This document is a compilation of assorted policy points on key TMDL development issues.  This document can serve as a cheat sheet for citizens who are commenting on TMDLs, but don't have the time or inclination to wade through the regulations and all the random guidance and memos out there.  It is by no means a complete run down of TMDL policy, but rather a shorthand look at some key citations. 

The document is broken out by the different components of a TMDL.  Citations are provided to support your use of these points in comments or at public hearings.  For access to the citation sources, visit EPA’s TMDL web site  and click on "policy documents".

I. Description of waterbody, pollutant of concern, pollutant sources and priority ranking.

According to regulations the TMDL must:

• Identify the pollutant of concern.
• Include a description of the water quality standard  -- including the designated use(s) of the waterbody and the applicable numeric or narrative water quality criterion.[1]
• A description of the process used to derive the target value if the TMDL is based on a target other than a numeric water quality criterion (ex. narrative standards.)
• Identify the waterbody and its priority ranking as referenced in the state’s 303(d) list.
• Include a description of nonpoint and point sources of that pollutant, including the magnitude and location of the sources.  Wherever possible, natural background sources must be described and their location and magnitude must be described.

II. Loading Capacity.

Regulations say the TMDL must:

• Define loading capacity as the greatest amount of loading that a water can receive without violating water quality standards.[2]
• Take into account "...critical conditions for stream flow, loading, and water quality parameters."3]
• Use "...a pollutant-by-pollutant approach or biomonitoring approach.  In many cases both techniques may be needed."[4]
• Use site-specific information wherever possible.[5]
• Express loadings as either mass-per-time, toxicity or other appropriate measure.[6]
• Provide for public review of the calculations used to establish the TMDL (as expressed in the state’s Continuing Planning Process.)[7]
• Identify the waterbody’s loading capacity for the pollutant and describe the rationale used to establish the cause-and-effect relationship between the numeric target and the identified sources of the pollutant.
• Include supporting documentation for the analysis as part of the TMDL submittal. 
• The critical condition(s) must be described and related to the conditions in the waterbody as part of the loading capacity analysis.[8]

The TMDL should contain a description of any important assumptions made in developing the TMDL such as:

• The assumed land use in the watershed
• Population characteristics, wildlife resources and other relevant information used to develop the TMDL.
• Any analysis of growth trends used in developing the TMDL
• An explanation and analytical basis for using surrogate measures in the TMDL, if applicable.

III.  Load Allocations  (see also Implementation Plans)

Regulations say the load allocation must:

• Be defined as: "The portion of a receiving water’s loading capacity that is attributed either to one of its existing or future nonpoint sources of pollution or to natural background sources."[9]
• Be "best estimates of loading" and may be allocations to specific nonpoint sources or broad allocations to a class of sources.[10]
• Distinguish between natural and nonpoint source loads wherever possible.[11]
• If a TMDL finds there are no nonpoint sources or natural background sources of the pollutant of concern, the load allocation must be zero. [12]   This allocation must be rationalized -- an allocation of zero means that allocating all of the loading capacity to point sources will result in the achievement of water quality standards. 

Guidance and other EPA documents say the TMDL should:

• For waters"impaired solely or primarily by nonpoint sources, each EPA Region should work in partnership with each State to achieve TMDL load allocations for nonpoint sources.  All available Federal, State, and local programs and authorities should be used, including non-regulatory, regulatory, or incentive-based programs"[13]

IV.  Wasteload Allocations

Regulations say the TMDL must:

•  Identify the portion of the loading capacity allocated to point sources of pollution -- both existing and future point sources.[14]
• Only allow wasteload allocations to be offset by load allocations where "Best Management Practices (BMPs) or other nonpoint source pollution controls make more stringent load allocations practicable."[15]
• Guidance and other EPA documents say Wasteload Allocation should:
• Ensure divisions of the loading capacity into wasteload allocations and load allocations are reasonable.  If a point source is given a less stringent WLA based on the assumption that nonpoint source load reductions will occur, the TMDL should demonstrate reasonable assurance that the nonpoint source reductions will occur within a reasonable time.[16]
• Implement antibacksliding provisions from section 402(o) -- check your TMDL to ensure that WLA either lower existing limits or met the provisions in 402(o).  The WLA will normally result in new or more stringent water quality-based limits than those contained in a previously issued permit.  In a limited number of cases, however, it is conceivable that less stringent water quality-based limits could result.  In these cases, permit limits must conform to the antibacksliding provisions.[17]

V.  Margin of Safety

The Clean Water Act says:

• A margin of safety is required to account for any lack of knowledge concerning the relationship between load allocations and water quality.[18]

Regulations say the Margin of Safety must:

• Account for any lack of knowledge concerning the relationship between load allocations and water quality.[19]

Guidance and other EPA documents say:

• EPA guidance says that the MOS can be implicit or explicit.  However, if the MOS is implicit the conservative assumptions in the analysis that account for the MOS must be described.  If the MOS is explicit, the amount of the loading capacity set aside for the MOS must be identified.[20]

VI.  Seasonal Variation.

The Clean Water Act says:

• A TMDL must consider seasonal variations and the method used to account for seasonal variations must be described.[21]

Regulations say:

• A TMDL must consider seasonal variations and the method used to account for seasonal variations must be described.[22]

VII.  Monitoring and TMDLs.

Guidance says:

• EPA recommends a monitoring plan when a TMDL is developed under a phased approach (see glossary).   The monitoring plan should include collection of additional data to determine if the load reductions required by the TMDL actually lead to the attainment of water quality standards.[23]
• EPA says, "The Clean Water Act authorizes imposition of monitoring and data collection requirements on the owner or operator of a point source discharge.  Requirements may include ambient and biological assessments, toxicity reduction evaluations, in-plant monitoring, etc."[24] 
• Section 308 authorities can be used to request the information directly or the information can be collected through permit reporting requirements or an administrative order.[25]

VIII.  Implementation Plans

Guidance and other EPA documents say:

• For all waters "impaired solely or primarily by nonpoint sources, each state should describe its plan for implementing load allocations for nonpoint sources.  The State implementation plan may describe how load allocations will be achieved by nonpoint sources for individual waters, for several waters within a watershed, or for all affected waters in the state."[26]
• Again for waters primarily or solely impaired by nonpoint sources:  "States may submit implementation plans to EPA as revisions to State water quality management plans, coupled with a proposed TMDL, or as part of an equivalent watershed or geographic planning process."[27]
• The plans mentioned in the previous bullet should include:  1.)  reasonable assurances that the nonpoint source load allocations will be achieved; 2.) a public participation process; and 3.)  "recognition" of other watershed management processes (ex. source water protection programs or the CPP.[28]
• EPA Regions have been asked to work in partnership with States/Tribes to achieve nonpoint source load allocations for impaired waters impaired solely or primarily by nonpoint sources.  The Regions have been directed to do this by assisting States/Tribes with developing implementation plans with reasonable assurances that reductions will actually be achieved.  EPA does not, however, approve the implementation plans.[29]

IX.  Reasonable Assurances

Guidance and other EPA documents say:

• In waters impaired by a blend of point and nonpoint sources, if a point source is given a less stringent WLA based on the assumption that nonpoint source load reductions will occur, the TMDL should demonstrate reasonable assurance that the nonpoint source reductions will occur in order for the TMDL to be approvable. [30]
• For waters impaired primarily or solely by nonpoint sources, EPA says reasonable assurances should be included in the TMDL in the implementation plans described above.  Such reasonable assurances may be:  "non-regulatory, regulatory, or incentive-based, consistent with applicable laws and programs."[31] 

 
[1] 40 C.F.R. 130.7(c)(1)

[2] 40 C.F.R. 130.2(f)

[3] 40 C.F.R. 130.7(c)(1)

[4] 40 C.F.R. 130.7(c)(1)

[5] 40 C.F.R. 130.7(c)(1)

[6]  40 C.F.R. 130.2(i)

[7] 40 C.F.R. 130.7(c)(1)(ii)

[8] 40 C.F.R. 130.7(c) (1)

[9] 40 C.F.R. 130.2 (g)

[10] 40 C.F.R. 130.2(g)

[11] 40 C.F.R. 130.2(g)

[12] 40 C.F.R. 130.2(i)

[13] New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.

[14] 40 C.F.R. 130.2(h)

[15] 40 C.F.R. 130.2 (i)

[16] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991.

[17] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991, Chapter 3.

[18]  CWA 303(d)(1)(C)

[19] 40 CFR 130.7 (c)(1)

[20] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991.

[21] CWA 303(d)(1)(C)

[22] 40 C.F.R. 130.7(c)(1)

[23] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991.

[24] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991, Chapter 3.

[25] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991, Chapter 3.

[26]  New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.

[27] New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.

[28] New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.

[29]   New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.

[30] Guidance for Water Quality-Based Decisions:  The TMDL Process (EPA 440/4-91-001) 1991.

[31] New Policies for Establishing and Implementing Total Maximum Daily Loads, Bob Perciasepe (then EPA AA for the Office of Water) memo to the EPA Regions dated August 8, 1997.