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Federal Register / Vol. 86, No. 52 / Friday, March 19, 2021 / Rules and Regulations the use of compliance schedules in NPDES permits to meet WQBELs derived from the applicable WQS 40
CFR 131.15. Each of these approaches is discussed in more detail in the next sections. Whichever approach a state pursues, however, all NPDES permits would need to comply with EPAs regulations at 40 CFR 122.44d1i.
A. Designating Uses EPAs final aluminum criteria apply to fresh waters in Oregon where the protection of fish and aquatic life is a designated use see Oregon Administrative Rules at Chapter 340
Division 41. The Federal regulation at 40 CFR 131.10g provides requirements for establishing, modifying, and removing designated uses when attaining the use is not feasible for one of the six factors in the regulation. If Oregon removes designated uses such that no fish or aquatic life uses apply to any particular water body affected by this rule and adopts the highest attainable use,21 the State must also adopt criteria to protect the newly designated highest attainable use consistent with 40 CFR 131.11. It is possible that criteria other than the federally promulgated criteria would protect the highest attainable use. If EPA
finds removal or modification of the designated use and the adoption of the highest attainable use and criteria to protect that use to be consistent with CWA Section 303c and the implementing regulation at 40 CFR part 131, the Agency would approve the revised WQS. EPA would then undertake a rulemaking to withdraw the corresponding Federal WQS for the relevant waters.

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B. WQS Variances Oregons WQS provide authority to apply WQS variances when implementing federally promulgated criteria for aluminum, as long as such WQS variances are adopted consistent with 40 CFR 131.14 and submitted to EPA for review under CWA Section 303c. The Federal regulation at 40 CFR
131.3o defines a WQS variance as a time-limited designated use and 21 If a state or authorized tribe adopts a new or revised WQS based on a required use attainability analysis, then it must also adopt the highest attainable use 40 CFR 131.10g. The highest attainable use is the modified aquatic life, wildlife, or recreation use that is both closest to the uses specified in section 101a2 of the CWA and attainable, based on the evaluation of the factors in 40 CFR 131.10g that precludes attainment of the use and any other information or analyses that were used to evaluate attainability. There is no required highest attainable use where the state demonstrates the relevant use specified in section 101a2 of the Act and sub-categories of such a use are not attainable see 40 CFR 131.3m.

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criterion, for a specific pollutant or water quality parameter, that reflects the highest attainable condition during the term of the WQS variance. A WQS
variance may be appropriate if attaining the use and criterion would not be feasible during the term of the WQS
variance because of one of the seven factors specified in 40 CFR
131.14b2iA, including if NPDES
permit limits more stringent than technology-based controls would result in substantial and widespread economic and social impact. WQS variances adopted in accordance with 40 CFR
131.14 including a public hearing consistent with 40 CFR 25.5 provide a flexible but defined pathway for states and authorized tribes to issue NPDES
permits with limits that are based on the highest attainable condition during the term of the WQS variance thereby allowing dischargers to make water quality improvements when the WQS is not immediately attainable but may be in the future. When adopting a WQS
variance, states and authorized tribes specify the interim requirements of the WQS variance by identifying a quantitative expression that reflects the highest attainable condition HAC
during the term of the WQS variance, establishing the term of the WQS
variance, and describing the pollutant control activities expected to occur over the specified term of the WQS variance.
WQS variances provide a legal avenue by which NPDES permit limits can be written to comply with the WQS
variance rather than the underlying WQS for the term of the WQS variance.
If dischargers are still unable to meet the WQBELs derived from the applicable WQS once a WQS variance term is complete, the regulation allows the State to adopt a subsequent WQS
variance if it is adopted consistent with 40 CFR 131.14. EPA is promulgating criteria that apply to the use designation that Oregon has already established.
Oregons WQS regulations currently include provisions to use WQS
variances when implementing criteria, as long as such WQS variances are adopted consistent with 40 CFR 131.14
and approved by EPA. Oregon may use the States EPA-approved WQS variance procedures when adopting such WQS
variances.
C. NPDES Permit Compliance Schedules EPAs regulations at 40 CFR 122.47
and 131.15 address how permitting authorities can use schedules for compliance with a limit in the NPDES
permit if the discharger needs additional time to undertake actions like facility upgrades or operation changes to meet a WQBEL based on the applicable
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WQS. EPAs regulation at 40 CFR 122.47
allows a permitting authority to include a compliance schedule in the NPDES
permit, when appropriate and where authorized by the state, in order to provide a discharger with additional time to meet a WQBEL implementing applicable WQS. EPAs regulation at 40
CFR 131.15 requires that a state that intends to allow the use of NPDES
permit compliance schedules adopt specific provisions authorizing their use and obtain EPA approval under CWA
Section 303c to ensure that a decision to allow a permit compliance schedule is transparent and allows for public input 80 FR 51022, August 21, 2015.
EPA already has approved Oregons State law provision authorizing the use of permit compliance schedules see OAR 3400410061, consistent with 40
CFR 131.15. Oregons compliance schedule authorizing provision is not affected by this rule. Oregon is authorized to grant permit compliance schedules, as appropriate, based on the Federal water quality criteria for aluminum in Oregon, as long as such permit compliance schedules are consistent with EPAs permitting regulation at 40 CFR 122.47.
VIII. Economic Analysis To best inform the public of the potential impacts of this rule, EPA
evaluated the potential costs associated with State implementation of the Agencys aluminum criteria based on available information. This analysis is documented in Economic Analysis for the Final Rule: Federal Aluminum Aquatic Life Criteria Applicable to Oregon, which can be found in the record for this rule. For this analysis, EPA assumed that Oregon fully implements its existing narrative water quality criteria for aluminum i.e., baseline criteria and estimated the incremental impacts for compliance with the aluminum criteria in this rule.
For point source costs, EPA assumed any NPDES-permitted facility that discharges aluminum would have reasonable potential and would be subject to effluent limits and would incur compliance costs if it chose to continue discharging. EPA also evaluated nonpoint sources that contribute aluminum loadings to waters that would be considered impaired for aluminum under the final criteria, which may incur incremental costs for additional best management practices BMPs. The total cost annualized of this final rule would range from $1.2 million to $8.0 million at a 3% discount rate, and $1.2 million to $8.1 million at a 7%
discount rate, for the first 10 years. See Economic Analysis for the Final Rule:

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