Code of Federal Regulations Title 40. Protection of Environment § 40.123.45—CRITERIA FOR CATEGORY I PERMIT EFFLUENT LIMIT VIOLATIONS

This appendix describes the criteria for reporting Category I violations of NPDES permit effluent limits in the NPDES noncompliance report (NNCR) as specified under paragraph (a)(2)(iii) of this section. Any violation of a NPDES permit is a violation of the Clean Water Act (CWA) for which the permittee is liable. As specified in paragraph (a)(2) of this section, there are two categories of noncompliance, and the table below indicates the thresholds for violations in Category I. An agency's decision as to what enforcement action, if any, should be taken in such cases, shall be based on an analysis of facts, legal requirements, policy, and guidance.

Violations of Permit Effluent Limits

The categorization of permit effluent limit violations depends upon the magnitude and/or frequency of the violation. Effluent violations shall be evaluated on a parameter-by-parameter and outfall-by-outfall basis. The criteria for Category I permit effluent limit violations apply to all Group I and Group II pollutants and are as follows:

a. Criteria for Category I Violations of Monthly Average Permit Effluent Limits—Magnitude and Frequency

Violations of monthly average permit effluent limits which exceed or equal the product of the Technical Review Criteria (TRC) times the permit effluent limit and occur in any two or more months in a six-month period. The TRCs for the two groups of pollutants are as follows:

• Group I Pollutants (TRC) = 1.4

• Group II Pollutants (TRC) = 1.2

The following is a listing of the Group I and Group II pollutants.

GroupI PollutantsOxygen Demand

• Biochemical Oxygen Demand

• Chemical Oxygen Demand

• Total Oxygen Demands

• Total Organic Carbon

• Other

Solids

• Total Suspended Solids (Residues)

• Total Dissolved Solids (Residues)

• Other

Nutrients

• Inorganic Phosphorus Compounds

• Inorganic Nitrogen Compounds

• Other

Detergents and Oils

• MBAS

• NTA

• Oil and Grease

• Other detergents or algicides

Minerals

• Calcium

• Chloride

• Fluoride

• Magnesium

• Sodium

• Potassium

• Sulfur

• Sulfate

• Total Alkalinity

• Total Hardness

• Other Minerals

Metals

• Aluminum

• Cobalt

• Iron

• Vanadium

GroupII PollutantsMetals (all forms)

• Other metals not specifically listed under Group I

Inorganic

• Cyanide

• Total Residual Chlorine

Organics

• All organics are Group II except those specifically listed under Group I.

b. Criteria for Category I Violations of Monthly Average Permit Effluent Limits—Chronic

Violations of monthly average permit effluent limits which are exceeded in any four or more months in a six-month period.