UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D. C. 20460 

OFFICE OF 

WATER 

SUBJECT: Interpretation of Federal Antidegradation Regulatory 

Requirement 

FROM: 

TO: 

Tudor T. Davies Director 

Office of Science and Technology 

Water Management Division Directors 

Regions I - X 

The main purpose of this memorandum is to provide guidance 

on the interpretation of the antidegradation policy in 40 CFR 

131.12(a) (2) as it relates to nonpoint sources. Guidance on this 

subject was requested by the regional water quality standards 

coordinators at their March 1993 meeting. 

This memorandum also discusses the applicability of water 

quality standards to nonpoint sources, regardless of whether 

direct implementation mechanisms exist for nonpoint sources. 

The Federal antidegradation policy requirement is found in 

Section 131.12 of the water quality standards regulation (40 CFR 

Part 131). This guidance addresses the language and intent of the 

Federal regulatory requirement. However, water quality standards 

are State laws or regulations. It is the actual language of a 

State's antidegradation policy that is implemented as the State's 

water quality standard. This guidance does not supersede 

existing State law or regulation. 

In the early years of the standards program, most States 

adopted EPA's regulatory language or language consistent with the 

regulatory requirements for antidegradation. As the water 

program has evolved more attention is being given to actual 

antidegradation policy implementation and increasing attention to 

the need for controls on nonpoint sources. Although there are no 

Federally enforceable requirements for control of nonpoint 

sources in the Clean Water Act, water quality impacts from 
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nonpoint sources have become increasingly evident. Many States 

have asked what the antidegradation policy requires for the 

development and implementation of nonpoint source controls in 

high quality waters. 

There are two components of the water quality standards 

regulation that are relevant to this inquiry. First, the EPA 

rule provides that as one condition of allowing degradation of a 

high quality water, "the State shall assure that there shall be 

achieved the highest statutory and regulatory requirements for 

all new and existing point sources and all cost-effective and 

reasonable best management practices for nonpoint source 

control." (40 CFR 131.12(a) (2)). Second, degradation is also 

conditioned upon a State determination that "allowing a lower 

water quality is necessary to accommodate important economic or 

social development in the area in which the waters are located." 

Id. (Emphasis added.) 

THE ISSUE 

Do those provisions REQUIRE a State to establish and 

implement best management practices (BMPs) for nonpoint sources 

before allowing degradation in high quality waters? 

THE REGULATORY INTERPRETATION 

Section 131.12(a) (2) does not REQUIRE; a State to establish 

BMPs for nonpoint sources where such BMP requirements do not 

exist. 

We interpret Section 131.12 (a) (2) as REQUIRING States to 

adopt an antidegradation policy that includes a provision that 

will assure that all cost-effective and reasonable BMPs 

established under State authority are implemented for nonpoint 

sources before the State authorizes degradation of high quality 

waters by point sources. 

Section 131.12(a)(2) does not 

controls on nonpoint sources. The 

mandate that States establish 

Act leaves it to the States to 

determine what, if any, controls on nonpoint sources are needed 

to provide for attainment of State water quality standards. See 

CWA Section 319. States may adopt enforceable requirements, or 

voluntary programs to address nonpoint source pollution. Id. 

Section 40 CFR 131.12(a)(2) does not require that States adopt or 

implement best management practices for nonpoint sources prior to 

allowing point source degradation of a high quality water. 

However, States that have adopted nonpoint source controls must 

assure that such controls are properly implemented before 

authorization is granted to allow point source degradation of 

water quality. 
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The rationale behind the antidegradation regulatory 

statement regarding achievement of statutory requirements for 

point sources and all cost effective and reasonable BMPs for 

nonpoint sources is to assure that, in high quality waters, where 

there are existing point or nonpoint source control compliance 

problems, proposed new or expanded point sources are not allowed 

to contribute additional pollutants that could result in 

degradation. Where such compliance problems exist, it would be 

inconsistent with the philosophy of the antidegradation policy to 

authorize the discharge of additional pollutants in the absence 

of adequate assurance that any existing compliance problems will 

be resolved. 

EPA's regulation also requires maintenance of high quality 

waters except where the State finds that degradation is 

"necessary to accommodate important economic and social 

development in the area in which the waters are located." (40 CFR 

Part 131.12(a) (Emphasis added)). We believe this phrase should 

be interpreted to prohibit point source degradation as 

unnecessary to accommodate important economic and social 

development if it could be partially or completely prevented 

through implementation of existing State-required BMPs. 

EPA believes that its antidegradation policy should be 

interpreted, with respect to the matters discussed in this 

memorandum, on a pollutant-by-pollutant and waterbody-bywaterbody basis. For example, degradation of a high quality 

waterbody by a proposed new BOD source prior to implementation of 

required BMPs on the same waterbody that are related to BOD 

loading should not be allowed. However, degradation by the new 

point source of BOD should not be barred solely on the basis that 

BMPs unrelated to BOD loadings, or which relate to other 

waterbodies, have not been implemented. 

EPA understands that implementation of best management 

practices is an ongoing effort and that additional EPA guidance 

regarding best management practices may be needed in the future. 

Also, there are statutory changes under consideration that may 

impact the development and implementation of nonpoint source 

controls. EPA will be addressing such implementation issues in 

future guidance that is beyond the scope of this document. 

The State antidegradation policy may be used to support 

State efforts for obtaining additional authority to control 

nonpoint sources (e.g., several States consider their water 

quality standards to be "self-implementing" or directly 

enforceable). 

We recommend that States explain in their antidegradation 

polices or procedures how, and to what extent, the State will 

require implementation of otherwise non-enforceable (voluntary) 

BMPs before allowing point source degradation of high quality 
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waters. EPA understands this recommendation exceeds the Federal 

requirements discussed in this guidance. For example, nonpoint 

source management plans being developed under section 319 of the 

Clean Water Act are likely to identify potential problems and 

certain voluntary means to correct those problems. The State 

should consider how these provisions will be implemented in 

conjunction with the water quality standards program. 

APPLICABILITY OF WATER QUALITY STANDARDS TO NONPOINT SOURCES 

VERSUS ENFORCEABILITY OF CONTROLS 

The main issue that this memorandum addresses, the 

requirement in Section 131.21(a)(2) to implement existing 

nonpoint source controls before allowing degradation of a high 

quality water, is a subset of the broader issue of the 

applicability of water quality standards versus the 

enforceability of controls designed to implement standards. A 

discussion of the broader issue is included here with the intent 

of further clarifying the nonpoint source antidegradation 

question. In the following discussion, the central message is 

that water quality standards apply broadly and it is 

inappropriate to exempt whole classes of activities from 

standards and thereby invalidate that broader, intended purpose 

of adopted State water quality standards. 

Water quality standards serve the dual function of 

establishing water quality goals for a specific waterbody and 

providing the basis for regulatory controls. Water quality 

standards apply to both point and nonpoint sources. There is a 

direct Federal implementation mechanism to regulate point sources 

of pollution but no parallel Federal regulatory process for 

nonpoint sources. Under State law, however, States can and do 

adopt mandatory nonpoint source controls. 

State water quality standards play the central role in a 

State's water quality management program, which identifies the 

overall mechanism States use to integrate the various Clean Water 

Act water quality control elements into a coherent management 

framework. This includes, for example: (1) setting and revising 

water quality standards for all surface waterbodies, (2) 

monitoring water quality to provide information upon which water 

quality-based decisions will be made, progress evaluated, and 

success measured, (3) preparing a water quality inventory report 

under section 305(b) which documents the status of the States' 

water quality, (4) developing a water quality management plan 

which lists the standards, and prescribes the regulatory and 

construction activities necessary to meet the standards, (5) 

calculating total maximum daily loads and wasteload allocations 

for point sources of pollution and load allocations for nonpoint 

sources of pollution in the implementation of standards, (6) 

implementing the section 319 management plan which outlines the 

State's control strategy for nonpoint sources of pollution, and 
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(7) developing permits under Section 402. 

Water quality standards describe the desired condition of 

the aquatic environment, and, as such, reflect any activity that 

affects water quality. Water quality standards have broad 

application and use in evaluating potential impacts of water 

quality from a broad range of causes and sources and are not 

limited to evaluation of effects caused by the discharge of 

pollutants from point sources. In this regard, States should 

have in place methods by which the State can determine whether or 

not their standards have been achieved (including uses, criteria, 

and implementation of an antidegradation policy). Evaluating 

attainment of standards is basic to successful application of a 

State's water quality standards program. In the broad 

application of standards, these evaluations are not limited to 

those activities which are directly controlled through a 

mandatory process. Rather, these evaluations are an important 

component of a State's water quality management program 

regardless of whether or not an enforcement procedure is in place 

for the activity under review. 

Water quality standards are implemented through State or 

EPA-issued water quality-based permits and through State nonpoint 

source control programs. Water quality standards are implemented 

through enforceable NPDES permits for point sources and through 

the installation and maintenance of BMPs for nonpoint sources. 

Water quality standards usually are not considered self-enforcing 

except where they are established as enforceable under State law. 

Application of water quality standards in the overall context of 

a water quality management program, however, is not limited to 

activities for which there are enforceable implementation 

mechanisms. 

In simple terms, applicability and enforceability are two 

distinctly separate functions in the water quality standards 

program. Water quality standards are applicable to all waters 

and in all situations, regardless of activity or source of 

degradation. Implementation of those standards may not be 

possible in all circumstances; in such cases, the use 

attainability analysis may be employed. In describing the 

desired condition of the environment, standards establish a 

benchmark against which all activities which might affect that 

desired condition are, at a minimum, evaluated. Standards serve 

as the basis for water quality monitoring and there is value in 

identifying the source and cause of a exceedance even if, at 

present, those sources of impact are not regulated otherwise 

controlled. 

It is acceptable for a State to specify particular classes 

of activities for which no control requirements have been 

established in State law. It is not acceptable, however, to 

specify that standards do not apply to particular classes of 
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activities e.g. for purposes of monitoring and assessment). To 

do so would abrogate one of the primary functions of water 

quality standards. 

If you have any additional questions, please contact 

David K. Sabock, Chief, Water Quality Standards Branch, 202-260- 

1318. 

cc: 

Water Quality Branch Chiefs, Regions 1 - X 

Water Quality Standards Coordinators, Regions I - X 

Lee Schroer, OGC 

Geoffrey Grubbs, AWPD