                                       
                             Response to Comments
    Final Rule: Federal Aluminum Aquatic Life Criteria Applicable to Oregon
                                       
                                40 CFR Part 131
                        Docket ID: EPA-HQ-OW-2016-0694











Disclaimer 

The Response to Comments document presents the responses of the Environmental Protection Agency (EPA) to the seven public comment letters and one oral comment received on the proposed rule (84 FR 18454, May 1, 2019) for federal aluminum aquatic life criteria applicable to Oregon fresh waters. EPA has addressed all substantive comments. The responses presented in this document are intended to augment the responses to comments that appear in the preamble to the final rule or to address comments not discussed in that preamble. Although portions of the preamble to the final rule are paraphrased in this document where useful to add clarity to responses, if there is any conflict, the text of the final rule takes precedence over the preamble, and the preamble takes precedence over this document regarding the meaning of the revisions adopted in the final rule. 
Accordingly, the Response to Comments document, together with the administrative record should be considered collectively as EPA's response to all of the substantive comments submitted on the proposed rule. The Response to Comments document incorporates directly or by reference the substantive public comments that were submitted on the proposed rule.
Introduction
On April 18, 2019, EPA proposed to establish federal Clean Water Act (CWA) aquatic life criteria for fresh waters under the State of Oregon's jurisdiction to protect aquatic life from the effects of exposure to harmful levels of aluminum. The proposal was published in the Federal Register on May 1, 2019.
The EPA docket received seven comments on the Proposed Rule for Water Quality Standards; Aquatic Life Criteria for Aluminum in Oregon (the Proposed Rule) by June 17, 2019. Of the seven comments, one comment is similar to another comment (i.e., replicates the same language), and the remaining comments are considered unique comments. Two public hearings were held on June 11 and June 12, 2019. During the June 11[th] hearing, no oral comments were received, and during the June 12[th] hearing, one oral comment was received. Adding the one oral comment, the final number of unique comments on the Proposed Rule is seven. Table 1 details the comments received on the Proposed Rule.
Table 1. Comments received on the Oregon Aluminum Proposed Rule
                               Submission Number
                                Submission Type
                              Commenter Category
                                  Agency Name
                                Commenter Name
0131
Unique Submission
Private Citizen - General
 
Anonymous
0132
Unique Submission
Private Citizen - General
 
Anonymous
0133
Unique Submission
Regulated Community
Oregon Association of Clean Water Agencies (ACWA)
Susan L. Smith, Executive Director
0134
Unique Submission
Regulated Community
The Aluminum Association
Curt Wells, Senior Director of Regulatory Affairs
0135
Unique Submission
State Government Agency
Oregon Department of Environmental Quality
Justin Green, Division Administrator,
Water Quality Division
0136
Similar Submission
Regulated Community
Clean Water Services
Robert P. Baumgartner, Assistant Director
0137
Unique Submission
Academia
Oregon State University on behalf of Aluminum Ecotoxicity Research Group
William A. Stubblefield, Ph.D., Professor, and Allison Cardwell, Toxicologist/ Laboratory Manager Environmental and Molecular Toxicology
Public Hearing, June 12
Unique Submission
Consultant
West Yost Associates
Walt Meyer
This document provides a compendium of the substantive comments submitted by commenters binned by topic and EPA's responses to those comments. Comments have been copied into this document "as is" with no editing or summarizing by EPA. Footnotes are taken directly from the comments.
Some commenters provided supporting attachments and exhibits to their comment letters (e.g., scientific papers, background materials) that do not directly address the Proposed Rule. Those attachments are in the docket along with the original written comment. 
                  Table of Contents  -  Response to Comments
1.	Oregon's WQS	6
Oregon Department of Environmental Quality (Doc. # 0135)	7
2.	General Comments on EPA's CWA Section 304(a) National Recommended Aluminum Criteria	7
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)	8
Walt Meyer, West Yost Associates (Public Hearing, June 12, 2019)	8
3.	Proposed Aluminum Criteria for Oregon	9
Oregon Department of Environmental Quality (Doc. # 0135)	12
a.	Using criteria calculator to generate values that protect for the full range of ambient conditions	15
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)	17
The Aluminum Association (Doc. # 0134)	18
Oregon Department of Environmental Quality (Doc. #0135)	18
b.	Total recoverable aluminum and use of an emerging analytical method	22
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)	27
The Aluminum Association (Doc. # 0134)	29
Oregon Department of Environmental Quality (Doc. # 0135)	30
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)	32
c.	Default ecoregional criteria and DOC values...................................................33
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)	34
Oregon Department of Environmental Quality (Doc. # 0135)	35
d.	Implementation issues  -  critical low flows	36
Oregon Department of Environmental Quality (Doc. # 0135)	37
4.	Endangered Species Act	37
Anonymous (Doc. # 0132)	37
5.	Other	38
Anonymous (Doc. # 0131)	39
Oregon Association of Clean Water Agencies (ACWA) (Doc. # 0133)	39
The Aluminum Association (Doc. # 0134)	39
Oregon Department of Environmental Quality (Doc. # 0135)	39
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)	40
Attachments and References	40


Response to Comments
Oregon's WQS
This section provides a compendium of the comments submitted by commenters about Oregon's water quality standards. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
EPA disapproved the State's freshwater acute and chronic aluminum criteria in 2013. EPA has since updated its CWA Section 304(a) national recommended aluminum criteria for freshwater. Under CWA Section 304(a), EPA periodically publishes criteria recommendations for states to consider when adopting water quality criteria for particular pollutants to meet the CWA Section 101(a)(2) goal. EPA is finalizing criteria for Oregon consistent with the 2018 national recommended freshwater aquatic life criteria for aluminum. If a CWA Section 304(a) recommendation exists, states may use it as a basis for their water quality standards, or, alternatively, can use a modified version that reflects site-specific conditions, or another scientifically defensible method. EPA has completed consultation with the U.S. Fish and Wildlife Service (USFWS) and NOAA Fisheries pursuant to Section 7 of the Endangered Species Act on the Agency's proposed promulgation of the aluminum criteria for Oregon to ensure that the continued existence of any threatened or endangered species is not likely to be jeopardized by the Agency's action and that the Agency's action will not result in the destruction or adverse modification of habitat of such species. 
EPA encourages Oregon to adopt protective aluminum criteria into a State rule during a future update of the State's aquatic life criteria. If Oregon subsequently adopts and submits aluminum aquatic life criteria to EPA for Agency review and action, the Agency would approve the State's criteria if those criteria meet the requirements of CWA Section 303(c) and implementing regulation at 40 CFR part 131. If EPA's federally-promulgated criteria are more stringent and/or prescriptive than the State's criteria, EPA's federally-promulgated criteria are and will be the applicable water quality standards for purposes of the CWA until the Agency withdraws those federally-promulgated standards. EPA would expeditiously undertake such a rulemaking to withdraw the federal criteria if and when Oregon adopts, and the Agency approves, corresponding criteria that meet the requirements of CWA Section 303(c) and implementing regulation at 40 CFR part 131. After withdrawal of EPA's federally promulgated criteria, the State's EPA-approved criteria would become the applicable criteria for CWA purposes.
Specific Comments
Oregon Department of Environmental Quality (Doc. # 0135)
The Oregon Environmental Quality Commission last adopted freshwater aquatic life criteria for aluminum in 2004. On January 31, 2013, EPA disapproved Oregon's freshwater aluminum aquatic life criteria. At the time, there was no updated national recommended criteria for aluminum that DEQ could look to in order to replace the disapproved criteria. DEQ decided to defer revising the state's freshwater criteria for aluminum for two reasons. First, due to uncertainty about what would constitute protective criteria, DEQ chose not to undertake an effort to develop a criterion and to monitor EPA's efforts to complete its update of the national recommended criteria for aluminum. Second, any revised criterion will need to undergo Endangered Species Act consultation and EPA is better positioned to address previous concerns raised by the National Marine Fisheries Service and the U.S. Fish and Wildlife Service. Once EPA's proposed criteria pass endangered species act consultation with the two services for application in Oregon, DEQ will consider adopting the criteria into state rule during a future update of the state's aquatic life criteria. (p. 1)
General Comments on EPA's CWA Section 304(a) National Recommended Aluminum Criteria
This section provides a compendium of the technical comments submitted by commenters regarding general comments on EPA's CWA Section 304(a) national recommended aluminum criteria. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
 EPA has published the Response to Comments document associated with EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum available at https://www.epa.gov/wqc/aquatic-life-criteria-aluminum#2018.
 A commenter asked why the proposed rule "does not recognize the fact that aluminum toxicity is strongly affected by the water chemistry through its effects on bioavailability." The proposed aluminum criteria for Oregon does recognize the fact that aluminum toxicity is strongly affected by ambient water chemistry. The proposed rule was based on EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum, which include a calculator (the "2018 Aluminum Criteria Calculator") that utilizes ambient water chemistry inputs to calculate criteria values. Studies have shown that three water chemistry parameters  -  pH, dissolved organic carbon (DOC), and total hardness  -  can affect the toxicity of aluminum to aquatic species. These criteria use Multiple Linear Regression (MLR) models to normalize the toxicity data and provide a range of acceptable values. The criteria are calculated based on a site's pH, DOC, and total hardness. Unlike the fixed acute and chronic values found in EPA's 1988 criteria recommendation, the 2018 national recommended criteria provides users the flexibility to develop site-specific criteria based on local water chemistry, as described above. 
The final criteria for Oregon are likewise based on EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum, including use of the 2018 Aluminum Criteria Calculator to calculate criteria values based on ambient data inputs for pH, DOC, and total hardness.
Specific Comments
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)
Although the USEPA has finalized the national recommended freshwater aquatic life criteria for aluminum, the Agency's "response to comments" from the draft criteria have not yet been made public. Therefore, it is difficult to discern how comments or suggestions our research group made to USEPA's draft were considered and whether these comments would be applicable to this review of the proposed federal aquatic life criteria for aluminum in Oregon freshwaters. (p. 2)
Walt Meyer, West Yost Associates (Public Hearing, June 12, 2019)
I have just a question of why the proposed rule does not recognize the fact that aluminum toxicity is strongly affected by the water chemistry through its effects on bioavailability. EPA has done some good research through Oregon state on this issue, and this should be recognized in the proposed rule. (p. 9)
Proposed Aluminum Criteria for Oregon
This section provides a compendium of the technical comments submitted by commenters about the proposed aluminum criteria for Oregon. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
 A commenter suggested that EPA refer to "Instantaneous Water Quality Criteria" (IWQCs) (rather than "model outputs," "calculator outputs," or "numeric outputs"). EPA did not include the term "IWQC" in the proposal to be consistent with EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum (Final Aquatic Life Ambient Water Quality Criteria for Aluminum 2018, EPA 822-R-18-001, as cited in 83 FR 65663), which does not use that term. It also did not include the term because there could be confusion that "IWQCs" themselves are "criteria" (because the "C" in "IWQC" stands for "criteria"), when the national CWA Section 304(a) recommended criteria is calculator-based (the 2018 Aluminum Criteria Calculator V2.0). EPA's proposed rulemaking, "Aquatic Life Criteria for Aluminum in Oregon" (84 FR 18454) used the term "model outputs" to avoid conflating an output from one calculator run with a "criteria value." Regarding the phrase "model outputs," EPA agrees with a commenter's suggestion to consistently refer to the criteria as a "calculator," not as a "model," and has made this clarification in the text of the final rule and preamble. The 2018 Aluminum Criteria Calculator outputs are not themselves criteria. The 2018 Aluminum Criteria Calculator outputs are criteria magnitude values, which are only one part of the ambient water quality criteria construct of magnitude, duration, and frequency. In some cases, the outputs from one calculator run could serve as the appropriate values (for example, for assessment purposes), but in other cases, individual calculator outputs would be grouped in order to derive a "criteria value" representing a protective value for all the conditions represented by all the outputs for that specific site (for example, for purposes of developing a National Pollutant Discharge Elimination (NPDES) permit water quality based effluent limit (WQBEL)). The Agency recognizes that its 2007 national CWA Section 304(a) recommended freshwater aquatic life criteria for copper includes the term "IWQC." Subsequent adoption and implementation of those copper criteria have shown that the term is confusing to the public. Therefore, to minimize confusion, this final rule uses the terms employed in EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum document. The preamble to the final rule also contains clarifying language on this topic as suggested by commenters. 
 A commenter also said that the "IWQCs" (or as EPA would term them, "calculator outputs") are "both protective of aquatic life and regulatory in nature." EPA clarifies here that any given set of 2018 Aluminum Criteria Calculator outputs (criterion maximum concentration (CMC), criterion continuous concentration (CCC),) are only protective of aquatic life for the specific conditions that were input into the calculator to generate outputs; individual outputs cannot in and of themselves be assumed to be protective of aquatic life over the range of ambient conditions that occur at the site if the inputs to the calculator do not themselves reflect the range of ambient conditions. EPA does not agree with the statement that 2018 Aluminum Criteria Calculator outputs are inherently "regulatory in nature." Calculator outputs can be regulatory to the extent that the State chooses to use them as a basis for regulatory requirements through its implementation programs. As such, EPA has retained the first sentence of the regulatory criteria statement as originally proposed for the final rule rather than revise it as suggested by a commenter ("criteria are a function of the concentration..."). EPA also notes that one set of calculator outputs may not be "regulatory" per se, for example, if the State is using multiple calculator outputs as part of a function to generate a criteria value to represent the criteria for a specific site for purposes of calculating an NPDES permit limit. The individual calculator outputs would not be the basis for regulatory action; rather, they would be intermediate values used in calculations to generate a criteria value that then informs regulatory actions. Calculator outputs are akin to magnitude values and should include frequency and duration components to be considered water quality criteria. 
 A commenter suggested adding "criteria may also be found on the lookup tables" of EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum document. EPA disagrees that "criteria" may be found in the lookup tables; the lookup tables contain "calculator outputs," each of which represents what would be protective under the specific set of input conditions. EPA agrees that the sentence would be accurate if it began with "calculator outputs" rather than "criteria." However, this additional sentence is redundant and is not needed, because the national CWA Section 304(a) recommended aluminum criteria document is incorporated by reference in the regulatory text of the criteria statement, and it includes the lookup tables. Nothing in the regulatory text would prohibit the use of the lookup tables, which simply represent outputs of the 2018 Aluminum Criteria Calculator. EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum are encapsulated in the 2018 Aluminum Criteria Calculator. The lookup tables are meant to be a tool to identify calculator outputs for specific water chemistry conditions without having to access the actual calculator. Oregon is free to use the lookup tables that express outputs of the 2018 Aluminum Criteria Calculator as appropriate and at the State's convenience consistent with the criteria as promulgated in EPA's final rule.
A commenter requested that the criteria statement regarding protecting for "the range of ambient conditions" be moved out of the criteria statement box and into the "applicability" section of the regulatory language because they suggested that it referred to implementation of the criteria and that the criteria regulation should only contain a reference to the 2018 national recommended criteria for aluminum. In response, EPA has removed the text from the criteria statement box. Because EPA did not view such text as directly relevant to "applicability," the Agency instead moved the text into a footnote to the criteria box. The Agency is using Oregon's adopted water quality criteria for the copper Biotic Ligand Model (BLM) as its guide, specifically Endnote N, which states that Oregon, "will apply the BLM criteria for Clean Water Act purposes to protect the water body during the most bioavailable or toxic conditions." (see Endnote "N," https://www.oregon.gov/deq/Rulemaking Docs/tables303140.pdf). EPA has also edited the text suggested by the commenter. EPA appreciates that the commenter retained the concept of the need for the criteria to be protective throughout the range of ambient conditions. EPA understands the commenter's concern to be that the proposed text implied that the State would be required to calculate a set of static criteria values to apply for each specific site, for all CWA purposes, which was not EPA's intention. EPA has therefore revised the rule text to address this expressed concern of the commenter. The final rule language says, "To apply the aluminum criteria for Clean Water Act purposes" instead of "to apply the aluminum criteria for NPDES permits and TMDLs," in order to be more inclusive of the purposes for which criteria are used and must be protective. The final rule language says "criteria values based on ambient water chemistry conditions" instead of "multiple instantaneous criteria," because in the context of the sentence, the term refers to the values that have been calculated (possibly by considering multiple calculator outputs, depending on the circumstances and CWA purpose in question), and not to the individual calculator outputs themselves. The final regulatory language says, "must protect the water body over the full range of water chemistry conditions, including during conditions when aluminum is most toxic" rather than "shall be applied...during bioavailable or toxic conditions." This rewording clarifies that the criteria values must protect the water body across the range of ambient water chemistry conditions present, not only during "bioavailable or toxic conditions." The rewording refers only to "most toxic" rather than "most bioavailable or toxic" because the "most toxic" conditions would include when aluminum is "most bioavailable." 
A commenter requested that the criteria statement specify that the criteria are expressed in "recoverable or bioavailable" form rather than "total recoverable," as proposed. EPA did not take this suggestion. The criteria EPA is finalizing for Oregon are based on the 2018 Aluminum Criteria Calculator associated with EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum. The primary reason for the expression of the criteria as "total recoverable" metal concentrations is because the laboratory toxicity tests upon which EPA relied in the development of the aluminum criteria measured aluminum concentrations in tested samples using the available standardized test methods, which measure the "total recoverable" form of aluminum. Therefore, it would be inaccurate to label the criteria as anything other than "total recoverable" form. However, EPA agrees with commenters that use of an analytical method that includes a less aggressive initial acid digestion is appropriate to better characterize bioavailable aluminum in ambient waters. Note that EPA is including the option for Oregon to use a bioavailable analytical method for characterizing aluminum concentrations in ambient waters, except where measurements of total recoverable aluminum are required by federal regulations. For example, such methods could be utilized to characterize the aluminum concentrations in ambient waters to better reflect the bioavailable fraction of aluminum for attainment and assessment purposes, determining and allocating loads in a TMDL, and in determining the need for a water quality-based effluent limit in NPDES permits. Doing so, particularly when testing ambient samples expected to contain significant amounts of colloidal, particulate and clay-bound aluminum, will better approximate the fraction of aluminum that is "available" to aquatic life in Oregon fresh waters, as EPA explained in the 2018 national recommended aluminum criteria document. However, where federal regulations require it, including but not limited to NPDES permit limits and compliance reports, Oregon must utilize a method for total recoverable aluminum that is approved at 40 CFR Part 136.
Specific Comments
Oregon Department of Environmental Quality (Doc. # 0135)
In order to reflect the issues raised in our comments above, DEQ proposes the following revisions and clarifications to the proposed aluminum water quality criteria rule language for Oregon as follows:
PART 131 -- WATER QUALITY STANDARDS
 The authority citation for part 131 continues to read as follows: Authority: 33 U.S.C. 1251 et seq. Subpart D -- Federally Promulgated Water Quality Standards
 Add § 131.[XX] to read as follows: § 131.[XX] Aquatic life criteria for aluminum in Oregon.
 Scope. This section promulgates aquatic life criteria for aluminum in fresh waters in Oregon.
 Criteria for aluminum in Oregon. The aquatic life criteria in Table 1 apply to all fresh waters in Oregon to protect the fish and aquatic life designated uses.


                  (c) Applicability. (1) The criteria in paragraph (b) of this section are the applicable acute and chronic aluminum aquatic life criteria in all fresh waters in Oregon to protect the fish and aquatic life designated uses.
                  (2) The criteria established in this section are subject to Oregon's general rules of applicability in the same way and to the same extent as are other federally promulgated and state-adopted numeric criteria when applied to fresh waters in Oregon to protect the fish and aquatic life designated uses.
                  (3) To apply the aluminum criteria in NPDES permits and TMDLs, multiple instantaneous criteria based on the range of ambient water chemistry conditions that occur at a site shall be applied to protect the water body during bioavailable or toxic conditions.
                  (3)(4) For all waters with mixing zone regulations or implementation procedures, the criteria apply at the appropriate locations within or at the boundary of the mixing zones and outside of the mixing zones; otherwise the criteria apply throughout the water body including at the end of any discharge pipe, conveyance or other discharge point within the water body. (p. 5-6)	
The national recommended WQ criteria for aluminum produces instantaneous water quality criteria that reflect the bioavailability and toxicity of aluminum relative to the water quality conditions at the time the aluminum sample is collected. EPA's use of the term "numeric outputs" or "model outputs" minimizes the significance of the calculator output or look-up table values as the instantaneous water quality criteria that are both protective of aquatic life and regulatory in nature. The term "instantaneous water quality criteria" is unambiguous and is a term already established by EPA to refer to water chemistry-dependent water quality criteria. For consistency and precision, EPA should use the term "instantaneous water quality criterion" or "instantaneous criteria" throughout the preamble and rule.
EPA's use of the term "model" to refer to the national recommended criteria is imprecise. The national recommended aluminum criteria are more accurately termed a calculator, not a model. Although the national recommended criteria are based on two species-specific multi-linear regression models (MLR) of aluminum toxicity, the criteria itself is a calculator. EPA described this correctly in Section II. C. but misstates it as a model elsewhere.
DEQ suggests amending the terminology for consistency in the following passages:
      Section III. A p. 18458, paragraph 3:
            "The numeric outputs of the final 2018 recommended national criteria models for a given set of conditions will depend on the specific pH, DOC, and total hardness entered into the models. The model outputs (CMC and CCC) for a given set of input conditions are numeric values that would be protective for that set of input conditions. The instantaneous water quality criteria generated by the final 2018 national recommended criteria calculator, or found on the look-up tables, depend on the specific pH, DOC, and total hardness values entered into the calculator. The instantaneous water quality criteria are the protective acute and chronic criteria (CMC and CCC) for a given set of input water chemistry conditions."
            
            "Users of the models calculator can determine outputs the instantaneous water quality criteria in two ways:...." (p. 7)
Using criteria calculator to generate criteria values that protect for the full range of ambient conditions 
This section provides a compendium of the technical comments submitted by commenters about using the criteria calculator to generate criteria values that protect for the full range of ambient conditions. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
EPA appreciates comments supporting the proposal of a criteria calculator for the State of Oregon rather than a "one size fits all" set of numeric criteria. EPA agrees that advantages of the calculator approach include the ability to generate criteria values based on a more accurate characterization of aluminum toxicity in a water body based on the ambient water chemistry conditions, and the ability to refine criteria values in the future using additional data.
The preamble to the proposal suggested three different methods by which Oregon could, at its discretion, "reconcile model outputs" after running datasets from multiple ambient water samples through the 2018 Aluminum Criteria Calculator in order to identify or calculate criteria values to be used for implementation purposes. EPA did not propose to include these methods in the rule text and specified that other methods could be used at the State's discretion as well.
Commenters recommended that EPA refrain from referring to "reconciling" multiple calculator outputs because the word "reconcile" does not accurately capture the process of developing criteria values for use in implementation (e.g., for calculating WQBELs for an NPDES permit) nor does it clearly distinguish the criteria from implementation. Commenters requested that any discussion of such processes be removed from EPA's final rule and be removed from preamble or revised to not include the term "reconcile." EPA agrees that such processes constitute implementation and are therefore not included in the final rule text. However, the preamble to the final rule does discuss these processes as important aspects of state implementation for informational purposes. EPA appreciates commenters' examples of suggested re-wording for various proposal preamble passages to avoid the term "reconcile." The final preamble does not incorporate these re-wordings exactly, but it does include revisions to address the commenters' concern that the preamble should not include the term "reconcile."
EPA agrees with comments that it is not necessary to specify in the final rule any procedures for specifically managing outputs from multiple calculator runs. Such methods would be applied during the implementation of the criteria, and therefore, EPA agrees that the State should have the discretion to develop these specific methods. EPA expects that the State will develop implementation procedures that describe how the State will handle multiple calculator outputs for implementation purposes. EPA has provided descriptions of possible procedures in the preamble to the final rule for informational purposes only. EPA appreciates Oregon Department of Environmental Quality's (ODEQ) comment indicating that the State agrees with EPA's recommendation that ODEQ develop implementation materials. ODEQ indicated that it intends for those materials to be "as consistent as possible with [their] implementation procedures for copper, other hardness-based metals and ammonia." EPA recognizes the administrative benefits of consistency among implementation methods for different criteria, however, EPA encourages Oregon to examine the existing implementation methods for appropriateness for application to aluminum.
EPA disagrees with a characterization of the 2018 Aluminum Criteria Calculator as being "performance-based criteria" per se ("all discussion of `reconciling outputs' should be revised to clearly distinguish the performance-based criteria itself, i.e., the Aluminum Calculator, from procedures for [implementation.]") The 2018 Aluminum Criteria Calculator by itself would not constitute "performance-based criteria" as it alone would not provide the public or stakeholders with enough information to replicate outcomes, which would include regulatory decisions made as a result of processing calculator outputs.
Commenters pointed out that EPA's proposed preamble language and proposed rule language are inconsistent and could lead to confusion and lack of clarity regarding how the calculator-based criteria are supposed to function. EPA believes that the criteria, like other water chemistry-based criteria, should account for the variability in the water chemistry conditions that affect bioavailability and, therefore, the toxicity of the pollutant at the time and location it is measured. EPA agrees with commenters that the criteria calculator generates outputs that can serve as protective criteria values (criterion continuous concentration (CCC) and criterion maximum concentration (CMC)) under the applicable water chemistry conditions. Different CWA programs use water quality criteria in different ways; in order to implement the criteria for some CWA purposes (e.g., developing WQBELs for NPDES permits), the State will need to identify a set of criteria values that will protect the site over the range of ambient water chemistry conditions in order to have a basis for calculation. The purpose of water quality criteria is to protect a water body's designated uses under the full range of conditions that exist at the site, not only at specific instantaneous points in time. To protect the aquatic life designated use of a water body against toxic aluminum, the aluminum criteria must be protective under the full range of water chemistry conditions, not only instantaneously. EPA appreciates that commenters acknowledge that some aspects of implementation for the criteria, for example the procedures to analyze the reasonable potential for a discharge to exceed the criteria and to develop WQBELs, must include evaluating the variability in water chemistry conditions over time and ensure that the CMC and CCC are met together with the appropriate duration and frequency components of the criteria to protect the designated use of the water body.
Commenters indicated that the proposed rule language (i.e., the proposed text "Calculator outputs shall be used to calculate criteria values for a site that protect aquatic life throughout the site under the full range of ambient conditions..."), as well as preamble text using the terms "rectify" and "reconcile," could be interpreted to require the calculator outputs as an intermediate step to setting conservative, static, site-specific single-value criteria that apply under all conditions. EPA recognizes the confusion caused by the proposed language and is clarifying here that the intention of the final rule language is not to require Oregon to generate static values that will apply for each water at all times. The aluminum criteria must protect the aquatic life designated use under the full range of ambient water chemistry conditions, including during conditions when aluminum is most toxic. However, this may be achieved in a variety of ways through different implementation mechanisms. For example, the State could use multiple outputs of the calculator to generate a static set of criteria values that would be protective for the range of ambient water chemistry conditions at a site and use these to calculate a WQBEL for an NPDES permit for a water body. On that same water body, the State could use criteria values generated by the calculator for purposes of assessment and 303(d) listing, so long as all best available data are used in the calculations.
Commenters requested that EPA remove any suggestion that the calculator outputs produced by the 2018 Aluminum Criteria Calculator are not protective "for their associated water quality conditions" from Section II B. Proposed acute and chronic criteria for Oregon's Fresh Waters." The final preamble does not include any suggestion that calculator outputs are not protective for the water chemistry conditions under which the inputs were measured.
Specific Comments
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)
The proposed rule includes three methods by which it is suggested Oregon may "reconcile model outputs and calculate final criteria values for each circumstance," and requests comment on whether they should be promulgated as part of the final rule.  ACWA believes that inclusion of these suggestions is unnecessary and unduly complicates the rule.  The final rule should not include them. (p. 3)
The proposed aluminum criteria (page 18468, Table 1) includes the following statement.
            Calculator outputs shall be used to calculate criteria values for a site that protect aquatic life throughout the site under the full range of ambient conditions, including when aluminum is most toxic given the spatial and temporal variability of the water chemistry at the site.
This statement regards strategies for implementing the criteria, which are appropriately left to the State of Oregon to develop as part of its implementation procedures for the aluminum criteria. ACWA recommends that this statement be deleted in the final rule. (p. 3)
The reconciliation methods suggested by EPA unduly complicate the rule and should be eliminated. (p. 3)
Implementation strategies should be left to the State of Oregon to develop as part of its implementation procedures for the aluminum criteria. (p. 4)
The Aluminum Association (Doc. # 0134)
The Association supports EPA's proposed use of the December 2018 national recommended freshwater criteria for aluminum as noticed at 83 FR 65663 as the foundation for implementation of the Oregon water quality criteria for aluminum. In particular, the Association supports EPA's proposal to promulgate a criteria calculator for Oregon in 40 CFR Part 131 Subpart D to replace the nationwide `one size fits all' limits set in 1988. Aluminum aquatic toxicity varies widely based primarily on variances in pH, DOC, and hardness and entry of these waterbody specific inputs in the calculator will yield more accurate characterization of aluminum toxicity. In addition, as the criteria calculator is refined in the future using additional analytical data, it can be updated by EPA and Oregon in a more timely fashion to best reflect the current state of knowledge on aluminum aquatic toxicity. (p. 1-2)	 
Oregon Department of Environmental Quality (Doc. #0135)
Issue #1: The criteria wording and language in the preamble regarding developing site- specific criteria based on "reconciling" multiple calculator outputs confusing and inconsistent with our understanding of the national recommended criteria.
In discussion with EPA and other states, there was common understanding about how the aluminum water chemistry-based criteria, which are being promulgated as statewide performance-based criteria in Oregon, would function. As a result of these discussions, it was clear that the purpose of this criterion, like other water chemistry-based criteria, is to account for the variability in the water chemistry conditions that affect bioavailability and, therefore, the toxicity of the pollutant at the time and location it is measured. In this instance, the criterion is intended to function as a statewide performance-based criterion, based on the aluminum calculator that generates protective instantaneous criteria (CCC and CMC) under the applicable water chemistry conditions, rather than a procedure to developing a single fixed site-specific criteria for each site. EPA's description of the criteria in Section III. A. p. 18458 reflects this understanding:
            "The numeric outputs of the final 2018 recommended national criteria models for a given set of conditions will depend on the specific pH, DOC, and total hardness entered into the models. The model outputs (CMC and CCC) for a given set of input conditions are numeric values that would be protective for that set of input conditions."
Similarly, EPA's Analysis of the Protectiveness of Default Ecoregional Aluminum Criteria Values states:
            "Each ACC [Aluminum Criteria Calculator] output represents the criteria that would be protective under the specific input conditions."
However, the subsequent proposed rule language and the preamble are confusing and inconsistent with that understanding. The rule language associated with the proposed criteria describes the instantaneous criteria generated by the calculator from the national recommended water quality criteria as an intermediate step to setting conservative, static, site-specific single-value criteria that applies under all conditions. In multiple places throughout the federal register document, EPA refers to the need to "rectify" or "reconcile" calculator results to determine "the protective criteria for a site." The purpose of water chemistry-based criteria is to account for the variability in the water chemistry conditions that affect bioavailability and, therefore, the toxicity of the pollutant at the time and location it is measured.
The second sentence of the criteria statement in Table 1, states:
            "Calculator outputs shall be used to calculate criteria values for a site that protect aquatic life throughout the site under the full range of ambient conditions, including when aluminum is most toxic given the spatial and temporal variability of the water chemistry at the site."
DEQ is concerned that this statement could be interpreted to require that a single static criterion be established for a site that then applies through time. To reflect the fact that the criterion generates instantaneous criteria using the aluminum calculator or via look-up tables in order to evaluate the toxicity of individual aluminum samples, DEQ provides suggested rule language revisions below, in the section of this letter titled "Suggested Revisions to the Proposed Criteria Language," that are intended to improve the clarity and accuracy of the criteria statement.
States have been implementing water chemistry-based water quality criteria for many years for hardness-based metals and ammonia. Oregon is also successfully implementing the copper biotic ligand model as water-chemistry based criteria. DEQ agrees that NPDES permit limits and other CWA requirements must appropriately consider and incorporate the range of CMCs and CCCs calculated for a site based on the range of water chemistry conditions that occur at that location in order to fully protect aquatic life uses. DEQ acknowledges that the procedures to analyze the reasonable potential for a discharge to exceed the criteria and to develop WQBELs must evaluate the variability in water chemistry conditions over time and ensure that the CMC and CCC for sensitive, bioavailable water chemistry conditions for aluminum toxicity are met.
The phrase "reconciliation of model outputs" as part of the explanation of the water quality criteria is unclear and confusing and should be removed. Any suggestion that the instantaneous criteria values produced by the calculator are not protective "for their associated water quality conditions" should be removed from Section II B. Proposed acute and chronic criteria for Oregon's Fresh Waters. And finally, all discussion of "reconciling outputs" should be revised to clearly distinguish the performance-based criteria itself, i.e., the Aluminum Calculator, from procedures for how the instantaneous criteria generated by the calculator will be appropriately incorporated and implemented in Clean Water Act programs. (p. 2-3)
For the reasons explained Issue #1 above, DEQ strongly recommends that references to "reconciling" multiple calculator outputs not be included in the final aluminum criteria for Oregon. During implementation of the criteria in NPDES permitting procedures or TMDL development, protective limits and waste load allocations must be established to protect the aquatic life use throughout the range of temporal variability in aluminum toxicity that is expected to occur at a location. But this is not a process that "reconciles" multiple calculator outputs. As such, any discussion of "reconciliation" of calculator outputs should be removed. Discussion related to the range of criteria that apply at a site, due to the variability in water chemistry conditions, should be contained in implementation procedures developed by the state, consistent with other water chemistry based criteria.
For example, the following excerpts from the federal register document that refer to "reconciliation" methods as part of the criteria should not be included in the final criteria rule or preamble, or should be revised as shown.
 Section III. A. p.18458: "In order to calculate numeric water quality criteria that will protect the aquatic life designated uses of a site over the full range of ambient conditions and  toxicity, multiple model outputs will be need to be reconciled." 
 p. 18459: "The EPA's proposed rule provides that the criteria calculator, which incorporates pH, DOC, and total hardness as input parameters, be used to calculate protective acute and chronic instantaneous aluminum criteria values for a site as set forth in the final 2018 recommended national criteria. These calculated instantaneous criteria values would protect aquatic life under the full range of ambient conditions found at each site including conditions when aluminum is most toxic given the spatial and temporal variability of the water chemistry at the site."
 p. 18459: EPA states: "Oregon has the discretion to select the appropriate method to reconcile model outputs and calculate the final criteria values for each circumstance as long as implement the resulting calculated instantaneous water quality criteria values shall for Clean Water Act purposes to protect aquatic life throughout the site and throughout the range of spatial and temporal variability, local water chemistry conditions that occur at a site, including when aluminum is most toxic."
DEQ agrees with EPA's recommendation on p. 18459 that DEQ develop implementation materials and we will do so, with the intent of being as consistent as possible with our implementation procedures for copper, other hardness-based metals and ammonia. (p. 7-8)
Total recoverable aluminum and use of an emerging analytical method
This section provides a compendium of the technical comments submitted by commenters about the use of the total recoverable aluminum analytical method and an emerging analytical method using an initial digestion at pH 4. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
EPA appreciates comments supporting EPA's use of its 2018 national recommended criteria for aluminum as the basis for promulgating aluminum criteria for Oregon.
As required by the CWA, EPA periodically reviews and revises Section 304(a) national ambient water quality criteria (AWQC) recommendations to ensure the criteria accurately reflect the latest scientific knowledge. EPA updated its national AWQC recommendations for aluminum in December 2018 through its authority under CWA Section 304(a). Water quality criteria are developed following the guidance established in EPA's "Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses" (Stephan et al. 1985). EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum document explains at pp. 1-2, "This document describes scientifically defensible water quality criteria values for aluminum pursuant to CWA Section 304(a), derived utilizing best available data in a manner consistent with the 1985 Guidelines."
The aluminum criteria EPA is finalizing for Oregon are based on EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum, which are based on the latest science and are scientifically defensible. In its 2018 national recommended criteria, EPA expressed the aluminum criteria as "total recoverable" metal concentrations. The primary reason for the expression of the criteria as total recoverable aluminum concentrations is because the laboratory toxicity tests used in the effects assessment in the development of the aluminum criteria reported the aluminum concentrations as total recoverable aluminum. 
EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria document for aluminum explains the appropriateness of the "total recoverable" form for aluminum criteria at pp. 22-23, where it describes the results of laboratory studies that examined total and dissolved aluminum and concluded that:
      "... because measurements of dissolved aluminum do not reflect the full spectrum of forms of aluminum that results in toxicity, all laboratory exposure data used for criteria derivation will be based on measurements of total aluminum. Measurements with methods using lesser degrees of acidification (that is, acid soluble and pH 4 extractable) are generally not available. If aluminum criteria are based on dissolved concentrations, toxicity will be underestimated, because aluminum hydroxide precipitates that contribute to toxicity would not be measured (GEI Consultants, Inc. 2010; U.S. EPA 1988). All concentrations from toxicity tests are expressed as total aluminum in this document (unless otherwise specified)."
EPA agrees with commenters that the only currently-approved EPA methods (40 CFR part 136) are for total recoverable aluminum. EPA agrees with commenters that current test methods for total recoverable aluminum may, in some waters, overestimate the amount of toxic aluminum present in natural waters because they may include aluminum in forms that are otherwise bound to suspended solids, clays, or particulate matter and therefore not toxic to aquatic life. Laboratory dilution waters from tests used in the effects assessment for EPA's criteria development did not contain suspended solids, clays, or particulate matter where aluminum could be bound and therefore are not biologically available under most ambient water chemistry conditions. 
As discussed in Section 2.6.2 of EPA's 2018 national recommended criteria document for aluminum, the different forms of aluminum vary in toxicity. The criteria document discusses differences between aluminum toxicity in a controlled laboratory setting and the toxicity of aluminum in ambient waters that contain suspended particles, clays, and aluminosilicate minerals not present in lab waters. Dissolved and particulate (e.g., aluminum hydroxides) aluminum, as well as small sized colloids containing aluminum, exhibit toxic effects on aquatic life depending on the pH, DOC, and total hardness of the waters. Total recoverable aluminum methods determine the total concentration of monomeric (both organic and inorganic) forms of aluminum, polymeric and colloidal forms, as well as particulate forms and aluminum sorbed to clays present in a sample. These methods use a strong acid (pH <2) digestion step when preparing the sample for measurement. Alternatively, methods to determine dissolved concentrations of aluminum involve filtering test samples prior to digestion, excluding particulate forms of aluminum from the test sample. Methods to determine dissolved concentrations may underestimate toxicity if aluminum hydroxide precipitates that contribute to toxicity are not measured; therefore, dissolved aluminum measurements are not appropriate for comparison to the aluminum criteria EPA is promulgating for Oregon.

EPA acknowledges, as several commenters noted during the comment periods for both EPA's 2017 draft national recommended aluminum criteria and EPA's proposed criteria for Oregon, not all forms of aluminum that may be present in ambient waters would be biologically available or "bioavailable" to aquatic species. Bioavailable aluminum is the toxicologically relevant fraction of aluminum. Large suspended particles, clays, and aluminosilicate minerals are not bioavailable. EPA's 2018 national recommended criteria document for aluminum (Section 2.6.2 from pp. 22-25) explains the science behind this understanding of aluminum chemistry and toxicity in more detail.
EPA appreciates commenters' providing reference to two manuscripts describing an emerging analytical method that measures bioavailable aluminum using an initial digestion at pH 4 (Rodriguez et al., and Oregon State University) to characterize ambient waters. EPA recognized the existence of this emerging analytical method in EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum document at pp. 24-25 and 79: 
      "EPA Methods 200.7 and 200.8 are the only currently approved methods for measuring aluminum in natural waters and wastes for NPDES permits (U.S. EPA 1994a,b). Research on new analytical methods is ongoing to address concerns with including aluminum bound to particulate matter (i.e., clay) in the total recoverable aluminum concentrations (OSU 2018c). One approach would not acidify the sample to pH less than 2 but rather to pH 4 (pH 4 extracted method) to better capture the bioavailable fraction of aluminum (CIMM 2016, OSU 2018c). Thus, this draft pH 4 extracted method under development is expected to reduce the uncertainty regarding bioavailable aluminum measurements in the aquatic environment." 

      "The validation of the pH 4 extraction method is still on-going, with the expectation that this approach will better estimate the bioavailable fraction of aluminum in natural waters."

Commenters urged that measures of aluminum generated by analytical methods under development (i.e., a bioavailable analytical method) would be appropriate to compare to the proposed criteria values. Some commenters asserted that, therefore, the criteria should be expressed as "recoverable or bioavailable" as well. EPA expressed the 2018 national recommended criteria for aluminum as total recoverable metal concentrations. As mentioned above, the primary reason for the expression of the criteria as total recoverable aluminum concentrations is because the laboratory toxicity tests used in the effects assessment in the development of the aluminum criteria reported the aluminum concentrations as total recoverable aluminum. As discussed earlier, the forms of aluminum introduced into the laboratory toxicity tests upon which EPA relied for criteria development do not include suspended solids or clays where aluminum may be bound. Aluminum bound in suspended solids or clays would be extracted when using total recoverable methods that have a strong acid (<pH 2) digestion step, but these forms of aluminum would not be biologically available to aquatic species in ambient waters. Empirical laboratory testing indicates that total recoverable (pH -0.05 to +0.7 digestion) and bioavailable measurements of aluminum in lab waters are essentially equal up to approximately 1 mg/L of aluminum. Studies are currently being conducted at Oregon State University with test solutions with greater than 1 mg/L of aluminum to better understand the relationship above 1 mg/L. Initial studies indicate there is little variability between "total recoverable" and "bioavailable" above 1 mg/L in laboratory waters. 
It is not necessary to apply a conversion or translation factor to compare field measurements using a bioavailable method against the promulgated aluminum total recoverable criteria. This is because both bioavailable and total recoverable analytical methods quantify the toxic fraction of aluminum equivalently in laboratory test waters given that standard toxicity test waters do not include suspended solids or clays per test protocols. For NPDES compliance monitoring and reporting, total recoverable measurements for metals are required. Total recoverable measurements should not overestimate the concentration of the toxic forms of aluminum present because well-treated effluent, like laboratory test waters, lack colloidal and clay-bound aluminum. By comparison, for ambient water measurements, analytical methods that measure bioavailable aluminum should provide more accurate quantification of the toxic fraction of aluminum. For assessment and listing purposes, ambient field measurements analyzed using a bioavailable analytical method may be compared directly to the criteria because both represent the toxic fraction of aluminum. 
EPA expects that an analytical method that includes a less aggressive initial acid digestion that liberates bioavailable forms of aluminum (including amorphous aluminum hydroxide) yet minimizes dissolution of mineralized forms of aluminum such as aluminosilicates associated with suspended sediment particles or clays (referred to as a bioavailable analytical method) will better estimate the bioavailable fraction of aluminum in natural ambient conditions. As a result, EPA is including the option for Oregon to use such a bioavailable analytical method for characterizing aluminum concentrations in ambient waters, though notes that there are other regulatory applications where measurements of total recoverable aluminum are required by federal regulations. Per commenters' suggestions, the final rule describes the State's flexibility to use a bioavailable analytical method in regulatory text and preamble. The final rule includes a footnote to the criteria table explaining that for characterizing ambient waters, Oregon may also utilize, as scientifically appropriate and as allowable by State and federal regulations, analytical methods that measure the bioavailable fraction of aluminum (e.g., utilizing a less aggressive initial acid digestion, such as to a pH of approximately 4 or lower, that includes the measurement of amorphous aluminum hydroxide yet minimizes the measurement of mineralized forms of aluminum such as aluminum silicates associated with suspended sediment particles and clays). Oregon shall use measurements of total recoverable aluminum where required by federal regulations (e.g. for certain CWA program implementation, such as NPDES permit limits and compliance reports, when aluminum must be expressed as "total recoverable aluminum" and measured using analytical methods approved at 40 CFR Part 136). This will allow for characterization of ambient waters to better reflect the bioavailable fraction of aluminum. EPA is not prescribing use of any specific method and looks to further research and method standardization efforts to identify best practices.
A commenter suggested that total recoverable analytical methods for the criteria will result in non-toxic forms of aluminum being included, thereby causing inaccurate and inappropriate CWA 303(d) listings of Oregon waters as impaired for aluminum. As stated above, EPA has included a footnote to the final criteria statement specifically noting that for characterizing ambient waters, Oregon may utilize, as scientifically appropriate and as allowable by State and federal regulations, analytical methods that measure the bioavailable fraction of aluminum. The State's use of such a method would need to comply with other requirements in the State's own program, for example, any applicable Quality Assurance/Quality Control requirements. 
EPA recognizes that in some circumstances, assessing waters using the total recoverable analytical method could result in the listing of some waters (i.e., those with high amounts of total suspended solids) as impaired, even though the elevated aluminum measurements could be largely attributed to non-bioavailable forms of aluminum. EPA's existing regulations do not require use of analytical test methods promulgated at 40 CFR Part 136 in the implementation of CWA Section 303 programs, including assessment and listing of waters, nor in the determination of the need for a WQBEL. However, EPA's regulations do require that states assemble and evaluate all existing and readily available water quality-related data and information for use in developing their CWA Section 303(d) lists. 40 CFR 130.7(b)(5). The requirement to assemble and evaluate all data and information for assessment and listing purposes includes situations where only total recoverable aluminum data and information are available. However, in those circumstances, the State is not required to rely on that data for listing purposes as long as it provides a technical, science-based rationale for not using the data and information. 40 CFR 130.7(b)(6)(iii). For example, the State may be able to demonstrate that total recoverable aluminum samples are not representative of water quality conditions because non-toxic forms of aluminum are leading to an exceedance above the criterion. When data and information are available for both total recoverable and bioavailable aluminum, the State must evaluate all of it, but need not rely on all of it for assessment and listing purposes. Applicable regulations do not prohibit the State from assigning more weight to data and information about bioavailable aluminum than total recoverable aluminum for assessment and listing purposes.
ODEQ commented that "based on discussions with EPA, DEQ understands that EPA agrees that analytical methods to measure bioavailable aluminum are acceptable for applying the aluminum criteria." While EPA does agree that analytical methods that measure bioavailable aluminum are acceptable for ambient waters, EPA does not agree that the same applies to effluent discharges since no similar method has been published for effluent discharges. The method should be applied only where scientifically appropriate and allowed by federal regulations. The method cannot be applied at this time for any waters other than ambient waters, which limits the application of the method to certain aspects of implementation under the CWA programs. EPA also agrees that the final rule should be clear that bioavailable analytical methods that have been published and meet QA/QC requirements are acceptable for implementation of the criteria at the time of finalizing this rule in order to characterize ambient waters, as scientifically appropriate and as allowable by State and Federal regulations. To the extent that the bioavailable analytical methods for aluminum that have been published comply with the State's own QA/QC requirements, the State can use them in the context of assessment and CWA Section 303(d) listing for characterization of ambient waters only. EPA views that use of a bioavailable analytical method would also be appropriate in characterizing ambient water concentrations for NPDES permitting purposes, specifically, calculation of reasonable potential analysis and waste load allocations that inform the development of water quality-based effluent limits (WQBELs). For developing TMDLs and load allocations, field measurements analyzed using a bioavailable method also may be used as the basis for identifying allocations for TMDLs, both wasteload allocations (WLA) for point sources and load allocations (LA) for nonpoint sources. EPA clarifies here that EPA does not presuppose use of a bioavailable analytical method would be appropriate for all CWA implementation purposes. For example, NPDES WQBELs and compliance reports for aluminum are required by regulation to be expressed as total recoverable (40 CFR 122.45(c)). 
Comments suggested that the final rule should include a more robust discussion and additional guidance on appropriate measurement of "bioavailable" aluminum. EPA acknowledges that a bioavailable method may provide a better option for identifying the fraction of toxic aluminum in ambient waters and may be used in certain applications during the implementation of the CWA. EPA is in the process of developing implementation support materials for the 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum. The Agency will consider including more information on implementation in that context, as more scientific information regarding such methods becomes available.
 EPA prepared an economic analysis to accompany this final rule (available in the rule docket) that describes in detail how implementation of the final aluminum criteria for Oregon could result in potential exceedances of aluminum for assessment and 303(d) listing purposes relying on a large set of existing Oregon-specific ambient data. The economic analysis used conservative assumptions (for example, using ecoregional default values based on a 10[th] percentile of the output distribution in all cases), which likely overpredict the number of estimated exceedances. EPA thanks commenters for providing anecdotal information about data from Oregon facilities that was used to examine possible exceedances of aluminum and comparing total aluminum with total suspended solids (TSS). Without access to the actual data, which were not provided to the docket, and information about what assumptions were made in using the 2018 Aluminum Criteria Calculator to predict exceedances, EPA is unable to corroborate the validity of the commenters' claims regarding numbers and percentages of exceedances and is unable to compare those estimates with EPA's estimates. Additionally, the final rule specifically identifies how the State can use a bioavailable analytical method in the context of assessment and listing and other CWA programs, where appropriate.
Specific Comments
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)
As detailed in EPA's Final Aquatic Life Ambient Water Quality Criteria for Aluminum, 2018, aluminum is the third most common element in the earth's crust, occurring predominantly in the form of aluminosilicate minerals, including clays.  These clays are ubiquitous in the environment and are common as suspended load in the water column of surface waters.  Aluminum in these forms is not biologically available and thus not toxic to aquatic life.  Although other solid forms of aluminum can be toxic (supporting the expression of the aluminum criteria in terms of total aluminum), it is critical that aluminum in non-toxic solids not be part of the regulated total aluminum load.  Unfortunately, the only EPA-approved analytical methods for total aluminum (EPA Methods 200.7 and 200.8) employ aggressive digestion techniques that dissolve these clays, releasing the aluminum that is otherwise tightly bound in their structure.  The result is that non-toxic solid forms of aluminum are included in the total aluminum result. Although the discussion of the proposed criteria suggests that this inclusion "may be considered conservative," it is incorrect to count non-toxic forms of aluminum as toxic and doing so would lead to burdensome and unnecessary overregulation with no benefit to water quality.
ACWA members evaluated data from wastewater treatment plant effluent, stormwater discharges, and surface waters.  The analysis was conducted using the proposed EPA calculator to determine the applicable water quality criteria and compare the criteria to the measured aluminum concentration.  The results were also compared to total suspended solids (TSS) data to evaluate the relationship between aluminum and suspended solids in storm and surface waters.
The data set for treatment plant effluent consisted of several hundred samples from six wastewater treatment plants and included concurrent aluminum, pH, hardness, and dissolved organic carbon (DOC). Only advanced wastewater treatment plants that used alum for phosphorus removal exceeded the proposed aluminum criteria.
The evaluation also included over 100 samples of municipal stormwater data from 6 outfalls.  The samples included concurrent aluminum, pH, hardness, and DOC.  Between 40 and 90 percent of the municipal stormwater samples taken at a given site exceeded the calculated aluminum criteria.  Data from industrial stormwater discharges were also examined.  The industrial stormwater data set included over 300 samples from 27 locations, but included only total aluminum and pH, necessitating estimation of DOC and hardness.  Between 8 and 100 percent of samples at a given site exceeded the proposed aluminum criteria.  Total aluminum content was strongly correlated with TSS for the municipal and industrial stormwater sites.
Additionally, Clean Water Services, the wastewater and stormwater management utility serving over a half million people in Washington County, OR., evaluated several hundred surface water samples with concurrent aluminum, pH, hardness, and DOC collected from 23 sites in the Tualatin River Basin. Between 5 and 57 percent of surface water samples exceeded the proposed aluminum criteria.  As in the stormwater samples, total aluminum was strongly correlated with TSS.
The City of Portland also evaluated over 200 surface water samples with concurrent aluminum, DOC, hardness, and pH collected across nine geographic assessment units in the lower Willamette River Basin and Columbia River.  Between 11 and 70 percent of the surface water samples exceeded the proposed aluminum criteria.
This evaluation concluded that suspended sediments account for nearly all of the aluminum found in surface waters and stormwater discharges.  It is clear that applying the proposed aluminum criteria would result in most waterbodies in Oregon being designated as water quality limited for aluminum, including those not impacted by wastewater effluent, stormwater discharges, or agricultural runoff.
Designating water bodies as water quality limited has profound and far-reaching effects.  Total Maximum Daily Loads must be established and NPDES permits for discharges to these waters must contain water quality-based effluent limits based on the criteria.  In Oregon, listing requires that water quality criteria will apply as "end-of-pipe" limits until TMDLs are developed. The resources expended by states and dischargers to comply with these requirements is only justified when there will be improvements in water quality through reduction of toxic pollutants.  Where the water quality criteria are not based on toxicity, the requirements are unnecessary and will not improve water quality.
To avoid the potential negative consequences of expressing the water quality criteria as total aluminum, EPA should allow Oregon to use analytical methods that differentiate between toxic and non-toxic solid phases that contain aluminum.  This approach is used in New Mexico, which adopted a pre-filtration technique to exclude non-toxic forms of aluminum as part of the water quality criteria for aluminum.  As described in the Final Aquatic Life Ambient Water Quality Criteria for Aluminum, 2018, such methods have been developed at Oregon State University.  ACWA recommends that EPA include specific language in the final rule that enables Oregon to implement methods that exclude non-toxic clay particles.   The following language (based on California practice) is suggested:
            Compliance with the aluminum criteria can be demonstrated using either total or acid­ soluble (inductively coupled plasma/atomic emission spectrometry or inductively coupled plasma/mass spectrometry) analysis methods, as supported by U S. EPA 's Ambient Water Quality Criteria for Aluminum document (EPA 44015-86-008), or other standard methods that exclude aluminum silicate particles as approved by the State of Oregon. (p. 1-3)
The draft rules should be modified to eliminate the overly conservative analytical methods that will result in non-toxic forms of aluminum being included and thereby causing inaccurate and inappropriate listings of Oregon waters as impaired for toxic aluminum. (p. 4)
The Aluminum Association (Doc. # 0134)
Although the finalization of the new recommended freshwater criteria for aluminum for nationwide use, and specifically for Oregon in the proposed rule, is a strong first step, it must be paired with an analytical test method that more accurately captures the amount of bioavailable aluminum actually available in a waterbody. As EPA is aware, current test methods for total aluminum and total recoverable aluminum typically over-estimate the amount of bioavailable aluminum present in natural waters due to the presence of non-toxic mineral forms of aluminum present in Total Suspended Solids (TSS) constituents in those natural waters. Similarly, current test methods for dissolved aluminum typically under- estimate the amount of bioavailable aluminum present in the water column due to the presence of colloidal solids with toxicity potential that are filtered out in obtaining the dissolved fraction for analysis. Fortunately, a consortium of experts in aluminum eco-toxicity has developed a new method using a pH 4 digestion that more accurately reflects the actual amount of aluminum toxicity in natural waters. The manuscript for this method was recently accepted for publication in the Journal of Environmental Toxicology and Chemistry (https://setac.onlinelibrary.wiley.com/doi/10.1002/etc.4448) and a copy of it is attached to these comments for reference. Additionally, engagement with the American Society of Testing and Materials (ASTM) is underway to achieve certification of this method by a voluntary consensus organization. Use of this method will a result in a more accurate comparison of the actual bioavailable aluminum present in natural waters with the criteria calculator output of the aluminum levels necessary to protect aquatic organisms, which is bioavailability based. Therefore, the Association urges the EPA to include a recommendation in the final rule that Oregon utilize the bioavailable aluminum test method for comparison of its waters against the criteria calculator output. (p. 2)	 
Oregon Department of Environmental Quality (Doc. # 0135)
Issue #2: Methods for measuring bioavailable aluminum should be addressed and acknowledged as acceptable
Based on discussions with EPA, DEQ understands that EPA agrees that analytical methods to measure bioavailable aluminum are acceptable for applying the aluminum criteria. The national recommended aluminum criteria states that the criteria for aluminum generated by the calculator and lookup table would also be protective for aluminum measured with an appropriate method for bioavailable aluminum. On pages 24-25 of the national recommended criteria for aluminum,  EPA allows for the use of alternative analytical methods that better measure the bioavailable fraction of aluminum and specifically refers to a recently published analytical method that measures bioavailable aluminum developed by the Aquatic Toxicology Laboratory at Oregon State University (OSU 2018). This analytical method for measuring bioavailable aluminum has now been published in the Journal of Environmental Toxicology and Chemistry, a peer-reviewed scientific journal, and is being developed as an ASTM.
For most metals toxic to aquatic life, the bioavailable and, therefore, toxic form is the dissolved fraction in the water column. For aluminum, bioavailability is high for intermediate suspended colloidal forms of aluminum as well as the dissolved forms. For this reason, the national recommended criteria are expressed as total recoverable aluminum. However, the national recommended criteria for aluminum recognizes that while the dissolved fraction underestimates the bioavailability of aluminum, the total recoverable fraction tends to over-estimate aluminum bioavailability. Therefore, measuring aluminum as total recoverable is likely to overestimate aluminum toxicity. In evaluating dissolved and total recoverable aluminum data across the state, DEQ found that the total recoverable aluminum concentration ranges from 10 to100 times greater than the corresponding dissolved aluminum concentration. The bioavailable aluminum concentration is somewhere within that range.
DEQ recommends that EPA revise the language of the proposed criteria rule to allow the criteria to also be expressed as bioavailable aluminum. The current wording of the proposed criteria specifically expresses the criteria as "total recoverable aluminum." See DEQ's suggested rule language revisions in the section of this letter titled "Suggested Revisions to the Proposed Criteria Language" below.
DEQ also recommends that EPA's final rule should be clear that analytical methods measuring bioavailable aluminum that have been published and meet QA/QC requirements, are acceptable for application of the proposed aluminum criteria, consistent with the nationally recommended water quality criteria for aluminum. (p. 3-4)
In the suggested rule language revisions above, DEQ suggests that the rule express the aluminum criterion as either bioavailable or recoverable aluminum. At a minimum, the final rule's preamble should clearly allow the use of an analytical method that measures bioavailable aluminum concentration as an acceptable alternative to the total recoverable aluminum method. For example, the following wording revisions are suggested.
            "The final 2018 recommended national aluminum criteria are expressed as total recoverable or bioavailable metal concentrations. The EPA notes that while the criteria values for metals are typically expressed as dissolved metal concentrations, the current EPA-approved CWA Test Method 12 for aluminum in natural waters and waste waters measures total recoverable aluminum. The use of total recoverable aluminum may be considered conservative because it includes monomeric (both organic and inorganic) forms, polymeric and colloidal forms, as well as particulate forms and aluminum sorbed to clays. However, toxicity data comparing toxicity of aluminum using total recoverable aluminum and dissolved aluminum demonstrated that toxic effects increased with increasing concentrations of total recoverable aluminum even though the concentration of dissolved aluminum was relatively constant. If the aluminum criteria were based on dissolved concentrations, toxicity would likely be underestimated, as colloidal forms and hydroxide precipitates of the metal that can dissolve under natural conditions and become biologically available would not be measured. However, the 2018 national recommended aluminum criteria are protective for aluminum measured using an alternate analytical method that accurately measures the bioavailable fraction of aluminum. The criteria document contains more discussion of the studies that informed the choice to use total recoverable aluminum as the basis for the final 2018 recommended national criteria and discusses the option of using an alternative bioavailable aluminum method." (p. 8-9)
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)
Our group developed a significant portion of the empirical toxicity test data and bioavailability models for EPA's national freshwater aquatic life criteria for aluminum (final 2018 recommended national criteria). This document reflects the current "state-of-the-science" for evaluating the potential effects of aluminum in the environment. We are supportive of the EPA's approach to use the multiple linear regression (MLR) bioavailability-based model and the proposal of its use in Oregon in deriving aluminum site-specific water quality standards.
As you will see, our primary comment is associated with the most appropriate analytical technique to measure bioavailable Al in natural waters. Our research group has developed a method to accomplish this; this method is described in our recent publication in the journal Environmental Toxicology and Chemistry (Rodriguez et al 2019) and is available as an open access publication.
(...)
As stated in the proposed rule, the use of total recoverable aluminum may be considered conservative because it includes monomeric (both organic and inorganic) forms, polymeric and colloidal forms, as well as particulate forms and aluminum contained in clays. This demonstrates the necessity to employ an analytical technique of measuring Al in natural waters which is specific to the fraction of Al that is bioavailable to aquatic organisms. Because natural waters contain mineral forms of Al that may not be bioavailable, aggressive analytical digestions (such as that used in the total recoverable method that uses strong acids and heating) may lead to overestimation of bioavailable Al in natural waters containing suspended solids. To address the issues of appropriate analytical methodology for measuring Al in natural waters, our research group has developed a method that will be helpful in measuring the amount of "bioavailable" Al in natural waters (referred to as a pH 4 digestion). This method has been published in the journal, Environmental Toxicology and Chemistry (Rodriguez et al. 2019) and is available as an open access publication at https://doi.org/10.1002/etc.4448. In addition, our group is currently working on standardizing the method through ASTM International. We believe that the proposed rule should include a more robust discussion and additional guidance on an appropriate way, such as the published pH 4 method, to analytically measure bioavailable Al and avoid measuring non-toxic mineral phases. (p. 1, 2)
Default ecoregional criteria and DOC values (derivation, and inclusion in final rule)
This section provides a compendium of the technical comments submitted by commenters about the default ecoregional criteria and DOC values. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
EPA calculated default criteria values and default DOC input values which were included in the preamble to the proposal (in addition, EPA included technical documents detailing the methodologies for calculating these default values in the docket: "Analysis of the Protectiveness of Default Ecoregional Aluminum Criteria Values" and "Analysis of the Protectiveness of Default Dissolved Organic Carbon Options"). The Agency solicited comment on how default values should be derived and whether such values should be promulgated for Oregon. The final rule does not include default values (neither default inputs nor default ecoregional criteria values).
EPA appreciates comments supporting use of default inputs when input parameter values for DOC are unavailable and the use of default ecoregional criteria values for when data for more than one input parameter are unavailable. 
EPA expects the State to have either default values or procedures for how to handle waters with insufficient data to run the 2018 Aluminum Criteria Calculator, in order to ensure that all waters will be protected by the aluminum criteria. Oregon has discretion regarding how to approach defaults, but EPA does expect that the State will provide publicly available default procedures or values so that the public and implementing entities will be aware of how all of the State's fresh waters that are jurisdictional under the CWA will be protected by the criteria.
EPA agrees with comments that it is preferable to collect sufficient ambient data to run the calculator, rather than using defaults. EPA also agrees with comments that defaults may be overly conservative in certain circumstances. Defaults are conservative by design, because in the absence of actual ambient data regarding the pH, DOC, and total hardness of a water body, it is incumbent upon the State to make protective assumptions to ensure that the designated use of the water body will be protected. 
Some commenters said that default values should be used for "screening purposes only." EPA recognizes that the State may choose to use specific default values as "screening values" to identify possible water quality problems; however, EPA would still expect that the State would have publicly available procedures for calculating or identifying criteria values to be used for CWA implementation purposes, in the absence of ambient water chemistry data.
Commenters requested that EPA allow the State discretion to implement the State's own DOC default inputs from its copper BLM criteria rule. EPA analyzed the State's DOC default procedures and found that in most of the ecoregions, the default DOC values those procedures would generate would be protective as default inputs for aluminum as well, with some exceptions and considerations. EPA refers the State to the technical support materials EPA provided on this analysis in support of the aluminum criteria proposal ("Analysis of the Protectiveness of Default DOC Options" Docket ID: EPA-HQ-OW-2016-0694-0116) and encourages the State to continue refining its DOC default input procedures to ensure the calculated aluminum criteria values will be protective of the designated use for all of Oregon's fresh waters that are jurisdictional under the CWA  .

EPA appreciates comments supporting the option of ecoregional criteria default values based on the 10[th] percentile of the distribution of calculator outputs calculated within an ecoregion, which is the procedure that EPA suggested in the preamble to the proposal ("Analysis of the Protectiveness of Default Ecoregional Al Criteria Values" Docket ID: EPA-HQ-OW-2016-0694-0114). EPA agrees with comments that while default values may be needed in some situations, the best approach is to collect the needed ambient water chemistry data in order to facilitate using the calculator to calculate criteria values protective of a waterbody over the full range of water chemistry conditions, including during conditions when aluminum is most toxic. Commenters suggested that EPA include a procedure for calculating default ecoregional criteria rather than a table of pre-calculated values. EPA has elected not to finalize default criteria procedures or values for this rule, but EPA encourages the State to use the procedure EPA described in the technical support materials provided in the docket associated with this rulemaking.
Specific Comments
Oregon Association of Clean Water Agencies (OR ACWA) (Doc. # 0133)
The proposed rule includes a request for comment on promulgating ecoregional default criteria for aluminum and geo-regional default DOC input values where available data are insufficient to characterize a site.  ACWA members have compared actual site-specific criteria derived from complete data sets in some ecoregions to the proposed ecoregional default criteria. Additionally, ACWA members have compared site-specific measured DOC values in the Willamette and Columbia River geo-regions with the proposed default input values.  The default criteria and DOC input values were consistently overly conservative relative to actual site criteria and measured DOC concentrations in these circumstances.   Using the default criteria and DOC input values could thus result in identifying water quality criteria exceedances that do not actually exist.  While default criteria and DOC input values may be useful in coarse-level screening, they should not be applied beyond that.  The effort required for obtaining criteria calculation inputs are not so onerous that default criteria should be needed, given the risk of false positives. If EPA includes the default criteria and DOC input values in the final rule, it should be with a caution to only use them for screening purposes.  The rule should clearly identify the appropriate hierarchy, encouraging the collection and use of site specific-data. (p. 3)
Site-specific data derived from complete data sets demonstrate that the ecoregional default criteria for aluminum and available geo-regional default DOC input values are consistently overly conservative and their use should be limited to screening purposes only. (p. 4)
Oregon Department of Environmental Quality (Doc. # 0135)
Issue #3: DEQ recommendations for default criteria procedures 
DEQ recommends that EPA's criteria rule for Oregon be silent regarding procedures for applying default criteria where one or more of the calculator inputs is missing and allow the state to develop implementation procedures. DEQ supports using default inputs for calculating instantaneous water quality criteria for aluminum samples when input parameter values for DOC are missing. DEQ also supports EPA publication of default Eco-regional aluminum criteria as an option for the state to use when more than one input parameter is missing.
Default DOC inputs
EPA should provide DEQ the discretion to implement DOC defaults using the same procedures for aluminum that the state already has in rule for implementing the copper BLM criteria. This will help to avoid unnecessary complexity and confusion, and potential errors that could occur by having slightly different implementation procedures for these two similarly structured water chemistry-based metals criteria. DEQ has already established DOC default substitution methods that were approved by EPA for use with the copper biotic ligand model. Any change in this approach would similarly be subject to EPA's review and approval. EPA's recommended default DOC concentrations are set at the 15th or 20th percentile of DOC concentration as presented in Section III B. These default values are similar to those already established for copper. This is an important issue as current data collected by the state and the USGS suggests that a large proportion of aluminum measurements do not have concurrent DOC data and DEQ will frequently need to rely on these values. This procedure will help to ensure that permit analysis and development can be completed in an efficient and timely manner. 
Default regional criteria
DEQ recognizes that because of non-linearity in the criteria response to pH and hardness it is more complex to establish protective input default values for each parameter in the same way such values can be established for DOC. This contrasts from ammonia, hardness-based metals, and copper criteria, which respond linearly to change in the concentration of respective input parameters. In the situation that pH and/or hardness data are not available to evaluate an aluminum sample, the use of EPA's proposed Ecoregional aluminum criteria defaults, which are based on the 10th percentile of the distribution of instantaneous criteria values calculated within the ecoregion, is an appropriate option. In addition, using the 10th percentile of the distribution of instantaneous criteria for a waterbody or site, if there is sufficient data, rather than for the whole ecoregion, would also be an appropriate method to ensure protection of aquatic life and would likely be more accurate for the site. DEQ expects these situations to be rare, as current data collected by the state and the USGS suggests that less than 1% of total recoverable aluminum samples in the state do not have corresponding pH and hardness data for calculating instantaneous criteria using the aluminum calculator.
Default criteria values may be needed to assess available aluminum data where the input parameter data are not available. However, the appropriate approach to implement the criteria in NPDES permits and TMDLs is to collect the needed data and determine the site-specific criteria values that result in a protective WQBEL or waste-load allocation given the variability of water chemistry conditions observed for the waterbody or site.
Rather than including the specific aluminum concentration values in the rule (Section III A. Table 1), DEQ recommends that EPA include the procedure for using the 10th percentile of Ecoregional criteria calculated using measured data. The specific aluminum concentration values in the proposed rule are based on the currently available data set. Revising the rule to include the procedure instead, will allow the specific values to be updated as additional data is collected. (p. 4-5)
Implementation - critical low flows
This section provides a compendium of the technical comments submitted by commenters about implementation issues concerning critical low flows and the aluminum criteria. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
The proposal preamble discussed low flow definitions, but the proposed regulatory text did not include a low flow definition for implementing the aluminum criteria in permits. EPA has not included a critical low flows provision in the final rule. Oregon continues to have the discretion to apply its own established procedures for critical low flows in the context of implementation in NPDES permitting.
Specific Comments
Oregon Department of Environmental Quality (Doc. # 0135)
Issue #4: EPA should not include critical low flows as part of the aluminum rule
The EPA proposed rule includes a low flow definition for implementing the aluminum criteria in permits. DEQ agrees that permits and other CWA programs need to implement the criteria based on specified low flow levels. However, this is already an overarching requirement for the state and there is nothing inherently different for aluminum than other aquatic life criteria in this regard. Therefore, EPA should remove this provision from the final rule and rely on the state's established procedures and applicable state and federal guidance and regulations to ensure consistent implementation for all aquatic life criteria. (p. 5)
Endangered Species Act
This section includes comments submitted by commenters about Endangered Species Act Section 7(a)(2) consultation. Comments have been copied into this document "as is" with no editing or summarizing.
EPA Summary Response
As the commenter mentions, EPA initially considered approving Oregon's previously submitted aluminum criteria. However, after requesting formal consultation, but before receiving a Biological Opinion from NOAA Fisheries or USFWS, EPA realized that the Agency's initial understanding that Oregon's criteria were entirely equivalent to the Agency's 1988 CWA Section 304(a) recommended criteria was incorrect. While EPA's 1988 recommended criteria applied at pH values of 6.5-9.0, the Agency later identified a footnote to Oregon's revised aluminum criteria table specifying that Oregon's aluminum criteria applied to waters with pH values less than 6.6 and hardness values less than 12 mg/L. The State had not supplied a scientific rationale to justify the application of the criteria to pH values less than 6.6 and hardness values less than 12 mg/L. NOAA Fisheries published a reasonable and prudent alternative for aluminum as part of its Biological Opinion after determining that the Oregon criteria would jeopardize certain threatened and endangered species under its purview. EPA disapproved the revised aluminum criteria subsequent to the publication of the Biological Opinion. This federal rulemaking is intended to resolve the previous disapproval of Oregon's aluminum criteria.
For this rulemaking, EPA transmitted a Biological Evaluation to NOAA Fisheries Service and USFWS on September 20, 2019. On February 13, 2020, EPA received a final Biological Opinion from USFWS that determined that EPA's proposed action is likely to adversely affect but will not jeopardize the continued existence of bull trout and will not destroy or adversely modify its designated critical habitat. USFWS also concluded that the proposed action may affect, but is not likely to adversely affect, eight other federally-listed species and is not likely to destroy or adversely modify the critical habitat for the other species that were included in the consultation. On July 1, 2020, EPA received a final Biological Opinion from NOAA Fisheries that determined that EPA's proposed action is likely to adversely affect, but will not jeopardize the continued existence of 18 federally-listed species and will not destroy or adversely modify designated critical habitat for the species that were included in the consultation. The receipt of the NOAA Biological Opinion concludes the consultation for this rulemaking under ESA Section 7(a)(2). Documents associated with ESA consultation are available in the docket associated with this rulemaking (Docket ID: EPA-HQ-OW-2016-0694).
Specific Comments
Anonymous (Doc. # 0132)
I wanted to leave a comment in support of this rule being proposed. In conducting      research and looking at the summary of the proposed plan and how it has been addressed in the past, there are some points that I would like to make. The EPA had initially considered approving Oregon's aluminum criteria and had even decided to receive consultation from the National Marine Fisheries Service and the U.S. Fish and Wildlife Service, but had rescinded this decision and before receiving a biological opinion, they had argued that the agencies understanding of CWA section 304a. They had decided to disapprove the aluminum criteria because the agency had initially specified that the aluminum criteria applied to waters with pH values less than 6.6 when the criteria applies to water with pH level 6.5-9.0. I don't understand how the EPA could go about their decision in the past without jurisdiction from the USFWS or the NMFS. I want to provide some information regarding what aluminum does when interacting with water. Aluminum metal forms a layer of aluminum oxide that can become up to a couple millimeters thick when touching water. Once that layer corrodes, hydrogen gas is released. This can greatly harm animal and marine life and the NMFS had even concluded that seven of Oregon's revised freshwater would jeopardize the endangered species in Oregon. I wholly agree and hope that the state will accept the proposed water quality standard from the EPA and CWA. (p. 1)
Other
This section includes comments submitted by commenters regarding other topics not addressed by the previous sections. Comments have been copied into this document "as is" with no editing or summarizing.
 EPA Summary Response
EPA appreciates the commenter's interest in and support of the rule and agrees that the final aluminum criteria EPA is promulgating for fresh waters in Oregon are both protective and implementable.  
EPA has provided the final Economic Analysis for this rule in the docket associated with this rulemaking. That document discusses potentially affected entities in the State of Oregon. EPA agrees that because Oregon would be one of the first states to implement EPA's 2018 national CWA Section 304(a) recommended freshwater aquatic life criteria for aluminum, Oregon's implementation of the criteria may be precedential for other states in the future.
EPA appreciates the commenter's support for applying a water chemistry-based approach to calculate aluminum criteria for freshwater aquatic life in Oregon.
EPA acknowledges the commenter's support of using model-based criteria to create site-specific criteria values and agrees that other states will benefit from recognizing the precedent and adopting aluminum (and potentially other metals) criteria that account for ambient water chemistry's impacts on metal toxicity.    
Specific Comments
Anonymous (Doc. # 0131)
I agree with this proposed rule change and support it. I feel that the U.S as a whole can do much more to prevent marine pollution, in general, in order to protect and conserve our aquatic life. As a resident of the Pacific North West, I think that this proposed rule affects me as well since Oregon and Washington are on the same coast. (p. 1)
Oregon Association of Clean Water Agencies (ACWA) (Doc. # 0133)
Adoption of the aluminum criteria as proposed would significantly impact ACWA members and the communities they serve.  ACWA supports the promulgation of aluminum criteria to protect aquatic life in Oregon and is providing these comments to ensure that the final aluminum criteria will be both protective and implementable. (p. 1)
The Aluminum Association (Doc. # 0134)
Member companies own and operate over 200 manufacturing facilities located throughout the United States, some of which are located in Oregon and would therefore be affected by the proposed rule once finalized. In addition, Oregon is one of the first states to implement the revised national recommended water quality criteria for aluminum (EPA-822-R-18-001) and thus its implementation may be precedential for other states revising their criteria in the future.  As such, the Association's Water Workgroup has significant interest in the proposed rule and is providing the comments below for EPA's consideration in finalizing the proposed rule. (p. 1)
Oregon Department of Environmental Quality (Doc. # 0135)
DEQ generally supports EPA's efforts to develop water quality criteria that account for the effects of water chemistry on toxicity. This approach improves the accuracy and protectiveness of criteria for many toxic metals and other toxic substances. DEQ also supports the application of a water chemistry-based approach for freshwater aquatic life criteria for aluminum in Oregon.
(...)
The proposed rule and federal register document includes many optional components or implementation procedures for which EPA directly solicits stakeholder input. EPA will be considering a wide range of public input that could result in significant differences in the structure and function of the final criteria and the content of the final rule and preamble. DEQ looks forward to further conversation with EPA as it develops its response to comments and makes decisions about the content of the final rule. (p. 1, 9)
Oregon State University on behalf of Aluminum Ecotoxicity Research Group (Doc. # 0137)
We recognize that the adoption of this rule by Oregon would make it one of the first states in the nation to use a bioavailability-based multiple linear regression model to create site-specific standards. This would set an important precedence for other states to follow in recognizing the importance of water quality in metal standard development. (p. 1)







