United States
Environmental Protection
Agency
Office of Water
(WH-553)
Washington, D.C. 20460
EPA 440/4-91 -001
April 1991
&EPA
Guidance for Water
Quality-based Decisions
The TMDL Process
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Guidance for Water
Quality-based Decisions:
The TMDL Process
Assessment and Watershed Protection Division
U.S. Environmental Protection Agency
Washington, D.C. 20460
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This document provides guidance only. It does not establish or affect legal rights or
obligations. This guidance may be reviewed and revised periodically to reflect
changes in EPA's strategy for the implementation of water quality-based controls, to
include new information, or to clarify and update the text. Decisions in any particular
case will be made by applying the Clean Water Act and implementing regulations.
Comments are invited and will be considered in future revisions. Comments or
inquiries should be directed to :
Watershed Branch
Assessment and Watershed Protection Division (WH-553)
U.S. Environmental Protection Agency
401 M St. SW
Washington, D.C. 20460
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FOREWORD
This document, "Guidance for the Implementation of Water
Quality-based Decisions: The TMDL Process," is intended to define
and clarify the requirements under section 303(d) of the dean Water
Act Its purpose is to help State water quality program managers
understand the application of total maximum daily loads within the
water quality-based approach to establish pollution control limits for
waters not meeting water quality standards.
Water quality management has become increasingly more
complicated. Problems such as toxic contaminants, sediments,
nutrients, and habitat alteration result from a variety of point and
nonpoint sources. The TMDL process is established under the Clean
Water Act as the mechanism to address these problems in a
comprehensive manner in situations where technology-based controls
are not adequate.
Through this guidance we hope to reduce the uncertainties
associated with TMDLs and to establish the TMDL process as an
effective water quality management tool for both point and nonpoint
source pollution control
Martha G. Prothro, Director
Office of Water Regulations and Standards
US Environmental Protection Agency
Washington, D.C
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TABLE OF CONTENTS
Page
CHAPTER 1 - INTRODUCTION 1
Purpose and Summary 1
Policies and Priniciples 2
Clean Water Act Section 303(d) 4
Water Quality Planning and Management Regulation 6
CHAPTER 2 - THE WATER QUALITY-BASED APPROACH TO
POLLUTION CONTROL 9
Step One: Identification of Water Quality-Limited Waters 11
Step Two: Priority Ranking and Targeting 13
Step Three: TMDL Development 14
Step Four: Implementation of Control Actions 16
Step Five: Assessment of Water Quality-Based Control Actions 16
CHAPTERS - DEVELOPMENT AND IMPLEMENTATION OF THE TMDL 19
Development of the TMDL 19
The TMDL Objective 19
The TMDL Process 19
Selection of Approach 20
The Phased Approach 22
Approval of TMDLs by EPA 23
Implementation of the TMDL 23
NPDES Process for Point Sources 23
State or Local Process for Nonpoint Sources 24
Assessment of the TMDL 25
CHAPTER 4-EPA AND STATE RESPONSIBILITIES 27
EPA/State Agreements 27
State Responsibilities 27
Identification of Water Quality-Limited Waters Still Requiring TMDLs 27
Identification and Scheduling of Targeted Waterbodies 29
TMDL Development 29
Continuing Planning Process 29
Water Quality Management Plan 30
Public Notice and Participation 30
Reporting 31
Other Specific Responsibilities 31
EPA Responsibilities 32
Review of 303(d) lists 32
TMDL Review and Approval 32
Program Audits 33
Technical Assisfan^y and Training 33
Guidance Documents and Reports 33
EPA Headquarters Responsibilities 33
EPA Regional Responsibilities 33
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Page
APPENDIX A- RELATIONSHIP TO OTHER GUIDANCE 35
Monitoring Guidance 35
Cooperative Monitoring/Citizen Volunteer Monitoring Guidance 35
Wastetaad Allocation Technical Guidance 36
Technical Support Document for Water Quality-Based Toxics Control 36
Permit Writers Guidance 37
Nonpoint Source Guidance 37
APPENDIX B-SUPPORTING PROGRAMS 38
EPA Water Quality Criteria and Standards 38
Section 305
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CHAPTER 1 INTRODUCTION AND
EXECUTIVE SUMMARY
Purpose and Summary
The purpose of this guidance document
is to explain the programmatic elements and
requirements of the TMDL process as estab-
lished by section 303(d) of the Clean Water
Act and by EPA's Water Quality Planning
and Management Regulations (40 CFR Part
130). A TMDL, or total maximum daify load,
is a tool for implementing State water quality
standards and is based on the relationship
between pollution sources and in-stream
water quality conditions. The TMDL estab-
lishes the allowable loadings or other quan-
tifiable parameters for a waterbody and
thereby provides the basis for States to estab-
lish water quality-based controls. These
controls should provide the pollution reduc-
tion necessary for a waterbody to meet water
quality standards.
Section 303(d) of the Act establishes the
TMDL process to provide for more stringent
water quality-based controls when technol-
ogy-based controls are inadequate to
achieve State water quality standards. When
implemented according to this guidance, the
TMDL process can broaden the opportunity
for public participation, expedite water qual-
ity-based National Pollutant Discharge
Elimination System (NPDES) permitting,
and lead to technically sound and legally
defensible decisions for attaining and main-
taining water quality standards. In addition,
the TMDL process provides a mechanism
for integrating the management of both the
point and nonpoint pollution sources that
together may contribute to a waterbody's
impairment.
Chapter Two of this guidance document
provides a description of the TMDL process
in the context of the water quality-based ap-
proach to pollution reductions. This ap-
proach includes the identification and
priority ranking of water quality-limited wa-
ters, the targeting and scheduling of high
priority waters, the development of TMDLs,
and the implementation of control actions
that should result in the attainment of water
quality standards. Assessment for water
quality standards attainment provides the in-
formation needed to identify water quality-
limited waters and for the evaluation of the
TMDL and control actions.
The development and implementation
of the TMDL establishes the link between
water quality standards assessment and
water quality-based control actions. The
third chapter of this document describes how
a State should proceed with developing
TMDLs once waters are targeted for action
and then how to implement them. Special
consideration is given to such issues as ade-
quacy of data and information, how to con-
sider nonpoint source contributions, and
when to use a modified approach, called the
phased approach, that results in a TMDL
with special requirements. Implementation
of the TMDL is discussed in terms of the
mechanisms that are available to reduce
both point and nonpoint loads.
The final chapter of this guidance de-
scribes the specific roles and responsibilities
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that the States and EPA have in implement-
ing CWA section 303(d). EPA review and
approval of lists of waters submitted by the
States, the priority rankings of these waters,
and the TMDLs are set forth in the Water
Quality Planning and Management Regula-
tion. This guidance presents a detailed dis-
cussion of the submission of lists and
TMDLs, and the review and approval pro-
cesses. The States' responsibility to involve
the public in the TMDL process is also high-
lighted in this chapter. The value and im-
portance of public participation is also
emphasized throughout the document
This guidance focuses on the program-
matic aspects rather than the technical issues
of the TMDL process. Numerous technical
guidance manuals have been developed by
EPA to assist States in calculating wasteload
allocations (WLA). A list of these manuals
can be found in Appendix A along with a
description of other relevant guidance docu-
ments. A brief description of selected tech-
nical considerations can be found in
Appendix D and information about EPA
supported models can be found in Appendix
E. The other appendices provide the reader
with useful and relevant information such as
descriptions of related water quality pro-
grams (Appendix B) and a general outline of
an EPA/State agreement for TMDL devel-
opment (Appendix F).
Policies and Principles
To achieve the water quality goals of the
Clean Water Act, EPA's first objective is to
ensure that technology-based controls on
point sources are established and main-
tained. Where such controls are insufficient
to attain and maintain water quality stan-
dards, water quality-based controls are re-
quired. Under the authority of section
303(d) of the Clean Water Act, EPA expects
States to develop TMDLs for their water
quality-limited waters where technology-
based effluent limitations or other legally
required pollution control mechanisms are
not sufficient or stringent enough to imple-
ment the water quality standards applicable
to such waters.
More intensive assessments of water
quality and an evaluation of pollution
sources should be conducted where water
quality standard violations occur or where
indications of declining water quality or hab-
itat loss are observed. A TMDL should be
developed and appropriate control actions
taken on all pollution sources and follow-up
monitoring should be conducted to assure
that water quality standards are met. If fol-
low-up monitoring indicates that water qual-
ity standards are not or will not be met, a
revised TMDL is required.
Lack of information about certain types
of pollution problems (for example, those
associated with nonpoint sources or with cer-
tain toxic pollutants) should not be used as a
reason to delay implementation of water
quality-based controls. When developed ac-
cording to a phased approach, the TMDL
can be used to establish load reductions
where there is impairment due to nonpoint
sources or where .there is a lack of data or
adequate modeling. EPA regulations pro-
vide that load allocations for nonpoint
sources may be based on "gross allotments"
(40 CFR 13(U(g)) depending on the avail-
ability of data and appropriate techniques
for predicting loads. In addition, before ap-
proving a TMDL in which some of the load
reductions are allocated to nonpoint sources
in lieu of additional load reductions allo-
cated to point sources, there must be specific
assurances that the nonpoint source reduc-
tions will in fact occur. Therefore, this guid-
ance provides that in specific situations, the
TMDL must include a schedule for the im-
plementation of control mechanisms, moni-
toring, and assessment of standards
attainment. If standards are not attained, a
TMDL revision is required. Data collected
through monitoring would then be useful in
revising the TMDL. While this phased ap-
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PRINCIPLES
Biennial Submission of Lists. Every two years, States will submit their required 303(d) identification of water
quality-limited waters still needing TMDLs including a priority ranking of waterbodies to EPA. These lists may
be included with a State's biennial 305(b) report or as a separate report submitted at the same time as the 305(b)
report. (See page 27.)
Priority TMDLs. Along with the biennial submission of 303(d) lists, States will identify high priority waters
targeted for TMDL development over the next two years. (See page 29.)
Approach for TMDL Development When specific criteria are met, a TMDL with additional specifications for
monitoring and implementation under the phased approach should be developed to provide for immediate
pollution reduction and for collection of additional information. (See page 14 and 22.)
Implementation of Controls Based on TMDLs. States will continue to improve and maintain point source
controls through WLAs and NPOES permits while implementing and maintaining nonpoint source controls
through LAs and State or local requirements (see page 23.)
Nonpoint Source Controls. LAs for nonpoint sources will be accompanied by a description of nonpoint source
load reduction goals and the procedure for reviewing and revising nonpoint source controls. Such descriptions
will be referenced in reviewing TMDLs for approval (See page 24.)
Time Schedule. TMDLs will be developed on a schedule negotiated with EPA Regional offices. Time schedules
for the review of TMDLs will also be negotiated with EPA Regional offices, but will occur within the statutory
requirement of 30 days. (See pages 29 and 32.)
Geographic Targeting. States should develop TMDLs that account for both point and nonpoint sources on a
geographically targeted waterbody basis. Geographically targeted waterbodies could include segments, basins,
and watersheds as defined by the States. (See page 14.)
Threatened Good Quality Waters. States are expected to include threatened good quality waters in their
identification and prioritization of waters still needing TMDLs. (See page 12.)
Public Participation. States are expected to ensure appropriate public participation in the TMDL development
and implementation process. (See page 30.)
Environmental Indicators. States should measure the effectiveness of control actions by monitoring changes
in ambient water quality or biological conditions. Measuring environmental progress or showing environmental
results is a critical need and has become a key clement in EPA's strategic planning process.
proach requires additional monitoring of the
waterbody to evaluate the effectiveness of
nonpoint source management measures or
more stringent effluent limitations, it does
not delay the establishment of such control
mechanisms where there is a lack of informa-
tion.
As required by the Clean Water Act,
States are to identify and report to EPA their
water quality-limited waters. These waters
are to be identified according to the provis-
ions established in EPA's Water Quality
Management and Planning Regulation at 40
CFR 130.7(b). The identified waters should
include those impaired due to point and non-
point sources and may include threatened
good quality waters. EPA is establishing
with this guidance that States should submit
to EPA, in conjunction with the 305(b) water
quality assessment reports, in April of 1992,
the list of water quality-limited waters that
still require TMDLs. Every two years there-
after, a State should update its list of 303(d)
waters and submit it with the 305(b) report.
This guidance describes in detail the identi-
fication process and the specific information
that should be submitted to EPA.
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As required by the Clean Water Act,
States are to rank by priority all waters need-
ing TMDLs. Since each State has a unique
organizational arrangement for the protec-
tion of water quality, this guidance does not
prescribe how a State should set its priorities.
However, priority ranking should result in
the identification of targeted waterbodies
for which immediate TMDL development
should be undertaken. In the biennial sub-
mission of their updated list of 303(d) waters,
EPA expects States to identify the waters
targeted for TMDL development in the
forthcoming two years.
Historically, the water quality-based pol-
lution control program has focused on re-
ducing the load of chemical contaminants
(e.g. nutrients, biochemical oxygen demand,
metals) to waterbodies. EPA has defined
the terms load, loading capacity, and load
allocation in regulations and technical guid-
ance documents so that wasteload alloca-
tions can be calculated. Chemical
contaminant problems will continue to con-
stitute a major portion of pollution control
efforts and the terms "load" and "load reduc-
tion" are used throughout this document.
However, it is becoming increasingly appar-
ent that in some situations water quality stan-
dards particularly designated uses and
biocriteria can only be attained if non-
chemical factors such as hydrology, channel
morphology, and habitat are also addressed.
EPA recognizes that it is appropriate to use
the TMDL process to establish control mea-
sures for quantifiable non-chemical param-
eters that are preventing the attainment of
water quality standards. Control measures,
in this case, would be developed and im-
plemented to meet a TMDL that addresses
these parameters in a manner similar to
chemical loads. As methods are developed
to address these problems, EPA and the
States will incorporate them into the TMDL
process.
The principles (see page 3) established
by EPA in this guidance reflect these policies
and reaffirm the existing regulatory require-
ments. They are intended to help States
manage their surface water quality programs
in a manner consistent with the intent and
requirements of section 303(d) of the CWA
and the Water Quality Planning and Man-
agement Regulations hi 40 CFR130. These
principles are discussed throughout this
guidance.
Clean Water Act Section 303 (d)
Section 303(d) of the Act (see next page)
requires States to identify waters that do not
or are not expected to meet applicable water
quality standards with technology-based
controls alone. Waters impacted by thermal
discharges are also to be identified. States
are required to establish a priority ranking
for these waters, taking into account the pol-
lution severity and designated uses of the
waters.
Once the identification and priority
ranking of water quality-limited waters are
completed, States are to develop TMDLs at
a level necessary to achieve the applicable
State water quality standards. Completed
TMDLs must allow for seasonal variations
and a margin of safety that accounts for any
lack of knowledge concerning the relation-
ship between effluent limitations and water
quality.
States are required to submit to EPA the
"waters identified and loads established" for
review and approval by EPA. If disap-
proved, EPA will establish the TMDLs at
levels necessary to implement the applicable
water quality standards. For waters that are
not identified under sections 303(d)(l)(A)
and (1)(B) as being water quality-limited,
States are to estimate TMDLs for informa-
tion purposes.
Subsections 4(A) and (B) were added to
CWA section 303(d) with the 1987 amend-
ments in order to ensure consistency with the
water quality standards process for use clas-
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FEDERAL WATER POLLUTION CONTROL ACT
Section 303(d)
(1) (A) Each State shall identify those waters within its boundaries for which the effluent limitations required by section
301 (b) (1)(A) and section 301 (b) (1) (B) are not stringent enough to implement any water quality standard applicable
to such waters. The State shall establish apriority ranking for such waters, taking into account the severity of the
pollution and the uses to be made of such waters.
(B) Each State shall identify those waters or parts thereof within its boundaries for which controls on thermal
discharges under section 301 are not stringent enough to assure protection and propagation of a balanced indigenous
population of shellfish, fish, and wildlife.
(C)Each State shall establish for the waters identified in paragraph (1)(A) of this subsection, and in accordance with
the priority ranking, the total maximum daify load, for those pollutants which theAdministrator'identifies under'section
304(a) (2) as suitable for such calculation. Such load shall be established at a level necessary to implement the
applicable water quality standards with seasonal variations and a margin of safety which takes into account any lack
of knowledge concerning the relationship between effluent limitations and water quality.
(D) Each State shall estimate for the waters identified in paragraph (1)(B) of this subsection the total maximum daify
thermal load required to assure protection and propagation of a balanced, indigenous population of shellfish, fish
and wildlife. Such estimates shall take into account the normal water temperatures, flow rates, seasonal variations,
existing sources of heat input, and the dissipative capacity of the identified waters or parts thereof. Such estimates
shall include a calculation of the maximum heat input that can be made into each such pan and shall include a
margin of safety which takes into account any lack of knowledge concerning the development of thermal water quality
criteria for such protection and propagation in the identified waters or pans thereof.
(2) Each State shall submit to the Administrator from time to time, with the first such submission not later than one
hundred and eighty days after the date of publication of the first identification of pollutants under section
304(a)(2)(D), for his approval the waters identified and the loads established under paragraphs (1)(A), (1)(B),
(1)(C), and (I)(D) of this subsection. The Administrator shall either approve or disapprove such identification and
load not later than thirty days after the date of 'submission. If the Administrator approves such identification and load,
such State shall incorporate them into its current plan under subsection (e) of this section. If the Administrator
disapproves such identification and load, he shall not later than thirty days after the date of such disapproval identify
such waters in such State and establish such loads for such waters as he determines necessary to implement the water
quality standards applicable to such waters and upon such identification and establishment
them into its current plan under subsection (e) of this section.
(3) For the specific purpose of developing information, each State shall identify all waters within its boundaries which
it has not identified under paragraph (1)(A) and (1)(B) of this subsection and estimate for such waters the total
maximum daify load with seasonal variations and margins of safety, for those pollutants which the Administrator
identifies under section 304(a)(2) as suitable for such calculation and for thermal discharges, at a level that would
assure protection and propagation of a balanced indigenous population offish, shellfish and wildlife.
(4) LIMITATIONS ON REVISION OF CERTAIN EFFLUENT LIMITATIONS. -
(A) STANDARD NOT ATTAINED.-For waters identified under paragraph (1)(A) where the applicable water
quality standard has not yet been attained, ary effluent limitation based on a total rnaximum daify load or other waste
load allocation established under this section may be revised onfy if (i) the cumulative effect of all such revised effluent
limitations based on such total maximum daify load or waste load allocation will assure the attainment of such water
quality standard, or (ii) the designated use which is not being attained is removed in accordance with regulations
established under this section.
(B)STANDARDATTAINED.-Forwatersidentifiedunderparagraph (1)(A) where the quality of such waters equals
or exceeds levels necessary to protect the designated use for such waters or otherwise required by applicable water
quality standard, any effluent limitation based on a total maximum daify load or other waste had allocation
established under this section, or any water quality standard established under this section, or any other permitting
standard may be revised onfy if such revision is subject to and consistent with the antidegradation policy established
under this section.
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sification and with the NPDES antibackslid-
ing requirements.
Water Quality Planning and
Management Regulation
EPA's Water Quality Planning and Man-
agement Regulation at 40 CFR Part 130 es-
tablishes the program and policies that
implement CWA section 303(d) require-
ments. Section 130.7 describes the TMDL
process and the State's responsibility for
identifying waters still requiring TMDLs,
setting priorities and developing TMDLs,
submitting the waters identified with priority
rankings and the TMDLs to EPA for ap-
proval, and the incorporation of the TMDLs
into the State's Water Quality Management
Plan.
To implement the program, the regula-
tion establishes the following definitions for
loading capacity, load allocation, wasteload
allocation, total maximum daily load, water
quality-limited segments and water quality-
limited segments still requiring TMDLs. A
definition for margin of safety (MOS) is also
provided.
Loading capacity (LC) - The greatest
amount of loading that a water can receive
without violating water quality standards.
(40 CFR 130.2(0)
Load allocation (LA) - The portion of a
receiving water's loading capacity that is at-
tributed either to one of its existing or future
nonpoint sources of pollution or to natural
background sources. Load allocations are
best estimates of the loading, which may
range from reasonably accurate estimates to
gross allotments, depending on the availabil-
ity of data and appropriate techniques for
predicting the loading. Wherever possible,
natural and nonpoint source loads should be
distinguished. (40 CFR 130.2(g))
Wasteload allocation (WLA) -The por-
tion of a receiving water's loading capacity
that is allocated to one of its existing or fu-
ture point sources of pollution. WLAs con-
stitute a type of water quality-based effluent
limitation. (40 CFR 130.2(h))
Total maximum daily load (TMDL) -
The sum of the individual WLAs for point
sources and LAs for nonpoint sources and
natural background. If a receiving water has
only one point source discharger, the TMDL
is the sum of that point source WLA plus the
LAs for any nonpoint sources of pollution
and natural background sources, tributaries,
or adjacent segments. TMDLs can be ex-
pressed in terms of either mass per time,
toxitity, or other appropriate measure that
relate to a State's water quality standard. If
Best Management Practices (BMPs) or
other nonpoint source pollution control ac-
tions make more stringent load allocations
practicable, then WLAs can be made less
stringent Thus, the TMDL process provides
for nonpoint source control tradeoffs. (40
CFR
In practice, the terms TMDL and WLA
have at times been incorrectly used inter-
changeabfy instead of considering both LA
and WLA as components of a TMDL. A
TMDL, as referenced in this guidance, in-
cludes both WLAs and LAs, established in
accordance with EPA 's regulations.
Water quality-limited segments - Those
water segments that do not or are not ex-
pected to meet applicable water quality stan-
dards even after the application of
technology-based effluent limitations re-
quired by sections 301(b) and 306 of the Act.
(40 CFR 130.20')) Technology-based con-
trols include, but are not limited to, best
practicable control technology currently
available (BPT) and secondary treatment.
Water quality-limited segments still re-
quiring TMDLs Segments identified
through a process established by paragraph
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130.7(b)(l) of EPA's Water Quality Plan-
ning and Management Regulation. Waters
need TMDLs when certain specified pollu-
tion reduction requirements (identified in
the regulation under subparagraphs
(b)(l)(i), (ii), and (iii)) are not stringent
enough to implement water quality stan-
dards for such waters. The specified pollu-
tion controls include technology-based
effluent limitations required by sections
301(b) and 306 of the Clean Water Act and
other appropriate requirements that can
provide a more stringent level of treatment
than federally-required technology-based
effluent limitations. (40 CFR 130.7(b)(l))
This document contains the terms 303(d)
waters and 303(d) lists. These waters (and
waters on the 303(d) lists) are those water
quality-limited segments that still require
TMDLs as defined by the regulation. Thus, a
water segment that meets its water quality stan-
dards after the implementation of water qual-
ity-based control actions would retain its water
quality-limited status but would no longer be
on a State's 303 (d) list of waters still requiring
TMDLs.
Margin of Safety (MOS) - A required
component of the TMDL that accounts for
the uncertainty about the relationship be-
tween the pollutant loads and the quality of
the receiving waterbody. (CWA section
303(d)(l)(Q) The MOS is normally incor-
porated into the conservative assumptions
used to develop TMDLs (generally within
the calculations or models) and approved by
EPA either individually or in State/EPA
agreements. If the MOS needs to be larger
than that which is allowed through the con-
servative assumptions, additional MOS can
be added as a separate component of the
TMDL (in this case, quantitatively, a TMDL
= LC = WLA -I- LA + MOS).
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CHAPTER 2 - THE WATER QUALITY-BASED APPROACH
TO POLLUTION CONTROL
The Water Quality Planning and Man-
agement Regulation (40 CFR 130) links a
number of Clean Water Act sections, includ-
ing section 303(d), to form the water quality-
based approach to protecting and cleaning
up the nation's waters (diagrammed in Fig-
ure 1). This chapter describes the overall
approach for the development of TMDLs
and subsequent implementation of water
quality-based point and nonpoint source
pollution control measures based on water
quality standards. Other related guidance
on various aspects of the water quality-based
approach are described in Appendix A.
The water quality-based approach em-
phasizes the overall quality of water within a
waterbody and provides a mechanism
through which the amount of pollution en-
tering a waterbody is controlled based on the
intrinsic conditions of that body of water and
the standards set to protect it. This approach
begins with the determination of waters not
meeting (or not expected to meet) water
quality standards after the implementation
of technology-based controls (such as BPT
and secondary treatment). Waters identi-
fied through this process are considered
water quality-limited and must be priori-
tized. An overall plan to manage the excess
pollutants in each waterbody can then be
developed. The necessary limitations on the
introduction of pollutants to the waterbody
are identified through the development of a
TMDL under section 303(d).
Previous practices for implementing
303(d) have focused primarily on point
sources and wasteload allocations (WLA).
All water quality-based permit limits are
based on a WLA. The WLA is either re-
viewed individually by EPA or where there
exists a State/EPA technical agreement, is
developed consistent with that agreement.
In recent years nonpoint source contribu-
tions to water quality problems have become
better understood and it is now clear that
EPA and State implementation of 303(d)
must encompass nonpoint source pollution
problems and seek to address problems oc-
curring over large geographic areas. As a
consequence, this document describes a
more rigorous process for implementing
303(d) and reinforces the need to develop
TMDLs that include load allocations (LA)
as well as wasteload allocations.
As shown in Figure 1, the water quality-
based approach contains the following steps:
1. Identification of water quality-
limited waters still requiring TMDLs.
2. Priority ranking and targeting.
3. TMDL development.
USEPA. 1985. Guidance for State Water Monitoring and Wasteload Allocation Program. OW/OWRS,
EPA 440/4-85-031. Washington, D.C.
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Figure 1
General Elements of the
Water Quality-Based Approach
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of Wat* Quality.
Control Acttona
Priority Ranking and Targeting
wtth othar
lng and managamant
AndftNPS contratolbr
pnortty ranking to target
waterbodlMforTtlDU
cnaMyatandafda
of TMOLs
approach whan
achadula for phaaad
if nacaaaary
tMOLdavatoomant
Implamantnonpolntao
Not«: TMOL d«valopm«nt for targatad watarbodiaa la aummarizad in Figura 2 (p. 21)
10
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4. Implementation of control actions.
5. Assessment of water quality-based
control actions.
Steps 1, 2, and 3 are addressed by the
CWA in section 303(d). Steps 4 and 5 are
integral parts of the process and are briefly
described in this document.
States are to review and revise water
quality standards, as necessary, every three
years and NPDES permits are to be re-eval-
uated and issued every five years. The water
quality-based approach links these two pro-
cesses and is, therefore, an ongoing process
of evaluation and modification. In addition
to standards and permits revisions, section
319(b) nonpoint source (NFS) management
plans can and should be continually updated
as well.
Step One: Identification of Wetter
Quality-Limited Waters
The water quality-based approach to pol-
lution control begins with the identification
of problem waterbodies. State water quality
standards form the basis and "yardstick" by
which States can assess the waterbody status
and implement needed pollution controls.
State water quality standards include three
elements: designated uses for the water-
body, criteria (physical, chemical, and bio-
logical) to protect the designated uses, and
an antidegradation statement States need
to identify those waters not meeting any one
of these components of water quality stan-
dards.
EPA's Water Quality Planning and Man-
agement Regulation establishes the process
for identifying water quality-limited seg-
ments still requiring TMDLs. Waters re-
quire TMDLs when certain pollution control
requirements (see box) are not stringent
enough to implement water quality stan-
dards for such waters.
Identifying Waters Still Requiring
TMDLs: 40 CFR 130.7(b)
(b)(l) Each State shall identify those water quality
segments still requiring WLAs/LAs and TMDLs
within its boundaries for which:
(i) Technology-based effluent limitations re-
quired by sections 301(b), 306,307, or other
sections of the act;
(ii) More stringent effluent limitations (includ-
ing prohibitions) required by either State
or local authority preserved by section 510
of the Act, or Federal authority (e^, law,
regulation, or treaty); and
(iii) Other pollution control requirements (e.g.,
best management practices) required by
local, State, or Federal authority
are not stringent enough to implement any water
quality standard applicable to such waters.
The most widely applied water pollution
controls are the technology-based effluent
limitations required by section 301(b) and
306 of the Clean Water Act. In some cases,
a State or local authority may establish en-
forceable requirements beyond technology-
based controls. Examples of such
requirements may be those that (1) provide
more stringent NPDES permit limitations to
protect a valuable water resource or (2) pro-
vide for the management of certain types of
nonpoint source pollution.
To exempt a water quality-limited water
from the TMDL process, the pollution con-
trol requirements cited in the regulation
under 130.7(b)(i),(ii), and (iii) (see box)
must be established and enforced by Fed-
eral, State, or local laws or regulations and
be stringent enough that, when applied, the
receiving waterbody will meet water quality
standards. These requirements must also be
specifically applicable to the particular water
quality problem and, if not yet implemented,
a schedule for the timely implementation of
11
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such requirements must be established.
Chapter 4 contains more specific require-
ments pertaining to identification of water
quality-limited waters still requiring TMDLs
(see p. 27).
Identification of threatened good quality
waters is an important pan of this approach.
Adequate control of new discharges from
either point or nonpoint sources should be a
high priority for States to maintain the exist-
ing use or uses of these waterbodies. In the
identification of threatened waters it is im-
portant that the 303(d) process consider the
water quality standards program to ensure
that a State's antidegradation policies as es-
tablished in State law are followed.
By identifying threatened good quality
waters, States take a more proactive, "pollu-
tion prevention" approach to water quality
management (see below).
Pollution Prevention Advantages
Consistent with 40 CFR 130.7 (c)(l)(ii) which re-
quires that TMDLs be established for all pollutants
that prevent or are expected to prevent water qual-
ity standards from being achieved.
Encourages States to maintain and protect «nst'"g
water quality.
Easier and less costly in the long term to prevent
impairments rather than retrofit controls to dean
up pollution problems.
Meets EPA objectives to support the State's col-
lection of data on impacted or threatened waters.
Each State may have different methods
for identifying and compiling information on
the status of its waterbodies depending on its
specific programmatic or cross-program-
matic needs and organizational arrange-
ments. Typically, States utilize both existing
information and new data collected from on-
2 40 CFR 130.10 (d)(6)
going monitoring programs to assess
whether water quality standards are being
met, and to detect trends.
States assess their waters for a variety of
purposes, including the targeting of cleanup
activities, assessing the extent of contamina-
tion at potential Superfund sites, and for
meeting federally mandated reporting re-
quirements. While the identification of
water quality-limited waters may appear to
be a major task for the States, a significant
amount of this work has already begun or has
been completed under sections 305(b),
304(1), 314(a), and319(a) of the Clean Water
Act as amended in 1987. (Appendix B pro-
vides a summary of these supporting CWA
programs.)
Section 305(b) requires States to prepare
a water quality inventory every two years to
document the status of waterbodies that
have been assessed. Under section 304(1),
States identified all surface waters adversely
affected by toxic (65 classes of compounds),
conventional (such as BOD, total suspended
solids, fecal conform, and oil and grease),
and nonconventional (such as ammonia,
chlorine, and iron) pollutants from both
point and nonpoint sources. Under section
314(a), States identified a list of publicly
owned lakes for which uses are known to be
impaired by point and nonpoint sources.
Section 319 State Assessment Reports iden-
tified waters adversely affected by nonpoint
sources of pollution. Lists prepared to sat-
isfy requirements under section 305(b),
304(1), 314(a) and 319 should be very useful
in preparing 303(d) lists.
Other existing and readily available data
and information sources should be utilized
in preparing section 303(d) lists. See, for
example, Appendix C, which presents
screening categories similar to those found
in current regulations promulgating the
304(1) requirements. Figure C-l in the Ap-
pendix depicts a sample process for identify-
12
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ing 303(d) waters. Other data sources are
listed as an appendix of the Final Guidance
for Implementation of Requirements Under
Section 304(1) of the Clean Water Act as
Amended. March 1988. The Toxic Chemi-
cal Release Inventory (TRI) developed
under Title HI, Superfund and Reauthonza-
tion Act (SARA) is an important informa-
tion source as well as any relevant State-run
database.
Section 303(d) requires States to identify
those water quality-limited waters needing
TMDLs. States should regularly update
their lists of waters (or the databases which
store the information to produce the lists) as
assessments are made and report these lists
to EPA once every two years. States should
include, in their biennial 303(d) lists, infor-
mation on which waterbodies have been
added or deleted from the List and which
waterbodies were assessed since the last re-
porting period. (See page 27 for further de-
tails on submission of lists to EPA.)
Step Two: Priority Ranking and
Targeting
Once waters needing additional controls
have been identified, a State prioritizes its
list of waters using established ranking pro-
cesses that should consider all water pollu-
tion control activities within the State.
Priority ranking has traditionally been a pro-
cess defined by the State and may vary in
complexity and design. A priority ranking
should enable the State to make efficient use
of its available resources and meet the objec-
tives of the Clean Water Act.
The Clean Water Act states that the pri-
ority ranking for such waters must take into
account the severity of the pollution and the
uses to be made of such waters. Several
documents (see box) are available from EPA
to assist States in priority setting.
Priority Setting Documents
Settinc Priorities' The Kev to Nonnoint Source
(OWRS, July 1987).
Selecting Priority Nonpoint Source Projects! You
Better Shop Around (OW and OPPE, August
1989, EPA 506/2-89/003).
and Reservoir Restoration and Quid-
ance Manual, First Edition (OWRS, EPA 440/5-
88-002).
TTlf I-flVe a"d Reservoir Restoration and fiuifj-
ance Manual, Second Edition (OWRS, EPA
440/4-90-006).
State Clean Water Strategies: Meeting the
Challenges for the Future (OW, December 1988).
According to EPA's State Clean Water
Strategy document: "Where all water quality
problems cannot be addressed immediately,
EPA and the States will, using multi-year
approaches, set priorities and direct efforts
and resources to maximize environmental
benefits by dealing with the most serious
water quality problems and the most valu-
able and threatened resources first."
Targeting high priority waters for TMDL
development should reflect an evaluation of
the relative value and benefit of waterbodies
within the State and take into consideration
the following:
Risk to human health and aquatic
life.
Degree of public interest and sup-
port.
Recreational, economic, and aes-
thetic importance of a particular
waterbody.
Vulnerability or fragility of a particu-
lar waterbody as an aquatic habitat.
13
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Immediate programmatic needs such
as wasteload allocations needed for
permits that are coming up for revi-
sions or for new or expanding dis-
charges, or load allocations for
needed BMPs.
Waters and pollution problems iden-
tified during the development of the
section 304(1) "long list."
Court orders and decisions relating
to water quality.
National policies and priorities such
as those identified in EPA's Annual
Operating Guidance.
States are required to submit their prior-
ity rankings to EPA for review. EPA expects
all waters needing TMDLs to be ranked,
with "high" priority waters - targeted for
TMDL development within two years fol-
lowing the listing process - identified. (See
page 29 for further details on submission of
priorities to EPA.)
In order to effectively develop and im-
plement TMDLs for all waters identified,
States should establish multi-year schedules
that take into consideration the immediate
TMDL development for targeted waterbod-
ies and the long-range planning for address-
ing all water quality-limited waters still
requiring TMDLs. While it would be ex-
pected that these schedules would change
when a State's priorities change in response
to "hot spots" or critical situations at any
given time, a long-range schedule provides
several advantages to a State (see box).
Step Three: TMDL Development
For a water quality-limited water that
still requires a TMDL, a State must establish
a TMDL that quantifies pollutant sources
and allocates allowable loads to the contrib-
Advantages to Long-range Schedules
Encourages integration with the permitting
cycle, the water quality standards revisions,
and other required water quality manage-
ment activities.
Allows for long-term monitoring which may
be needed to assess control action.
Sets consistency in developing TMDLs.
Establishes a basis for setting overall water
quality management priorities.
Supports a geographic approach for TMDL
development for targeted waterbodies.
uting point and nonpoint sources so that the
water quality standards are attained for that
waterbody. The development of TMDLs
should be accomplished by setting priorities,
considering the geographic area impacted by
the pollution problem, and, in some cases,
using a phased approach to establishing con-
trol measures based on the TMDL.
The TMDL is developed using one or a
combination of three technical approaches
to protect receiving water quality: the chem-
ical specific approach, the whole effluent
toxicity approach, and the biocrite-
ria/bioassessment approach. The chemical
specific approach is one where loadings are
evaluated in terms of the impact on physical-
chemical water quality conditions (e.g., dis-
solved oxygen or toxicant concentrations).
While an integrated approach that considers
all three techniques is preferred for the pro-
tection of aquatic life, the chemical specific
approach is usually the one used to address
loads that affect those water quality stan-
dards which protect human health.
Many water pollution concerns are area-
wide phenomena that are caused by multiple
dischargers, multiple pollutants (with poten-
14
-------
tial synergjstic and additive effects), or non-
point sources. Atmospheric deposition and
ground water discharge may also result in
significant pollutant loadings to surface wa-
ters. As a result, EPA recommends that
States develop TMDLs on a geographical
basis (e.g., by watershed) in order to effi-
ciently and effectively manage the quality of
surface waters.
The TMDL process is a rational method
for weighing the competing pollution con-
cerns and developing an integrated pollution
reduction strategy for point and nonpoint
sources. The TMDL process allows States to
take a holistic view of their water quality
problems from the perspective of instream
conditions. Although States may define a
waterbody to correspond with their current
programs, it is expected that States will con-
sider the extent of pollution problems and
sources when defining the geographic area
for developing TMDLs. In general, the geo-
graphical approach for TMDL development
supports sound environmental management
and efficient use of limited water quality
program resources. In cases where TMDLs
are developed on watershed levels, States
should consider modifying permitting cycles
so that all permits in a given watershed ex-
pire at the same time.
For traditional water pollution prob-
lems, such as dissolved oxygen depletion and
nutrient enrichment, there are well validated
models that can predict effects with known
levels of uncertainty. This is not true for such
non-traditional pollution problems as urban
stormwater runoff and pollutants that in-
volve sediment and bioaccumulative path-
ways. Predictive modeling for these
problems therefore uses conservative as-
sumptions, but in many cases the degree of
certainty cannot be well quantified until
more data becomes available to develop sen-
sitivity analyses and model comparisons.
For TMDLs involving these non-traditional
problems, the margins of safety should be
increased and additional monitoring re-
quired to verify attainment of water quality
standards and provide data needed to recal-
culate the TMDL, if necessary.
EPA regulations provide that load allo-
cations for nonpoint sources and/or natural
background "are best estimates of the load-
ing which may range from reasonably accu-
rate estimates to gross allotments... A
phased approach to developing TMDLs may
be appropriate where estimates are based on
limited information. The phased approach
is a TMDL that includes monitoring require-
ments and a schedule for re-assessing TMDL
allocations to ensure attainment of water
quality standards. Uncertainties that cannot
be quantified may also exist for certain pol-
lutants discharged primarily by point
sources. In such situations a large margin of
safety and follow-up monitoring is appropri-
ate.
Where nonpoint source controls are in-
volved, the phased approach is also neces-
sary. Under the CWA, the only federally
enforceable controls are those for point
sources through the NPDES permitting pro-
cess. In order to allocate loads among both
nonpoint and point sources, there must be
reasonable assurances that nonpoint source
reduction will in fact be achieved. Where
there are not reasonable assurances, under
the CWA, the entire load reduction must be
assigned to point sources. With the phased
approach, the TMDL includes a description
of the implementation mechanisms and the
schedule for the implementation of non-
point source control measures.
3 40CFR130.2(g).
-------
By pursuing the phased approach where
applicable, a State can move forward to im-
plement water quality-based control mea-
sures and adopt an explicit schedule for
implementation and assessment States can
also use the phased approach to address a
greater number of waterbodies including
threatened waters or watersheds which
would otherwise not be managed. Specific
requirements relating to the phased ap-
proach are discussed in Chapter 3.
Step Four: Implementation of Control
Actions
Once a TMDL or a phased TMDL has
been established for a waterbody (or water-
shed) and the appropriate source loads de-
veloped, implementation of control actions
should proceed. The State or EPA is respon-
sible for implementation, the first step being
to update the water quality management
plan. Next, point and nonpoint source con-
trols should be implemented to meet
wasteload allocations and load allocations,
respectively. Various pollution allocation
schemes (i.e., determination of allowable
pollution among different pollution sources
in the same waterbody) can be employed by
States to optimize alternative point and non-
point source management strategies.
The NPDES permitting process is used
to limit effluent from point sources. Chapter
3 provides a more complete description of
the NPDES process and how it fits into the
water quality-based approach to permitting.
Construction decisions regarding publicly
owned treatment works (POTWs) and ad-
vanced treatment facilities must also be
based on the most stringent of technology-
based or water quality-based limitations.
These decisions should be coordinated so
that the facility plan for the discharge is con-
sistent with the limitations in the permit.
In the case of nonpoint sources, both
State and local laws may authorize the im-
plementation of nonpoint source controls
such as the installation of Best Management
Practices (BMPs). Section 319 State man-
agement programs can be a useful tool to
implement nonpoint source control mea-
sures and ensure improved water quality.
Many BMPs, however, may be implemented
even where regulatory programs do not exist.
In such cases, a State needs to document the
coordination which may be necessary among
State and local agencies, landowners, opera-
tors, and managers and then evaluate BMP
implementation, maintenance, and overall
effectiveness to ensure that load allocations
are achieved. Chapter 3 discusses some of
the technical issues associated with im-
plementation of nonpoint source control
measures.
Step Five: Assessment of Water
Quality-Based Control
Actions
Throughout the previous four steps,
monitoring is a crucial element of water
quality-based decision making. In this step,
monitoring provides data for an indepen-
dent evaluation of whether the TMDL and
control actions that are based on the TMDL
protect or improve the environment and are
sufficient to meet changing waterbody pro-
tection requirements such as revised water
quality standards or changing pollution
sources (e.g., urbanization).
Monitoring programs often begin with
baseline monitoring. Such monitoring
should not be regarded as a prerequisite to
implementing control measures for a water-
body. If monitoring has not yet begun, con-
trol measures and monitoring should be
implemented simultaneously to assure that
pollution abatement activities are not de-
layed.
In the case of point sources, assessments
are facilitated in that dischargers are re-
quired to provide reports on compliance
16
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with NPDES permit limits. In some in-
stances, dischargers may also be required in
the permit to assess impact of their discharge
on the receiving water. A monitoring re-
quirement can be put into the permit as a
special condition as long as the information
is collected for purposes of writing a permit
limit. States are also encouraged to use in-
novative monitoring programs (e.g., cooper-
ative monitoring and volunteer
monitoring^) to provide for adequate point
and nonpoint source monitoring coverage.
States should also ensure that effective
monitoring programs are in place for evalu-
ating nonpoint source control measures.
EPA recognizes monitoring as a high priority
activity in a State's nonpoint source manage-
ment program. To facilitate the im-
plementation and evaluation of NFS
controls States should consult current guid-
ance.
4 USEPA. 1984. Planning and Managing Cooperative Monitoring Projects. OW/OWRS. EPA
440/4-84-018. Washington, D.C.
5 USEPA. 1990. Volunteer Water Monitoring: A Guide for State Managers. OW, EPA 440/4-90-010.
Washington, D.C.
6 55 FR 35262, August 28,1990.
7 USEPA. February, 1968. Draft Nonpoint Source Monitoring and Evaluation Guide. OW/NPS Branch.
Washington, D.C.
8 USEPA. September 19,1989. Nonpoint Source Monitoring and Reporting Requirements for Watershed
Implementation Grants. OW/NPS Branch. Washington, D.C.
17
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CHAPTER 3 DEVELOPMENT AND IMPLEMENTATION
OF THE TMDL
Development of the TMDL
The TMDL process is an important ele-
ment of the water quality-based approach. It
links the development and implementation
of control actions to the attainment of water
quality standards. This chapter expands the
discussion introduced in Chapter 2 on how
to develop TMDLs and implement controls
for water quality-limited waters. Appendix
D and E provide supporting information on
some important technical considerations
and EPA supported models for TMDL de-
velopment.
The TMDL Objective
As stated hi 40 CFR 131.2, "[water qual-
ity] standards serve the dual purposes of es-
tablishing the water quality goals for a
specific waterbody and serve as the regula-
tory basis for the establishment of water-
quality-based treatment controls and
strategies beyond the technology-based lev-
els of treatment required by section 301(b)
and 306 of the Act." Standards also contain
antidegradation provisions to prevent the
degradation of existing water quality.
The objective of a TMDL is to allocate
allowable loads among different pollutant
sources so that the appropriate control ac-
tions can be taken and water quality stan-
dards achieved. The TMDL provides an
estimate of pollutant loadings from all
sources and predicts the resulting pollutant
concentrations. The TMDL determines the
allowable loads and provides the basis for
establishing or modifying controls on pollu-
tant sources.
The TMDL Process
The total pollutant load to a waterbody is
derived from point, nonpoint, and back-
ground sources. Pollutant loads may be
transported into waterbodies by direct dis-
charge, overland flow, ground water, or at-
mospheric deposition. The TMDL concept
has successfully been applied to develop
wasteload allocations for point source dis-
charges in low flow situations where non-
point sources are not a concern. TMDLs can
and should be used, however, to consider the
effect of all activities or processes that cause
or contribute to the water quality-limited
conditions of a waterbody. Activities may
relate to thermal changes, flow changes, sed-
imentation, and other impacts on the aquatic
environment. Control measures to imple-
ment TMDLs, therefore, are not limited to
NPDES authorities but should also be based
on State and local authorities and actions to
reduce nonpoint source pollution.
An example of how to apply such a
TMDL might be in the control of excess
sediment which causes loss of a beneficial
use of a waterbody. If standards, established
to protect against the loss of a beneficial use
(e.g., fish spawning), are not met and, if the
process causing the problem (i.e., excess sed-
imentation) can be quantified, then it may be
appropriate to use the TMDL process to
assess the adverse impacts and potentially
set controls on the problem activity. In this
19
-------
example, the activity might be urban devel-
opment for which effective controls can be
implemented to reduce sediment loading to
the impacted waterbody.
The TMDL process distributes portions
of the waterbody's assimilative capacity to
various pollution sources - including natural
background sources and a margin of safety
so that the waterbody achieves its water qual-
ity standards. The analyst may use predictive
modeling procedures to evaluate alternative
pollution allocation schemes in the same
waterbody. By optimizing alternative point
and nonpoint source control strategies, the
cost effectiveness and pollution reduction
benefits of allocation tradeoffs may be eval-
uated (see Appendix D). The approach nor-
mally used to develop a TMDL for a
particular waterbody or watershed consists
of five activities (see box).
TMDL Development Activities
Selection of the pollutant to consider.
Estimation of the waterbody assimilative ca-
pacity.
Estimation of the pollution from all sources
to the waterbody.
Predictive analysis of pollution in the water-
body and determination of total allowable
pollution load.
Allocation (with a margin of safety) of the
allowable pollution among the different pol-
lution sources in a manner that water quality
standards are achieved.
In developing a TMDL it is important to
keep in mind certain constraints on the WLA
portion that are imposed by antibacksliding
regulatory provisions. The WLA will nor-
mally result in new or more stringent water
quality-based limits than those contained in
a previously issued permit. In a limited num-
ber 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 provis-
ions contained in section 402(o) of the CWA.
Selection of Approach
Figure 2 illustrates the critical decisions
and the appropriate steps in the TMDL pro-
cess for developing load allocations and im-
plementing and evaluating control actions.
In some cases, as illustrated by the left side
of the diagram, TMDL development can be
straight-forward and relatively simple. In
other cases, as depicted by the right side of
the diagram, a phased approach may be
more appropriate. Regardless of which path
is followed, the allocation of loads and estab-
lishment of control actions should ensure
that all water quality-limited waters will
meet their standards.
Once a waterbody is selected for action,
an analyst must decide if the available data
and information about the sources, fate, and
transport of the pollutant to be controlled is
adequate. The level of effort and scientific
knowledge needed to acquire adequate data
and perform meaningful predictive analyses
is often a function of the pollutant source,
pollutant characteristics, and the geographi-
cal scale of the pollution problem. As de-
scribed in Chapter 2, modeling the fate and
transport of conventional pollutants (e.g.
biochemical oxygen demand) and point
source contributions is better developed
than modeling for non-traditional pollution
problems. For certain non-traditional prob-
lems, if there are not adequate data and
predictive tools to characterize and analyze
the pollution problem with a known level of
uncertainty, a phased approach may be nec-
essary.
The phased approach is required when
the TMDL involves both point and nonpoint
20
-------
Flguro 2 Dovatopmont of TMDL« for Targatod Watorbodtoa
Identify 303(d) Targeted Watorbody
Dovolop TMOL Incluolng:
WLAaforPS
LA» for NPS and Background
Source*
Margin of Safoty
1
Dovolop TMOL Inckidtag:
RoqtriromonU
WLAa for P8 which
- Maintain oxtettog imlt* or
oatabflah now Kmlta
LAa for NPS which
- Maintain or hnplomont now
NPS controhjlBMPs)
Margin of aafoty
Schodula for ph»B««:
InatalatJon and valuation
of NPS control*
Data cotoctton
WQ8 aaaoaamont
Additional modolng If n»«d»d
Imolomontatlon of Schodulo
Approval
by EPA
I
bnplomont Control* and CompJoU Roqulrod Data CoBoctJon
NPOC8 pormfta for point aourco control*
Stato or local procoaaoa for nonpolnt aourco control*
Addition*! monitoring
Final caUbration of modol*
WQSa not achlovod
Aaaoaamont
of Wator Qualty
baaod Control*
WQS* achlovod
Romovo Watorbody from 303(d) U«t
21
-------
sources and the point source WLA is based
on a LA for which nonpoint source controls
need to be implemented. There must be
assurances that nonpoint source control
measures will achieve expected load reduc-
tions in order to allocate a wasteload to a
point source with a TMDL that also allocates
expected nonpoint source load reductions.
In this case, a phased approach is required
because the TMDL that is developed has
additional requirements that provide these
assurances.
Despite the additional requirements of
the phased approach, States may actually
prefer it because the additional data col-
lected can be used to verify expected load
reductions, evaluate effectiveness of control
measures, and ultimately determine whether
a TMDL needs to be revised.
The Phased Approach
Under the phased approach, the TMDL
has LAs and WLAs calculated with margins
of safety to meet water quality standards.
The allocations are based on estimates which
use available data and information, but mon-
itoring for collection of new data is required.
The phased approach provides for further
pollution reduction without waiting for new
data collection and analysis. The margin of
safety developed for the TMDL under the
phased approach should reflect the ade-
quacy of data and the degree of uncertainty
about the relationship between load alloca-
tions and receiving water quality.
The TMDL, under the phased approach,
includes (1) WLAs that confirm existing lim-
its or would lead to new limits for point
sources and (2) LAs that confirm existing
controls or include implementing new con-
trols for nonpoint sources. This TMDL re-
quires additional data to be collected to
determine if the load reductions required by
the TMDL lead to attainment of water qual-
ity standards. Data collection may also be
required to more accurately determine as-
similative capacities and pollution alloca-
tions.
In addition to the allocations for point
and nonpoint sources, a TMDL under the
phased approach will establish the schedule
or timetable for the installation and evalua-
tion of point and nonpoint source control
measures, data collection, the assessment for
water quality standards attainment, and, if
needed, additional predictive modeling.
The scheduling with this approach should be
developed to coordinate all the various ac-
tivities (permitting, monitoring, modeling,
etc.) and involve all appropriate local au-
thorities and State and Federal agencies.
The schedule for the installation and im-
plementation of control measures and their
subsequent evaluations will include descrip-
tions of the types of controls, the expected
pollutant reductions, and the time frame
within which water quality standards will be
met and controls re-evaluated.
Where no monitoring program exists, or
where additional assessments are needed, it
is necessary for States to design and imple-
ment a monitoring plan. The objectives of
the monitoring program should include as-
sessment of water quality standards attain-
ment, verification of pollution source
allocations, calibration or modification of se-
lected models, calculation of dilutions and
pollutant mass balances, and evaluation of
point and nonpoint source control effective-
ness. In their monitoring programs, States
should include a description of data collec-
tion methodologies and quality assur-
ance/quality control procedures, a review of
current discharger monitoring reports, and
be integrated with volunteer and coopera-
tive monitoring programs where possible. If
properly designed and implemented, the
monitoring program will result in a sufficient
data base for assessment of water quality
standard attainment and additional predic-
tive modeling if necessary.
22
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Approval of TMDLs by EPA
TMDLs developed for all water quality-
limited waters are submitted to EPA for re-
view and approval. States are encouraged to
coordinate with EPA prior to formal submis-
sion of their TMDLs. Chapter 4 explains
EPA and State responsibilities for the review
and approval process.
Implementation of the TMDL
After identifying the necessary pollutant
load reductions through the development of
TMDLs and after approval by EPA, State
water quality management plans should be
updated and control measures im-
plemented. This section provides a brief re-
view of point and nonpoint source control
implementation. Additional guidance is
available and is referenced throughout the
remainder of this chapter.
NPDES Process for Point Sources
Both technology-based and water qual-
ity-based controls are implemented through
the National Pollutant Discharge Elimina-
tion System (NPDES) permitting process.
Permit limits based on TMDLs are called
water quality-based limits.
Wasteload allocations establish the level
of effluent quality necessary to protect water
quality in the receiving water and ensure
attainment of water quality standards. Once
allowable loadings have been developed
through WLAs for specific pollution
sources, limits are incorporated into NPDES
permits. It is important to consider how the
WLA addresses variability in effluent qual-
ity. On the one hand, allocations for nutri-
ents or bioaccumulative pollutants could be
expressed as the required average effluent
quality because the total loading of these
pollutants is of concern. On the other hand,
an allocation for toxic pollutants should be
expressed as a shorter-term requirement be-
cause the concentration of these pollutants
is typically of more concern than the total
loading.
As a result of the 1987 Amendments to
the Act, Individual Control Strategies (ICSs)
were established under section 304(1)(1) for
certain point source discharges of priority
toxic pollutants. ICSs consist of NPDES per-
mit limits and schedules for achieving such
limits, along with documentation showing
that the control measures selected are ap-
propriate and adequate (i.e., fact sheets in-
cluding information on how water
quality-based limits were developed, such as
total maximum daily loads and wasteload
allocations). Point sources with approved
ICSs are to be in compliance with those ICSs
as soon as possible or in no case later than
three years from the establishment of the
ICS (typically by 1992 or 1993).
The Clean Water Act (and correspond-
ing State statutes) authorizes imposition of
monitoring and data collection require-
ments on the owner or operator of a point
source discharge. Requirements may in-
clude ambient and biological assessments,
toxicity reduction evaluations, in-plant mon-
itoring, etc. Needed data collection may be
initiated through a direct request under Sec-
tion 308 if there is a reasonable need for the
information for EPA to carry out the objec-
tives of the Clean Water Act The request
must also meet the Paperwork Reduction
Act requirements. Information may also be
The reader is referred to the Permit Writer's Guide to Water Quality-based Permitting for Toxic
Pollutants (Jury, 1987) and the Technical Support Document for Water Quality-based Toxics Control
(1985) for additional information on deriving actual permit limits.
23
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Examples of Best Management Practices
AGRICULTURE
Animal waste management
Conservation tillage
Contour farming
Contour strip cropping
Cover crops
Crop rotation
Fertilizer management
Integrated pest management
Livestock exclusion
Range and pasture management
Sod-based rotations
Terraces
CONSTRUCTION
Disturbed area limits
Nonvegetative soil stabilization
Runoff detention/retention
Surface roughening
URBAN
Flood storage
Porous pavements
Runoff detention/retention
Street cleaning
SILVICULTURE
Ground coyer maintenance
T imiting disturbed areas
Log removal techniques
Pesticide/herbicide management
Proper handling of haul roads
Removal of debris
Riparian zone management
Road and skid trial management
MINING
Block-cut or haul-back
Underdrains
Water diversion
MULTICATEGORY
Buffer strips
Detention/sedimentation basins
Devices to encourage infiltration
Grassed waterway
Interception/diversion
Material ground cover
Sediment traps
Streamside management zones
Vegetative stabilization/mulching
collected through permit reporting require-
ments, or an administrative order. These
authorities can be used to collect data from
point sources when developing or assessing
the effectiveness of a TMDL.
Permit requirements for data collection
should be established when longer term data
(e.g., for several seasons) are needed. The
permit should include a statement that the
permit can be modified or revoked and reis-
sued if the data indicate an exceedance of
State water quality standards.
State or Local Process for Nonpoirtt Sources
In addition to permits for point sources,
nonpoint source controls may be established
by implementing Best Management Prac-
tices (BMPs) so that surface water quality
objectives are met. These controls should be
based on LAs developed using the TMDL
process. When establishing permits for
point sources in the watershed, the record
should show that in the case of any credit for
future nonpoint source reductions, (1) there
is reasonable assurance that nonpoint source
controls will be implemented and main-
tained or (2) that nonpoint source reductions
are demonstrated through an effective mon-
itoring program. Assurances may include
the application or utilization of local ordi-
nances, grant conditions, or other enforce-
ment authorities. For example, it may be
appropriate to provide that a permit may be
reopened for a WLA which requires more
stringent limits because attainment of non-
-------
point source load allocation was not demon-
strated.
In order to fully address waterbodies that
are impaired or threatened by nonpoint
source pollution, States should implement
their nonpoint source management pro-
grams and ensure adoption of control mea-
sures (best management practices) by all
contributors of nonpoint source pollution in
those watersheds. Example BMPs are listed
on the following page. State nonpoint
source management programs may include,
as appropriate, nonregulatory or regulatory
programs for enforcement, technical assis-
tance, financial assistance, education, train-
ing, technology transfer, and demonstration
projects.
It is difficult to ensure, a priori, that im-
plementing nonpoint source controls will
achieve expected load reductions. Nonpoint
source control measures may fail to achieve
projected pollution or chemical load reduc-
tions due to inadequate selection of BMPs,
inadequate design or implementation, or
lack of full participation by all contributing
sources of nonpoint pollution. States
should describe nonpoint source load reduc-
tions and establish a procedure for reviewing
and revising BMPs in TMDL documenta-
tion. The key objective for documenting
load reduction goals and review procedures
is to establish a rational procedure for site-
specific evaluation of waterbodies with sig-
nificant nonpoint source pollution loads.
States should consult additional nonpoint
source guidance for assistance in developing
appropriate monitoring and evaluation ap-
proaches.
Assessment of the TMDL
Once control measures have been im-
plemented, the impaired waters should be
assessed to determine if water quality stan-
dards have been attained or are no longer
threatened. The monitoring program used
to gather the data for this assessment should
be designed based on the specific pollution
problems or sources. For example, past ex-
perience has shown that several years of data
are necessary from agricultural nonpoint
source watershed projects to detect trends
(i.e., improvements) in water quality. As a
result, long term monitoring efforts must be
consistent over time in order to develop a
data base adequate for analysis of control
actions.
As shown in Figure 2, a TMDL that allo-
cates loads and wasteloads to meet water
quality standards must be established. If the
waterbody does achieve the applicable State
water quality standards, the waterbody may
be removed from the 303(d) list of waters
still needing TMDLs. If the water quality
standards are not met, the TMDL and allo-
cations of load and wasteloads must be mod-
ified. This modification should be based on
the additional data and information gath-
ered as required by the phased approach for
developing a TMDL, where appropriate, as
part of routine monitoring activities, and
when assessing the waterbody for water
quality standards attainment.
10
11
12
USEPA. July, 1987. Setting Priorities: The Key to Nonpoint Source Control OW/OWRS, EPA.
Washington, D.C.
USEPA. February, 1988. Draft Nonpoint Source Monitoring and Evaluation Guide. OW/NPS Branch,
Washington, D.C.
USEPA. September 19,1989. Nonpoint Source Monitoring and Reporting Requirements for Watershed
Implementation Grants. OW/NPS Branch, Washington, D.C.
25
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CHAPTER 4 - EPA AND STATE RESPONSIBILITIES
Effective implementation of water qual-
ity-based controls requires an integrated and
cooperative partnership between EPA and
the States. The main responsibility for water
quality management resides with the States
in the implementation of water quality stan-
dards, the administration of the NPDES pro-
gram (where the State has received EPA
approval to do so), and the management of
nonpoint sources of pollution. When the
authority to implement nonpoint source
control measures is at the local level, inter-
agency and intergovernmental coordination
is especially important. The State should
take the lead in facilitating and encouraging
the cooperation of local authorities. EPA is
responsible for ensuring that the Clean
Water Act requirements are met through the
enactment and enforcement of regulations,
issuing program guidance, and providing
technical assistance. The partnership devel-
oped between States and EPA should be
tailored to meet individual State needs while
also meeting the requirements of the Clean
Water Act This chapter describes specific
State and EPA responsibilities in the part-
nership.
EPA/State Agreements
EPA and the State should agree on the
process to develop TMDLs and this process
should be consistent with EPA technical
guidance documents unless deviation from
the guidance is technically justified. An
agreement should be written which de-
scribes technical and administrative proce-
dures (i.e., how background data are applied,
how and which models are to be used, how
TMDLs are developed, how loads should be
allocated, etc.). (See Appendix F for a gen-
eral EPA/State Agreement outline.) This
agreement reduces the administrative bur-
den of the EPA review and approval process
(see TMDL Review and Approval," p. 30).
State Responsibilities
Identification of Water Quality-Limited Wa-
ters Still Requiring TMDLs
According to section 303(d) of the Clean
Water Act and EPA water quality planning
and management regulations, States are re-
quired to identify waters that do not meet or
are not expected to meet water quality stan-
dards even after technology-based or other
required controls are in place. The
waterbodies are considered water quality-
limited and require TMDLs.
When a State reports its list of 303(d)
waters, it is important that this list contain
only those water quality-limited waters that
still require TMDLs. Some water quality-
limited waters may already have had suffi-
cient controls established for them and
currently meet water quality standards.
These should not be on the list. In addition,
the EPA regulations (40 CFR 130.7(b)) rec-
ognize the applicability of other appropriate
pollution control requirements that can pro-
vide a more stringent level of control than
technology-based effluent limitations.
When not listing a water quality-limited
water a State must show that the controls
specified by 40 CFR 130.7(b) (see p. 11) are
enforceable, specific to the pollution prob-
lems, and stringent enough to meet water
27
-------
quality standards. If the controls are not yet
implemented, a State must provide a sched-
ule for timely implementation.
The waters identified should be reported
to EPA in the 3Q5(b) water quality assess-
ment reports due April 1 every even year. If
a State prefers, the 303(d) list of waters can
be submitted separately at the same time.
While initially it may be convenient to build
upon the reporting processes described in
Chapter 2, the 303(d) list should be updated
to reflect the latest monitoring and assess-
ment data available.
To facilitate the reporting of 303(d) wa-
ters, the current section 305(b) Waterbody
System (WBS), a tool used for reporting
305(b) information, contains fields already
designated for this identification. The WBS
provides a geographically based framework
for entering, documenting, and reporting in-
formation on the quality of individual
waterbodies as they are defined by each
State. The primary function of the WBS is to
document water quality assessments and the
water quality status of waterbodies, includ-
ing causes and sources of use impairment.
As a convenience to the States, the WBS has
been modified and will continue to be up-
dated to include data fields on whether
TMDLs are still needed or are in place. The
WBS will also provide information to EPA
to assist in tracing the development of
TMDLs and overall program implementa-
tion.
Identification of Causes and Sources of
Pollution - When identifying the 303(d) wa-
ters, the causes of the impairment also
should be identified for each segment listed.
The Waterbody System has two separate
fields that provide further information on a
particular water segment: "nonattainment
causes" and "nonattainment sources." The
"cause" field consists of a list of constituents
or conditions that are causing nonattainment
of water quality standards by a waterbody.
The Waterbody System's Users Guide (third
edition, version 2.0) contains 23 standard
causes (see Appendix G) and includes such
parameters or categories as pesticides, met-
als, ammonia, and pathogens. States may
develop their own user-defined codes by
specifying additional codes under each stan-
dard cause.
Similarly, a field exists hi the Waterbody
System for identifying the sources of the pol-
lutants or conditions that are listed under
causes for the nonattainment of uses in the
waterbody. Twelve general source catego-
ries are identified (see Appendix G) and
include such things as industrial point
sources, municipal point sources, combined
sewer overflow, agriculture, and silviculture.
The User's Guide also identifies 45 sub-
categories. Again the States may develop
then* own subcategories to describe causes of
impairment of each water segment identi-
fied with this system. States should consult
with the Guidelines for the Preparation of
the 3Q5(b) Report (to be issued every odd
numbered year) and the Waterbody System
User's Guide for guidance in developing and
formatting their information.
Documentation and Rationale for List-
ing - Along with the list of 303(d) waters
submitted to EPA, adequate documentation
to support the listing of waters should be
submitted. States have a number of readily
available sources of data and information to
use when compiling their lists (see pages 12
and 13). These sources, listed in Appendix
C, should be used by States to develop their
lists of 303(d) waters. However, additional
information may be required under certain
circumstances.
Documentation for listing should also
provide a description of the methodologies
used to develop the list, a description of the
data and information used to identify water
quality-limited waters, and a rationale for
any decision to not use any one of the cate-
gories listed in Appendix C. It is not ex-
pected that each and every waterbody listed
by a State be accompanied by the detailed
documentation as described.
Adequate public participation should be
a part of the listing process to make sure all
water quality-limited waters are identified.
This will support the State in defending its
list of such waters should the need to do so
28
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used if they are technically defensible and
approved by EPA.
For their TMDL submissions, States
should include the proposed TMDLs,
WLAs, LAs, and the supporting information
that the Region will need to evaluate the
State's water quality analysis and determine
whether to approve or disapprove the sub-
mitted TMDLs. Regions and States should
reach an agreement on the specific informa-
tion needed prior to their submission. For a
TMDL developed under the phased ap-
proach, States should also submit to EPA a
description of the controls to be established,
the schedule for data collection, establish-
ment of the control measures, assessment for
water quality standards attainment, and ad-
ditional modeling if needed.
Quality assurance (QA) and Quality con-
trol (QC) requirements should also be met.
Specific technical QA/QC is necessary in the
use of environmental data and models.
However, when using models, such as
wasteload allocation models which involve
"real" environmental data as well as paramet-
ric and mathematical relationships, model
sensitivity studies can help establish the lev-
els of QA/QC required for specific data. For
example, the allowable range of uncertainty
in the data can be established through model
sensitivity studies. This allowable range of
uncertainty may indicate, for example, the
need for tight limits on precision for a partic-
ular pollutant parameter. Further discus-
sion is provided elsewhere.
Continuing Planning Process
Each State is required to establish and
maintain a continuing planning process
(CPP) as described in section 303(e) of the
USEPA. September, 1980. Guidelines and Specifications for Preparing Quality Assurance Project Plans.
QAMS-004/80. Washington, D.C.
USEPA. December, 1980. Interim Guidelines and Specifications for Preparing Quality Assurance Plans.
QAMS-005/80. Washington, D.C.
USEPA. May, 1984. Guidance for Preparation of Combined Work/Quality Assurance Project Plans for
Environmental Monitoring. OWRS QA-1. Washington, D.C.
arise, since, in its oversight responsibilities,
EPA reserves the right to ask for additional
information regarding the State's decision to
not list particular waterbodies.
Identification and Scheduling of Targeted
Waterbodies
Targeted waterbodies scheduled for
TMDL development over the next two years
are to be identified and reported along with
the 303(d) list of waters that are submitted
during the 305(b) reporting process. These
high priority TMDLs are to be based on
State developed priorities that consider the
severity of the impact and the uses of the
water along with the other considerations
described in Chapter 2. State submissions
which include the identification of 303(d)
targeted waters are subject to review and
approval or disapproval by EPA. EPA will
expect the States to include public participa-
tion in the development of the list of high
priority targeted waterbodies. Targeting
waterbodies for control action should be a
key component of a State's water quality
management and planning programs. Wa-
ters that are identified in State annual work
plans will be compared to the targeted
waterbodies and will be considered by EPA
during its review and approval of the annual
work plans.
TMDL Development
Each State develops TMDLs for its water
quality-limited waters. The procedure for
TMDL approval by EPA is depicted in Fig-
ure 3. States should use EPA's technical
support document and WLA technical guid-
ance series (see Appendix A) when develop-
ing TMDLs. Alternative approaches can be
13
14
29
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Figures TMDL Development and Approval Procedure
8ttto/EPAAflrMflwnt
on Technical Procedural
CPP Approved
byEPA
EPAApprewdUiitrf
IM, by Pnoftty,
INMdhgTMOU
SUtoD*Mtop»TMDU
>*
Region May Aaatt Slate m
Developing TMDLj
PuMcNoto*
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Warranted.
Submto to EPA tor Approval.
No
EPA Ag*ovy« TMDL «>
BOTIQ DtwitopM In
AoQOrtttnot wNn
8ec*on303
-------
described in a State's CPP, the TMDLs
should be made available for public com-
ment States and involved local communi-
ties should participate in determining which
pollution sources should bear the treatment
or control burden needed to reach allowable
loadings. By involving the local communi-
ties in decision making, EPA expects that a
higher probability of successful TMDL im-
plementation will result.
In the identification of water quality-lim-
ited waterbodies, States need to involve the
public as part of their review of all existing
and readily available data and information.
This is especially true in such cases where a
waterbody may be perceived as being at risk
due to new dischargers and changes in land
use. In such cases a waterbody's water qual-
ity may be "threatened" and therefore should
be given consideration for listing as a 303(d)
water. EPA expects States to include public
participation in its development of high pri-
ority targeted waterbodies that will proceed
with TMDL development within two years
following the listing process.
In the development of a TMDL, a State
should issue a public notice offering an op-
portunity for a public hearing pertinent to
the TMDL under review. It is recom-
mended that this be done in conjunction with
public notices and hearings on NPDES per-
mits, construction of municipal wastewater
treatment works, water quality standards re-
visions, and Water Quality Management
Plan updates. Each notice should identify
TMDLs as part of the subject matter.The
State may wish to proceed to issuance of a
final TMDL without a hearing once notice is
given and there has been little or no response
by the public.
Also, if a State determines that the water
quality-based controls may be controversial,
the State should involve the EPA Regional
office, as well as the public, early in the pro-
cess and continue to involve them through-
out the process.
Reporting
State submission of a list of waters still
needing TMDLs and loads established is re-
quired by the Clean Water Act and the
Water Quality Planning and Management
regulations (40 CFR 130.7). These lists
should complement EPA/State Agreements
and the CPP, and be incorporated into the
WQMP. States should submit the 303(d)
lists either as part of or at the same time as
the biennial section 305(b) reports. As part
of this reporting requirement, States are ex-
pected to identify those waters targeted for
TMDL development in the next two years.
Targeted waterbodies are then scheduled for
TMDL development through the annual
work plan. In addition, the pollutants or
conditions causing violations of water quality
standards and the point and nonpoint
sources of the pollution causing those condi-
tions should be identified for each water-
body on the 303(d) list (see page 28). States
should consult the Section 305(b) Water-
body System's Users Guide (August, 1989)
to appropriately categorize sources and
causes of pollutants.
Other Specific Responsibilities
Other State responsibilities are to
Ensure that needed environmental
data are provided to EPA, including
appropriate assessment data; appro-
priate screening data; and all regula-
tory data including data needed for
approvals of the 303(d) lists and
TMDLs, and
Ensure that appropriate quality as-
surance/quality control procedures
are used for all data used in State
decision making and for all data re-
ported to EPA, including data re-
ported by dischargers.
31
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EPA Responsibilities
Review of303(d) Lists
Section 303(d) and the Water Quality
Planning and Management Regulation (40
CFR 130.7(d)) requires EPA to review and
approve or disapprove States' lists of water
quality-limited waters and the established
pollutant loads. The lists are expected to be
submitted biennially and will be approved or
disapproved based in part on the State's doc-
umentation and rationale for developing
such lists as described under the State Re-
sponsibilities section of this chapter.
If, after reviewing the State lists and doc-
umentation, EPA is satisfied that the State
has identified and appropriately listed all
impaired waters and those targeted for ac-
tion, EPA will then approve the lists and
send a letter approving the submittal to the
State, During this approval process, EPA
may request a State to provide additional
information if there is "good cause" to do so.
"Good cause" may include, but is not limited
to, more recent or accurate data; more accu-
rate water quality modeling; flaws in the
original analysis that led to the water being
identified pursuant to 40 CFR 130.7; or
changes hi conditions (e.g., elimination of
discharges).
If the EPA disapproves (via a letter of
disapproval to the State) a State's list of wa-
ters needing new or revised TMDLs and
those targeted for action, the Region (work-
ing closely with the State) then identifies
those waters where new or revised, and tar-
geted TMDLs are necessary.
TMDL Review and Approval
Section 303(d) and the Water Quality
Planning and Management regulation (40
CFR 130.7(d)) requires EPA to review all
TMDLs for approval or disapproval. EPA
may tailor its review to what is reasonable
and appropriate. For example, where a State
has clearly described its TMDL process hi its
approved CPP (and EPA/State Agreement),
EPA may conduct an in-depth review of a
sample of the State's TMDLs to determine
how well the State is implementing its ap-
proved process and conduct a less detailed
review of the remaining TMDLs. This in-
depth review of samples of the State submis-
sions, in conjunction with a less detailed
review of all other TMDLs submitted to
EPA by the State, will provide a reasonable
basis for EPA approval or disapproval of
individual TMDLs. The in-depth sample re-
view may include TMDLs supporting major
construction projects and other major con-
trol measures. For those States that do not
have an approved process, Regions are ex-
pected to conduct in-depth reviews of all
TMDLs. The Region's review should also
consider how well the States are following
applicable technical guidance for establish-
ing TMDLs, WLAs, and LAs.
EPA must, at a minimum, determine
whether the State's TMDLs are "established
at a level necessary to implement the appli-
cable water quality standards with seasonal
variations and a margin of safety that takes
into account any lack of knowledge concern-
ing the relationship between effluent limita-
tions and water quality. No TMDL will be
approved if it will result hi a violation of
water quality standards.
If the State chooses not to develop the
needed TMDLs for appropriate pollutants
17 CWA section 303(d)(l)
32
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on a timely basis or, if the TMDLs are unac-
ceptable to EPA, EPA has a role under the
Act to develoo the TMDLs in cooperation
with the State. This will be done by focus-
ing available EPA resources on the most
critical water quality problems.
EPA must either approve or disapprove
the State's TMDL within 30 days after sub-
mission by the State. Where a TMDL is
approved, EPA transmits a letter of such
approval. If EPA disapproves a State's sub-
mission and the State does not agree to cor-
rect the problems, then EPA shall, within 30
days of the disapproval date, establish such
TMDLs as necessary to implement the water
quality standards. EPA solicits public com-
ment and after considering public comment
and making appropriate revisions, EPA
transmits the revised TMDL to the State for
incorporation in the State's Water Quality
Management Plan. EPA prefers to dis-
charge this duty through a cooperative effort
with the States.
Program Audits
EPA expects to measure performance on
the basis of environmental results and ad-
ministrative goals by means of program au-
dits. To achieve this performance
measurement, EPA will periodically con-
duct audits of State water quality programs
primarily through Regional visits to the
States, review of State toxics control pro-
grams, and State action plan summaries of
EPA'sSurface Water Toxics Control Pro-
gram. These program audits will serve to
determine where additional training or
other assistance may be needed and to deter-
mine implementation of program objectives.
Technical Assistance and Training
EPA Headquarters and Regional offices
are available to provide technical assistance
and advice to the States in developing
TMDLs. EPA Headquarters in coordina-
tion with the EPA Center for Exposure As-
sessment Modeling (CEAM) provides for
training and assistance on modeling. EPA
Headquarters also provides training and
technical assistance to users of the Water-
body System (WBS).
Guidance Documents and Reports
EPA Headquarters is responsible for de-
veloping associated program guidance, tech-
nical support with assistance from EPA
research laboratories, and producing the bi-
ennial National Water Quality Inventory
Report to Congress developed from the
State section 305(b) assessment reports.
EPA Headquarters Responsibilities
EPA Headquarters is responsible for
making sure the CWA mandates regarding
TMDLs are carried out, providing oversight
of the Regional offices and the States, devel-
oping program policy and guidance, support-
ing the development of computer software
for calculating TMDLs, developing techni-
cal guidance documents, and providing tech-
nical training and assistance. Other
responsibilities of EPA Headquarters are
summarized on the next page.
EPA Regional Responsibilities
The EPA Regional offices are responsi-
ble for assisting Headquarters in developing
policy and guidance, distributing policy and
18 See Scott Decision: Scnn v Hammond 741 F.2d 992(7th Cir. 1984)
19 40 CFR 130.7(d)
20 40 CFR 122,123,130; Surface Water Toxics Control Program.
33
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guidance to the States, awarding grants to the
States for developing and implementing
water quality-based controls, and providing
technical assistance to the States. In addi-
tion, the Regional offices are responsible for
reviewing and approving or disapproving the
following: each State's TMDL process, the
annual work program, the list of waters
where TMDLs are needed, the list of tar-
geted waters, and specific TMDLs, WLAs,
and LAs. The EPA Regional offices are also
responsible for reporting on State im-
plementation to Headquarters. Other re-
sponsibilities of EPA Regional offices are
summarized below.
Other EPA Headquarters Responsibility
Prepare guidance and ensure that appropriate technical training and terknir»t assistance is available for
monitoring, water quality analysis, and data reporting.
Perform national assessments and evaluate the national water quality effects of CWA programs.
Make national data systems more useful for national, regional, and State managers by upgrading and
cross-linking the f^tmg systems and developing interactive data retrieval and analysis mechanisms for
line managers. Continue support of the River Reach and Industrial Facility Discharge files.
Ensure that appropriate quality assurance/quality control procedures are used in all national data
collection efforts and provide laboratory support for national studies of pollutants requiring special
analyses.
Prepare Headquarters budget requests, and in consultation with the Regions, prepare requests for
Regional and State water quality monitoring and analysis programs.
Peer review major agency program activities involving water monitoring and consult with other program
offices on water monitoring activities.
Other EPA Regional Responsibilities
Ensure that the appropriate regulatory monitoring is performed by the States and dischargers needed for
developing and implementing water quality-based controls and identifying needed nonpoint source
controls. This includes data required to identify waters needing water quality-based controls, data needed
to develop controls, and data needed to assess the effectiveness of controls.
Provide technical assistance and training to the States on water quality monitoring and analyses. For work
involving toxics, provide assistance in both the pollutant specific and the biomonitoring approaches and
whole effluent tenacity.
Ensure that appropriate quality assurance/quality control procedures are used for all Regional and Stale
water quality data and for all data used in Regional decision making including data reported by permittees.
Perform Regional water quality assessments primarily based on State data, as needed to prepare Environ-
mental Management Reports.
Ensure that Regional data systems are compatible with and do not unnecessarily duplicate national data
systems.
34
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APPENDIX A - RELATIONSHIP TO OTHER GUIDANCE
Monitoring Guidance
The Clean Water Act specifies that
States and Interstate Agencies, in coopera-
tion with EPA, establish water quality mon-
itoring systems necessary to review and
revise water quality standards, calculate
TMDLs, assess compliance with permits,
and report on conditions and trends in ambi-
ent waters. EPA's current program guid-
ance discusses the programmatic
relationships of monitoring as an informa-
tion collection tool for many program needs.
NPS pollution concerns are discussed in
draft guidance along with some means to
monitor and evaluate NPSs. Revised
Monitoring Program Guidance is planned
for FY 1991.
Cooperative Monitoring/Citizen
Volunteer Monitoring Guidance
Cooperative monitoring involves shared
efforts by individuals or groups in assessing
water quality conditions. Cooperative ar-
rangements are encouraged by the Clean
Water Act as referenced in section 104. Co-
operative monitoring projects require care-
ful planning and strong management
21 USEPA. 1985. Guidance for State Water Monitoring and Wasteload Allocation Programs. OW/OWRS,
EPA 44Q/4-85-031. Washington, D.C.
22 USEPA. 1987. Draft Nonpoint Source Monitoring and Evaluation Guide. OW/OWRS, EPA.
Washington, D.C.
23 USEPA. 1984. Planning and Managing Cooperative Monitoring Projects. OW/OWRS, EPA
440/4-84-018. Washington, D.C.
24 USEPA. 1990. Volunteer Water Monitoring: A Guide for State Managers. OW, EPA 440/4-90-010.
Washington, D.C.
controls. Current guidance23 24 describes
the factors to be considered in designing and
implementing cooperative and volunteer
monitoring projects so that specific provis-
ions are made for the collection and analysis
of scientifically valid water quality data, and
so that the State water pollution control
agencies have the necessary information for
final review and approval of all projects.
Cooperative monitoring projects can
serve the same usefulness as other monitor-
ing studies; however, they also provide a
mechanism to maximize limited resources.
In addition to "tapping" additional resources
for monitoring, there are other incentives for
States and the regulated community to coop-
erate, such as having more site-specific data
from which to develop site-specific, scientif-
ically-based water quality criteria.
Citizen volunteer monitoring involves
identifying sources of pollution, tracking the
progress of protection and restoration pro-
jects, and/or reporting special events such as
fish kills and storm damage. For more infor-
mation on citizen monitoring programs, con-
tact the EPA Office of Water Regulations
-------
and Standards (OWRS), Monitoring Branch
at202/382-7056.
Wasteland Allocation Technical Guid-
ance
Technical guidance manuals prepared by
EPA explain how to prepare wasteload allo-
cations (WLAs). These manuals are listed at
the right. Those available can be obtained
from the OWRS Monitoring Branch at
202/382-7056.
Technical Support Document for
Water Quality-based Toxics Control
The Technical Support Document
(TSD) for Water Quality-based Toxics Con-
trol presents recommendations to regula-
tory authorities when they are faced with the
task of controlling the discharge of toxic pol-
lutants to the nation's waters. Included in
this document are detailed discussions on
EPA's recommended criteria for whole ef-
fluent toxicity, a screening analysis method-
ology for effluent characterization, human
health risk assessment, the use of exposure
assessments for wasteload allocations, and
the development of permit requirements
and compliance monitoring. The TSD pro-
vides guidance for assessing and regulating
the discharge of toxic substances. It supports
EPA's initiative to control toxic pollution by
involving the application of biological and
chemical assessment techniques and pro-
poses solutions to complex and site-specific
pollution problems. Information on this
document can be obtained from EPA's
Water Quality and Industrial Permits
Branch at 202/475-9537.
Technical Guidance Manuals for
Performing Wasteload Allocations
Book Tide
I. General Guidance
n. Streams and Rivers
- Biochemical Oxygen Demand/Dissolved
Oxygen
Nutrient/Eutrophication
- Toxic Substances
Simplified Analytical Method for Deter-
mining NPDES Effluent Limitations for
POTWs Discharging into Low-Row
Streams
m. Estuaries
Estuaries and Wasteload Allocation
Models
- Application of Estuarine Waste Load Al-
location Models
Use of Mixing Zone Models in Estuarine
Waste Load Allocations*
Critical Review of Estuarine Waste Load
Allocation Modeling*
IV. Lakes and Impoundments
Biochemical Oxygen Demand/Dissolved
Oxygen
Nutrient/Eutrophication
- Toxic Substances
V. Technical Support Document for
Water Quality-Based Toxics Control
VI. Design Conditions
Design Flow
Design Temperature, pH, Hardness, and
VII.
vra.
IX.
Permit Averaging
Screening Manual
Biochemical Oxygen Demand/Dissolved
Oxygen
Toxic Organics
- Toxic Metals
Nutrients/Eutrophication
Innovative Wasteload Allocations*
* not yet available
25 USEPA. 1985. Technical Support Document for Water Quality-based Toxics Control. OW/OWRS and
OWEP, EPA 440/4-85 Washington, D.C. A revised draft (April 23,1990) is available and will replace the
1985 Guidance once it is finalized.
36
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Permit 'Writers Guidance
The Permit Writer's Guide to Water
Quality-based Permitting For Toxic Pollu-
tants - provides State and Federal NPDES
permit writers and water quality manage-
ment staff with a reference on water quality-
based permit issuance procedures. This
guidance presents fundamental concepts
and procedures in detail and refers to more
advanced toxics control procedures, such as
dynamic modeling of complex discharge sit-
uations, which may not yet be incorporated
into many State programs. The guidance
explains aspects of water quality-based tox-
ics control in terms of what a permit writer
currently needs to know to issue a water
quality-based toxics control NPDES permit.
The NPDES permits program is now fo-
cused on control of toxic pollutants and the
guidance document is directed at supporting
these control efforts. Water quality prob-
lems related to conventional pollutants, such
as those associated with point source contri-
butions to oxygen depletion, are addressed
in other guidance documents.
The Permit Writer's guide addresses
three areas of toxic effects: aquatic life,
human health, and the bioaccumulation of
specific chemicals. Each effect must be dealt
with on an individual basis using available
data and tools. This guidance also cata-
logues the principal procedures and tools
available.
The guidance supports an integrated tox-
ics control strategy using both whole effluent
toxicity-based assessment procedures and
pollutant-specific assessment procedures.
Both procedures are needed to enforce State
water quality standards.
Nonpoint Source Guidance
Section 319 of the Clean Water Act es-
tablishes direction and financial assistance
for the implementation of State NFS pro-
grams. NPS guidance encourages States to
develop State Clean Water Strategies for
integrating and unifying the States' approach
to water quality protection and clean-up.
Three steps are identified for this process:
comprehensive assessment of impaired or
threatened waters, targeted protection of
waters, and development of strategic man-
agement plans. States are to develop NPS
programs which build upon related pro-
grams (e.g., Clean Lakes, National Estuar-
ies, Stormwater Permits, Ground Water,
Toxics Controls, State Revolving Funds, and
Wetlands) and to coordinate their efforts
with other federal agencies.
The 1987 amendments to the CWA in-
clude provisions to encourage States to ac-
celerate efforts to control nonpoint source
pollution. The amendments require States
to prepare a Nonpoint Source Assessment
Report and a 4-year Management Program.
Funds are provided to assist the States in
implementing these programs. Information
on this guidance can be obtained from EPA's
Nonpoint Source Control Branch at
202/382-7085.
26 USEPA. 1987. Permit Writer's Guide to Water Quality-based Permitting for Toxic Pollutants.
OW/OWEP, EPA 440/4-87-005. Washington, D.C.
27 USEPA. 1987. Nonpoint Source Guidance. OW/OWRS, EPA. Washington, D.C.
37
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APPENDIX B SUPPORTING PROGRAMS
EPA Water Quality Criteria and
Standards
The water quality standards program, as
envisioned in Section 303(c) of the Clean
Water Act, is a joint effort between the
States and EPA. The States have primary
responsibility for setting, reviewing, revising
and enforcing water quality standards. EPA
develops regulations, policies, and guidance
to help States implement the program and
oversees States activities to ensure that State
adopted standards are consistent with the
requirements of the Act and the implement-
ing Water Quality Standards regulation (40
CFR Part 131). EPA has authority to review
and approve or disapprove State standards
and, where necessary, to promulgate Federal
water quality standards.
A water quality standard defines the
water quality goals of a waterbody, or portion
thereof, by designating the use or uses to be
made of the water, by setting criteria neces-
sary to protect the uses, and by preventing
degradation of water quality through anti-
degradation provisions. States adopt water
quality standards to protect public health or
welfare, enhance the quality of water, and
serve the purposes of the Clean Water Act.
"Serve the purposes of the Act" (as defined
in Sections 101(a), 101(a)(2), and 303(c) of
the Act) means that water quality standards
should: 1) include provisions for restoring
and maintaining chemical, physical, and bio-
logical integrity of State waters, 2) provide,
wherever attainable, water quality for the
protection and propagation offish, shellfish,
and wildlife and recreation in and on the
water ("fishable/swimmable"), and 3) con-
sider the use and value of State waters for
public water supplies, propagation of fish
and wildlife, recreation, agriculture and in-
dustrial purposes, and navigation.
In the current Water Quality Standards
regulation, section 131.11 encourages States
to adopt both numeric and narrative criteria.
Criteria protect both short-term (acute) and
long-term (chronic) effects. Numeric cri-
teria are important where the cause of toxic-
ity is known or for protection against
pollutants with potential human health im-
pacts or bioaccumulation potential. Nu-
meric water quality criteria may also be the
best way to address nonpoint source pollu-
tion problems. Narrative criteria can be the
basis for limiting toxicity in waste discharges
where a specific pollutant can be identified
as causing or contributing to the toxicity but
there are no numeric criteria in the State
standards, or where toxicity cannot be traced
to a particular pollutant. Whole effluent tox-
icity (WET) testing is also appropriate for
discharges containing multiple pollutants
because WET testing provides a method for
evaluating synergistic and antagonistic ef-
fects on aquatic life. Biological criteria pro-
vide a means to measure aquatic community
structure and function. EPA considers a
combination approach of narrative, nu-
meric, and biological criteria necessary to
protect beneficial uses fully from the broad
range of point and nonpoint sources of pol-
lution.
In addition, the Clean Water Act in Sec-
tion 303(c)(2)(B) requires States to adopt
numeric criteria for priority toxic pollutants
for which EPA has published criteria guid-
38
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ance when the discharge or presence of these
pollutants could reasonably be expected to
interfere with the designated uses in affected
waters. States may adopt criteria with State-
wide application or site-specific criteria.
EPA's regulation requires each State to
adopt, as pan of its water quality standards,
an antidegradation policy consistent with 30
CFR 131.12. The regulation also requires
each State to have implementation methods
for its antidegradation policies, i.e., decision
criteria for assessing activities that may im-
pact the integrity of a waterbody. Activities
covered by the antidegradation policy and
implementation methods include both point
and nonpoint sources of pollution. Section
131.12 effectively sets out a three-tiered ap-
proach for the protection of water quality.
Tier 1" (40 CFR 131.12 (a)(l)) of anti-
degradation maintains and protects existing
uses and the water quality necessary to pro-
tect these uses. "Tier II" (section
131.12(a)(2)) protects the water quality in
waters whose quality is better than that nec-
essary to protect "fishable/swimmable" uses
of the waterbody. Outstanding national
resource waters (ONRWs) are provided the
highest level of protection under the anti-
degradation policy (Tier IIT).
States may, at their discretion, adopt pol-
icies in their standards affecting the applica-
tion and implementation of standards. EPA
specifically recognizes mixing zones, vari-
ances, low flow exemptions, and schedules of
compliance for water quality-based permit
limits. Guidance on these subjects is avail-
able from EPA's Office of Water Regula-
tions and Standards, Criteria and Standards
Division.
Section 305 (b) - Water Quality
Assessment
Section 305(b)28 establishes a process for
reporting information about the quality of
the nation's water resources to EPA and
Congress. Each State, Territory, and Inter-
state Commission develops a program to
monitor the quality of its surface and ground
waters and report the current status of water
quality biennially to EPA. This information
is compiled into a biennial report to Con-
gress. The 305(b) report allows EPA to:
Determine the status of water qual-
ity.
Identify water quality problems and
trends.
Evaluate the causes of poor water
quality and the relative contributions
of pollution sources.
Report on the activities underway to
assess and restore water quality.
Determine the effectiveness of con-
trol programs.
Ensure that pollution control pro-
grams are focused on achieving envi-
ronmental results in an efficient
manner.
Determine the workload remaining
in restoring waters with poor quality
and protecting threatened waters.
Use information from the lists of wa-
ters developed under sections 304(1)
28 USEPA. 1989. Guidelines for the Preparation of the 1990 State Water Quality Assessment (section
305(b) Report). OW/OWRS. Washington, D.C.
39
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ters that still do not meet applicable water
quality standards. The short list (section
304(I)(1)(B)) is a list of State waters that are
not expected to meet applicable standards
after technology-based controls have been
met, due entirely or substantially to dis-
charge of toxic pollutants from point sources.
A fourth list is the list of point source dis-
chargers of priority toxic pollutants to waters
listed under section 304(1).
Section 319
Program
Nonpoint Source
and 319 and continue to m^int^in and
update the statutorily-required lists
of waters identified under sections
303(d)and314.
For each assessed waterbody, informa-
tion is provided on the water quality-Limited
status, use nonattainment causes and
sources, cause magnitude, and source mag-
nitude. Much of the information from the
305(b) assessments provide useful informa-
tion for developing lists of water quality-lim-
ited segments asked for in section 3Q3(d).
Section 304(1) ~ Impaired Waters
Section 304(1)29 required lists of im-
paired waters and sources to be submitted to
EPA as a "one time" effort These lists of
waters (known as the short, long, and mini
lists) provide three types of designations for
impaired waters and source impacts. The
mini list (section 304(l)(l)(A)(i)) is a list of
waters that the State does not expect to
achieve numeric water quality standards for
priority pollutants (section 307(a)) after
technology-based requirements have been
met, due to point or nonpoint source pollu-
tion. The long List (section 304(l)(l)(A)(ii))
is a comprehensive list of waters that are not
meeting the fishable and swimmable goals of
the Act whether due to toxicity or other im-
pairments; point or nonpoint sources; or
toxic, conventional, or nonconventional pol-
lutants. A waterbody which meets its desig-
nated use criteria and does not meet
fishable/swimmable criteria would be Listed
on the section 304(1) long List but not neces-
sarily on the section 303(d) List of waters
needing TMDLs. It would be appropriate
for a State to use the information on all
waters from its long Lists and apply these data
in developing the section 303(d) list of wa-
29 USEPA. March, 1988. Final Guidance for Implementation of Requirements under section 304(1) of the
Clean Water Act as Amended OWRS and OWEP. Washington, D.C
One key initiative of the 1987 Water
Quality Act Amendments to the Clean
Water Act was the addition of section 319
which established a national program to con-
trol nonpoint source pollution. Under this
program, States are asked to assess their NFS
pollution problems and submit that assess-
ment to EPA. These assessments include a
list of "navigable waters within the State
which, without additional action to control
nonpoint sources of pollution, cannot rea-
sonably be expected to attain or maintain
applicable water quality standards or the
goals and requirements of this Act." Other
paragraphs of section 319 require the identi-
fication of categories and subcategories of
NPS pollution which contribute to the iden-
tification of impaired waters; descriptions of
the procedures for identifying and im-
plementing BMPs; control measures for re-
ducing NPS pollution; and descriptions of
State and local programs used to abate NPS
pollution. Based upon the assessments,
State nonpoint source management pro-
grams are prepared and presented to EPA
for approval. Once these programs are ap-
proved, grant funds are made available for
the implementation of the program.
40
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Section 319 assessments identify waters
with impairments due primarily to NPSs for
which TMDLs (including LAs) may need to
be developed to establish protection of
water quality. States are encouraged to use
these tools where appropriate to achieve or
protect beneficial uses of the water.
Section 314 Clean Lakes Program
Historically, the Clean Lakes Program
has been active in awarding grants for the
study and restoration of publicly-owned
lakes. Under this program, states are en-
couraged to develop integrated water quality
strategies that include lake and reservoir
management, restoration, and protection ac-
tivities. EPA provides financial assistance as
available; however, greater emphasis is now
on developing technical support material
(e.g., a Lake and Reservoir Restoration
Guidance Manual).
Section 320 - National Estuary
Program
Authorized by Congress in 1985, and for-
mally established in 1987 by amendments to
the Clean Water Act, the National Estuary
Program (NEP) builds upon the lessons of
the Chesapeake Bay, Great Lakes, and other
earlier programs in a geographic, basin-wide
approach to environmental management.
The EPA Administrator selects estuaries for
NEP participation through State governors'
nominations. To be selected estuaries must
demonstrate a likelihood of success and evi-
dence of institutional, financial, and political
commitment to solve their problems.
Among the environmental problems ad-
dressed in the NEP estuaries are the loss of
aquatic habitats, toxic contamination of es-
tuarine sediments, increases in nutrient lev-
els, bacterial contamination, and hypom. As
methods for assessing and successfully man-
aging these estuaries are developed, this na-
tional demonstration program aims to
communicate its lessons to the more than
150 estuaries located along our coasts.
For approved estuaries, the Administra-
tor convenes management conferences, a
grouping of interested Federal, Regional,
State, and local governments, affected indus-
tries, scientific and academic institutions,
and citizen organizations. Management
conferences strive for an open, consensus-
building approach to defining program goals
and objectives, identifying problems to ad-
dress, and designing pollution preven-
tion/control and resource management
strategies to meet each objective. Manage-
ment conferences are required to create and
begin implementation of a Comprehensive
Conservation and Management Plan
(CCMP) designed to protect and restore the
estuary.
Monitoring Program
Ambient water quality monitoring is a
data gathering tool used for almost all water
quality assessment. Monitoring programs
serve to identify waters needing TMDLs,
quantify loads, verify models, and evaluate
effectiveness of water quality controls (in-
cluding BMP effectiveness). Once TMDLs
have been established for a given waterbody,
follow-up monitoring is recommended to
document improvement or lack of improve-
ment. Since the TMDL process is iterative,
monitoring data can provide the information
for updating and revising current TMDLs.
Ambient monitoring is used for setting per-
mit conditions, compliance, and enforce-
ment, and detecting new problems and
trends.
Effluent Limitation Guidelines and
Standards
EPA develops effluent limitation guide-
lines and new source performance standards
for industrial dischargers. These are uni-
form technology-based limitations for indus-
41
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trial facilities discharging directly into the
nation's waters. EPA also develops pretreat-
ment standards for those facilities which dis-
charge into Publicly Owned Treatment
Works (POTWs).
During the effluent guidelines promul-
gation process, EPA develops a profile of the
industry to determine pollutant loadings of
untreated wastewater for which effluent lim-
itation guidelines are being developed. Pol-
lutants of concern and technologies for
treating them are then identified. EPA then
prepares estimates of total investment, oper-
ation and maintenance costs of complying
with each technology option, and evaluates
the regulatory options, both technically and
economically, to select a technology as the
basis for the guidelines.
Effluent limitations, guidelines, and
standards are established for three types of
industrial pollutants: conventional, toxic,
and nonconventional. Effluent guidelines
generally limit the amount of pollutant that
can be discharged at an individual facility.
The numerical limits in the guidelines are
determined using industry-specific produc-
tion data and the treatability data for the
selected technology.
NPDES Permits and Individual
Control Strategies
All discrete sources of wastewater must
obtain a National Pollutant Discharge Elim-
ination System (NPDES) permit that regu-
lates the facility's discharge of pollutants.
The approach to controling and eliminating
water pollution is focused on the pollutants
determined to be harmful to receiving wa-
ters and on the sources of such pollutants.
Authority for issuing NPDES permits is es-
tablished under section 402 of the CWA.
Point sources are generally divided into
two types: "industrial" and "municipal.'' Na-
tionwide, there are approximately 50,000 in-
dustrial sources which include commercial
and manufacturing facilities. Municipal
sources, also known as POTWs, number
about 15,700 nationwide. Wastewater from
municipal sources results from domestic
wastewater discharged to POTWs as well as
the "indirect" discharge of industrial wastes
to sewers.
Section 304(1)(1)(D) required, at a min-
imum, the development of individual control
strategies (ICSs) for point source discharges
of priority toxic pollutants to waters identi-
fied on the short list. (The short list is com-
posed of State waters for which applicable
section 307(a) priority pollutant standards
are not expected to be achieved after tech-
nology-based controls have been met, due
entirely or substantially to point sources.)
An ICS consists of NPDES permit limita-
tions and schedules for achieving established
limitations, along with other documentation
to demonstrate that the controls selected are
appropriate and adequate.
Marine and Estuarine Waters
In January 1990, EPA published its Na-
tional Coastal and Marine Policy, which es-
tablishes EPA's goals for coastal and marine
protection. They include:
Recover full use of the nation's
shores, beaches, and water.
30 USEPA. 1989. Overview of selected EPA Regulations and Guidance Affecting POTW Management.
OW/OMPC, EPA 440/69-89/008. Washington, D.C. (Hotline: 800-424-9346)
31 USEPA. 1987. Permit Writer's Guide to Water Quality-based Permitting for Toxic Pollutants.
OW/OWEP, EPA 440/4-87-005. Washington, D.C.
42
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Restore the nation's shell fisheries
and salt-water fisheries.
Minimize the use of coastal and ma-
rine water for waste disposal.
Improve and expand coastal science.
Support international efforts to pro-
tect coastal and marine resources.
EPA's programs to protect ocean and
coastal waters and the Great Lakes from
nutrient and toxic pollutants emanating from
point and nonpoint sources are im-
plemented under the Qean Water Act and
the Marine Protection, Research, and Sanc-
tuaries Act (Ocean Dumping Act).
Marine and estuarine waters are, in many
cases, the ultimate sink for pollutants which
emanate from upland sources. Estuarine
and marine waters are particularly complex
and it is often difficult to predict pollutant
fate and transport. To address the increased
complexity and effect on aquatic life, water
quality management efforts must increase
accordingly. TMDLs can be a useful tool for
management of marine and estuarine wa-
ters. Technical guidance is currently being
revised to support estuarine modeling.
Groundwater
Contaminated ground water discharge to
surface water may be a source of contami-
nants in water quality-limited surface waters.
While ground water and surface water are
often treated as separate systems, they are in
reality highly interdependent components of
the hydrologic cycle. Subsurface interac-
tions with surface waters occur in a variety of
ways. In several studies, ground water dis-
charge accounted for as much as 90% or
more of stream flow in humid regions.
Therefore, the potential pollutant contribu-
tions from ground water to surface waters
should be investigated when developing
TMDLs. Additional information is avail-
able from the EPA Office of Ground Water
Protection.
CERCLA
The Comprehensive Environmental Re-
sponse, Compensation, and Liability Act
(CERCLA) or "Superfund" provides broad
federal authority to respond directly to re-
leases or threatened releases of hazardous
substances. This law also provides for the
cleanup of inactive or abandoned hazardous
waste sites. Under CERCLA, EPA assesses
the nature and extent of contamination at a
site, determines the public health and envi-
ronmental threats posed by a site, analyzes
the potential cleanup alternatives, and takes
action to clean up the site. In instances
where a CERCLA site has impact on a
nearby waterbody, the level of cleanup
needed to maintain water quality standards
of surface waters should have a direct rela-
tionship to the TMDL for the affected sur-
face waters. As part of the CERCLA
process, all "applicable or relevant and ap-
propriate requirements" of statutes such as
the CWA must be followed. Load alloca-
tions developed pursuant to section 303(d)
may, in appropriate circumstances, be "ap-
plicable or relevant and appropriate."
POTWs that discharge CERCLA haz-
ardous substances in effluent at levels that
equal or exceed NPDES permit limitations,
or for which no specific limitations exist, or
in spills or other releases, may be subject to
the notification requirements and liability
provisions under CERCLA. In addition,
32 USEPA. Technical Guidance Manual for Performing Wasteload Allocations, Book III Estuaries.
43
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POTWs that disposed of sludge in im-
poundments or landfills that are Superfund
sites may be required to pay for cleanup of
those sites. At times, POTWs may be re-
quested to accept wastewaters from Super-
fund cleanup activities. If discharge of
CERCLA wastewaters to a POTW is
deemed appropriate, the discharger must
ensure compliance with substantive and pro-
cedural requirements of the national pre-
treatment program and all local
pretreatment regulations before discharging
wastewater to the POTW.
The provisions of CERCLA extend well
beyond the regulation of POTW discharges.
The most common types of Superfund sites
governed by CERCLA include abandoned
hazardous waste sites and inactive mines,
many of which do not discharge to POTWs.
SARA
The Superfund Amendments and
Reauthorization Act (SARA, Hotline 800-
535-0202), which amended CERCLA, also
established in Title IH a new program to
increase the public's knowledge of and ac-
cess to information on the presence of haz-
ardous chemicals in their communities and
releases of these chemicals into the environ-
ment Title m (Community Right to Know
Program) requires facilities to notify State
and local officials if they have extremely haz-
ardous substances present at their facilities
in amounts exceeding certain "threshold
planning quantities." If appropriate, the fa-
cility must also provide material safety data
sheets on hazardous chemicals stored at
their facilities, or lists of chemicals for which
these data sheets are maintained, and report
annually on the inventory of these chemicals
used at their facility. The law may also re-
quire facilities to submit information each
year on the amount of toxic chemicals re-
leased by the facilities to all media (air,
water, and land), if they fall within Standards
Industrial Classification Codes 20 to 39 and
meet certain threshold limits.
44
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APPENDIX C SCREENING CATEGORIES
This list of screening categories is based on categories promulgated as the minimum data
set a State should consider when developing their list of impaired waters pursuant to section
304(1) of the Clean Water Act. When developing lists pursuant to this guidance and to meet
the requirements of section 303(d), a State should, at a minimum, use these categories to
identify their water quality-limited waters. States should also consider additional information,
such as TRI data, streamflow information collected by USGS, locally available data, and public
comments on proposed 303(d) lists.
1. Waters where fishing or shellfish bans
and/or advisories are currently in effect
or are anticipated.
2. Waters where there have been repeated
fishkills or where abnormalities (cancers,
lesions, tumors, etc.) have been observed
in fish or other aquatic life during the last
ten years.
3. Waters where there are restrictions on
water sports or recreational contact.
4. Waters identified by the State in its most
recent State section 305(b) report as ei-
ther "partially achieving" or "not achiev-
ing" designated uses.
5. Waters listed under sections 304(1) and
319oftheCWA.
6. Waters identified by the State as priority
waterbodies. (State Water Quality Man-
agement plans often include priority
waterbody lists which are those waters
that most need water pollution control
decisions to achieve water quality stan-
dards or goals.)
7. Waters where ambient data indicate po-
tential or actual exceedances of water
quality criteria due to toxic pollutants
from an industry classified as a primary
industry in Appendix A of 40 CFR Part
122.
8. Waters for which effluent toxicity test
results indicate possible or actual ex-
ceedances of State water quality stan-
dards, including narrative "free from"
water quality criteria or EPA water qual-
ity criteria where State criteria are not
available.
9. Waters with primary industrial major dis-
chargers where dilution analyses indicate
exceedances of State narrative or nu-
meric water quality criteria (or EPA
water quality criteria where state stan-
dards are not available) for toxic pollu-
tants, ammonia, or chlorine. These
dilution analyses must be based on esti-
mates of discharge levels derived from
effluent guidelines development docu-
ments, NPDES permits or permit appli-
cation data (e.g., Form 2C), Discharge
Monitoring Reports (DMRs), or other
available information.
10. Waters with POTW dischargers requir-
ing local pretreatment programs where
dilution analyses indicate exceedances of
State water quality criteria (or EPA
water quality criteria where State water
quality criteria are not available) for
45
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toxic pollutants, ammonia, or chlorine.
These dilution analyses must be based
upon data from NPDES permits or per-
mit applications (e.g., Form 2C), Dis-
charge Monitoring Reports (DMRs), or
other available information.
11. Waters with facilities not included in the
previous two categories such as major
POTWs, and industrial minor discharg-
ers where dilution analyses indicate ex-
ceedances of numeric or narrative State
water quality criteria (or EPA water
quality criteria where State water quality
criteria are not available) for toxic pollu-
tants, ammonia, or chlorine. These dilu-
tion analyses must be based upon
estimates of discharge levels derived
from effluent guideline development
documents, NPDES permits or permit
application data, Discharge Monitoring
Reports (DMRs), or other available in-
formation.
12. Waters classified for uses that will not
support the "fishable/swimmable" goals
of the Clean Water Act.
13. Waters where ambient toxicity or ad-
verse water quality conditions have been
reported by local, State, EPA, or other
Federal agencies, the private sector, pub-
lic interest groups, or universities. These
organizations and groups should be ac-
tively solicited for research they may be
conducting or reporting. For example,
university researchers, the United States
Department of Agriculture, the National
Oceanic and Atmospheric Administra-
tion, the United States Geological Sur-
vey, and the United States Fish and
Wildlif e Service are good sources of field
data and research.
14. Waters identified by the State as im-
paired in its most recent Clean Lake As-
sessments conducted under section 314
of the Clean Water Act.
15. Waters identified as impaired by non-
point sources in America's Clean Water:
The States' Nonpoint Source Assess-
ments 1985 (Association of State and In-
terstate Water Pollution Control
Administrators (ASIWPCA)) or waters
identified as impaired or threatened in a
nonpoint source assessment submitted
by the State to EPA under section 319 of
the Clean Water Act.
16. Surface waters impaired by pollutants
from hazardous waste sites on the Na-
tional Priority List prepared under sec-
tion 105(8)(A) of CERCLA.
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APPENDIX D - SELECTED TECHNICAL
CONSIDERATIONS
Design Conditions
When developing a TMDL, design con-
ditions are those critical conditions that must
be specified in order to determine attain-
ment of water quality standards. In specify-
ing conditions in the waterbody, an attempt
is made to use a reasonable "worst case"
condition. For example, stream analysis
often uses a low flow (e.g., 7-day low flow,
once in 10-years commonly known as ?QiO or
biologically-based 4-day 3-year flows) high
temperature design condition.
In situations where nonpoint source
loadings at wet weather flow conditions are
more significant than the point source load-
ings, the use of low flow-related design con-
ditions is inappropriate. Wet weather flow
conditions may be appropriate for analysis of
nonpoint and intermittent point source dis-
charges such as storm sewers. Other factors
such as rainfall intensity and duration, time
since previous rainfall, pollutant accumula-
tion rates, and stream flow previous to rain-
fall should be considered in selecting design
conditions for nonpoint source analysis. In
some instances (e.g., carcinogenic pollu-
tants), it is appropriate to use the harmonic
mean flow to estimate loading capacity.
Often conditions of best management
practices may be specified for factors other
than physical conditions. For example, as-
sumptions about cropping patterns, logging
rates, or grazing practices may be necessary
to determine the pollution loading estimates
of a waterbody. Design conditions are less
standardized for these factors and a reason-
able worst case condition often must be de-
veloped on a case-by-case basis.
In general, for point sources, continuous
discharges present the greatest stress under
low flow, dry weather conditions. For pollu-
tants transported in runoff, critical condi-
tions will be rainfall-related, but may occur
under a variety of flow conditions. ForNPSs
or intermittent point sources, generally, high
flow, wet weather conditions need to be eval-
uated. For carcinogenic pollutants, har-
monic mean flows may be appropriate.
Additional details for selecting design con-
ditions are provided in technical guidance.
Mathematical Models
When the analyst is calculating a numer-
ical TMDL, several mathematical models
can be used to evaluate alternative pollutant
loading scenarios. Models supported by the
EPA Center for Exposure and Assessment
Modeling (CEAM) are summarized in Ap-
33 USEPA. 1985. Technical Support Document for Water Quality-based Toxics Control OW/OWEP and
OWRS, EPA 440/4-85-032. Washington, D.C. A revised draft (April 23,1990) is available and will
replace the 1985 Guidance when finalized.
47
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pendix E. While it is beyond the scope of this
guidance to provide a detailed rationale for
model selection, the following briefly pres-
ents a discussion on model characteristics
and selection.
Model characteristics
Models can be characterized in numer-
ous ways such as by their data requirements,
ease of application, etc. This section sum-
marizes models based on four categories:
temporal characteristics, spatial characteris-
tics, specific constituents and process simu-
lated, and transport processes.
Temporal characteristics - This in-
cludes whether the model is steady-
state (inputs and outputs constant
over time), time-averaged (for exam-
ple, tidally-averaged), or dynamic. If
the model is dynamic, an appropriate
time step needs to be selected. For
example, streams may require short
time steps (hourly or less) while
lakes, which typically have residence
times in excess of weeks, can gener-
ally be modeled with longer time
steps (e.g., daily or more). Similarly,
loads from NFS models are often
lumped together into event or annual
loadings.
Spatial characteristics - This includes
the number of dimensions simulated
and the degree of spatial resolution.
In most stream models, one-dimen-
sional models are used since typically
vertical and horizontal gradients are
small. For large lakes and estuaries,
two- or three-dimensional models
may be more appropriate because
both vertical and horizontal concen-
tration gradients commonly occur.
Segmented or multiple catchment
models may be more appropriate for
heterogeneous watersheds, whereas,
lumped single-catchment models are
more appropriate for homogeneous
or less complex situations.
Specific constituents and processes
simulated - Models vary in the types
of constituents and processes simu-
lated and in the complexity of the
formulations used to represent each
process. For example, simple DO
models include only reaeration and
BOD decay while more complex
models include other processes such
as nitrification, photosynthesis, and
algal respiration.
Transport processes - These include
advection, dispersion, runoff, inter-
flow, ground water interactions, and
the effects of stratification on these
processes. Most river models are
concerned only with downstream ad-
vection and dispersion. Lake and es-
tuary models may include advection
and dispersion in one or more dimen-
sions, as well as the effects of density
stratification. For toxic modeling, it
may be important to use models
which account for near-field mixing
since many of these pollutants may
exert maximum toxicity close to the
point of discharge. To incorporate
both point and nonpoint sources into
TMDLs, it will be important to con-
sider integrated watershed models.'
Model selection
A model should be selected based on its
adequacy for the intended use, for the spe-
cific waterbody, and for the critical condi-
tions occurring at that waterbody. While the
selection of an appropriate model should be
made by a water quality analyst, it is useful
for program managers to be familiar with the
decisions which must be made. Four basic
48
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steps have been identified that an analyst
would go through to select an appropriate
model:
Identify models applicable to the sit-
uation.
Define the appropriate level of anal-
ysis.
Incorporate practical constraints into
the selection criteria.
Select a specific model.
Identify models applicable to the situation.
An obvious choice for narrowing the selec-
tion of an appropriate model is based on the
waterbody type (river, estuary, or lake) and
the type of analysis (BOD/DO, toxics, etc.)
A preliminary list of models may also be
screened by selecting models which consider
the appropriate constituents and processes
that are important for the pollutant being
studied.
Define the appropriate type of analysis.
Four types of models are:
Simple calculator models - These in-
clude dilution and mass balance cal-
culations, Streeter-Phelps equations
and modifications thereof, analytical
solutions to transport equations,
steady-state nutrient loading models,
regression models, and other simpli-
fied modeling procedures that can be
performed on desk top calculators.
Steady state computer models
These models compute average spa-
tial profiles of constituents along a
river or estuary assuming everything
remains constant with time, including
loadings, upstream water quality con-
ditions, stream flow rates, meteoro-
logical conditions, etc.
Ouasi-dynamiy models - These mod-
els are a compromise between
steady-state models and dynamic
models. Quasi-dynamic models as-
sume most of the above factors re-
main constant, but allow one or more
of them to vary with time, for example
waste loading rates or stream flow
rates. Some of the models hold the
waste loading and flow rates constant,
but predict effects such as the diurnal
variations hi dissolved oxygen due to
algal photosynthesis and respiration.
Dynamic models - These models pre-
dict temporal and spatial variations hi
water quality due to varied loadings,
flow conditions, meteorological con-
ditions, and internal processes within
the watershed or waterbody. Dy-
namic models are useful for analyzing
transient events (e.g., storms and long
term seasonal cycles) such as those
important in lake eutrophication
analyses.
The above model types are listed in order
of increasing complexity, data requirements,
and cost of application. In addition, lognor-
mal probabilistic models and Monte Carlo
simulation techniques have been used to
modify some of the above approaches.
Probabilistic models use lognormal proba-
bility distributions of model inputs to calcu-
late probability distributions of model
output Since this method does not incorpo-
rate fate and transport processes, it can only
be used to predict the concentration of a
substance after complete mixing and before
decay or transformation significantly alters
the concentration. Monte Carlo simulations
combine probabilistic inputs with determin-
istic models. A fate and transport model is
run a large number of times based on ran-
49
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domly selected input values. The output
from these models are then rank ordered to
produce a frequency distribution. These fre-
quency distributions may then be compared
to instream criteria (e.g., criteria maximum
concentration (CMC) and criteria continu-
ous concentration (CCC)) to determine if
water quality standards are met.
Incorporate practical constraints. In gen-
eral, the analyst should consider the data
requirements for each level of analysis, the
availability of historical data, the modeling
effort required for each level of analysis, and
available resources. Availability of histori-
cal data for calibration and verification is one
of the key cost savings considerations.
Select a specific model. The analyst should
consider model familiarity, technical sup-
port and model availability, documentation
quality, application ease, and professional
recognition and acceptance of a model.
Pollutant Allocation Schemes
Individual States use various load alloca-
tion schemes appropriate to their needs and
may specify that a particular method be used.
Methods of allocating loads have been his-
torically applied to point sources. Applica-
tion of these methodologies to nonpoint
sources has not been well studied to date.
Three common methods for allocating loads
(equal percent removal, equal effluent con-
centrations, and a hybrid method) are dis-
cussed below. Other methods are detailed
in another EPA document
The first method is equal percent re-
moval and exists in two forms. In one, the
overall removal efficiencies of the sources
are set so they are all equal. In the latter, the
incremental removal efficiencies beyond the
current discharge are equal. This method is
appropriate when the incremental removal
efficiencies are relatively small, so that the
necessary improvement in water quality can
be obtained by minor improvement in treat-
ment at each point source, at little cost.
The second common allocation method
specifies equal effluent concentrations. This
is similar to equal percent removal if influent
concentrations at all sources are approxi-
mately the same. However, if one source has
substantially higher influent levels, then
equal effluent concentrations will require
higher overall treatment levels than the
equal percent removal approach.
The third commonly used method of al-
locating loads can be termed a hybrid
method. With this method, the criteria for
waste reduction may not be the same from
one source to the next One source may be
allowed to operate unchanged while another
may be required to provide the entire load
reduction. More generally, a proportional-
ity rule may be assigned that requires the
percent removal to be proportional to the
input source loading or flow rate.
Multiple Discharges
TMDLs are particularly critical for
waterbodies when the effect from multiple
pollution sources overlap. The key concern
associated with multiple point or nonpoint
pollution sources is the potential for com-
bined impacts. To perform this analysis, it
may be necessary to apply near-field mixing
models (mixing zone analysis) in addition to
34 USEPA. 1985. Technical Support Document for Water Quality-based Toxics Control OW/OWEP and
OWRS, EPA 44W4-85-032. Washington, D.C. A revised draft (April 23,1990) is available and will replace
the 1985 Guidance when finalized.
50
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a far-field model which considers pollutants
from numerous point or nonpoint sources
(after the mixing zone). A recommended
procedure for evaluating toxicity from mul-
tiple discharges is summarized in EPA guid-
ance.
Allocation Tradeoffs
Where appropriate and technically feasi-
ble, certain cost-effective benefits may be
gained by making tradeoffs among
wasteload allocations. Such a practice is sim-
ilar to what would be done during the initial
considerations of tradeoffs of loads between
point and nonpoint sources. In the case of
watershed or estuary management, this may
be particularly useful to achieve pollution
reduction in the most cost-effective manner
possible.
The incentive for trading load allocations
is to achieve the required level of control by
choosing to control one pollutant source
over another. Technological feasibility, eco-
nomic issues, and regulatory authority are all
factors to consider when trading allocations.
For example, to reduce nutrient loads to a
receiving water, nonpoint source controls
that can be adequately maintained and en-
forced, may be much more cost effective
than increasing the level of control on a point
source discharger.
Pollutant trades are most likely to occur
between point and nonpoint sources. How-
ever, where effluents from different point
source dischargers are comparable, trades
may be acceptable so long as water quality
standards (including antidegradation regula-
tions and policies) and minimum applicable
technology-based controls are met Simi-
35 USEPA. 1985. Techical Support Document for Water Quality-based Toxics Control. OW/OWEP and
OWRS, EPA 440/4-85-032. Washington, D.C. A revised draft (April 23,1990) is available and will replace
the 1985 Guidance when finalized.
larly, tradeoffs between nonpoint sources
are also acceptable.
The Dillon Reservoir (west of Denver,
Colorado) is an example of point and non-
point source phosphorus load tradeoffs. In
this example, the cost associated with point
source reduction was $1.5 million per year,
whereas the cost associated with NPS con-
trols was $0.2 to $1.0 million per year. Be-
cause of this cost differential, tradeoffs
allowed publicly-owned treatment works to
achieve reductions in phosphorus loads to
the Dillon Reservoir by controlling NPSs
rather than expanding the sewage treatment
system.
Persistent and/or Highly
Bioaccumulative Toxic Pollutants
Persistent and/or bioaccumulative toxic
pollutants require special attention during
analysis of toxicity and TMDL development.
The primary concern is that toxic pollutants
that enter a waterbody at levels that are non-
toxic in the water column may accumulate in
sediment or aquatic life. These pollutants
may then adversely affect aquatic/wildlife or
pose a risk to humans by exposure to hazard-
ous chemicals through consumption of con-
taminated fish or shellfish. Chemicals that
bioaccumulate at high rates include some
metals, organic compounds, and or-
ganometalh'c compounds. Current technical
guidance for wasteload allocation (see Ap-
pendix A) summarize a number of models
which are appropriate for modeling the fate
and transport of toxics in streams/rivers,
lakes, and estuaries. Additional details for
assessing and controlling risk have been ad-
dressed in technical support documentation.
51
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Use of Two-number Criteria
Because of inherent variation in effluent
and receiving water flows and pollutant con-
centrations, specifying a concentration that
must not be exceeded at any time or place
may not be appropriate for the protection of
aquatic Life. The format usually selected for
expressing water quality criteria to protect
aquatic life consists of recommendations
concerning concentration magnitudes, dura-
tion of averaging periods, and average fre-
quencies of allowed excursions. Use of this
magnitude-duration-frequency format al-
lows water quality criteria for aquatic life to
be adequately protective without being as
overprotective as if criteria were expressed
using a simpler format In many cases, these
considerations are evaluated during the
standards setting process and TMDLs are
used to develop controls that result in attain-
ment of applicable water quality standards.
Duration of exposure considers the
amount of time organisms will be exposed to
toxicants. It is expressed as that period of
time over which the instream concentration
is averaged for comparison with criteria con-
centrations. Frequency is defined as how
often exposures that exceed the criteria can
occur during a given period of time (e.g.,
once every three years) without unaccept-
ably affecting the community. To account
for acute toxic effects, States may adopt
acute criteria expressed as the criteria maxi-
mum concentration (CMC) occurring in a
one-hour averaging period. Similarly,
chronic criteria expressed as the criteria con-
tinuous concentration (CCC) should be de-
veloped as toxicant concentrations which
should not be exceeded over longer periods
of time. For the purposes of modeling, the
ambient concentration should not exceed
the CMC more than once every three years.
(If the biological community is under stress
because of spills, multiple dischargers, or has
a low recovery potential, or if a local species
is very important, the frequency should be
decreased.)
Although these criteria are mostly used
for application to low flow conditions, the
lexicological basis for the criteria is equally
valid for high flow conditions. It is important
for States to protect designated water uses
during all flow conditions; therefore, the
two-number criteria should be used for all
flow conditions unless separate guidance for
adopting wet weather criteria is available.
However, States should apply duration and
frequency parameters to account for the high
flow, intermittent nature of nonpoint source
loadings.
Sediment Issues
The problems associated with clean and
contaminated sediment are not the same.
Clean sediment can impair fish reproduction
by silting-up spawning areas, and can in-
crease turbidity. Draft (clean) sediment cri-
teria have been developed in Idaho that
include turbidity, inter-gravel dissolved oxy-
gen, and cobble embeddedness. The criteria
developed may be most appropriate for sal-
monid streams, but the framework may have
wide application. The major concerns re-
garding contaminated sediment are pollu-
tant releases to the water column,
bioaccumulation, and biomagnification.
Sediment criteria being developed by EPA
have centered on evaluating and developing
an understanding of the principal factors that
influence the sediment/contaminant interac-
tions with the water column (Equilibrium
Partitioning Approach). (The Science Advi-
sory Board will be reviewing methods for
establishing sediment criteria for metal con-
taminants and procedures for establishing
standardized bioassays in 1991.) Through
such an understanding, exposure estimates
of benthic and other organisms can be made.
Chronic water quality criteria, or possibly
other lexicological endpoints, can then be
used to predict potential biological effects.
-------
In some cases, sediment criteria alone sions can be made. Additionally, ground
would be sufficient to identify and to estab- water inputs through sediments should be
lish clean up levels for contaminated sedi- distinguished from inputs from the sediment
ments. In other cases, the sediment criteria alone, so that proper control measures are
should be supplemented with biological or implemented.
other types of analysis before clean-up deci-
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APPENDIXE - MATHEMATICAL MODEL SUPPORT
The Center for Exposure Assessment
Modeling (CEAM) was established in July,
198? to meet the water quality and exposure
modeling needs of States and EPA program
and Regiona! offices. CEAM provides ex-
posure assessment technology, training, and
consultation for analysts and decisions-mak-
ers operating under various legislative man-
dates, including the Clean Water Act.
With support and resources from the
Monitoring Branch in the Assessment and
Watershed Protection Division, Office of
Water Regulations and Standards, CEAM
maintains a distribution center for water
quality models and databases for the user
community. Users are kept up to date
through user group meetings, a newsletter,
and an electronic bulletin board. For the
major wasteload allocations models, CEAM
offers 2- to 5-day training courses at EPA
Headquarters, Regional sites, and the Ath-
ens Environmental Research Laboratory fa-
cility. Longer-term "on-the-job" training at
CEAM for individuals is also available.
Technical assistance and review are pro-
vided by CEAM scientists and engineers, as
well as by affiliated academics and consul-
tants. Exposure calculations and assess-
ments for especially difficult or unusual
discharge situations can be arranged as re-
sources allow.
The center currently distributes 21 simu-
lation models and databases. These can be
applied to urban runoff (SWMM4, HSPF9),
leaching and runoff from soils (PRZM,
HSPF9), transport through soil and ground
water (MULTIMED, RUSTIC), conven-
tional pollution of streams (QUAL2E,
HSPF9, WASP4), toxic pollution of streams
(HSPF9, WASP4, EXAMS2, DYNTOX),
toxic pollution of lakes and estuaries
(WASP4, EXAMS2), conventional pollu-
tion of lakes and estuaries (WASP4), near-
field mixing and dilution in rivers, lakes,
estuaries, and oceans (CORMIX1), cohe-
sive sediment transport (SED2D-V). river
and tidal hydrodynamics (DYNHYD5,
RIVMOD, HYDRO2D-V, HYDRO3D),
geochemical equilibrium (MINTEQA3),
and aquatic food chain bioaccumulation
(FGETS). Software and databases distrib-
uted to aid in data analysis include ANNIE-
IDE, DBAPE, and the CLC Database.
Currently available models are summarized
below. Those with no version number are
available as test code, and will be routinely
distributed when fully tested.
Table E-l CEAM Supported Models
Model Name Version No.
DYNTOX 1.0
EXAMSn 2.94
HSPF 9.01
MINTEQA3/PRODEFA3 3.00
PRZM 1.00
QUAL2E-UNCAS 3.11
SWMM 33
WASP4/TOXI/EUTRO 4.22
DYNHYD5 5.02
GCSOLAR 1.10
FGETS 1.00
CORMIX1 1.00
ANNIE-IDE 1.11
DBAPE 1.05
CLC Database 2.00
RUSTIC
MULTIMED
HYDRO2D-V
SED2D-V
HYDRO3D
RIVMOD
54
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CEAM operates an Electronic Bulletin
Board System (BBS) to meet the increasing
demand for supported exposure assessment
models. It allows efficient communication
between users with modem-equipped com-
puters and CEAM support staff as well as
immediate acquisition of models by those
under extreme time pressure. The services
presently offered are: 1) downloading of
CEAM supported models, 2) uploading of
user input data sets for staff review and prob-
lem solving, 3) a bulletin area listing current
CEAM activities and events, such as training
courses, helpful hints about the models, and
model documentation, and 4) a message
area for discussion of computer modeling
problems and enhancements. To access the
CEAM BBS, a user must call 404/546-3403
or FTS 250-3402 and follow the interactive
prompts. The communications parameters
are 9600/2400/1200 baud, no parity, 8 data
bits, and 1 stop bit.
Information about obtaining the models
may be obtained by writing the Center for
Exposure Assessment Modeling. U.S. EPA,
College Station Road, Athens, GA 30613, or.
by calling 404-546-3549.
55
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APPENDIXF GENERAL EPA/STATE
AGREEMENT OUTLINE FOR
DEVELOPMENT OF TMDLs
Since conditions, procedures, and methodologies may vary between EPA Regions and their
States, a general outline of an example agreement is provided. This outline can be used in
conjunction with the referenced technical guidance documents to prepare EPA/State Agree-
ments.
I. General
A. Purpose, Scope, and Authority
B. Statement of Policy
D. Water Quality Standards Considerations
A. General
B. Type of Stream Classifications
ID. Allocation Procedures and Policies
A. Basic Approach for Establishing
Boundaries for TMDL Development
B. Determination of TMDL, WLA, and LA
Using Water Quality Models
C. Determination of TMDL, WLA, and LA
Using Other Analytical Tools
D. Special Case Policies
IV. Public Participation Process
V. Approval of TMDL, WLA, and LA
VI. Incorporation of Allocations into NPDES Permits
A, General
B. Priority Considerations
Appendix. State Continuing Planning Process (CPP)
56
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APPENDIX G - CAUSES AND SOURCES OF POLLUTION
Causes and Sources: Section 305(b) Waterbody System User's Guide, Third Edition
(Version 2.0), August 1989, USEPA, Office of Water, Assessment and Watershed Protection
Division, pages A-27 through A-31.
Causes
Causes are the pollutants or conditions
that are causing or expected to cause ex-
ceedances of water quality standards. One
or more of the following categories should
be used to identify causes of impairment:
- unknown tenacity
- pesticides
- priority organics
- Donpriority organics
- metals
- ammonia
- chlorine
- other organics
- nutrients
- pH
- siltation
- filling and draining
organic enrichment/
DO
saliniry/TDS/chlorides
thermal modifications
flow alterations
other habitat
alterations
pathogens
radiation
oil and grease
taste and odor
suspended solids
noxious aquatic plants
cause unknown
Sources
Sources are the point and nonpoint
sources of the pollution categories that are
listed as causes identified above. One or
more of the following categories should be
used to identify sources of impairment:
- source unknown
- industrial point
sources
- combined sewer
overflow
- silviculture
- urban runoff/storm
sewers
- land disposal
- habitat modification
- municipal point
sources
- agriculture
- construction
- resource extraction
- hydromodification
Other categories:
- atmospheric deposition -
- highway maintenance/
runoff
- in-place contaminants
- recreational activities
- salt storage sites
storage tank leaks
spills
- natural
- upstream impound-
ments
57
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LIST OF ACRONYMS
ARAR Applicable or Relevant and Appropriate Requirements
AT Advanced Treatment
BAT Best Available Technology
BCT Best Conventional Technology
BMP Best Management Practice
BODs 5-day Biochemical Oxygen Demand
BPJ Best Professional Judgement
BPT Best Practicable Control Technology
CCC Criteria Continuous Concentration
CEAM/BBS Center for Exposure Assessment Modeling/Electronic Bulletin Board System
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
CLP Clean Lakes Program
CMC Criteria Maximum Concentration
CPP Continuing Planning Process
CSO Combined Sewer Overflow
CWA Clean Water Act
DO Dissolved Oxygen
EPA Environmental Protection Agency
FR Federal Register
ICS Individual Control Strategy
LA Load Allocation
LC Loading Capacity
MOS Margin of Safety
NCMP National Coastal and Marine Policy
NEP National Estuary Program
NPDES National Pollutant Discharge Elimination System
NPS Nonpoint Source
POTW Publicly Owned Treatment Works
QA/QC Quality Assurance/Quality Control
SARA Superfund Amendments and Reauthorization Act
TMDL Total Maximum Daily Load
TRE Toxic Reduction Evaluation
TRI Toxic Release Inventory
TSD Technical Support Document
WBS Waterbody System
WLA Wasteload Allocation
WQMP Water Quality Management Plan
WWTP Wastewater Treatment Plant
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SELECTED OFFICES, DIVISIONS, BRANCHES,
AND SECTIONS WITHIN EPA
General
Phone N
Contact
OW Office of Water 382-5700
OWRS Office of Water Regulations and Standards 382-5400
AED Analysis and Evaluation Division 382-5389
ITD Industrial Technology Division 382-7120
CSD Criteria and Standards Division 382-7301
AWPD Assessment and Watershed Protection Division 382-7040
Monitoring Branch 382-7056
Monitoring Management Section (TMDLs/WLAs)
Monitoring Analysis Section
Water Quality Analysis Branch 382-7046
Information Services Section
Special Studies Section
Exposure Assessment Section
Nonpoint Source Control Branch 382-7085
Clean Lakes Section
Nonpoint Source Control Section (BMPs/LAs)
OMEP Office of Marine and Estuarine Protection 382-7166
OWEP Office of Water Enforcement and Permits 475 -8488
OMPC Office of Municipal Pollution Control 382-5850
ODW Office of Drinking Water 382-5543
OGWP Office of Ground Water Protection 382-7077
OWP Office of Wetlands Protection 475-7791
All area codes are 202.
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