TMDL Modeling Toolbox
What is the Toolbox?
The TMDL Modeling Toolbox is a collection of models,
modeling tools, and databases that have been utilized over
the past decade in the development of Total Maximum Daily
Loads (TMDLs). The Toolbox takes these proven technologies
and provides the capability to more readily apply the models,
analyze the results, and integrate watershed loading models
with receiving water applications. The design of the toolbox
is such that each of the models are stand alone applications.
The toolbox provides an exchange of information between
the models through common linkages. Due to the modular
design of the Toolbox, additional models can be added easily
to integrate with the other tools. In addition, the toolbox
provides the capability to visualize model results, a linkage
to GIS and non-geographic databases (including monitoring
data for calibration), and the functionality to
perform data assessments.
What models are
in the Tool box?
The Toolbox allows for the
steady-state/dynamic simula-
tion of mass transport and
water quality processes in all
types of surface water environ-
ments, including overland flow,
small creeks, rivers, lakes, estuaries,
coastal embayments, and offshore ar-
eas. The Toolbox contains assessment
tools, watershed models, and receiving
water models including the following:
Assessment Tools:
• Water Resources Database (WRDB)
• Watershed Characterization System (WCS)
• WCS Sediment Tool
• WCS Mercury Tool
• WCS LSPC Tool
Watershed Models:
• Loading Simulation Program in C++ (LSPC)
• Watershed Assessment Model (WAMView)
• Storm Water Management Model (SWMM)
Receiving Water Models:
• A Dynamic One-Dimensional Model of Hydrodynamics
and Water Quality (EPDRivl)
• Stream Water Quality Model (QUAL2K)
• CONservational Channel Evolution and Pollutant Trans-
port System (CONCEPTS)
• Environmental Fluid Dynamics Code (EFDC)
• Water Quality Analysis Simulation Program (WASP)
Why is the Toolbox being developed?
With the significant increase in the need for sophisticated
modeling approaches for TMDL development,
EPA determined that it is necessary to
establish a level of consistency and
defensibility for TMDL mod-
eling tools. The Toolbox
is designed to address a
broad range of waterbody
types and pollutants.
EPA actively supports
the components of the
TMDL Modeling Toolbox.
EPA is committed to enhanc-
ing and improving components
of the Toolbox to meet the technical
demands of the TMDL program and
watershed protection. This will ensure
defensibility when TMDLs are faced
with legal challenges. Additionally,
knowledge gained through TMDL de-
velopment experience and modeling with
the Toolbox in one region of the country can
be readily distributed throughout others.
United States
Environmental Protection
Agency
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Have any of the Toolbox components
been used forTMDL development?
The Toolbox models and databases have been used both inde-
pendently and collectively to develop defensible TMDLs for a
wide array of issues including pathogens, sediment, nutrients,
dissolved oxygen, metals, temperature, and toxicants. The
WCS Sediment Tool has been applied to sediment-impaired
waters throughout the southeast. Mercury TMDLs were de-
veloped in Georgia using a combination of the WCS Mercury
Tool and WASE LSPC has been used in Alabama for pathogen
TMDLs; Georgia, Tennessee, Kentucky, and Alabama for nu-
trient and/or dissolved oxygen TMDLs; and Alabama, West
Virginia, and Arizona for metals TMDLs. EFDC has been used
widely throughout the country to support TMDL development
- Washington, California, Oklahoma, Florida, Mississippi,
Alabama, North Carolina, West Virginia, Delaware, Pennsyl-
vania, and Massachusetts. Toolbox model linkages have been
successful in a number of situations, most notably for TMDL
development in the Neuse Estuary NC, Cape Fear River NC,
and Fenholloway River Estuary FL (EFDC and WASP) and
TMDL development for Mobile Bay AL, Flint Creek AL,
Coosa Lakes AL, Lake Allatoona GA, and Alabama River
AL (LSPC, EFDC, and WASP).
Is training available for the Toolbox?
A series of training courses is being designed to instruct
users on the application of the Toolbox models, databases,
and linkages. This training will consist of regu-
larly scheduled training modules throughout the
country, self-paced training available on the web,
and specialty conferences. Materials from these
training modules will be available at the Toolbox
homepage.
Is technical support
available for the Toolbox
and TMDL development?
Yes, technical support and assistance in
TMDL development is available from the
Watershed and Water Quality Modeling
Technical Support Center. The mission
of the Center is to provide technical as-
sistance and support to EPA Regions,
State, and Local governments in the
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application of the Toolbox and development of TMDLs.
The Center which is part of EPAs Office of Research and
Development (ORD) is committed to providing access to
technically defensible tools and approaches that can be used
in the development of TMDLs, waste load allocations and
watershed protection plans. Contact information for the
Center is given below.
Where can I access the Toolbox and
training materials?
A website for distribution of the Toolbox modules is supported
by EPA. It includes all models and tools, as well as documen-
tation and installation instructions. The Toolbox Website is
http://www.epa.gov/athens/wwqtsc/index.html. For additional
inquiries and information please contact:
Tim A.Wool
Watershed and Water Quality Modeling
Technical Support Center
U.S.EPA-NERL
960 College Station Road
Athens, GA 30605
(404) 562-9260
Wool.Tim@epa.gov
United States
Environmental Protection
Agency
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