Chapter 3. Establishing and Implementing TMDLs

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

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The purpose of this chapter is to provide guidance on establishing and implementing TMDLs. The chapter summarizes the minimum elements of a TMDL submittal and provides guidance on strategies for conducting the technical analyses on which TMDLs and their maximum allowable pollutant loads are based. Documentation of decision-making during the TMDL establishment process is emphasized. States, Territories, and authorized Tribes are also encouraged to develop an implementation strategy that stresses tracking specific, appropriate measures; achieving carefully selected milestones; and providing for timely intervention actions if a TMDL is not meeting expectations.

3.1 What is a TMDL?

A total maximum daily load (TMDL) is a written plan and analysis established to ensure that a waterbody will attain and maintain water quality standards including consideration of existing pollutant loads and reasonably foreseeable increases in pollutant loads. It is intended to provide an opportunity to compare relative contributions from all sources and consider technical and economic trade-offs between point and nonpoint sources. A TMDL must be established for each waterbody and pollutant combination on Part 1 of your list of impaired or threatened waterbodies.

The goal of a TMDL is to allocate pollutant loads and (through its implementation plan) define a set of actions such that water quality standards will be achieved. The resulting allocation should also be feasible to implement. In cases with limited data, it is recommended that States, Territories, and authorized Tribes proceed with establishing a TMDL, collect and interpret additional data, and track progress toward the goal of meeting water quality standards. The conditions under which a TMDL would be revised should be clearly articulated in the implementation portion of the TMDL submittal.

The TMDL process is an essential element of the water quality-based approach to watershed management. It develops the pollution reduction needed to meet water quality standards and then links the development and implementation of control measures to the attainment of water quality standards. Through the establishment and implementation of a TMDL; pollutant loadings from all sources are estimated; links are established between pollutants, sources, and impacts on water quality; maximum pollutant loads are allocated to each source; and appropriate control mechanisms are established or modified so that water quality standards can be achieved.

Within each TMDL is a carefully identified maximum allowable pollutant load or loads needed to meet water quality standards for defined critical conditions. This is the maximum amount of a pollutant that may be contributed to a waterbody so that it attains and maintains water quality standards. The TMDL may vary with time or the specific location and distribution of the pollutant sources, therefore, it is necessary to determine the waterbody's critical conditions or periods for which the TMDL or TMDLs are developed. The maximum allowable pollutant load is distributed to the wasteload allocations for point sources, load allocations for nonpoint sources, a margin of safety sufficient to account for uncertainty and lack of knowledge, consideration of seasonal variation, and allowances for future growth.

Summary of Statutory and Regulatory Requirements for Establishing TMDLs

A TMDL must be established for all waterbody and pollutant combinations on Part 1 of the list. TMDLs are not required for waterbodies on Part 2, 3, or 4 of the list (§ 130.31(a)).

A TMDL must be established according to the priority rankings and schedules (§ 130.31(b)).

TMDLs must be established at a level necessary to attain and maintain water quality standards, as defined by 40 CFR 131.3(I), considering reasonably foreseeable increases in pollutant loads (§ 130.33(b)(9)).

TMDLs must include the following minimum elements (§ 130.33(b)):

1. The name and geographic location, as required by §130.27(c), of the impaired or threatened waterbody for which the TMDL is being established and the names and geographic locations of the waterbodies upstream of the impaired waterbody that contribute significant amounts of the pollutant for which the TMDL is being established;
2. Identification of the pollutant for which the TMDL is being established and quantification of the pollutant load that may be present in the waterbody and still ensure attainment and maintenance of water quality standards;
3. Identification of the amount or degree by which the current pollutant load in the waterbody deviates from the pollutant load needed to attain or maintain water quality standards;
4. Identification of the source categories, source subcategories, or individual sources of the pollutant for which the wasteload allocations and load allocations are being established consistent with § 130.2(f) and § 130.2(g);
5. Wasteload allocations to each industrial and municipal point source permitted under § 402 of the Clean Water Act discharging the pollutant for which the TMDL is being established ; wasteload allocations for storm water, combined sewer overflows, abandoned mines, combined animal feeding operations, or any other discharges subject to a general permit may be allocated to categories of sources, subcategories of sources or individual sources; pollutant loads that do not need to be allocated to attain or maintain water quality standards may be included within a category of sources, subcategory of sources or considered as part of background loads; and supporting technical analyses demonstrating that wasteload allocations when implemented, will attain and maintain water quality standards;
6. Load allocations, ranging from reasonable accurate estimates to gross allotments, to nonpoint sources of a pollutant, including atmospheric deposition or natural background sources; if possible, a separate load allocation must be allocated to each source of natural background or atmospheric deposition; load allocations may be allocated to categories of sources, subcategories of sources or individual sources; pollutant loads that do not need to be allocated may be included within a category of sources, subcategory of sources or considered as part of background loads; and supporting technical analyses demonstrating that load allocations, when implemented, will attain and maintain water quality standards;
7. A margin of safety expressed as unallocated assimilative capacity or conservative analytical assumptions used in establishing the TMDL; e.g., derivation of numeric targets, modeling assumptions, or effectiveness of proposed management actions which ensures attainment and maintenance of water quality standards for the allocated pollutant;
8. Consideration of seasonal variation such that water quality standards for the allocated pollutant will be met during all seasons of the year;
9. An allowance for future growth which accounts for reasonably foreseeable increases in pollutant loads; and
10. An implementation plan

As appropriate to the characteristics of the waterbody and pollutant, the maximum allowable pollutant load may be expressed as daily, monthly, seasonal or annual averages in one or more of the following ways (40 CFR&nb130.34(b)):

• The pollutant load that can be present in the waterbody and ensure that it attains and maintains water quality standards;
• The reduction from current pollutant loads required to attain and maintain water quality standards;
• The pollutant load or reduction of pollutant load required to attain and maintain riparian, biological, channel or geomorphological measures so that water quality standards are attained and maintained; or
• The pollutant load or reduction of pollutant load that results from modifying a characteristic of the waterbody, e.g., riparian, biological, channel, geomorphological, or chemical characteristics, so that water quality standards are attained and maintained.

The TMDL implementation plan must include the following (§ 130.33(b)(10)):

• A description of the control actions and/or management measures which will be implemented to achieve the wasteload allocations and load allocations, and a demonstration that the control actions and/or management measures are expected to achieve the required pollutant loads;
• A time line, including interim milestones, for implementing the control actions and/or management measures, including when source-specific activities will be undertaken for categories and subcategories of individual sources and a schedule for revising NPDES permits;
• A discussion of your reasonable assurances, as defined at 40 CFR § 130.2(p), that wasteload allocations and load allocations will be implemented;
• A description of the legal under which the control actions will be carried out;
• An estimate of the time required to attain and maintain water quality standards and discussion of the basis for that estimate;
• A monitoring and/or modeling plan designed to determine the effectiveness of the control actions and/or management measures and whether allocations are being met;
• A description of measurable, incremental milestones for the pollutant for which the TMDL is being established for determining whether the control actions and/or management measures are being implemented and whether water quality standards are being attained; and
• A description of your process for revising TMDLs if the milestones are not being met and projected progress toward attaining water quality standards is not demonstrated.

Previously, EPA did not distinguish between a TMDL and its maximum allowable pollutant load. A TMDL itself was defined as the amount of a pollutant or pollutants that can be present in a waterbody and still attain and maintain water quality standards and was considered to be equal to or less than the loading capacity or assimilative capacity of the waterbody for that pollutant. In the 1999 Regulation, the definition of "TMDL" is expanded to encompass the entire submittal package, including the ten required elements listed below. The term " maximum allowable pollutant load" is introduced as the amount of pollutant or pollutants that can be present in a waterbody such that it attains and maintains water quality standards.

3.1a Required Elements of the TMDL Submittal

EPA will only approve TMDL submittals that include the ten elements listed below:

1. The name and geographic location, as required by §130.27(c), of the impaired or threatened waterbody for which the TMDL is being established and the names and geographic locations of the waterbodies upstream of the impaired waterbody that contribute significant amounts of the pollutant for which the TMDL is being established (40 CFR 130.33(b)(1)).
2. Identification of the pollutant for which the TMDL is being established and quantification of the maximum pollutant load that may be present in the waterbody and still ensure attainment and maintenance of water quality standards (40 CFR 130.33(b)(2)).
3. Identification of the amount or degree by which the current pollutant load in the waterbody deviates from the pollutant load needed to attain or maintain water quality standards (40 CFR 130.33(b)(3)).
4. Identification of the source categories, source subcategories, or individual sources of the pollutant for which the wasteload allocations and load allocations are being established consistent with § 130.2(f) and § 130.2(g) (40 CFR 130.33(b)(4)).
5. Wasteload allocations to each industrial and municipal point source permitted under § 402 of the Clean Water Act discharging the pollutant for which the TMDL is being established ; wasteload allocations for storm water, combined sewer overflows, abandoned mines, combined animal feeding operations, or any other discharges subject to a general permit may be allocated to categories of sources, subcategories of sources or individual sources; pollutant loads that do not need to be allocated to attain or maintain water quality standards may be included within a category of sources, subcategory of sources or considered as part of background loads; and supporting technical analyses demonstrating that wasteload allocations when implemented, will attain and maintain water quality standards (40 CFR 130.33(b)(5)).
6. Load allocations to nonpoint sources of a pollutant, including atmospheric deposition or natural background sources. If possible, a separate load allocation must be allocated to each source of natural background or atmospheric deposition; load allocations may be allocated to categories of sources, subcategories of sources or individual sources. Pollutant loads that do not need to be allocated may be included within a category of sources, subcategory of sources or considered as part of the background load. supporting technical analyses must demonstrate that load allocations, when implemented, will attain and maintain water quality standards (40 CFR 130.33(b)(6)).
7. A margin of safety expressed as unallocated assimilative capacity or conservative analytical assumptions used in establishing the TMDL; e.g., derivation of numeric targets, modeling assumptions, or effectiveness of proposed management actions which ensures attainment and maintenance of water quality standards for the allocated pollutant (40 CFR 130.33(b)(7)).
8. Consideration of seasonal variation and high and low flow conditions such that water quality standards for the allocated pollutant will be met during all seasons of the year and during all design flow conditions (40 CFR 130.33(b)(8)).
9. An allowance for future growth which accounts for reasonably foreseeable increases in pollutant loads (40 CFR 130.33(b)(9)).
10. An implementation plan, which may be developed for one or a group of TMDLs (40 CFR 130.33(b)(10)).

3.1b Quantifying the Allowable Pollutant Load

A waterbody's allowable pollutant load contains wasteload allocations for point sources, load allocations for nonpoint sources, a margin of safety (MOS) sufficient to account for uncertainty and lack of knowledge, and an allowance for future growth. The allowable pollutant load must ensure that the waterbody will attain and maintain water quality standards regardless of seasonal variations or design flow conditions and in consideration of reasonably foreseeable increases in pollutant loads. The illustration below shows how the allowable pollutant load is the total of these components.

Allowable Pollutant Load = Wasteload Allocation + Load Allocation + (MOS) + (Future Growth)

The components making up the allowable pollutant load have a place within the overall TMDL strategy, but the relationship is likely to be more complex than a simple equation would imply. For example, the pollutant from individual pollutant sources may decay or transform in the process of transport to a waterbody. The MOS is in parentheses because it might not always be a separate component of the allowable pollutant load, but might instead be included as part of the wasteload allocations and load allocations through conservative assumptions. Future growth is also in parentheses because the maximum allowable pollutant load may allow for future growth by including a separate allocation for this purpose or by allocating acceptable wasteloads and loads in a way that incorporates potential growth.

TMDLs must contain an expression of the allowable pollutant load as a load or reduction of load necessary to ensure that the waterbody will attain and maintain water quality standards, including aquatic or riparian habitat, biological, channel or geomorphological or other conditions that represent attainment and maintenance of water quality standards (§ 130.34(a)).

The terms used to express a TMDL and its allowable pollutant load may be adapted to be appropriate to the characteristics of the waterbody and pollutant for which the TMDL is being established. These terms include, but are not limited to, (1) The pollutant load that can be present in the waterbody and ensure that it attains and maintains water quality standards; (2) The reduction from current pollutant loads required to attain and maintain water quality standards; (3) The pollutant load or reduction of pollutant load required to attain and maintain riparian, biological, channel or geomorphological measures so that water quality standards are attained and maintained; or (4) The pollutant load or reduction of pollutant load that results from modifying a characteristic of the waterbody, e.g., riparian, biological, channel, geomorphological, or chemical characteristics, so that water quality standards are attained and maintained (§ 130.34(b)).

The allowable pollutant load, in whatever way it is expressed, may be allocated in many ways, allowing for trade-offs among sources. However, It is critical that all sources of a pollutant be accounted for in computing the load capacity. If a receiving water has only one point source discharger, the allowable pollutant load is the sum of that point source's wasteload allocation plus the load allocations for any nonpoint sources of pollution and natural background sources, tributaries, or adjacent segments, plus an MOS. If point sources do not have the reasonable potential to cause or contribute to the impairment or threat to the waterbody, the allowable portion of the overall load to point source dischargers would be their existing permitted load. Similarly, if nonpoint sources are not causing or contributing to the impairment or threat to the waterbody, the allowable portion of the overall load to nonpoint sources for that waterbody would be their existing nonpoint load of the pollutant. Depending upon the specific pollutant, there may be a load allocation to account for natural background sources. In most cases, wasteload allocations and load allocations may be established for categories of sources, subcategories of sources, or individual sources. Wasteload allocations may be increased if there are reasonable assurances that loads from nonpoint sources will be similarly reduced, and water quality standards will be attained.

Some minor or remotely located point and nonpoint sources may be treated as background as long as the actual allocations to specific sources will result in the attainment or maintenance of water quality standards. Documentation that supports the technical validity of the relationship among the components of the allowable pollutant load must be submitted with the TMDL documentation.

3.1c Wasteload Allocations

A wasteload allocation is defined at 40 CFR 130.2(g) as the portion of a TMDL's pollutant load allocated to a point source of a pollutant. Wasteload allocations for industrial and municipal point source facilities permitted under section 402 of the Clean Water Act must be allocated to individual point sources of the pollutant that need to be controlled to attain and maintain water quality standards. (See Appendix B for a list of point source categories used by the Permit Compliance System.) Pollutant loads that do not need to be reduced to attain or maintain water quality standards can be included within a category of sources, a subcategory of sources, or considered as part of background loads.

Industrial and municipal point source facilities with individual NPDES permits must receive individual wasteload allocations. Wasteload allocations for point source discharges subject to a general permit may be allocated to the category of sources subject to the general permit, a subcategory of those sources, or the individual sources. The nature of the wasteload allocation also depends upon the type of point source. Relatively continuous discharges (dry and wet weather) or controlled batch discharges may receive a numeric wasteload allocation that can be translated into a numeric water quality-based effluent limit (see Technical Support Document). The quality and quantity of non-continuous discharges (e.g., storm water, combined sewer overflows) tend to be episodic and more difficult to model and predict. Initial wasteload allocations for these sources may be narrative and subsequently be revised to incorporate numeric requirements as information and models for the waterbody system are refined to account for wet weather and episodic events.

3.1d Load Allocations

A load allocation is defined at 40 CFR 130.2(f) as the portion of a TMDL's pollutant load allocated to nonpoint sources of a pollutant, including atmospheric deposition or natural background sources. Load allocations are best estimates of the loading, which may range from reasonably accurate estimates to gross allotments, depending on the availability of data and appropriate techniques for predicting the loadings. Natural background sources, atmospheric deposition, and nonpoint source loads should be distinguished. Load allocations may be allocated to categories of sources, subcategories of sources, or individual sources. Load allocations must be reflected in the implementation plan.

Like wasteload allocations, load allocations are ultimately estimates of pollutant loading that take into account temporal fluctuations. It is often necessary to recognize that nonpoint source pollutant loading estimates will vary depending on hydrologic conditions and human activities.

Clean sediment loads from a watershed, for example, can often vary significantly from year to year depending on whether the year is relatively "wet" or "dry." Similarly, bacterial or nutrient runoff associated with applied poultry litter is likely to vary significantly within a year depending on when the litter is applied and rainfall events occur. When a range of values is identified to represent a nonpoint source load, the most appropriate value in the range should be designated as the load allocation. The most appropriate value will be the one that is protective of water quality during those periods when water quality problems would be expected to occur (e.g., during warm weather conditions). The selection should account for seasonal variation and be protective of the waterbody when water quality problems occur (e.g., during the growing season or during ice-out) and must ensure that at any given time the allocation will attain the water quality standard. In some cases it might be appropriate to select different load allocations for different seasons of the year.

Care should be taken in considering the potential cumulative impacts from source loading on the receiving waters. In some cases loading throughout the year has an impact that is manifested only when the appropriate conditions occur. For example, metals from various sources are accumulated throughout the year in the bottom sediments of the receiving water. Under certain flow conditions resuspension of the sediment and associated metals may result in a violation of water quality standards.

3.1e Margin of Safety

The margin of safety (MOS) is a required component of a TMDL's maximum allowable pollutant load that accounts for uncertainty about pollutant loadings and waterbody response. The allowable pollutant load for each TMDL must include an MOS sufficient to account for uncertainties in establishing the TMDL and describe the manner in which an MOS is provided. The MOS may be established by leaving a portion of the assimilative capacity unallocated or by use of conservative analytical assumptions to account for the uncertainties in establishing the TMDL (e.g., derivation of numeric targets, modeling assumptions, or effectiveness of proposed management actions). If a separate allocation of a capacity is set aside to provide an MOS, the amount of such allocation should be described. If protective assumptions are relied on to provide an MOS, the specific areas of the analysis that accommodate the MOS should be identified.

3.2 The Process for Establishing a TMDL

TMDL establishment is a process during which each of the discrete TMDL submittal elements will be developed. Figure 3-1 describes the relationship between the elements of a TMDL submittal and the steps of the TMDL establishment process. The following steps are identified as the process for establishing TMDLs:

• Name and geographic location
• Problem identification
• Target analysis
• Source identification and assessment
• Linkage of the source and target
• Allocating pollutant loads
• Implementation and monitoring plan development

The sections below describe this process in greater detail and provide guidance about how to approach the most difficult steps of the TMDL process.

3.2a Name and Geographic Location of Waterbody

The first step in the technical approach for establishing a TMDL is to specify the specific name and geographic location of the threatened or impaired waterbody (40CFR 130.33(b)(1)). EPA Reach File Version 3 (RF3) forms the basis for linking the 303(d) ID to geographic information. RF3 is a national hydrologic database that uniquely identifies and interconnects more than three million stream segments or "reaches" that compose the nation's surface water drainage system. RF3 was created from digital hydrography data produced by USGS. EPA enhanced these datasets by assigning a unique reach code to each stream segment, determining the upstream/downstream relationships of each reach, and, when possible, identifying the stream name for each reach. States, Territories and authorized Tribes may either develop their own GIS coverages/shape files of their threatened and impaired waterbodies and submit them to EPA with their 303(d) lists, or adopt the standardized approach (preferred by EPA) of georeferenceing their waterbodies to RF3.

3.2b Problem Identification

The second step in the technical approach for establishing a TMDL is to identify the problem. Problem identification highlights and clarifies the key factors and background information for a listed waterbody and pollutant combination, and describes the nature of the impairment and the context for the TMDL. This step can be the key to successfully developing a strategy for completing the remaining components of the TMDL process.

When developing a TMDL, it is necessary to formulate a strategy that addresses the causes and potential sources of the water quality impairment and available management options. The characterization of the causes and sources should be an extension of the process originally used to place the waterbody and pollutant combination on the section § 303(d) list. Typically, the impairment or threat that resulted in the listing will be related to water quality standards that are being violated--either pollutant concentrations that exceed numeric criteria or waterbody conditions that do not match those specified by narrative criteria. In many cases, the problem itself will be self-evident and its identification will be relatively straightforward. In other cases, the complexity of the system might make it more difficult to definitively state the relationship between the sources and impairment.

EPA suggests that a number of specific questions be addressed during this initial strategy-forming stage. (See the box below.) Answering these questions will help define an approach for establishing the TMDL. Developing a clear, concise problem statement based on the problem identification analysis will describe the setting addressed by the TMDL, making the TMDL more understandable for public participation activities and useful for implementation planning.

Key Questions to Consider When Identifying the Problem

• What are the designated or existing uses and associated impairments?
• What was the violation of water quality standards that caused the listing of the waterbody and pollutant combination? What data support the listing of the waterbody as impaired or threatened?
• What pollutant is preventing the attainment of designated uses?
• What are the known and potential sources of the pollutant and what are the pathways it might take to reach the waterbody? What are the upstream contributions?
• What characteristics of the waterbody or its watershed might be exacerbating or mitigating the problem?
• What data are readily available? What is the geographic setting of the TMDL?
• What temporal considerations will affect development of the TMDL?
• How will margin of safety and uncertainty issues be addressed in the maximum allowable pollutant load?
• What efforts to protect the watershed are already under way?
• What are some potential control options?

3.2c Target Analysis

Target analysis is the third component of the technical approach for establishing TMDLs. From a broad management perspective, the purpose of target analysis is to define the relationship between designated uses, numeric measure(s) of success, and pollutant loading. The primary goals of target analysis are (1) to clarify whether the ultimate goal of the TMDL is to comply with a numeric water quality criterion, comply with an interpretation of a narrative water quality criterion, or attain a desired condition that supports meeting a specified designated use; (2) to identify the waterbody's critical conditions; (3) to identify appropriate ways to measure (track) progress toward achieving stated goals; and (4) to tie the measures to pollutant loading.

Identification of the maximum allowable pollutant load is one required element of an approvable TMDL. It must be expressed in a manner that will ensure the waterbody will attain and maintain water quality standards or some desired condition—expressed as aquatic or riparian habitat, biological, channel, geomorphological, or other condition—that represents attainment and maintenance of water quality standards (40 CFR 130.34(a)).

This section suggests using a simple three-point strategy for conducting a target analysis for TMDLs:

1. How does the designated use relate to the allowable pollutant load?

States, Territories, and authorized Tribes begin to answer this question during § 303(d) listing and the problem identification step in the TMDL establishment process. To be put on Part 1 of the § 303(d) list, a waterbody and pollutant combination is identified and, usually, the designated use that is impaired by the pollutant is evident.

The waterbody and pollutant combination for which a TMDL is established affects how the maximum allowable pollutant load is expressed, as well as its relationship to other relevant targets. The problem statement developed during problem identification is often the best place to begin explaining how the maximum allowable pollutant load and various targets and measures interrelate. For example, excessive phosphorus might make swimming in a lake unpleasant because of blue-green algae blooms. In this case, phosphorus loading might be most appropriately managed for a 30-day average load of phosphorus or a 5-year running average over a 90-day growing season to properly incorporate natural cycles and interactions into decision making. For example, variations in rainfall from year to year will affect nutrient inputs from atmospheric deposition as well as runoff from the watershed. Available data might be used to establish the mathematical relationship between phosphorus loading, in-lake phosphorus concentrations, and algae biomass.

Alternatively, a river where the health of the aquatic community is affected by excessive copper concentrations during storm events is most appropriately managed for acute concentrations during a storm event. The relationship between copper loading and in-stream copper concentrations during a storm must be established to support decisions about limiting copper loads.

Numeric or narrative water quality criteria can be used to establish the relationship between an impaired use and maximum allowable pollutant load. Water quality standards, as defined by 40 CFR 131.3(I), are composed of designated uses and numeric or narrative water quality criteria, which are intended to represent attainment of specific uses. For conventional pollutants, numeric water quality criteria are usually the most appropriate target.

When no numeric water quality criterion is available, a site-specific quantified target that results in the attainment or maintenance of water quality standards must be developed as part of the TMDL. Development of a site-specific target requires information on the type of waterbody, its geographic location, how seasonal variations in rainfall and temperature affect waterbody functions, the designated use, and stakeholder preferences and concerns.

2. Are surrogate targets appropriate or necessary?

In some situations, there are no numeric water quality criterion or quantifiable pollutant load that can be used to define the allowable pollutant load and express the TMDL. In these situations, surrogate targets that have a quantifiable relationship with the water quality criterion or pollutant load can be used to provide numeric indicators or quantified measures to express the TMDL. The relationship between a surrogate measure, the water quality standard, and the pollutant load should be clearly described. For example, although an allowable pollutant load that addresses excursions of temperature criteria because of a denuded riparian corridor is ultimately expressed in terms of heat units over time, it is most appropriately discussed in terms of degrees of temperature (degrees Fahrenheit or Celsius). Most water quality criteria that address heat list a range of acceptable temperatures over a specific period of time (e.g., a daily maximum, minimum, and average during the spring). The management measures implemented to reduce the overall heat load may actually be miles, meters, or square yards of riparian zone restored. These measures must be related to their impact on heat load and also temperature: X miles of riparian zone restored is expected to cause water temperature to decrease by Y degrees Fahrenheit. Table 3-1 provides some examples of how a TMDL and these associated targets may be expressed for various pollutants.

Table 3-1. Expressing a TMDL and its associated targets

Use Impaired	Likely Expression of Associated Water Quality Criterion	Surrogate or Suite of Surrogate Measures	Pollutant and Possible Load Expression
Coldwater aquatic life	Temperature must not exceed 20C for trout waters or 24C for non-trout waters. No discharge at a temperature over 70F is permitted at any time to streams classified for trout. From June through September, no discharge is permitted that will raise the stream temperature more than 2F over that which existed before the addition of heat. From October through May, no discharge is permitted that will raise the stream temperature more than 5F over that which existed before the addition of heat of artificial origin or to a maximum of 50F, whichever is less.	Riparian shading Width-depth ratio Sinuosity (meander pattern) Miles of restored riparian zone Number of trees planted Percentage of increased shading	Temperature(e.g.,excess heat) kilojoules/da
Coldwater aquatic life Warmwater aquaticlife Industry	A healthy populationof native coldwater species. Turbidity in thewater column must not exceed 20 NTUs. Total dissolvedsolids must not exceed 500 mg/L.	Turbidity Suspended sediment Miles of stabilizedstream bank Embeddedness ofbottom sediments Size distribution of bottom sediments (e.g., D50 or D84) Diversity of fish populations Population of fish of a species of interest Miles of restored bank Number of BMPsb implemented Number of acres of BMPs implemented	Clean sediment tons of sediment per year kilograms of sediment per day
Coldwater aquaticlife Primary and secondarycontact recreation Drinking water >Agriculture Industry	In no case may nutrient concentrations of a body of water be altered so as to cause an imbalance in natural populations of aquatic flora or fauna. Nutrient concentrations must be at concentrations that prevent the stimulation of aquatic growths that are injurious to designated uses. Nitrate as nitrogen concentrations in surface waters must not exceed 10 mg/L or any criteria that exceeds the narrative nutrient criteria.	Biomass Dissolved oxygen concentration Secchi depth Residence time ordegree of flushing (for lakes) Positive user surveyresponse (for lakes) Decreased # algaeblooms Increased clarity	Nutrients (phosphorus, nitrogen) kilograms total phosphorus per year (running 5-year average) pounds of total nitrogen during the 3-month growing season
Coldwater aquatic life Warmwater aquatic life Primary and secondary contact recreation	Must not average less than 5.0 mg/L in a 24-hour period and must never be less than 4.0 mg/L.	Phosphorus concentration Nitrogen concentration Biochemical oxygen demand Biomass Sediment oxygen demand Temperature	Dissolved oxygen Load of phosphorus Load of BODc

^a NTU: Nephelometric turbidity unit
^b BMP: Best management practice
^c BOD: Biochemical oxygen demand

3. What are appropriate ways to measure (track) progress?

There are numerous ways to measure progress toward attainment of water quality standards. The most obvious is a decreasing trend of pollutant loads. When a surrogate or suite of surrogates is selected as a more understandable way to measure attainment of water quality standards, measures of progress can also be defined more broadly. In some cases surrogate indicators may be more responsive, allowing for the progress to be more quickly discerned. The key is to clearly state how progress will be measured.

3.2d Identifying the Amount or Degree of Deviation from the Allowable Pollutant Load

One of the elements of an approvable TMDL submittal to EPA requires States, Territories, and authorized Tribes to identify the amount or degree by which the current pollutant load deviates from the target representing attainment or maintenance of water quality standards. This determines how much the pollutant load must be reduced to meet the maximum allowable pollutant load and therefore sets the stage for allocation of the pollutant among its sources. It also facilitates linking water quality targets and sources by relating targets and surrogate measures to the expression of source loads.

In some cases the analysis of required pollutant reductions may lead to a preliminary conclusion that the water quality standard is unattainable. It might be appropriate to conduct a use attainability analysis to determine whether it is appropriate to remove or otherwise change the use. Technical guidance on conducting use attainability analyses is available from EPA in the Water Quality Standards Handbook (USEPA, 1994b).

Key Questions to Consider When Conducting a Target Analysis

• What is the water quality standard that applies to the waterbody?
• How does the designated use relate to the maximum allowable pollutant load?
• Are surrogate targets appropriate or necessary?
• What factors affect the selection of a surrogate target?
• What is the maximum allowable pollutant load?
• What is the amount or degree by which current conditions deviate from the allowable load?
• What are appropriate ways to measure (track) progress?

3.2e Source Identification and Assessment

Source identification and assessment is the fourth component of the technical approach for establishing TMDLs (40 CFR 130.33(b)(4)). A source assessment lists and characterizes individual pollutant source(s), categories of sources, or subcategories of sources that are responsible for waterbody impairment and quantifies the degree to which each source (source category or subcategory) contributes to the problem. It is at this point that the character of each pollutant source, its temporal loading variability, and its location with respect to the waterbody of concern become important. The factors to identify when conducting a source assessment include the following:

• Source type (e.g., point, nonpoint, background, atmospheric)
• Relative location of each source category
• Magnitude of loads from each source category
• Transport mechanisms of concern (e.g., runoff, erosion)
• Time scale of loading to the waterbody (i.e., duration and frequency of pollutant loading to receiving waters)

The evaluation of pollutant loading is typically performed using a variety of tools, including existing monitoring information, air photography analysis, simple calculations, spreadsheet analysis using empirical methods, and a range of computer models from simple to sophisticated. The selection of the appropriate method for determining loads is based on the complexity of the problem, the availability of resources, time constraints, the availability of monitoring data, and the management objectives under consideration.

Grouping sources into categories should be carefully considered during source identification and assessment. The appropriate selection of the various loading categories will facilitate completion of subsequent analyses. Sources can be grouped into categories by type, ownership, location (e.g., by subwatershed or distance from the waterbody), and other factors. Factors that might be useful to consider include the following: delivery mechanisms; type and location of sources relative to waterbody of concern; management options under consideration; social, political, and economic factors; and physical characteristics of the watershed including slope, geology, soils, and drainage network. When grouping sources into categories or subcategories, it is important that there is a recognizable link between the categories, the allocation of loads, and the implementation plan.

Key Questions to Consider When Identifying and Assessing Sources

• What sources are contributing to the problem and how can they best be characterized?
• How should sources be grouped to facilitate load estimation and allocation?
• What are the primary processes or delivery mechanisms from the various source categories under consideration?
• What is the appropriate level of spatial and temporal detail for determination of the source loading?
• What are the appropriate analysis techniques for estimating the source loads?

3.2f Linking Water Quality Targets and Sources

Linking water quality targets and pollutant sources is the fifth component of the technical approach for establishing TMDLs. Establishing the relationship between the in-stream water quality target and pollutant loads allows an estimation of the degree to which historical and existing loads exceed allowable loads, and the associated degree of pollutant reduction needed to attain water quality standards. In addition, linkage analysis facilitates the evaluation of management options that will achieve the desired load reductions. The link can be established through a range of techniques from the use of qualitative assumptions backed by sound scientific justification to the use of sophisticated modeling techniques. Ideally, the linkage will be supported by monitoring data that associate certain waterbody responses to flow and loading conditions. When long-term monitoring data are unavailable, it might be necessary to use a combination of methods, including monitoring data, analytical tools (including simulation models), and qualitative information. The monitoring data help to define characteristics such as baseline water quality conditions, pollutant source loading rates, and waterbody system dynamics. The available monitoring data will be supplemented by analytical tools that represent system processes or their responses to specified inputs and the best professional judgement of persons collecting data. The linkage consists of evaluating the relationship between source loadings and the waterbody's response to those loads over time if long-term data is available.

Key Questions to Consider When Linking Sources and Water Quality Targets

• What type of analysis is appropriate for linking the water quality target and the sources?
• What are the basic components of analysis for linking the water quality targets and the sources?
• What are the complicating factors that can influence the linkage analysis?

3.2g Allocating Pollutant Loads

Allocating pollutant loads is the sixth component of the technical approach for establishing TMDLs. Its purpose is to create a technically feasible and reasonably fair division of the allowable load among sources. To be approved, a TMDL's allocation scheme must demonstrate that (1) water quality standards will be attained and maintained and (2) the load reductions are technically achievable. Ultimately, the allocation strategy is used as the foundation for the implementation and monitoring plan. Understanding the relationship between pollutant loads and the condition of the waterbody is the basis for evaluating alternative allocation strategies. If there is a range of allocation strategies that could be implemented, the TMDL should provide various allocation options. This allows for a more rigorous evaluation and decision making process by the stakeholders and regulators. A waterbody's assimilative capacity can be allocated among sources in numerous ways (USEPA, 1991a, 1991b). States, Territories, and authorized Tribes may consider several factors, including technical and programmatic feasibility, cost-effectiveness, relative source contributions, equity, and the likelihood of implementation, to develop the most effective allocation strategy.

Although there are many ways to express the distribution of the maximum allowable pollutant load, the concept of allocation is central to the TMDL process because it reinforces the importance of identifying what sources need to be addressed to eliminate the impairment. Load-based allocations (e.g., allowable loads or needed load reductions per unit of time) are a required element of the TMDL submittal. The allocations provide a framework for identifying the specific source reduction levels needed to address individual sources, categories of sources, or subcategories of sources. In most TMDLs, the allocation component does not identify specific implementation measures; rather, those measures are identified in the implementation and monitoring plan. It is usually advantageous to develop at least portions of the implementation plan at the same time as the determination of allocations for the following reasons:

• Makes efficient use of assessment and planning resources and the time of participants.
• Increases the likelihood that actions needed to implement the allocations will actually be carried out.
• Improves the analytical basis for supporting arguments regarding "reasonable assurances" that allocations will be effective in meeting the maximum allowable pollutant load specified in the TMDL.

The type, number, and character of pollutant sources affecting an impaired or threatened waterbody will affect how a TMDL is established, which allocation strategy is most effective, and the follow-up monitoring and evaluation activities required. For example, a TMDL that addresses a waterbody impaired by a conventional pollutant, such as biochemical oxygen demand, that is discharged from a single point source will be relatively straightforward. A numeric target is available through State, Territorial, or authorized Tribal water quality standards. Source assessment should consider a low-flow condition (potentially using one of the well-developed analytical techniques available) and allocate maximum pollutant loads both to natural background and to the single discharger that ensures that the water quality standards are attained and maintained. The allocation can be implemented through the discharger's NPDES permit. Follow-up monitoring to ensure compliance with the allocation and success of the TMDL can be a requirement of the permit or can be conducted by the State, Territory, or authorized Tribe at one or two monitoring sites downstream of the discharge.

Establishing a TMDL that addresses a lake or river impaired by a nutrient load comprised of the discharge from several wastewater treatment plants, runoff during storms from grazed pastures, and groundwater that is affected by failing septic systems is different. Narrative water quality standards for nuisance algae, color, and odor should be translated into a numeric surrogate target for the most limiting nutrient. Source assessment should consider how the low-flow and the storm-flow conditions interplay. Although allocations to the point source dischargers can be implemented through their NPDES permits, mechanisms for implementing the allocations to septic systems and pastureland should be formulated and explained in the implementation and monitoring plan.

Allocating Wasteloads to Point Sources

A wasteload allocation is a required element of a TMDL submittal (40 CFR 130.33(b)(5)). EPA has developed numerous technical guidance manuals to assist States, Territories, and authorized Tribes in calculating wasteload allocations for point sources that are identified as contributing to the impairment of a waterbody. The text box on Page 3-17 provides a list of these manuals, as well as a description of other relevant guidance documents. Wasteload allocations should be expressed as (1) numeric maximum allowable loads, (2) required numeric reductions in pollutant loads, and/or (3) narrative effluent requirements.

Expressing wasteload allocations as numeric maximum allowable loads and required numeric reductions in pollutant loads is particularly useful for individual, continuous discharges. The Abaseline@ permitting program and methods for developing water quality-based effluent limits from water quality standards and wasteload allocations were originally designed to regulate continuous discharges from industrial and municipal point sources, where variability of effluent flow and quality can be predicted and modeled using relatively simple techniques. Developing numeric wasteload allocations and numeric water quality-based effluent limits is a relatively straightforward process for these types of discharges.

On the other hand, many of the sources that have recently come under the regulatory umbrella of the NPDES program, or for which there has been renewed interest in controlling through the NPDES program, are associated with episodic runoff. Point sources composed predominately of runoff include: municipal storm water from large and medium-sized cities and runoff from construction and industrial sites (more than 250,000 sources regulated under the NPDES program by 2002); approximately 10,000 combined sewer overflow points across the country; and approximately 15,000-20,000 concentrated animal feeding operations anticipated to be subject to regulation and control as point sources.

For diffuse sources of pollutant loads that are managed through a point source discharge, the quantity and quality of the runoff tends to be episodic and can be difficult to model and predict. Polluted runoff collected and controlled as a point source is frequently discharged from a large number of outfalls, complicating measurement of effluent quality. It may be difficult to establish meaningful wasteload allocations for such point sources. The method of choice for controlling polluted runoff is generally a Abest management practice@ (e.g., silt fences, street sweeping) approach rather than the treatment systems commonly associated with continuous discharges. It is more difficult to monitor or predict the effectiveness of best management practices on reducing the discharge of pollutants into waterways and, therefore, more difficult for a permitting authority to determine with certainty that the requirements it places on sources of polluted runoff will meet a numeric wasteload allocation requirement.

Despite the complexity of addressing episodic sources as part of a TMDL, it is important to consider these sources when developing wasteload allocations in order to continue to make progress toward attaining water quality standards. While the total wasteload allocation computed in the TMDL is assigned an overall maximum numeric allowable load, narrative effluent requirements may be the most appropriate mechanism for achieving the numeric allocation of the non-continuous, wet weather discharge fraction, particularly in the first round of TMDLs and wasteload allocation development. As additional information is gathered and water quality models and the TMDL are refined, a numeric wasteload limit may be developed. The permitting authority may then require that the point source demonstrate that the best management practices it is implementing will achieve the required wasteload allocation or may develop a numeric water quality-based effluent limit that will apply to the discharge under specific wet weather conditions.

Allocating Loads to Nonpoint Sources and Natural Background Sources

A load allocation is a required element of a TMDL submittal (40 CFR 130.33(b)(6)). Load allocations should be expressed as (1) numeric maximum allowable loads, (2) required numeric reductions in pollutant loads, and/or (3) narrative statements of desired conditions (e.g., habitat, biology). EPA regulations allow load allocations for nonpoint sources to be based on "gross allotments" (40 CFR 130.2(f)) depending on the availability of data and appropriate techniques for predicting loads. In addition, before EPA approves a TMDL in which some of the load reductions are allocated to nonpoint sources in lieu of additional load reductions allocated to point sources, there must be reasonable assurances that the nonpoint source reductions will in fact occur.

Allocating a Margin of Safety

An MOS, expressed as unallocated assimilative capacity or conservative analytical assumptions used in establishing the allowable pollutant load (e.g., derivation of numeric targets, modeling assumptions, or effectiveness of proposed management actions), is a required element of the TMDL submittal (40 CFR 130.33(b)(7)). Table 3-2 presents six approaches for incorporating an MOS into a TMDL's maximum allowable pollutant load. The approach used should be clearly identified in the submittal of the TMDL.

Table 3-2. Approaches for incorporating a margin of safety in a TMDL

Type of Margin of Safety	Available Approaches
Explicit	Set numeric targets at more conservative levels than analytical results indicate Add a safety factor to pollutant loading estimates Do not allocate a portion of available loading capacity; reserve for MOS
Implicit	Use conservative assumptions in derivation of numeric targets Use conservative assumptions when developing numeric model applications Use conservative assumptions when analyzing prospective feasibility of practices and restoration activities.

The following factors should be considered in evaluating and deriving an appropriate MOS for the waterbody and pollutant combination of concern:

• The limitations in available data for characterizing the waterbody and the pollutant, for addressing the components of the TMDL establishment process.
• The analysis and techniques used in evaluating the components of the allowable pollutant load, and for deriving an allocation scheme.
  • Characterization and estimates of source loadings (e.g., confidence regarding data limits, analysis limits or assumptions).
  • Analysis of relationships between the source loading and receiving water impact.
  • Prediction of receiving water response under various allocation scenarios (e.g., the predictive capability of the analysis, simplifications in the selected techniques).
• The expression of analysis results in terms of confidence intervals or ranges. Confidence may be addressed as a cumulative effect on the load allocation or individually for each component of the analysis.
• The implications of the MOS on the overall load reductions identified in terms of reduction feasibility and implementation time frames.

Establishing TMDLs requires the use of a variety of analytical techniques. Some analytical techniques are widely used and applied in evaluation of source loading and determination of the impacts on waterbodies. For certain pollutants the methods used are newer or in development. However, for some pollutants the process for allocating an explicit margin of safety may be more difficult.

Some of the considerations in evaluating confidence limits for analytical techniques include the following:

• Interpretation of data in performing the analysis. Application of traditionally employed analytical techniques still requires the analyst to interpret monitoring information and make the appropriate assumptions and simplifications. Trained analysts determine how to best apply the model to address the dominant and significant characteristics of the system. In some cases only a portion of the nalysis will be relatively unknown. For example, when evaluating a river with oxygen violations, the point source loadings, upstream nonpoint source loading, and in-stream characteristics may be well defined. The contribution of in-stream BOD from bottom sediments may, however, be unclear. The analyst may make an assumption on the significance of this source and estimate a value for the purpose of deriving the allowable pollutant load; however, the monitoring and implementation plan would target this assumption for further investigation.
• Adequacy of the calibration. The analysis may be well verified under some, but not all, conditions of concern. For example, statistical analysis between observed and simulated values may show good agreement under a number of flow conditions, but data may not be available to check other flow conditions.
• New and developing methods. When applying new and developing methods, the selection of analysis techniques should be based on scientific rationale and/or interpretation of observed data. Concerns regarding the appropriateness and scientific integrity of the analysis should be defined, and the approach for verifying the analysis through monitoring and implementation should be addressed. Without the benefit of long-term experience and testing of the methods used to derive the maximum allowable pollutant load, the potential for the estimate to require refinement is high.

The confidence that an analyst has in the conclusions can be expressed as a range or a confidence interval. For example, the source loading could be expressed as varying within ± 10 percent of the estimated values. The confidence measure can range from small to large depending on the specific characteristics of the analysis. Further data collection and analysis might result in improving the estimate and narrowing the range. In establishing a maximum allowable pollutant load with limited data, the range of the confidence interval could be large (e.g., ±50 percent). In these cases caution should be used to select an MOS that is reasonable and results in an overall allocation that represents the best estimate of how standards can be achieved. The selection of the MOS should clarify the implications for monitoring and implementation planning in refining the estimate, if necessary. The TMDL process accommodates the ability to track and ultimately refine assumptions within the TMDL implementation planning component.

Two conceptual examples can be used to illustrate how an appropriate MOS can be selected by integrating consideration of these factors.

Example 1. The impact of several point source discharges is evaluated using steady-state modeling under low- flow (e.g., 7Q10) conditions. The point source discharges and the upstream background conditions and known, accepted modeling techniques are used to evaluate the appropriate load reductions for each source. The MOS could be defined explicitly based on evaluation of the model accuracy or implicitly through the use of equivalent conservative assumptions regarding the model development. The MOS is based on a direct assessment of model accuracy, as well as historical experience in using this model throughout the country. Conducting a sensitivity analysis on the precision of point source loads (10%) and background conditions (20%) shows a change of 5% on model runs. The MOS is well defined and results in an additional 5 percent load reduction from the contributing sources.

Example 2. A eutrophic lake requires significant load reductions from nonpoint sources within the contributing watershed. A simplified loading assessment was performed to evaluate the average annual loadings. A defensible eutrophication model was used to evaluate the in-lake target of chlorophyll α. Adequate data were available for calibration and validation of the model. Considerable discussion has been held among the stakeholders over the accuracy of the loading estimate. Four different analyses have been proposed with loading numbers that range ±40 percent from the initial load estimate used to derive the allowable pollutant load. Stakeholders have agreed that additional monitoring of lake inflows should be initiated to better refine this number. The allowable pollutant load, based on an average value from four analyses, is established with a cautious 10 percent MOS, and the monitoring and implementation plan is initiated with the intention that the load reductions will be revised, if necessary. Follow-up monitoring is initiated at the major tributary inflows to the lake. Three years of monitoring data show that the observed load is consistent with the predicted load used in the analysis. The in-lake condition shows an improving trend. Since monitoring milestones are met, there is no indication that the TMDL needs to be revised.

Seasonality

Consideration of seasonal variation such that water quality standards for the allocated pollutant will be met during all seasons of the year is a required element of a TMDL submittal (40 CFR 130.33(b)(8)). TMDLs must maintain or attain water quality standards throughout the year and consider variations in the waterbody's assimilative capacity caused by seasonal changes in temperature and flow, or sensitive periods for aquatic biota (e.g., algae growth, fish spawning, larval emergence), and other factors.

TMDLs should also consider seasonal fluctuations in pollutant loads to the waterbody. Some nonpoint sources contribute pollutant loads only during precipitation events, a distinct rainy season, or snowmelt. Similarly, some point sources operate only during certain times of year (e.g., food processing during canning season or wastewater treatment during tourist season).

The issue of seasonality may or may not affect the final character of a TMDL, depending on when the waterbody impairment occurs and how pollutant loading is related. For example, the algae growth in a lake may be a response to total annual phosphorus loading, rather than just the loading that occurs during the summer growth season. Therefore, all sources may need allocations and control measures implemented throughout the year, not just the sources shown to contribute during the summer.

Future Growth

In many instances, population growth and the land use changes that accompany new development have the potential to negatively impact threatened and impaired waters. Increased sewage treatment flows, increased runoff from expanded areas of impervious surface cover, and other hydromodifications associated with urban growth can make the challenge of protecting and restoring the nation's waters even more difficult. Therefore, as states develop effective TMDLs and implementation strategies, they must give serious consideration of the consequences of reasonably foreseeable increases in pollutant loads attributed to future growth. As such, an allocation to future growth is a required element of a TMDL submittal (40 CFR 130.33(b)(9)). EPA expects States, Territories, and authorized Tribes to include future growth in their allocation strategy and carefully document their decision-making process (states/territories/and authorized tribes can decide on a zero allocation if they desire). The TMDL documentation should clearly explain the implications of the growth allocation decision on new and existing point and nonpoint sources of a pollutant. It should also explain what other local planning processes may be affected .

Supporting Decisions Within the TMDL Record

EPA, States, Territories, and authorized Tribes should carefully document and support the decision-making process that they use. If it is determined that a TMDL should be developed, States, Territories, and authorized Tribes and EPA should clarify the role of any assumptions and ensure that judgment is exercised by trained and experienced professionals, based on the best available science and data. Assumptions should be well documented and submitted as part of the TMDL submittal. The implications of key assumptions should be addressed in the formulation of the MOS for the allowable pollutant load. Monitoring plans, also included within the TMDL submittal should address specialized data collection needs for addressing uncertainty in the analysis. Stakeholders should be informed and involved early in the TMDL establishment process to promote understanding, acceptance and commitment to implementation.

Equity Issues

Allocations entail distribution of control needs or expectations among different point and nonpoint sources. Because costs of controlling different sources can vary substantially, the allocation analysis should consider whether the allocations reasonably distribute control costs . Analysts should develop and consider cost/benefit analyses of potential control actions to assist in fairly distributing control costs. Responsible parties will be more likely to carry out actions needed to implement TMDLs if they feel their share of the control burden is fair. Therefore, analysts should consult with affected stakeholders during the development of an allocation strategy. Many methods for developing allocations that can result in equitable control burdens are available. See Guidance for water quality-based decisions: The TMDL process (USEPA, 1991b) for additional guidance on allocation development. In some communities, stakeholders may already have laid the groundwork for allocating pollutant loads and addressed potential equity issues through local watershed planning.

Innovative Approaches

TMDLs provide excellent opportunities to consider alternative approaches for making watershed based water quality management decisions. One opportunity is to consider alternatives for making wasteload and load allocation decisions among point and nonpoint sources and evaluating the social and economic consequences of these allocations. States, Territories, and authorized Tribes are encouraged to consider innovative approaches (e.g., watershed permitting and pollutant trading) when establishing a pollutant load allocation strategy. Watershed-based ollutant trading is one example of an innovative approach that can be employed in the TMDL allocation process. In it's broadest sense, trading involves one source of a pollutant buying reductions in releases of that pollutant from another source elsewhere on the same waterbody or watershed, instead of implementing tighter controls on that pollutant at his/her facility. Trading is a feasible option in those situations where there are substantial differences in the marginal cost of additional controls between contributors of a pollutant to a common waterbody. Not only does trading offer a means of achieving water quality goals in a more cost-effective fashion, but it also can be used to encourage attainment of goals sooner than applicable deadlines and/or generate greater reductions than required by law. (See Draft Framework for Watershed-Based Trading USEPA May 1996, EPA-800-R-96-001). Trading and reallocation of loadings may occur once a TMDL has been approved and does not require that the TMDL be reopened provided that the following guidelines fro trades or systems for reallocating loadings are met:

• The TMDL implementation plan should provide reasonable assurances that allocations will be achieved and water quality standards met when using the approach.
• All legal requirements associated with the allocation process (and the TMDL process in general) are met.
• Any trades or systems for reallocation of loadings involving point sources are established as enforceable conditions of NPDES permits and are consistent with the overall loading requirement established in the TMDL.
• The TMDL implementation plan should contain detailed, specific provisions for follow-up evaluation of the innovative approach and potential revision or elimination of the innovative approach in favor of a more traditional approach based on that review.

Example of Establishing a Sediment TMDL

Problem Identification: Fish are unable to spawn in a creek because excess sediment is clogging the interstitial spaces of the stream bottom, there is no habitat for the insects that are a food source for fish, and the concentration of dissolved oxygen is insufficient for eggs and young fish to survive. Although the ultimate target for this problem may be to increase successful spawning by 20 percent, the maximum allowable pollutant load analysis and load allocation will be based on decreasing the amount of clean sediment in the stream system. The TMDL will need to establish a quantified link between spawning success and the amount of clean sediment on the stream bottom.

Target Analysis: Characterize the sediment transport regime of the stream system given the hydrologic conditions at hand; that is, determine how much sediment the stream can carry through the system without too much settling. Quantify how far the current system deviates from this ideal.

Source Assessment: Identify and characterize sources of sediment input, such as eroding banks or storm runoff.

Linkage of the Source and Maximum Allowable Pollutant Load: Use available data and information to develop relationships between the sources of sediment and the maximum allowable pollutant load. If necessary, establish a specialized monitoring strategy to obtain the data needed to establish this relationship.

Allocation: Allocate the total allowable sediment load; that is, determine the amount of sediment that each source may contribute or, conversely, determine by how much each source must decrease the amount of sediment it is contributing. Identify the appropriate MOS based on an understanding of the fundamental assumptions in the analysis regarding the in-stream endpoint, the load estimation, and the loading processes.

Implementation Plan: Identify the measures, such as specific best management practices or the number of miles of stream bank stabilization, that must be implemented to help identified sources meet their allocations (i.e., to help identified sources decrease their contribution to the total sediment load).

Monitoring Plan: Develop a set of milestones for evaluation of the implementation and progress toward meeting water quality standards using a suite of measures (i.e., BMP implementation, load estimates, bank conditions, percent fine sediments, and presence of fish). Since uncertainty is high, identify the conditions under which the TMDL might need to be revised.

3.2h Implementation and Monitoring

Implementation and monitoring is the seventh component of the technical approach for establishing TMDLs. Without implementation, a TMDL merely provides estimates of the pollutant load reductions needed to attain water quality standards. Therefore, EPA firmly believes that implementation and follow-up monitoring of TMDLs is crucial to the success of any State water quality program.

The regulation at 40 CFR 130.33(b)(10) requires States, Territories, and authorized Tribes to include an implementation plan as an element of a TMDL submittal. The plan may be developed for one or a group of TMDLs. Once EPA approves the TMDL, the plan must be included as an update to the State water quality management plan. States, Territories, and authorized Tribes are required to update their water quality management plans as needed to reflect changing water quality conditions and the results of implementation actions.

Minimum Elements of an Approvable Implementation Plan

Whether an implementation plan is for one TMDL or a group of TMDLs, it must include at a minimum the following eight elements:

• Implementation actions/management measures: a description of the implementation actions and/or management measures required to implement the allocations contained in the TMDL, along with a a description of the effectiveness of these actions and/or measures in achieving the required pollutant loads or reductions.

• Time line: a description of when activities necessary to implement the TMDL will occur. It must include a schedule for revising NPDES permits to be consistent with the TMDL. The schedule must also include when best management practices and/or controls will be implemented for source categories, subcategories and individual sources. Interim milestones to judge progress are also required.

• Reasonable assurances: reasonable assurance that the implementation activities will occur. Reasonable assurance means a high degree of confidence that wasteload allocations and /or load allocations in TMDLs will be implemented by Federal, State or local authorities and /or voluntary action. For point sources, reasonable assurance means that NPDES permits (including coverage under applicable general NPDES permits) will be consistent with any applicable wasteload allocation contained in the TMDL. For nonpoint sources, reasonable assurance means that nonpoint source controls are specific to the pollutant of concern, implemented according to an expeditious schedule and supported by reliable delivery mechanisms and adequate funding (see box).

• Legal or regulatory controls: a description of the legal authorities under which implementation will occur (as defined in 40 CFR 130.2(p)). These authorities include, for example, NPDES, Section 401 certification, Federal Land Policy and Management programs, legal requirements associated with financial assistance agreements under the Farm Bills enacted by Congress and a broad variety of enforceable State, Territorial, and authorized Tribal laws to control nonpoint source pollution.

• Time required to attain water quality standards: an estimate of the time required to attain water quality. The estimates of the time required to attain and maintain water quality standards must be specific to the source category, subcategory or individual source and tied to the pollutant for which the TMDL is being established. It must also be consistent with the geographic scale of the TMDL, including the implementation actions.

• Monitoring plan: a monitoring or modeling plan designed to determine the effectiveness of the implementation actions and to help determine whether allocations are met. The monitoring or modeling plan must be designed to describe whether allocations are sufficient to attain water quality standards and how it will be determined whether implementation actions, including interim milestones, are occurring as planned. The monitoring approach must also contain an approach for assessing the effectiveness of best management practices and control actions for nonpoint sources.

• Milestones for attaining water quality standards: a description of milestones that will be used to measure progress in attaining water quality standards. The milestones must reflect the pollutant for which the TMDL is being established and be consistent with the geographic scale of the TMDL, including the implementation actions. The monitoring plan must contain incremental, measurable milestones consistent with the specific implementation action and the time frames for implementing those actions.

• TMDL revision procedures: a description of when TMDLs must be revised. EPA expects that the monitoring plan would describe when failure to meet specific milestones for implementing actions or interim milestones for attaining water quality standards will trigger a revision of the TMDL.

Identifying Control Actions and/or Management Measures for Implementing Allocations

The implementation plan should describe what actions will be implemented by source category, source subcategory, or individual sources. The description of the actions should include an analysis of the anticipated or past effectiveness of the control actions and/or management measures expected to meet the allocations. The implementation plan should describe where the control actions and/or management measures will be implemented. Finally, this description should tie the implementation activity to the pollutant and the geographic scale of the TMDL.

Point Sources. One of the key TMDL implementation tools is the wastewater permitting program known as the National Pollutant Discharge Elimination System (NPDES). Under NPDES, all facilities which discharge pollutants from any point source into waters of the United States are required to obtain a permit. For these point sources, States, Territories and authorized Tribes must provide a list of NPDES permits, including applicable general permits, and a schedule for revising the permits based on the TMDL.

The permit provides two enforceable levels of control: technology-based limits (based on the ability of dischargers in the same industrial category to treat wastewater) and water quality-based limits (if technology-based limits are not sufficient to provide protection of the water body). Permit limits based on TMDLs are water quality-based limits. These water quality-based permit limits must be consistent with any applicable wasteload allocation contained in the TMDL for that watershed and pollutant combination. These discharge limits are expressed as numerical restrictions on discharges (e.g., not to exceed 10 kg/day copper) or when numerical restrictions are infeasible, as best management practices (BMPs). (See 40 CFR 122.44(k)). BMPs are more commonly used as effluent limits for point sources such as urban or industrial storm water, or for concentrated animal feeding operations.

In addition, the Clean Water Act (and corresponding State statutes) authorizes imposition of monitoring and data collection requirements on the owner or operator of a point source discharge for the purposes of supporting permit development and compliance assessment. Requirements may include effluent monitoring, ambient and biological assessments, toxicity reduction evaluations, in-plant monitoring, and others. Information collected from point sources may be used when developing or assessing the effectiveness of a TMDL. The primary mechanism for data collection from point sources is a requirement in the NPDES permit. Permit requirements for data collection are particularly useful when longer-term data (e.g., for several seasons) are needed. In addition, information may be collected through administrative orders or through a direct request under Section 308 if there is a reasonable need for the information for EPA to carry out the objectives of the Clean Water Act. (This request must also meet requirements of the Paperwork Reduction Act.) These authorities can be used to collect data from point sources when developing or assessing the effectiveness of a TMDL affecting those point sources, or deciding if current permits need revision. EPA recommends that permit requirements for data collection be required when ever needed to support TMDLs.

As part of the implementation plan, States, Territories, and authorized Tribes must provide a list of NPDES permits, including applicable general permits, and a schedule for revising or reissuing the permits.

Nonpoint Sources. For nonpoint source load allocations, States, Territories and authorized Tribes must prepare an implementation plan that includes a description of the proposed control measures. EPA expects that the State's, Territory's, or authorized Tribe's § 319 nonpoint source management program will be the basis for implementing load allocations. The implementation plan must contain a description of best management practices or other management measures. The plan will contain a description of who will carry out the controls and identify the source categories, subcategories, or individual sources of the pollutant for which the TMDL was approved. The implementation plan may deal with sources on a watershed basis s long as the scale of the implementation plan is consistent with the geographic scale for which the TMDL pollutant load allocations are established.

Nonpoint source pollution may be managed through implementation of best management practices (BMPs), regulatory processes, siting criteria, and operating methods. These control measures should be based on load allocations developed using the TMDL process. In establishing an overall allocation strategy, there is a strong interdependence between the nonpoint and point source elements. .For example, when permits are established for individual point sources based on an expectation of reductions from nonpoint sources there must be a reasonable assurance that nonpoint source controls will be implemented. Assurances may include local ordinances, grant conditions, or other enforcement authorities. For example, it might be appropriate to provide that a permit be reopened for a wasteload allocation that requires more stringent limits because attainment of a nonpoint source load allocation was not demonstrated.

To fully address waters that are impaired or threatened by nonpoint source pollution, States, Territories, and authorized Tribes should implement their nonpoint source management programs and ensure adoption of control measures by all contributors of nonpoint source pollution in those watersheds. Example BMPs and the primary pollutants controlled are presented in Table 3-3. Information on the cost and effectiveness of various BMPs can be found in numerous guidance documents (see reference section for a list).

There are regional differences in the effectiveness of BMPs due to differences in climate and physical conditions. State, Territorial and Tribal nonpoint source management programs may include, as appropriate, nonregulatory or regulatory load allocation programs for enforcement, technical assistance, financial assistance, education, training, technology transfer, and demonstration projects.

The achievement of nonpoint source load reductions is a complex challenge. Therefore, States, Territories, and authorized Tribes must describe nonpoint source load reductions and establish a procedure for reviewing and revising BMPs in TMDL documentation. Achievement of water quality standards is tracked using the selected milestones and measures. The key objective for documenting load reduction goals and review procedures is to establish a rational and self-correcting procedure for site-specific evaluation of TMDLs with significant nonpoint source pollution loads.

Mechanisms for Implementing Controls

Legal Authorities. The implementation plan must contain a description of the legal authorities under which implementation will occur. These authorities include, but are not limited to, NPDES, § 401 certification, Federal Land Policy and Management Act § 202, CZARA, State forest practices acts, CWA § 319 management programs, and various State, Territorial, Tribal and local programs.

Table 3-3. Common NPS management practices/measures and pollutants controlled

Source Category	Primary Pollutant(s) Controlled	Management Practices/Measures
Agriculture	Nitrogen, phosphorus, sediment	Tillage management for erosion control
	Nitrogen, phosphorus, pathogens, BOD	Control of runoff from confined animal facilities
	Nitrogen, phosphorus	Nutrient management
	Pesticides	Pesticide management
	Nitrogen, phosphorus, sediment, temperature (heat)	Grazing management
	Nitrogen, phosphorus, sediment, toxics	Irrigation water management
Forestry	Nitrogen, phosphorus, temperature (heat)	Preharvest planning
	Temperature (heat)	Streamside area management
	Sediment	Road construction/reconstruction/management
	Sediment	Timber harvest management
	Sediment	Site preparation and forest regeneration
	Sediment	Fire management
	Toxics	Forest chemical management
Urban	Sediment	New development
	Sediment	Watershed planning / protection
	Temperature, sediment	Site development
	Sediment	Construction site erosion and sediment control
	Toxics	Construction site chemical control
	Nitrogen, phosphorus, sediment	Existing development
	Nitrogen, phosphorus, pathogens	Onsite disposal systems management
	Nitrogen, phosphorus, toxics	Pollution prevention
	Nitrogen, phosphorus, sediment, toxics	Operation and maintenance of existing BMPs
Marinas/Boating	Pathogens, nitrogen, phosphorus, toxics	Marina/boating management
Hydromodification	Temperature (heat), sediment	Maintenance of physical, biological, and chemical characteristics of streams and surface water

Incentives may be used to demonstrate reasonable assurance that a control action and/or management measure will be implemented. If incentives are used, evidence of past success of the particular incentive should be included in the implementation plan. Examples of incentives that have proven successful include cost sharing of BMP installation, grants for a specific activity (e.g., public education), long-term leases or rentals of environmentally sensitive land or buffers, and tax incentives and disincentives. Tax incentives and disincentives involve establishing a tax system to encourage or discourage certain behaviors by offering tax reductions or increases.

Identifying Responsible Parties. The implementation and monitoring plan should clearly identify those responsible for ensuring the implementation of specified control actions and/or management measures. The most appropriate party will vary depending on how sources are grouped, the control actions and/or management measures required, and who is funding implementation. For example, it might be most useful to identify the facility administrator and operator when control actions are required of an individual discharger, but to indicate an appropriate organization when control actions are required of a grouping of dischargers or when management measures are required for a nonpoint source category.

Funding. Perhaps the most challenging element of reasonable assurance is the guarantee of adequate funding for nonpoint source controls. The identification of dedicated funding for specific program goals is important, but often difficult. For example, storm water utility fees are used in more than 100 communities. These utility fees provide reliable funding to pay for long-term storm water management planning, implementation, and operation and maintenance. A variety of program funding alternatives for local and state governments are presented in A State and Local Government Guide to Environmental Program Funding Alternatives (USEPA, 1994a.) Additional sources of funding that can be obtained from the Federal government for State and local governments as well as individuals (e.g., farmers) are presented in Catalog of Federal Funding Sources for Watershed Protection (USEPA, 1997g.)

Point source facilities generally have mechanisms in place to secure funds needed for implementing the retrofits, process modifications, and additional pollutant controls that may be required to meet the load allocations required within a TMDL. Whether they are affected individually or as part of a category of sources, facilities should be consulted about how to best fund required actions. EPA anticipates that the economic feasibility of various allocation strategies will be discussed at this stage of TMDL establishment.

Tracking Implementation

To achieve the specified load allocation, the implementation plan should include a time line for installation of identified management actions. Especially in the case of nonpoint source controls, the specific management actions will be distributed in various locations in the watershed. Tracking of the implementation of management actions over time will provide valuable information. The tracking of implementation will assist in determining the success of the load allocation, the adequacy of funding and resources, the potential for water quality improvement, and the need for corrective actions. Tracking information in the various subwatersheds within the contributing area can assist in the evaluation of water quality monitoring data for beneficial trends. For areas with predominantly nonpoint source controls, the use of tracking information can support demonstration of progress in the absence of clear benefit through water quality monitoring. The variability in nonpoint source loadings due to hydrologic variability can often make it difficult to discern short-term trends.

3.2i A Time Line Unifies the Implementation Plan and the Allocations

States, Territories, and authorized Tribes should consider their TMDL time line as a vehicle for tying the most important components and elements of the TMDL into an adaptive management strategy. The time line can be used to clearly and effectively link measures of use attainment, controls, attainment of milestones, progress toward attainment of water quality standards, and a final decision about whether to revise the TMDL.

Figure 3-2 provides a sample template for what milestone review of TMDL monitoring, tracking, and implementation might look like. The very top of the template includes relevant information about the waterbody and pollutant combination, as well as about the TMDL itself. Below are a series of time lines—one for each measure of success (numeric criteria, surrogate measures, supporting surrogates)—which clearly illustrate goals, important decision points, and ongoing trends (tracking). The bottom of the template lists the milestones, the observed trends, the measures of success, and the recommendations for follow-up action.

The schedule must detail when specific control actions will be implemented for point and nonpoint source categories, subcategories, and individual sources. For point sources, specific items that should be considered are the schedule for revising NPDES permits, when necessary, and any compliance schedules for specific point sources. For nonpoint sources, specific items that should be considered include the grant program schedules and weather-related issues (e.g., rainy seasons when it would be more difficult to put management measures in place).

Interpretation of the data gathering and comparison with the designated milestones and schedules might result in reevaluation of the TMDL for waterbody and pollutant combinations on Part 3 of the § 303(d) list and recommendations for placement of the waterbody and pollutant combination back on Part 1 of the list. The TMDL would then need to be scheduled for revision and reestablished; follow-up implementation and monitoring would need to be reinitiated. Figure 3-3 provides a conceptual overview of the relationship between TMDL establishment, implementation tracking and monitoring, and the § 303(d) listing cycle. Once the TMDL is approved, (i.e., for Part 3 waterbody and pollutant combinations,) the State, Territory, or authorized Tribe would consider the following options:

• Delisting. Observed data confirm that the waterbody meets water quality standards for the specific pollutant.
• Continued implementation and tracking. The monitoring shows that milestones have been met and the TMDL appears to be appropriate.
• Corrective actions identified. Although milestones have not been met, corrective actions have been identified and initiated. There is no reason to believe that the TMDL is inappropriate.
• Placement on the Part 1 list. The milestones have not been met, and monitoring shows that it is unlikely that the TMDL will be sufficient to meet water quality standards. Revision or refinement of the TMDL is recommended. The waterbody and pollutant combination is placed on Part 1 of the § 303(d) list and scheduled for revision.

3.2j Monitoring and Evaluation Ensures Timely, Informed Follow-up Actions

Each TMDL should include a monitoring plan designed to determine the effectiveness of control actions and/or management measures being implemented and whether the TMDL is working, as well as a procedure that will be followed if components of a TMDL must be refined.

The monitoring and adaptive management plan is a central component of a TMDL. This plan should incorporate each of the components discussed below along with adequate rationale for the selected monitoring and adaptive management approach. The plan should clearly indicate the monitoring goals and hypotheses, the parameters to be monitored, the locations and frequency of monitoring, the monitoring methods to be used, the schedule for review and potential revision, and the parties responsible for implementing the plan. It must contain incremental, measurable targets consistent with the specific implementation action and the time frames for implementing those actions. This information is needed to adequately assess whether the specified actions are sufficient to attain water quality standards.

The following are key factors to consider when developing a TMDL monitoring plan:

• Need to evaluate specific TMDL components. TMDL problem identification, indicators, numeric targets, source estimates, and allocations might need reevaluation to determine whether they are accurate and effective. The monitoring plan should define specific questions to be answered about these components through the collection of monitoring information. Potential questions include the following:

  - Are the selected measures of success capable of detecting designated or existing use impacts of concern and responses to control actions?

  - Have baseline or background conditions been adequately characterized?

  - Are the numeric targets set at levels that reasonably represent the appropriate desired conditions for designated or existing uses of concern?

  - Have all important sources been identified?

  - Have sources been accurately estimated?

  - Has the linkage between sources and in-stream impacts been accurately characterized?

  - Have other watershed processes that affect the pollutant's impact(s) on designated or existing uses (e.g., hydrology) been accurately characterized?

  - Where reference sites were used to help determine TMDL targets and load reduction needs, were reference site conditions accurately characterized?

  - Were models or methods used for the TMDL accurately calibrated?

• Need to evaluate implementation actions. It is often important to determine whether actions identified in the implementation plan were actually carried out (implementation monitoring) and whether these actions were effective in attaining TMDL allocations (effectiveness monitoring). Specific questions to be answered concerning implementation actions should be articulated as part of the monitoring plan. Some illustrations of variables that can be used for implementation tracking are listed in Table 3-4.

Table3-4. Example variables for assessing management measure implementation for urban, agricultural, and forestry sources (adapted from USEPA, 1997b)

URBAN SOURCES
Management Measure	Good Variable	Poor Variable	Appropriate Sampling Unit
New Development	Number of county staff trained in ESC control.   Width of filter strips relative to area drained.	Allocation of funding for development of education materials. Scheduled frequency of runoff control maintenance.	Subwatershed   Development site
Watershed Protection	Percent of highly erodible soils left in an undeveloped state.   Percent natural drainage ways altered.	Development of watershed analysis GIS system.   Assessed fines for violations of setback standards.	Subwatershed
Construction Site Erosion and Sediment Control (ESC)	Distance runoff travels on disturbed soils before it is intercepted by a runoff control device (relative to slope and soil type).   Adequacy of ESC practices relative to soil type, slope, and precipitation.	Number of ESC BMPs used at a construction site.   Number of ESC plans written.	Development site
Existing Development	Proper operation and maintenance of surface water runoff management facilities.   Installation of appropriate BMPs in areas assigned priority as being in need of structural NPS controls.	Development of a schedule for BMP implementation.   Setting priorities for structural improvements in development areas.	Subwatershed
Operating Onsite Disposal Systems (OSDS)	Increase in proper OSDS operation and maintenance 6 months after a public education campaign.   Average time between OSDS maintenance visits.	Scheduled frequency of OSDS inspections.   Authorization of funding for public education campaign on OSDS.	Subwatershed City Town

AGRICULTURE
Management Measure	Good Variable	Poor Variable	Appropriate Sampling Unit
Erosion and Sediment Control	Area on which reduced tillage or terrace systems are installed Area of runoff diversion systems or filter strips per acre of cropland Area of highly erodible cropland converted to permanent cover	Number of approved farm soil and erosion management plans Number of grassed waterways, grade stabilization structures, filter strips installed	Field   Acre
Facility Wastewater and Runoff from Confined Animal Facilities	Quantity and percentage of total facility wastewater and runoff collected by a waste storage or treatment system	Number of manure storage facilities	Confined animal facility Animal unit
Nutrient Management	Number of farms followingand acreage covered by approved nutrient management plans Percent of farmerskeeping records and applying nutrients at rates consistent with managementrecommendations Quantity and percentreduction in fertilizer applied Amount of fertilizer and manure spread between spreader calibrations	Number of farms with approved nutrient management plans	Farm   Field   Application
Pesticide Management	Number of farms with complete records of field surveys and pesticide applications and following approved pest management plans Number of pest field surveys performed on a weekly (or other time frame) basis Quantity and percent reduction in pesticides use	Number of farms with approved pesticide management plans	Field Farm Application
Grazing Management	Number of cattle-hours of access to riparian areas per day Miles of stream from which grazing animals are excluded	Miles of fence installed	Stream mile   Animal unit

FORESTRY
Management Measure	Good Variable	Poor Variable	Appropriate Sampling Unit
Preharvest Planning	Agreement between preharvest plan and harvest operation   Inclusion of all required elements in preharvest plan	HarvestNumber of preharvest plans developed/approved	Harvest operation   Preharvest plan
Streamside Management Areas (SMAs)	Width of SMAs   Leave trees in SMAs meet minimum requirements	Presence of waterbody on harvest site \   Number of stream crossings in SMA	100-ft stretch of SMA
Road Construction/   Reconstruction	Compaction of fill materials adequate to prevent erosion   Culverts cross streams at right angles	Miles of road constructed   Number of stream crossings installed	Fill areas along forest roads   Stream crossings
Road Management	Culverts free of obstructions   Temporary stream crossings removed	Completion of road inspections   Number of temporary stream crossings removed	Culverts   Forest road stream crossings
Timber Harvesting<	Proper slope at landings   Waterbodies free of slash materials	Acres harvested   >Number of cable yarding operations	Landings   100 yd of stream adjacent to harvest site
Site Preparation and Forest Regeneration	Adequate distribution of seedlings on prepared sites   Nonmechanical site preparation used in SMAs	Method of site preparation   Acres revegetated	100-yd2 plots   100 yd of SMA

• Stakeholder goals for monitoring efforts. Watershed stakeholders often participate in follow-up monitoring, and their interests, in addition to TMDL analysis, should be considered in devising monitoring plans.
• Existing monitoring activities, resources, and capabilities. Analysts should identify existing and planned monitoring activities to address TMDL monitoring needs in concert with these efforts, particularly where a long-term monitoring program is envisioned, the study area is large, or water quality agency monitoring resources are limited. Staff capabilities and training should also be considered to ensure that monitoring plans are feasible.
• Practical constraints to monitoring. Monitoring options can be limited by practical constraints (e.g., problems with access to monitoring sites and concerns about indirect impacts of monitoring on habitat).

Key Questions to Consider for Follow-Up Monitoring and Evaluation

• What key factors influence monitoring plan design?
• What is an appropriate monitoring plan?
• What is an appropriate review and revision schedule?
• What is an adequate description of the monitoring plan for the TMDL submittal?

3.3 Public Participation

Public participation is a requirement of the TMDL process and is vital to a TMDL's success. The regulation, at 40 CFR 130.37 states that the public must be allowed at least 30 days to review and comment on a TMDL prior to its submission to EPA for review and approval. In addition, with its TMDL submittal, a State, Territory, or authorized Tribe must provide EPA with a summary of all public comments received regarding the TMDL and the State's, Territory's, or authorized Tribe's response to those comments, indicating how the comments were considered in the final decision.

EPA believes, however, that stakeholders can contribute much more than their comments on a specific TMDL during the public review process. Given the opportunity, stakeholders can contribute credible, useful data and information about an impaired or threatened water body. They may also be able to raise funds for monitoring or to implement a specific control action and/or management measure.

More importantly, stakeholders can offer insights about their community that may ensure the success of one TMDL allocation strategy over an alternative, as well as the success of follow-up monitoring and evaluation activities. Stakeholders possess knowledge about a community's priorities, how decisions are made locally, and how different residents of a watershed interact with one another. A thorough understanding of the social, political, and economic issues of a watershed is as critical to successful TMDL development as an understanding of the technical issues. States, Territories, and authorized Tribes can create a sense of ownership among watershed residents and Adiscover@ innovative TMDL strategies through a properly managed public participation process.

Each State, Territory and authorized Tribe is required to establish and maintain a continuing planning process (CPP) as described in section 303(e) of the Clean Water Act. A CPP contains, among other items, a description of the process that the State, Territory or authorized Tribe uses to identify waters needing water quality based controls, a priority ranking of these waters, the process for developing TMDLs, and a description of the process used to receive public review of each TMDL. EPA encourages States, Territories, and authorized Tribes to use their CPP as the basis for establishing a process for public participation, involvement, and in many cases leadership, in TMDL establishment. On a watershed level, the continuing planning process allows programs to combine or leverage resources for public outreach and involvement, monitoring and assessment, development of management strategies, and implementation.

While stakeholder involvement in TMDL development and implementation may, in some cases, be a critical component to attaining water quality standards, this involvement must be balanced with the fact that EPA, States, Territories, and authorized Tribes are legally responsible for interpreting water quality standards, setting, targets, establishing a watersheds's total load, allocating loadings, and assuring implementation of all appropriate requirements.

3.3a Possible Approaches for Stakeholder Involvement/Public Participation in TMDL Development and Implementation

While the concept and possible benefits of involving the public in the TMDL process are potentially rewarding, the process of doing so is inherently challenging. As mentioned above, the involvement of key stakeholders in TMDL development and implementation does not change the legal responsibility of EPA, States, Territories, and authorized Tribes to meet water quality standards. However, early and ongoing stakeholder involvement generally leads to a more successful and effective TMDL development and implementation process. Therefore, consideration should be given to the following approach:

• Encourage Public Participation: encourage and support a substantial role for stakeholders in TMDL development, particularly in funding and participating in appropriate data collection and analysis and in TMDL implementation. The agency legally responsible for TMDL development (the State, Territory, authorized Tribe or EPA) must ensure that TMDL activities carried out by stakeholders meet all requirements applicable to TMDLs developed by the State, Territory or authorized Tribe including providing adequate opportunities for public comment/participation.
• Establish Written Agreements with Stakeholders: enter into a written agreement with stakeholders when allowing (and especially when relying upon) stakeholders to carry out any TMDL activities. The agreement should clarify stakeholder roles and State, Territory or authorized Tribe expectations for TMDL development, call for a balance of stakeholders to participate in TMDL activities, and specify when the overseeing State regulatory agency should step in if, at some agreed-upon point, adequate progress in TMDL development has not been made or the terms of the agreement are not being met. Prior to entering into an agreement with stakeholders to carry out any TMDL activities, States, Territories or authorized Tribes should clearly inform stakeholders of what is required for the TMDL.
• Assure Broad Representation and Objectivity: help assure objectivity in TMDL activities conducted by stakeholders, by requiring in the written agreement that stakeholders provide information to assist in documenting assumptions (while respecting confidential business information), and that stakeholders consult early and often with the State, Territory or authorized Tribe and other stakeholders on planned and ongoing activities. The agreement should also specify how the regulatory agency will ensure there are adequate mechanisms for providing all interested stakeholders with a meaningful opportunity to participate. Use of a neutral facilitator should be considered where appropriate.
• Establish Primacy of State, Territory, or authorized Tribal Responsibility: reaffirm that the State, Territory or authorized Tribe (in the written agreement and elsewhere) is legally responsible for interpreting water quality standards, setting targets, establishing the watersheds's total load, allocating loadings, and assuring implementation of all appropriate requirements. However, they should consider information voluntarily provided by stakeholders when developing a TMDL (to the extent such input is useful and deemed accurate, including stakeholder analyses or modeling to determine pollution sources and the watersheds's needed load reductions).
• Establish Boundaries around Public Participation Efforts: establish that the legally responsible agency may not delegate its role of assuring adequate public participation processes, meeting all legal requirements, and providing all interested stakeholders an opportunity to become involved. However, stakeholders may play an important role in public participation (e.g., by inviting and encouraging other stakeholders to participate fully in any parts of the TMDL process they undertake).

3.4 EPA Action on TMDLs

When EPA receives a TMDL for review and approval, it will first determine whether it contains the ten elements of a proper submittal. Once EPA ascertains that the TMDL submittal does contain the required minimum elements, the Agency's review will begin. EPA will then have 30 days to approve or disapprove the TMDL (40 CFR 130.35(a)). If the TMDL is approved, the State, Territory, or authorized Tribe is obliged to incorporate that TMDL into its water quality management plan. If EPA disapproves the TMDL, EPA will establish a new TMDL for that waterbody and pollutant within 30 days of the disapproval. Once developed, EPA will provide a 30 day public comment period on the new TMDL. If appropriate, EPA will revise the TMDL after the close of the public comment period. The TMDL will be sent to the State, Territory, or authorized Tribe for incorporation into its water quality management plan.

EPA may establish TMDLs for waterbodies and pollutants identified on Part 1 of the list if asked to do so; if EPA determines that the State, Territory, or authorized Tribe is not likely to establish TMDLs consistent with their schedule; or if EPA determines that TMDLs for interstate or boundary waterbodies must be established (40 CFR 130.36).

Contents

References