1.1 How many National Pollution Discharge Elimination System (NPDES) permits include copper?

According to data from EPA's Permit Compliance System (as of December 2006), there are approximately 1800 major¹ dischargers and 5000 total dischargers that have NPDES permit limits or monitoring requirements for total recoverable copper. There are over 400 major dischargers that have NPDES permit limits or monitoring requirements for dissolved copper.

1.2 Do states and authorized tribes need to adopt the BLM-based copper criteria into their water quality standards before a permit can use the BLM as the basis of a water quality-based permit limit?

Yes. NPDES permits are established at levels that "derive from and comply with" applicable water quality standards. The BLM accounts for the effect of site-specific water characteristics on pollutant bioavailability and toxicity to aquatic life. If a state or authorized tribe adopts a BLM-based copper criterion into its applicable water quality standards, a NPDES permit limit derivation procedure can utilize the BLM-based copper criterion.

1.3 How do you calculate a permit in terms of total recoverable copper from the dissolved copper criteria value calculated by the BLM?

Effluent limits for certain metals (including copper) are required to be expressed as the concentration of total recoverable metal. BLM output includes copper speciation and can be used to calculate total recoverable copper.

Additionally, "The Metals Translator: Guidance for Calculating a Total Recoverable Permit Limit from A Dissolved Criterion" (EPA-823-B-96-007) provides guidance on calculating total recoverable copper from dissolved copper. When collecting monitoring data for BLM input parameters, the need to collect additional parameters, such as total suspended solids (TSS) to calculate a translator value, should be considered.

1.4 How should permit compliance with BLM-derived limits be assessed?

Assessing permit compliance with BLM-derived limits is similar to assessing permit compliance with hardness-derived limits or any other numeric permit limit. A facility with effluent limitations based on BLM-derived criteria would measure total recoverable copper for compliance monitoring.

1.5 What guidance documents are available for assistance in establishing copper criteria and permit limits for copper?

There are several documents that provide information relevant to establishing copper criteria and permit limits for copper. These documents include:

• U.S. EPA (1986). Quality Criteria for Water 1986. EPA 440/5-86-001
• U.S. EPA (1991). Technical Support Document for Water Quality-based Toxics Control. EPA 5052-90-001
• U.S. EPA (1994). Interim Guidance on Determination and Use of Water-Effect Ratios for Metals. EPA 823-B-94-001
• U.S. EPA (1996). The Metals Translator: Guidance for Calculating a Total Recoverable Permit Limit from a Dissolved Criterion. EPA 823-B-96-007
• U.S. EPA (2001). Streamlined Water-Effect Ratio Procedure for Discharges of Copper. EPA 822-R-01-005
• U.S. EPA (2007). Aquatic Life Ambient Freshwater Quality Criteria – Copper 2007 Revision. EPA 822-R-07-001

1.6 Consistent with the anti-backsliding provisions of the Clean Water Act, can an effluent limitation for copper in a NPDES permit become less stringent if it is based on a state's revised copper BLM site-specific criterion?

If the anti-backsliding provisions of CWA section 402(o) apply to the effluent limitation being made less stringent, the effluent limitation may be revised to be less stringent if one of the "anti-backsliding" exceptions applies. In general, the term "antibacksliding" refers to a prohibition on the renewal, re-issuance, or modification of certain types of existing NPDES permit effluent limits, permit conditions, or standards to be less stringent than those established in the previous permit. There are, however, exceptions to the prohibition, which—if applicable in a particular case—would allow the relaxation of permit requirements based on a state's revised copper criterion. For example, CWA section 402(o)(1) prohibits revision of an effluent limitation established on the basis of CWA sections 301(b)(1)(C), 303(d) or 303(e) unless one of the exceptions in CWA section 303(d)(4) are met. CWA section 303(d)(4)(A) would allow the relaxation of a copper effluent limitation based on a TMDL or other waste load allocation in waters not attaining a state or tribe's revised copper criterion if the cumulative effect of all revised effluent limitations would assure attainment of the state's revised criterion. In waters attaining a state's or tribe's revised copper criterion, CWA section 303(d)(4)(B) would allow relaxation of a copper effluent limitation based on a TMDL or other waste load allocation or any water quality standard or any other permitting standard if such revised limitation was consistent with the state's (or tribe's) anti-degradation requirements.

1.7 How are downstream waters protected?

EPA's water quality standards regulations provide that in designating uses and the appropriate criteria, states (and tribes) "shall take into consideration the water quality standards of downstream waters and shall ensure that its water quality standards provide for the attainment and maintenance of the water quality standards of downstream waters." (40 CFR 131.10(b)). Similarly, EPA's NPDES permitting regulations provide that no permit shall be issued "[w]hen the imposition of conditions cannot ensure compliance with the applicable water quality requirements of all affected states." (40 CFR 122.4(d)). In cases where DOC increases downstream, which is likely to be the typical pattern, downstream uses should be sufficiently protected because DOC reduces copper toxicity. However, all relevant information about downstream water characteristics, including collection of new data if necessary, should be considered in applying a BLM criterion to a particular site.

¹ Major municipal dischargers include all facilities with design flows of greater than one million gallons per day and facilities with EPA or state approved industrial pretreatment programs.
Major industrial facilities are determined based on specific ratings criteria developed by EPA or a state.

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