are used by HSPF for
input and output time-series data. WDMUtil was designed to help manage the large volumes of
time-series data used with HSPF, as well as to add additional time series where needed.
• A pollutant loading program known as PLOAD. Developed by CH2M-Hill, PLOAD estimates nonpoint
sources of pollution on an annual average basis, for any user-specified pollutant, using either the
export coefficient or simple method approach.
BASINS 2.0
• Additions to the base data sets include USEPA Reach File Version 3 Alpha (RF3 Alpha), STATSGO
soils, DEM elevation data, federal and Indian land boundaries, water quality observation data,
ecoregions, fish and wildlife consumption advisories, shellfish contamination, and Clean Water
Needs Survey.
• New utilities to facilitate data preparation such as Watershed Delineation and Watershed
Characterization Reports.
• Expanded functionality of the nonpoint source modeling system to include in-stream transport and
visualization.
• Postprocessing tools for evaluation of model output.
Users are encouraged to continue to provide EPA with comments and recommendations for further
development. Future enhancements to the system might include adding additional types of information,
using higher-resolution data, providing Internet access to data and model updates, expanding
assessment and evaluation capabilities, providing enhanced data management and display tools, and
adding a wider range of nonpoint source water quality and ecological modeling techniques.

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System Overview and What's New
The BASINS 4.5 Core system combines several components to provide the range of tools needed for
performing watershed and water quality analyses. These interrelated components can be summarized
as follows:
•	National environmental databases
•	Watershed characterization tools
•	Utilities
•	Watershed and In-stream Water quality models (model plugins available and installed separately)
•	Analysis tools and Postprocessors
A graphical representation of the BASINS components and their operating platform is provided in the
figure below.

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BASINS
GIS
BASINS 4.5 System Overview
Web Data
Download
Tool
Political

Boundaries

TIGER Line


and Census

Data


Monitoring

Data

Hydrography
Digital
Elevation
Data
State Soils
Data
Meteorological
Data (Weather
Stations)
Tools and Utilities
Watershed Reports
Time-Series Management
%
Watershed Delineation
Surface Water Statistics
W
Additional
User Supplied
Data

	


		

DFLOW




Models*
HSPF/WinHSPF
Decision Making and
Analysis
Postprocessing
Graph/List
'3 s
Pollutant Loading Estimator
F_
Reporting/Scripts
Watershed Management
Sensitivity Analysis
Climate Analysis
Nutrient Management
Source Water Protection
TMDLs
UAAs
Project Archive
BASINS System Overview
The BASINS physiographic data, monitoring data, and associated assessment tools are integrated in a
customized geographic information system (GIS) environment. MapWindow GIS (MapWindow web site)
is the lightweight open-source GIS upon which BASINS 4.0 and subsequent versions are built. The GIS
used in earlier versions is ArcView 3.x developed by Environmental Systems Research Institute, Inc. The
simulation models are integrated into this GIS environment through a dynamic link in which the data
required to build the input files are generated in the GIS environment and then passed directly to the
models. The results of the simulation models can also be displayed visually and can be used to perform
further analysis and interpretation.
BASINS 4.0 was the first version of BASINS to be primarily based on a non-proprietary, open-source GIS
foundation. While not being dependent upon any proprietary GIS platform, the core of BASINS 4.0 was
designed to complement and interoperate with enterprise and full-featured GIS systems. BASINS 4.0
and 4.1 can import and export projects from ArcView 3.x and ArcGIS 9.x. This interoperability allows
users access to features available in these systems but not BASINS.

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Previous versions of BASINS included Model Plug-ins within the BASINS installation. However, in BASINS
4.5 Core, all Model Plug-ins are packaged and installed separately. The architecture allows users to
develop and include their own plug-ins in their BASINS 4.5 Core installation. A list of EPA provided
Model Plug-ins, along with a short description of its function, is provided below. WinHSPF and WASP
plug-ins will continue to be supported by U.S. EPA. The remaining Plug-ins in the list will be made
available for installation but will not be supported by U.S. EPA.
Watershed Model plug-ins:
• WinHSPF is an interface to the Hydrological Simulation Program Fortran (HSPF). HSPF is a watershed
scale model for estimating instream concentrations resulting from loadings from point and nonpoint
sources.
• SWAT is a physical based, watershed scale model that was developed to predict the impacts of land
management practices on water, sediment and agricultural chemical yields in large complex
watersheds with varying soils, land uses and management conditions over long periods of time.
SWAT2005 is the underlying model that is run from the BASINS MapWindow interface.
• SWMM is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous)
simulation of runoff quantity and quality from primarily urban areas. The routing portion of SWMM
transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and
regulators.
Instream / Water Quality Models:
• AQUATOX is a simulation model for aquatic systems that predicts the fate of various pollutants, such
as nutrients and organic chemicals, and their effects on the ecosystem, including fish, invertebrates,
and aquatic plants.

WASP is a dynamic compartment-modeling program for aquatic systems, including both the water
column and the underlying benthos.
Loading models:
• GWLF-E, an extension of the Generalized Watershed Loading Function (GWLF) model. GWLF-E is a
'mid-level' model that estimates monthly nutrient and sediment loads within a watershed.
• PLOAD, a pollutant loading model. PLOAD estimates nonpoint sources of pollution on an annual
average basis, for any user-specified pollutant, using either the export coefficient or simple method
approach.
The BASINS 4.x system architecture was completely reengineered for version 3.0. Unlike its

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predecessor, all customized components of BASINS 3.0, such as model interfaces, data management
utilities, and watershed assessment tools, are developed as BASINS extensions, thereby providing users
the capability to load only the extensions needed for their BASINS project. The new architecture also
allows the system to support several levels of hardware and software sophistication. For the developers,
it will be easier to maintain and provide updates of the individual extensions rather than issuing a new
version of the entire system. This makes it also easier for the users to upgrade their system.
The BASINS GIS provides built-in additional procedures for data query, spatial analysis, and map
generation. These custom BASINS procedures allow a user to visualize, explore, query available data,
and perform individualized and targeted watershed-based analyses. Some familiarity with desktop GIS
systems is helpful in accessing and fully utilizing the capabilities of BASINS and the custom analytical
tools. Furthermore, as users become familiar with GIS operations, environmental relationships can be
further investigated using complex queries, overlays, proximity analyses, and buffer analyses.
BASINS 4.5 Core provides the following additional enhancements and features:
• Updates the HUC8 layer of the 'Build New Project' national map to use the March 2017 update of
the Watershed Boundary Dataset (WBD).
• Provides access to both NHDPIus version 1.0 and 2.1 through the data download tool.

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Databases
The BASINS system includes a variety of databases that are extracted and formatted to facilitate
watershed-based analysis and modeling. The databases were compiled from a wide range of federal
sources. The data were selected based on relevance to environmental analysis, national availability, and
scale and resolution. As new data become available, updates may be distributed through the BASINS
Internet site (see Download). Users are also encouraged to import locally derived data sets or higher-
resolution layers into BASINS to support the most appropriate and accurate analysis. The data included
within BASINS are intended to provide a starting point and data for those areas where limited site-
specific information is available.
Four types of data are delivered with the BASINS analysis system:
• Base cartographic data
• Environmental background data
• Environmental monitoring data
• Point sources/loading data
Base Cartographic Data
BASINS' base cartographic data include administrative boundaries, hydrologic boundaries, and major
road systems. These data are essential for defining and locating study areas and defining watershed
drainage areas. The base cartographic data products included in BASINS are listed below.
Base Cartographic Data
Source
U.S. Geological Survey (USGS)
Data Product
Hydrologic Unit Boundaries
Major Roads
Populated Place Locations
Urbanized Areas
Federal Highway Administration
Description
Nationally consistent delineations
of the hydrographic boundaries
associated with major U.S. river
basins
Interstate and state highway
network
Location and names of populated
locations
Delineations of major urbanized
areas used in 1990 Census
USGS
Bureau of the Census

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State and County Boundaries USGS
Administrative boundaries
EPA Regions	USGS	Administrative boundaries
Census Shapefiles	Bureau of the Census	Boundary layers and associated
tabular data from the 1990 and
2000 Census of Population, as well
as the TIGER line files showing
roads, railroads, and other linear
features
Environmental Background Data
Environmental background data provide information to support watershed characterization and
environmental analyses. These data include information on soil characteristics, land use layers, and the
stream hydrography. This information is used in combination with modeling tools to perform more
detailed assessment of watershed conditions and loading characteristics. The environmental
background data included in BASINS are listed below.
Environmental Background Data
BASINS Data Product
Source
Description
Ecoregions Level III
U.S. Environmental Protection
Agency (USEPA)
Ecoregions and associated
delineations
National Water Quality
Assessment (NAWQA) Study
Unit Boundaries
USGS
Delineations of study areas
State Soil and Geographic
(STATSGO) Database
U.S. Department of Agriculture,
Natural Resources Conservation
Service (USDA-NRCS)
Soils information including soil
component data and soils
Managed Area Database
University of California, Santa
Barbara
Data layer including federal and
Indian lands
Reach File Version 1 (RF1)
USEPA
Provides stream network for major
rivers and supports development
of stream routing for modeling
purposes (1:500k)
National Hydrography
Datasetl
USGS
Spatial dataset based upon the
USGS DLG and the USEPA Reach
File Version 3, that is more refined

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NHDPIus 1.0/2.11	US EPA
and expanded. Contains
information about surface water
features which are combined to
form reaches (surface water
drainage network), facilitating in
routing for modeling
purposes(l:100K)
an integrated suite of application-
ready geospatial data sets that
incorporates many of the best
features of the National
Hydrography Dataset (NHD), the
USGS Watershed Boundary
Dataset (WBD), and the National
Elevation Dataset (NED), along
with other value-added attributes.
Digital Elevation Model	USGS
(DEM) 1
National Elevation Dataset USGS
(NED)1
Land Use and Land Cover	USGS
(GIRAS) 1
Topographic relief mapping;
supports watershed delineations
and modeling
Topographic relief mapping;
supports watershed delineations
and modeling
Boundaries associated with land
use classifications including
Anderson Level 1 and Level 2
National Land Cover Data USGS MRLC	GIS layers from the NLCD dataset
(NLCD) 1992, 2001, 2006, and
20111
Environmental Monitoring Data
BASINS contains several environmental data products developed from existing national water quality
databases. These databases were converted into locational data layers to facilitate the assessment of
water quality conditions and the prioritization and targeting of water bodies and watersheds. These data
can be used to assess the current status and historical trends of a given water body and also to evaluate
the results of management actions. The environmental monitoring data included in BASINS are listed
below.
BASINS Environmental Monitoring Data

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BASINS Data Product
Source
Description
Water Quality Monitoring
Stations and Data Summaries
USEPA
Bacteria Monitoring Stations
and Data Summaries
USEPA
Water Quality Stations and
Observation Data
STORET
USEPA
USEPA
Statistical summaries of water
quality monitoring for physical and
chemical-related parameters;
parameter-specific statistics
computed by station for 5-year
intervals from 1970 to 1994 and 3-
year interval from 1995 to 1997
Statistical summaries of bacteria
monitoring; parameter-specific
statistics computed by station for
5-year intervals from 1970 to 1994
and 3-year interval from 1995 to
1997
Observation-level water quality
monitoring data for selected
locations and parameters
Observation-level water quality
monitoring data from the EPA
STORET database
Station Locations from
NWIS1
USGS
Station locations for the selected
station types, including 'Daily
Discharge', 'Water Quality',
'Measurements' and 'Ground
Water'
USGS Data from NWIS1
Meteorologic Stationsl
Meteorologic Databasel
USGS
National Oceanic and Atmospheric
Administration (NOAA)
NOAA
NLDAS Meteorological Datal NASA/NOAA
Data values collected at the
selected USGS station locations
Location of stations in the updated
BASINS Meteorological database
(Version 2009)
BASINS Meteorological data from
the updated BASINS
Meteorological database (Version
2009)
Hourly meteorological data from
NLDAS (North American Land Data
Assimilation System) Phase 2

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Point Source/Loading Data
BASINS also includes information on pollutant loading from point source discharges. The location, type
of facility, and estimated loading are provided. These loadings are also used to support evaluation of
watershed-based loading summaries combining point and nonpoint sources. The point source/loading
data included in BASINS are listed below.
BASINS Point Source/Loading Data
BASINS Data Product	Source Description
Permit Compliance System (PCS) Sites and USEPA
Computed Annual Loadings
NPDES permit-holding facility information;
contains parameter-specific loadings to surface
waters computed using the EPA Effluent Decision
Support System (EDSS) for 1990-1999
IData Layers that are added into the BASINS project using the Data Download.

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Environmental Assessment Tools
Watershed characterization is key to understanding water quality issues and pollution sources in the
watershed. In addition to evaluation of the watershed condition, it provides the necessary information
to assess monitoring programs, identify data gaps, and develop watershed-water quality modeling
strategies.
The BASINS system includes tools designed to assist in summarizing key watershed information in a
format suitable for preparing Watershed Characterization Reports. These tools produce tables that
inventory and characterize both point and nonpoint sources at the watershed and subwatershed scales.
Watershed Characterization Reports
BASINS provides users the capability to generate eight different types of Watershed Characterization
Reports, each in tabular form:
•	1990 Population and Sewerage by Census Tract
•	2000 Population and Census Tract Table
•	Landuse Distribution Table
•	Permitted Point Source Facilities Table
•	Point Source Discharge Concentration and Loading Table
•	Water Quality Observations Stations Table
Watershed Characterization System
The BASINS Watershed Characterization System can be used to select and generate several standard
reports designed to describe the physical characteristics of watersheds (subbasins) you have defined.
This feature is more customized version of the Watershed Characterization Reports. The following
reports are available:
•	Water Bodies
•	Population Estimates
•	Housing and Sewage
•	Soil Characteristics

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•	Landuse Characterization
•	Permitted Point Sources
•	Data Summary

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Utilities
Manual Delineation Tool
The BASINS Manual Watershed Delineation tool allows the user to delineate subwatersheds manually.
It allows the user to subdivide a watershed into several smaller hydrologically connected watersheds
based on the user's knowledge of that watershed's drainage topography. The tool also provides users
the flexibility to edit shapes and attributes of manually delineated watersheds, outlets and generating
stream networks.
Automatic Delineation Tool
The BASINS Automatic Watershed Delineation tool allows the user to delineate subwatersheds based
on an automatic procedure using Digital Elevation Model (DEM) data. User specified parameters
provide limits that influence the size and number of subwatersheds created.
Land Use Reclassification
The Land Use Reclassification tool assists the user in grouping or renaming land use categories as
needed to support modeling and analysis. Land uses can be reclassified in one of two ways:
reclassification of the entire layer (all land uses) or reclassification of selected layers (single or multiple
land uses from within an entire layer).
Lookup Tables
The Lookup Tables provide users quick access to relevant reference information on data products
included within BASINS. Information is provided for products such as the map projection, definition of
agency codes for monitoring data, Standard Industrial Classification (SIC) codes, and the water quality
criteria and threshold values of selected pollutants.

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Analysis Tools and Postprocessors
Climate Assessment Tool (CAT)
The BASINS Climate Assessment Tool (CAT) provides a flexible set of capabilities for representing and
exploring climate change and its relationship to watershed science. Tools have been integrated into the
BASINS system allowing users to create climate change scenarios by modifying historical weather data,
and to and use these data as the meteorological input to several BASINS watershed models (HSPF,
SWAT, and SWMM). A capability is also provided to calculate specific hydrologic and water quality
endpoints important to watershed management based on model output (e.g. the 100-year flood or
7Q10 low flow event). Finally, the CAT can be used to assess the outcomes of a single climate change
scenario, or to automate multiple model runs to determine the sensitivity or general pattern of
watershed response to different types and amounts of climate change. In BASINS 4.5, CAT is included
within the WinHSPF model plugin installation package.
Time Series Functions
BASINS contains utilities to manage and analyze available project time-series data. Project time-series
data are managed through the Time-Series Management Utilities. The Graph menu item is used to
produce graphs of the selected time series. When the 'Graph' menu item is selected, a form is produced
for choosing from among a set of possible graph types. Among the implemented graph types include
Timeseries, Flow/Duration, Running Sum, Residual, Cumulative Difference, and Scatter. The List menu
item produces a listing of dates and associated values for the selected time series.

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Hardware and Software Requirements
BASINS Version 4.5 Core is a customized MapWindow GIS application that integrates environmental
data, analysis tools, and modeling systems. BASINS' hardware requirements are, at a minimum, similar
to those of the PC-based MapWindow system. There are no additional software requirements for
BASINS because all software components integrated into the program are open source.
Users must have administrator privileges to install BASINS.
BASINS can be installed and operated on machines with the Microsoft Windows operating system
equipped with the software, random access memory (RAM), virtual memory, and hard disk space
presented in the table below.
Because the performance (response time) under the minimum requirements option might be too slow
for some users especially when dealing with large data sets, a preferred set of requirements is also
included.
BASINS Hardware/Software Requirements
Hardware/Software
Minimum Requirements
Preferred Requirements
Processor
1GHz processor
2GHz processor or higher
Available hard disk space
2.0 Gb
10.0 Gb
Random access memory
(RAM)
512 Mb of RAM plus 2 Gb of page
space
1 Gb of RAM plus 2 Gb of page
space
Color monitor
16 bit color, Resolution 1024x768
32 bit color, Resolution 1600x1200
DVD/Compact disc
reader/writer
Optional
Optional
Internet Connection
WiFi
DSL or better
Operating system
Windows 7, Windows 8, or later
Same
Internet Explorer 9.0 or newer is required to view help files.

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Installation
Installation Instructions for BASINS 4.5 Core
BASINS 4.5 Core is available at http://www2.epa.gov/exposure-assessmetTt-models/basiris-user-
iiiformation-atid-euidatice.
BASINS 4.5 Core is distributed as a single installation program. The setup program provides a software
wizard which guides the user through the setup process.
Installation Requirements
It is assumed that BASINS users already have some familiarity with Microsoft Windows, as well as GIS
concepts, and that they have a basic understanding of water quality analysis techniques and modeling.
The user must have administrator privileges before starting the installation. Since some new system
files are included in this release, the user may need to restart Windows after some files have been
updated before continuing with the installation.
Installing BASINS 4.5 Core
The BASINS installation program copies BASINS system files and tools, and it also sets up BASINS icons
automatically.
The BASINS installation program allows the user to install the BASINS system. The BASINS system
installation program installs all of these components to your local hard drive in a fixed directory
structure. It also sets up a Windows BASINS program group that includes icons for the BASINS
components.
When running the installation program, follow the instructions on the screen.
Tip: The BASINS installation program does not copy any BASINS data (except the optional tutorial) to
your hard drive.
Tip: If you have multiple hard drives or partitioned drives, you may have only one BASINS directory in
each partitioned or physical drive.
General Notes

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It is recommended that the BASINS system be installed at the root of a drive. The user must have write
access to the folder in which BASINS is installed.
Be sure you have administrator privileges before starting the installation. Since some new system files
are included in this release, you may need to restart Windows after some files have been updated
before continuing with the installation.
Notes for Users Upgrading to BASINS 4.5 Core
If you have an earlier version of BASINS installed already, uninstall it before installing BASINS 4.5.
Earlier BASINS project files and data will not be deleted during the uninstall process. Earlier BASINS
projects (MapWindow .mwprj files) may not open correctly in BASINS 4.5 Core, but the map layers may
be loaded into new BASINS 4.5 Core projects.

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Finding Functionality from Earlier Versions
Users of earlier versions of BASINS (3.1 and prior) might need a few minutes to become familiar with the
new features and structure of BASINS 4.0 and subsequent versions. Not all of the earlier BASINS
components have a directly corresponding component in later versions of BASINS. This section is
included to help users of BASINS 3.1 find the functions of BASINS 4.0 and subsequent versions that fulfill
the same functional requirements as BASINS 3.1. Unless otherwise noted, a directly corresponding
component of the current version of BASINS exists for each component of BASINS 3.1.
As stated previously, BASINS 4.0 and subsequent versions are built upon a lightweight open-source GIS
known as MapWindow GIS (MapWindow web site, Introduction to MapWindow). BASINS 4.0 was the
first version of BASINS to be primarily based on a non-proprietary, open-source GIS foundation.
Environmental Assessment Tools
The Assessment Tools from BASINS 3.1, TARGET, ASSESS, and Data Mining, have been superseded in
version 4.0 and subsequent versions by the new Watershed Characterization Reports tool. The
Watershed Characterization Reports are more powerful than ever before, with a full scripting capability
and the ability to summarize within any set of user-specified polygons.
Utilities
The Theme Manager component from BASINS 3.1 has been discontinued for version 4.0 and
subsequent versions. All of the auxiliary map layers from BASINS 3.1 are loaded onto the map as the
project is created. The legend grouping capability of MapWindow is used to group the layers logically.
The BASINS Import Tool from BASINS 3.1 is not available in BASINS 4.0 and subsequent versions because
each of the BASINS components has been re-engineered to accommodate user-supplied GIS layers. It is
anticipated that users will want to import locally developed data, which might be more accurate, at a
higher resolution, or more reflective of current conditions. Such layers can be added to the map and
then used by the BASINS tools directly.
The functionality of the Grid Projector from BASINS 3.1 is now built into the core GIS. In BASINS 4.0 and
subsequent versions a grid may be downloaded, projected, and loaded into the project seamlessly, and
in one step. Since the core GIS handles grid data, no special extensions are needed to accommodate
grids.
The Predefined Delineation Tool of BASINS 3.1 has been discontinued for BASINS 4.0 and subsequent
versions. Any user-supplied layers can be brought into BASINS through the core GIS functionality.
Advanced functionality of each of the BASINS components has been developed to accommodate user-
supplied GIS layers. User-supplied subbasins and streams layers can be used as inputs to the Manual
Watershed Delineator to produce output streams and subbasins layers with the required attributes for
modeling.
The functionality of the Water Quality Observation Data Management utility is part of the core GIS

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functionality. With MapWindow GIS, users can manipulate water quality observation locations and
data.
DEM Reclassification is part of the standard MapWindow GIS legend editor features.
GenScn facilitates the display and interpretation of output data derived from model applications.
GenScn is not a model itself. It serves as a postprocessor for both the HSPF and SWAT models, as well as
a tool for visualizing observed water quality data and other time-series data. Beginning with BASINS 4.1,
GenScn is available as a separate download at http://www.aquaterra.com/basins4. Most of the
functionality of GenScn is now included in the core BASINS user interface.
WDMUtil is a utility program for managing Watershed Data Management (WDM) files, which contain
input and output time-series data for HSPF. Beginning with BASINS 4.1, WDMUtil is available as a
separate download at http://www.aquaterra.com/basins4. The import functionality of WDMUtil has
migrated to the BASINS 4.x feature Read Data with Script.
Performing 'WDMUtil' Functions in BASINS 4.5 Core
Much of the WDM Time-series management functionality of WDMUtil is available through the 'File'
menu option in BASINS, especially through the 'File:Manage Data' menu option. This functionality is
documented in the user's manual under Time-Series Management.
To create a new WDM file in BASINS: Use 'File:New Data'. Select 'WDM Time Series' as the file type,
and specify the file name using the open file dialog.
To import local weather data using scripts: Use 'File:OpenData'. Select 'Read Data with Script' as the
file type, navigate to the text file of timeseries data using the file dialog, and then a script selection form
appears. Click 'Find' to select the script to use, or click 'Edit' to create a new one, and then click 'Run' to
import the data.
To save the newly added timeseries to WDM: Use 'File:Save Data In'. Select the name of the WDM file
from those available in the current BASINS project, select the timeseries from the list of those available,
and click 'OK'. The timeseries will be written to the WDM file.
To view the contents of a WDM file: Use 'File:Manage Data'. Then choose the 'Analysis:List' menu item.
Select 'no' to see a full list of data sets available. A data selection window will appear which summarizes
the contents of the WDM file.
To edit attribute values: Use 'Analysis:List' to list the data. In the Timeseries List window, use
'File:Select Attributes' to select which attributes will be visible. Edit attributes as desired. Close the list,
then use 'File:Save Data In' to save the revised timeseries to the selected WDM file.
To edit timeseries values: Use 'Analysis:List' to list the data. Edit the values as desired. Close the list,
then use 'File:Save Data In' to save the revised timeseries to the selected WDM file.

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To delete a WDM timeseries: Use 'File:Manage Data'. Select the file name in the Data Sources window,
and then choose the 'File:Remove Data from File' menu item. Choose the timeseries to be deleted.
Functions for computing meteorological timeseries and performing time step disaggregation for
meteorological data are available within the 'Compute:Meteorologic Generation' menu option. These
functions are documented in the user's manual under Compute.
To perform meteorological computations: Use 'Compute:Meteorologic Generation', then choose the
particular function desired. Once the new timeseries is computed, save the new timeseries to WDM.
To disaggregate a meteorological timeseries: Use 'Compute:Meteorologic Generation', then choose the
particular disaggregation function desired. Once the new timeseries is computed, save the new
timeseries to WDM.

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BASINS Details
This section of the manual provides information on the utilities available in BASINS and detailed
instruction on how to construct and manage a project within BASINS. BASINS has a wide range of
implicit utilities as well as links and plug-ins that avail the utility of other software programs via the
BASINS interface. This section begins with a discussion of the BASINS interface, available plug-ins and
the utilities they provide, then moves on to the procedures necessary to build and manage a BASINS
project, and concludes with instruction on how to use information from the BASINS project to set up
separate independent, yet linked, watershed models.

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User Interface
The BASINS user interface is based on a customized MapWindow interface. Within the system, all forms
consist of menus, toolbars, text boxes, buttons, lists, tables, check boxes, and radio buttons. Both the
left and right mouse buttons are used for mouse interaction.
The BASINS windows are organized logically, with access to the most basic and relevant information
available easily, and more detailed information available through additional menus or buttons.
Similarly, some windows organize data by stacked tabs, with the most frequently used tabs at the top of
the stack.
The BASINS user interface was designed to ensure that the user knows where they are within the
system. Each window is labeled with a title that indicates its function and confirms to the user that the
menu item or button they used took them to the expected place. The name on the main window is
updated each time a project is opened to reflect the project's file name. An asterisk appears after the
project's file name when the project has unsaved changes.
BASINS Customized MapWindow Interface
The BASINS customized MapWindow interface contains all of the menu, button, and toolbar items that
are present in the standard MapWindow interface. This provides access to MapWindow's full array of
utilities, including raster and vector operations and managing their associated attribute tables. These
tools and menus are activated through the Plug-ins menu item on the main form, which is also used to
access a number of additional menus and tool bar items that execute watershed delineation, BASINS
utilities, data management and analysis tools, watershed characterization reports, and watershed
models. The BASINS customized MapWindow interface is shown below.
Note: Depending on which plug-ins are installed and activated, the user's main BASINS menus may look
different than the menu depicted in screenshots throughout this documentation.