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Water: Total Maximum Daily Loads (303d)

Technical Support Documents

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Draft Considerations for Revising and Withdrawing TMDLs (PDF) (16 pp, 189K)
The Draft Considerations for Revising and Withdrawing TMDLsidentifies circumstances involving withdrawing a TMDL or revising and re-submitting a TMDL to EPA, as well as those situations that would not be considered TMDL revisions. With over 46,000 approved TMDLs to date, the circumstances where a TMDL was developed and approved may have changed over time, and therefore, states may wish to revisit the original TMDL. EPA recognizes that states need to consider both the resources needed to revise TMDLs, as well as the resources needed to develop new TMDLs and implement existing TMDLs.
Please provide comments by May 7, 2012. Comments and questions on this draft document should be sent to Ruth Chemerys (chemerys.ruth@epa.gov).


Draft Considerations for the Development of Multijurisdictional TMDLs (PDF) (12 pp, 96K)
The Draft Considerations for the Development of Multijurisdictional TMDLs is intended to provide key considerations for TMDL practitioners concerning challenges specific to the development of multijurisdictional TMDLs. These types of TMDLs often involve multiple states and/or authorized tribes, span more than one EPA Region, and present a different set of practical challenges to TMDL development. Such challenges include assumptions about pollutant loadings at jurisdictional boundaries, targeting multiple water quality standards, determining appropriate assignment of wasteload allocations, and coordinating TMDL schedules and goals across multiple jurisdictions.
Please provide comments by May 7, 2012. Comments and questions on this draft document should be sent to Michael Haire (haire.michael@epa.gov).

Technical Guidance for Developing TMDL

PCB TMDL Handbook (PDF) (33 pp, 262K), December 2011.
The Polychlorinated Biphenyl (PCB) Total Maximum Daily Load (TMDL) Handbook provides EPA Regions, states, and other stakeholders with a compendium of updated information for addressing Clean Water Act section 303(d) waters impaired by PCBs.  This handbook identifies various approaches to developing PCB TMDLs and provides examples of TMDLs from around the country, complete with Web references.  It aims to help states complete more PCB TMDLs, and ultimately restore those waters impaired by PCBs.

Fact Sheet: PCB TMDL Handbook (PDF) (3 pp, 57K) December 2011.

Following are fact sheets summarizing examples of approved PCB TMDLs:


Draft Handbook for Developing Watershed TMDLs (PDF) (168 pp, 4.2MB), December 2008. The Draft Handbook for Developing Watershed TMDLs discusses the potential environmental, financial, and implementation benefits of developing TMDLs on a watershed scale, and provides practitioners with a series of screening factors that should help determine, based on pollutant type, waterbody type, data quality, and other considerations, the site specific suitability of the TMDL watershed approach. Additionally, the Draft Handbook highlights the connections between watershed TMDLs and other water programs, identifying opportunities for integrating watershed TMDLs into other similar water quality management efforts, such as watershed planning, permitting, and water quality trading.

Public comments on this draft report are due by February 18, 2009. Comments and questions on this draft document should be sent to Michael Haire (haire.michael@epa.gov).

TMDLs to Stormwater Permits Draft Handbook (PDF) (200 pp, 5.7MB), November 2008. Currently there are thousands of Clean Water Act section 303(d) waters listed as impaired for stormwater-source pollutants such as pathogens, nutrients, sediments and metals.   This Draft Handbook provides a technical reference for TMDL practitioners and permit writers on current methods being used to develop more detailed stormwater-source TMDL allocations, TMDL implementation plans including best management practices, and methods for translating TMDL allocations into NPDES stormwater permit requirements.

Atmospheric Mercury Deposition Project for Watershed Planning
The Atmospheric Mercury Deposition Project for Watershed Planning contains the results of a fine, 12-km grid cell modeling analysis for the lower 48 States. In this project, roughly 300 of the top mercury emitters in the US were "tagged" in order to allow source attribution analysis for individual areas of concern, such as waterbodies, watersheds, or catchments.
Fact Sheet: Model-based Analysis and Tracking of Airborne Mercury Emissions to Assist in Watershed Planning Report (PDF) (2 pp, 38K)
Model-based Analysis and Tracking of Airborne Mercury Emissions to Assist in Watershed Planning Report (PDF) (350 pp, 9.6MB) , August 2008

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, 971K) , 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) (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 Exit EPA Disclaimer
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:

Allocating Loads and Waste Loads

Web site provides information on watershed modeling frameworks which may be used to help evaluate the tradeoffs associated with different allocations. These frameworks are capable of identifying cost minimizing allocations and comparing cost distributions across stakeholders under different allocation scenarios. This web site demonstrates such a cost-minimization framework and provides examples of load allocations and cost distributions for a case study watershed.

EPA Office of Science and Technology Publications on Water Quality and Developing Total Maximum Daily Loads

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