PennWell previews TMDL text for June release

March 11, 2005
As part of a planned book release in June, PennWell Books offers an excerpt of Total Maximum Daily Load: Approaches & Challenges, now available for pre-orders. Edited by Virginia Polytech's Tamim Younos, TMDL presents concepts, approaches, case studies, and applications of the cutting-edge technologies used to develop and implement an effective and innovative TMDL program...

TULSA, OK, March 15, 2005 -- As part of a planned book release in June, PennWell Books offered the following excerpt from Chapter 2 of Total Maximum Daily Load: Approaches & Challenges, now available for pre-orders at or

Edited by Tamim Younos, Interim Director of the Virginia Water Resources Research Center and a Senior Research Scientist at Virginia Polytechnic Institute and State University, TMDL presents concepts, approaches, case studies, and applications of the cutting-edge technologies used to develop and implement an effective and innovative TMDL program. Case studies discussed in this book mostly focus on three major causes of water impairment in the United States: bacteria, sediments, and nutrients.

TMDL has nine chapters written by experts who have significant knowledge and experience on issues related to the TMDL program:
-- Chapters 1-3 introduce the readers to TMDL regulations, approaches, and stakeholder involvement.
-- Chapters 4-6 provide an overview of unique case studies and strategies.
-- Chapters 7-9 go beyond the traditional TMDL approach and discuss innovative and alternative approaches, i.e. effluent trading, adaptive management, and use attainability analysis.

Read on for an excerpt from Chapter 2...

Chapter 2: TMDL Development Approaches
By Bethany T. Neilson, David K. Stevens, Jeffery S. Horsburgh
Utah Water Research Laboratory, Utah State University

Every total maximum daily load (TMDL) project is unique. The variety in pollutants, pollutant sources, water body conditions, geographic and climatic conditions, and stakeholder needs ensure that this is the case. This variety encountered in developing TMDLs in watersheds throughout the United States has forced the TMDL community to build a suite of development approaches, including mathematical modeling and data centric approaches, to address the unique conditions encountered with each TMDL study.

The following list identifies many elements of a successful TMDL:
1. An accurate and consistent listing process (Section 303(d), "List of Impaired Waters")
2. Required data gathering for TMDL development
3. Public participation to ensure public awareness and buy-in
4. An appropriate TMDL development approach to describe and link pollutant sources with the water quality impairment
5. Implementation of management practices to reduce loadings and improve water quality
6. Adaptive management that includes monitoring and allows for changes in management practices if instream water quality standards are not met with new load allocations

This book discusses each of these elements in detail. This chapter focuses on Step 4, TMDL development approaches. TMDL development approaches vary from U.S. Environmental Protection Agency (EPA) region to region, state to state, and watershed to watershed. This variability causes confusion for TMDL developers when deciding which approach best suits a specific TMDL problem. This chapter summarizes typical approaches in each EPA region and provides information on typical TMDL approaches and choosing a suitable one.

Basis for Variability in TMDL Development Approaches
The final arbiter of acceptance of the approach(es) used by TMDL developers is the EPA regional TMDL coordinator who approves each TMDL petition. Though all regions have similar underlying requirements, differences in approaches are, in many respects, necessary artifacts of the TMDL program. The spectrum of problems encountered and the variety of circumstances regulators face dictate deliberate flexibility in TMDL regulations. This flexibility has led to the appearance of inconsistencies within the program, sometimes frustrating those in the trenches developing TMDLs. Neilson interviewed EPA regional TMDL coordinators and other key personnel to clarify the following key driving forces behind the variation in the TMDL approaches by region.i

Federal guidance for TMDL development
EPA headquarters' perspective on many issues in TMDL development is similar to that in other environmental legislation: with time, the program will evolve and the rough spots will smooth. Houck expressed this approach to environmental law best, stating, "Environmental law is a continuing experiment, and one ingredient of its success has been its tendency to throw several approaches at a problem and test their survival."ii With this backdrop, although some guidance comes from the federal level, each region's style evolves through meeting the unique needs of the states under its purview.

Factors in regional selection of approaches
TMDL programs in the 10 EPA regions have developed independently due, in part, to differing factors driving TMDL development such as priorities, resources, and, unfortunately, litigation. As the TMDL program has grown since the mid-1990s, EPA regions each developed local criteria and methods in the absence of specific protocols from headquarters.iii The result that regions have differing degrees and types of experience in the program and differing regional expectations is, therefore, not surprising.
Factors contributing to regional differences in the TMDL program are primarily state-focused and include the following:
1. State programs that affect the consistency of the TMDL program
2. State resource availability
3. Technical constraints
4. Litigation
5. Regional considerations in the selection of TMDL development approaches.

State programs that affect TMDL development
State water quality-related programs compound regional and national differences in the TMDL program. Although EPA provides national minimum water quality guidelines and is required to review and approve all state standards, water quality standards are established by each state independently. Narrative standards without fixed numerical criteria are often used for sediment and nutrients (particularly phosphorus), which are the No. 1 and 4 listed parameters nationally requiring TMDL development.iv When narrative standards are used, interpretation of those standards for determining loadings is challenging.

Related to the standards problem is the regional interpretation of a water quality standard exceedance. The Commonwealth of Puerto Rico offers one example: Ammonia concentrations in streams exceed the EPA guidelines by several orders of magnitude.v However, aquatic species thrive, apparently by virtue of elevated ammonia tolerance, calling the relevance of those guidelines into question in that situation. Similar awkwardness exists when natural concentrations violate standards, such as naturally low dissolved oxygen concentrations in marshes and

Since environmental groups and point and nonpoint source interests challenged them, the criteria for development of the Section 303(d) list have been the source of much debate. Some water bodies make the list because there are large amounts of data that demonstrate obvious water quality impairment. Some clearly impaired water bodies are not listed due to the lack of data while others were listed by mere drive-by water quality assessments. The most likely reason for inconsistencies in development of the Section 303(d) list is that detailed assessments are costly and states' resources are limited.

Limited resources and TMDLs
The issue of limited resources is prevalent from the EPA headquarters down to the state programs. The most pertinent resources are money, staff, and expertise, particularly related to water quality modeling. Each EPA region is provided with fixed resources from which to distribute a minimum amount consistently among their respective states for the purpose of TMDL development. Within each EPA region, the number of states, the number of Section 303(d) listed segments, variability in emphasis on environmental protection, and local political support, all further complicate the amount of resources available for any given TMDL study.

As an example, states in EPA Regions 1-3 (U.S. northeast) often have funds for data collection and modeling efforts in addition to those directly from the EPA regions. The added revenue comes from local dischargers who have a vested interest in equitable load allocations because treatment costs can run high. These states also have more organizations whose primary focus is protecting the environment because of high population density and the recognition of pollution problems that have existed for many years. These organizations (for example, environmental interest groups and watershed advisory groups) are often willing to support data collection financially or with volunteers.

i. Neilson, B. T. and D. K. Stevens. "Issues Related to the Success of the TMDL Program." T. Younos, ed., Water Resources Update, 122 (2002), Carbondale, IL Universities Council on Water Resources, 55-61.
ii. Houck, O. A. "TMDLs III: A New Framework for the Clean Water Act's Ambient Standards Program." ELR News and Analysis, 28 (1998): 10415-10443.
iii. State of Idaho Guidance for Development of Total Maximum Daily Loads. Boise, ID: Idaho Department of Environmental Quality, Idaho Division of Environmental Quality, 1999.
iv. U.S. Environmental Protection Agency (USEPA). National Section 303(d) List Fact Sheet. 2003. January 16, 2004,
v. Neilson and Stevens, 2002.
vi. Vellidis, G., M. Smith, A. Milton, and R. Lowrance. "Establishing the Natural Range of Dissolved Oxygen Levels in Streams of the Southern Coastal Plain of Georgia." Proc. Total Maximum Daily Load: Environmental Regulations. Albuquerque, NM, Nov. 8-12, 2003.


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