Technical Support Documents
An Approach for Using Load Duration Curves in the Development of TMDLs (PDF) (74 pp, 3.4MB), August 2007, EPA 841-B-07-006
This guide provides an overview on the use of duration curves for developing Total Maximum Daily Loads (TMDLs). It is written for TMDL practitioners who are familiar with relevant technical approaches and legal requirements. The guide describes basic steps needed to develop duration curves, which identify loading capacities, load and waste load allocations, margins of safety, and seasonal variations. The guide also discusses some considerations and limitations in using the approach, and includes several case examples.
Total Maximum Daily Loads with Stormwater Sources: A Summary of 17 TMDLs (PDF) (59 pp, 601K), July 2007, EPA 841-R-07-002
This report summarizes 17 TMDLs that have been developed for stormwater sources in 16 states throughout the country during the past eight years. They represent a range of pollutants, models used, and different allocation and implementation methods that will be helpful to TMDL practitioners and NPDES permitting agencies and permittees as they develop and implement new stormwater source TMDLs.
Draft Options for the Expression of Daily Loads in TMDLs (PDF),
(62 pp, 971 KB), June 2007
This technical document provides technically sound options for developing daily load expressions as a routine process in
TMDLs calculated using allocation time frames greater than daily (e.g., annual, monthly, seasonally). The document is
written for TMDL practitioners who are familiar with the relevant technical approach and regulatory requirements pertaining
to TMDLs.
Water Quality Trading Assessment Handbook, EPA 841-B-04-001, Nov. 2004,
This handbook provides an analytical framework to assess the conditions and water quality problem(s) in any
specific watershed and determine whether water quality trading (WQT) could be effectively used. The framework
is illustrated through the use of example trades in a hypothetical river basin which helps familiarize the reader
with the requisites and potential benefits of specific trading scenarios. The handbook is useful reading for
anyone who wants to learn more about WQT.
The Twenty Needs Report: How Research Can Improve the
TMDL Program (PDF) (PDF, 56 pp, 1.1 MB) July 2002, EPA841-B-02-002
This report is a synthesis of the main research recommendations identified in many recent studies of TMDL science needs and
research opportunities, prepared as an aid to research planning. The author developed this report in cooperation with EPA
research laboratories while studying TMDL-related research within EPA, but the content of the report is useful to persons
involved in water quality research in general.
Stressor Identification Guidance,
Dec. 2000, EPA 822-F-00-012
This guidance leads water resource managers through a rigorous process to identify stressors that cause biological
impairment in aquatic ecosystems and to assemble cogent scientific evidence that supports conclusions about potential causes.
Evaluation of Sediment Transport Data for Clean Sediment TMDLs (PDF)
(62 pp, 1.3MB), Nov. 2000
This report was prepared by the National Sedimentation Laboratory of USDA's Agricultural Research Service with
funding provided by USEPA's HQ Watershed Branch. The report provides a methodology to evaluate whether a stream
or river is impaired due to clean sediment. While this methodology shows promise in the coastal plains province
of the country, it needs to be further developed and tested in other provinces of the country to establish its generality.
Protocol for Developing Pathogen TMDLs: First Edition (PDF) (134 pp, 2MB), Jan. 2001, EPA 841-R-00-0002
Protocol for Developing Nutrient TMDLs (PDF) (137 pp, 2.5MB), November 1999, First Edition, EPA 841-B-99-007
Protocol for Developing Sediment TMDLs (PDF) (143 pp, 1.7MB), October 1999, First Edition, EPA 841-B-99-004
Compendium of Tools for Watershed Assessment and TMDL Development, 1997, EPA841-B-97-006
Other Web sites and Publications
Watershed and Water Quality Modeling Technical Support Center Web site
The Watershed and Water Quality Modeling Technical Support Center provides assistance to EPA Regions, State and Local Governments, and their contractors in the implementation of the Clean Water Act. The Center which is part of EPA's Office of Research and Development (ORD) is provides access to technically defensible tools and approaches that can be used in the development of Total Maximum Daily Loads (TMDL), waste load allocations, and watershed protection plans.
Following are two factsheets re. the Center and its tools:
- TMDL Modeling ToolBox Fact Sheet (PDF) (2 pp, 697K)
- Watershed and Water Quality Modeling Technical Support Center Fact Sheet (PDF) (2 pp, 734K)