Revision of December 2000 Regulatory Finding on the Emissions of Hazardous Air Pollutants From Electric Utility Steam Generating Units and the Removal of Coal- and Oil-Fired Electric Utility Steam Generating Units From the Section 112(c) List: Reconsideration, 62200-62213 [05-21456]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 70, Number 208 (Friday, October 28, 2005)]
[Proposed Rules]
[Pages 62200-62213]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-21456]



[[Page 62199]]

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Part III





Environmental Protection Agency





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40 CFR Parts 60 and 63



Revision of December 2000 Regulatory Finding on the Emissions of 
Hazardous Air Pollutants From Electric Utility Steam Generating Units; 
Standards of Performance; Proposed Rules

Federal Register / Vol. 70, No. 208 / Friday, October 28, 2005 / 
Proposed Rules

[[Page 62200]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[OAR-2002-0056; FRL-7989-3]
RIN 2060-AM96


Revision of December 2000 Regulatory Finding on the Emissions of 
Hazardous Air Pollutants From Electric Utility Steam Generating Units 
and the Removal of Coal- and Oil-Fired Electric Utility Steam 
Generating Units From the Section 112(c) List: Reconsideration

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of reconsideration of final rule; request for public 
comment; notice of public hearing.

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SUMMARY: On March 29, 2005, EPA published a final rule entitled 
``Revision of December 2000 Regulatory Finding on the Emissions of 
Hazardous Air Pollutants From Electric Utility Steam Generating Units 
and the Removal of Coal- and Oil-Fired Electric Utility Steam 
Generating Units from the Section 112(c) List'' (Section 112(n) 
Revision Rule). (See 70 FR 15994.) Following that final action, the 
Administrator received two petitions for reconsideration. In response 
to those petitions, EPA is announcing its reconsideration of certain 
aspects of the Section 112(n) Revision Rule. We are requesting comment 
on the particular issues identified below for which we are granting 
reconsideration. Those issues are referenced briefly in the 
SUPPLEMENTARY INFORMATION section of the preamble and described more 
fully later in this preamble.
    We are seeking comment only on the aspects of the Section 112(n) 
Revision Rule specifically identified in this notice. We will not 
respond to any comments addressing other aspects of the Section 112(n) 
Revision Rule or any related rulemakings.

DATES: Comments. Comments must be received on or before December 19, 
2005. Because of the need to resolve the issues raised in this notice 
in a timely manner, EPA will not grant requests for extensions beyond 
this date.
    Public Hearing. A public hearing will be held on November 17, 2005. 
For further information on the public hearing and requests to speak, 
see the ADDRESSES section of this preamble.

ADDRESSES: Comments. Submit your comments, identified by Docket ID No. 
OAR-2002-0056 (Legacy Docket ID No. A-92-55), by one of the following 
methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
     Agency Web site: https://www.epa.gov/edocket. EDOCKET, 
EPA's electronic public docket and comment system, is EPA's preferred 
method for receiving comments. Follow the on-line instructions for 
submitting comments.
     E-mail: a-and-r-docket@epa.gov.
     Fax: (202) 566-1741.
     Mail: Air and Radiation Docket and Information Center, 
U.S. EPA, Mailcode: 6102T, 1200 Pennsylvania Avenue, NW., Washington, 
DC 20460.
     Hand Delivery: Air and Radiation Docket and Information 
Center, U.S. EPA, Room B102, 1301 Constitution Avenue, NW., Washington, 
DC. Such deliveries are only accepted during the Docket's normal hours 
of operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions. Direct your comments to Docket ID No. OAR-2002-0056 
(Legacy Docket ID No. A-92-55). EPA's policy is that all comments 
received will be included in the public docket without change and may 
be made available online at https://www.epa.gov/edocket, including any 
personal information provided, unless the comment includes information 
claimed to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Do not submit 
information that you consider to be CBI or otherwise protected through 
EDOCKET, regulations.gov, or e-mail. The EPA EDOCKET and the Federal 
regulations.gov Web sites are ``anonymous access'' systems, which means 
EPA will not know your identity or contact information unless you 
provide it in the body of your comment. If you send an e-mail comment 
directly to EPA without going through EDOCKET or regulations.gov, your 
e-mail address will be automatically captured and included as part of 
the comment that is placed in the public docket and made available on 
the Internet. If you submit an electronic comment, EPA recommends that 
you include your name and other contact information in the body of your 
comment and with any disk or CD ROM you submit. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment. Electronic 
files should avoid the use of special characters, any form of 
encryption, and be free of any defects or viruses.
    Public Hearing. The public hearing will run from 8 a.m. to 5 p.m., 
Eastern time, and will be held in Room 111C at the EPA facility, 
Research Triangle Park, N.C. Persons interested in attending the 
hearing or wishing to present oral testimony should notify Ms. Pamela 
Garrett at least 2 days in advance of the public hearing (see FOR 
FURTHER INFORMATION CONTACT section of this preamble). The public 
hearing will provide interested parties the opportunity to present 
data, views, or arguments concerning this notice. The public hearing 
for this action will be held on the same date and at the same time and 
location as the public hearing for the related reconsideration action 
for the Clean Air Mercury Rule (CAMR), published elsewhere in today's 
Federal Register.
    If no one contacts Ms. Garrett in advance of the hearing with a 
request to present oral testimony at the hearing, we will cancel the 
hearing. The record for this action will remain open for 30 days after 
the date of the hearing to accommodate submittal of information related 
to the public hearing.
    Docket. The EPA has established an official public docket for 
today's notice, including both Docket ID No. OAR-2002-0056 and Legacy 
Docket ID No. A-92-55. The official public docket consists of the 
documents specifically referenced in today's notice, any public 
comments received, and other information related to this notice. All 
items may not be listed under both docket numbers, so interested 
parties should inspect both docket numbers to ensure that they have 
received all materials relevant to today's notice. Although listed in 
the index, some information is not publicly available, i.e., CBI or 
other information whose disclosure is restricted by statute. Certain 
other material, such as copyrighted material, is not placed on the 
Internet and will be publicly available only in hard copy form. 
Publicly available docket materials are available either electronically 
in EDOCKET or in hard copy at the Air and Radiation Docket and 
Information Center, U.S. EPA, Room B102, 1301 Constitution Avenue, NW., 
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 
p.m., Monday through Friday, excluding legal holidays. The telephone 
number for the Public Reading Room is (202) 566-1744, and the telephone 
number for the Air and Radiation Docket and Information Center is (202) 
566-1742.

FOR FURTHER INFORMATION CONTACT: For general and technical information, 
contact Mr. William Maxwell, Combustion Group, Emission Standards 
Division, Mailcode: C439-01, U.S. EPA, Research Triangle Park, NC 
27711; telephone number: (919) 541-5430; fax

[[Page 62201]]

number: (919) 541-5450; e-mail address: maxwell.bill@epa.gov. For 
questions about the public hearing, contact Ms. Pamela Garrett, 
Combustion Group, Emission Standards Division, Mailcode: C439-01, 
Environmental Protection Agency, Research Triangle Park, NC 27711; 
telephone number: (919) 541-7966; fax number: (919) 541-5450; e-mail 
address: garrett.pamela@epa.gov.

SUPPLEMENTARY INFORMATION:
    Outline. The information presented in this preamble is organized as 
follows:

I. General Information
    A. Does this reconsideration notice apply to me?
    B. How do I submit CBI?
    C. How do I obtain a copy of this document and other related 
information?
II. Background
III. Today's Action
IV. Discussion of Issues Subject to Reconsideration
    A. Legal Interpretations
    B. EPA's Methodology and Conclusions Concerning Why Utility Hg 
Emissions Remaining After Imposition of the Requirements of the CAA 
are not Reasonably Anticipated to Result in Hazards to Public Health
    C. Detailed Discussion of Certain Reconsideration Issues Related 
to Coal-Fired Utility Units as Set Forth in Section VI of the Final 
Section 112(n) Revision Rule
    D. EPA's Decision Related to Nickel (Ni) Emissions from Oil-
Fired Utility Units
    E. Documents Identified by Petitioners that are Dated After the 
Close of the Public Comment Period
V. Clarification and Correction of Statements Made in Final Section 
112(n) Revision Rule
VI. Statutory and Executive Order (EO) Reviews
    A. EO 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. EO 13132: Federalism
    F. EO 13175: Consultation and Coordination With Indian Tribal 
Governments
    G. EO 13045: Protection of Children from Environmental Health 
and Safety Risks
    H. EO 13211: Actions that Significantly Affect Energy Supply, 
Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA)

I. General Information

A. Does This Reconsideration Notice Apply to Me?

    Categories and entities potentially affected by today's notice 
include:

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                                                                  NAICS code   Examples of potentially regulated
                            Category                                  \1\                  entities
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Industry........................................................      221112  Fossil fuel-fired electric utility
                                                                               steam generating units.
Federal Government..............................................   \2\221122  Fossil fuel-fired electric utility
                                                                               steam generating units owned by
                                                                               the Federal government.
State/local/Tribal Government...................................   \2\221122  Fossil fuel-fired electric utility
                                                                               steam generating units owned by
                                                                               municipalities.
                                                                      921150  Fossil fuel-fired electric utility
                                                                               steam generating units in Indian
                                                                               country.
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\1\ North American Industry Classification System.
\2\ Federal, State, or local government-owned and operated establishments are classified according to the
  activity in which they are engaged.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by today's 
notice. This table lists examples of the types of entities EPA is now 
aware could potentially be affected by today's notice. Other types of 
entities not listed could also be affected. If you have questions 
regarding the applicability of today's notice to a particular entity, 
consult Mr. William Maxwell listed in the preceding FOR FURTHER 
INFORMATION CONTACT section.

B. How Do I Submit CBI?

    Do not submit this information to EPA through EDOCKET, 
regulations.gov, or e-mail. Clearly mark the part or all of the 
information that you claim to be CBI. For CBI in a disk or CD ROM that 
you mail to EPA, mark the outside of the disk or CD ROM as CBI and then 
identify electronically within the disk or CD ROM the specific 
information that is claimed as CBI. In addition to one complete version 
of the comment that includes information claimed as CBI, a copy of the 
comment that does not contain the information claimed as CBI must be 
submitted for inclusion in the public docket. Information so marked 
will not be disclosed except in accordance with procedures set forth in 
40 CFR part 2.

C. How Do I Obtain a Copy of This Document and Other Related 
Information?

    In addition to being available in the docket, an electronic copy of 
today's notice also will be available on the World Wide Web (WWW) 
through EPA's Technology Transfer Network (TTN). Following the 
Administrator's signature, a copy of this notice will be posted on the 
TTN's policy and guidance page for newly proposed rules at https://
www.epa.gov/ttn/oarpg. The TTN provides information and technology 
exchange in various areas of air pollution control.

II. Background

    On March 15, 2005, EPA signed a final action that revised the 
Agency's December 2000 finding made pursuant to Clean Air Act (CAA) 
section 112(n)(1)(A), and based on that revision, removed coal- and 
oil-fired electric utility steam generating units (Utility Units or 
power plants) from the CAA section 112(c) source category list. The 
final Section 112(n) Revision Rule was published on March 29, 2005. 
(See 70 FR 15994.) CAA section 112(n)(1)(A) is the threshold statutory 
provision underlying the Section 112(n) Revision Rule. That provision 
requires EPA to conduct a study to examine the possibility of hazards 
to public health that are reasonably anticipated to occur as the result 
of hazardous air pollutant (HAP) emissions from Utility Units after 
imposition of the requirements of the CAA. The provision also provides 
that EPA shall regulate Utility Units under CAA section 112, but only 
if the Administrator determines that such regulation is both 
``appropriate'' and ``necessary'' considering, among other things, the 
results of the study. EPA completed the study in 1998 (the Utility 
Study), and in December 2000 found that it was appropriate and 
necessary to regulate coal- and oil-fired Utility Units under CAA 
section 112. That December 2000 finding focused primarily on mercury 
(Hg) emissions from coal-fired Utility Units. In light of the finding, 
EPA in December 2000 listed coal- and oil-fired Utility Units on the 
CAA section 112(c) list of regulated source categories. On January 30, 
2004 (69 FR 4652), EPA proposed revising the December 2000 appropriate 
and necessary finding and, based on that revision, removing coal- and 
oil-fired Utility Units from the CAA section 112(c) list.
    In the final Section 112(n) Revision Rule, EPA revised the December 
2000 appropriate and necessary finding, having concluded that it is 
neither appropriate nor necessary to regulate coal- and oil-fired 
Utility Units under

[[Page 62202]]

CAA section 112. EPA took this action because the December 2000 finding 
lacked foundation and EPA received new information that confirmed that 
it is not appropriate or necessary to regulate coal- and oil-fired 
Utility Units under CAA section 112. Based solely on the revised 
finding, EPA removed coal- and oil-fired Utility Units from the CAA 
section 112(c) list.
    The final Section 112(n) Revision Rule discusses, among other 
things, two other recent rulemakings. First, on March 10, 2005, EPA 
finalized the Clean Air Interstate Rule (CAIR), which will reduce 
nitrogen oxide (NOX) and sulfur dioxide (SO2) 
emissions from coal-fired power plants by about 70 percent when fully 
implemented. As explained in the final Section 112(n) Revision Rule, 
EPA expects Hg co-benefit emissions reductions from CAIR. CAIR was 
published on May 12, 2005. (See 70 FR 25162.)
    Second, on March 15, 2005, EPA signed the final CAMR and 
established standards of performance for Hg for new and existing coal-
fired Utility Units, as defined in CAA section 111. CAMR was published 
on May 18, 2005. (See 70 FR 28606.)
    Following promulgation of the Section 112(n) Revision Rule, the 
Administrator received two petitions, filed pursuant to CAA section 
307(d)(7)(B), requesting reconsideration of many aspects of the final 
Section 112(n) Revision Rule.\1\ The purpose of today's notice is to 
initiate reconsideration of certain issues raised in those 
petitions.\2\
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    \1\ One petition was submitted by 14 States: New Jersey, 
California, Connecticut, Delaware, Illinois, Maine, Massachusetts, 
New Hampshire, New Mexico, New York, Pennsylvania, Rhode Island, 
Vermont, and Wisconsin (State petitioners). The other petition was 
submitted by five environmental groups and four Indian Tribes: The 
Natural Resources Defense Council (NRDC), the Clean Air Task Force 
(CATF), the Ohio Environmental Council, the U.S. Public Interest 
Research Group (USPIRG), the Natural Resources Council of Maine; the 
Aroostook Band of Micmacs, the Houlton Band of Maliseet Indians, the 
Penobscot Indian Nation, and the Passamaquoddy Tribe of Maine 
(Indian Township and Pleasant Point) (Environmental petitioners). In 
this notice, the term ``petitioners'' refers only to those entities 
that filed petitions for reconsideration of the Section 112(n) 
Revision Rule with EPA.
    EPA also received four petitions to reconsider the CAMR. EPA's 
response to those petitions is addressed in a separate Federal 
Register notice published today.
    \2\ In a letter dated June 24, 2005, we informed the petitioners 
that we intended to initiate a reconsideration process of the 
Section 112(n) Revision Rule for at least one issue raised in the 
petitions. We indicated that we would provide particulars in a 
subsequent Federal Register notice. This is that notice. Also in 
that June 24, 2005, letter, we denied petitioners' request that we 
administratively stay the Section 112(n) Revision Rule under section 
307(d)(7)(B). On August 4, 2005, the DC Circuit denied a similar 
request to stay the Section 112(n) Revision Rule pending the outcome 
of the litigation challenging the rule.
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III. Today's Action

    Today, we are granting reconsideration of, and requesting comment 
on, many of the issues raised in the two petitions for reconsideration. 
Generally, the petitioners claim the final Section 112(n) Revision Rule 
contains legal interpretations and information that are of central 
relevance to the final rule but that were not sufficiently reflected in 
the proposed rule, and that they, therefore, did not have an adequate 
opportunity to provide input on these matters during the designated 
public comment period.
    Further, the petitioners contend that additional information has 
become available since the close of the public comment period, and that 
this new information is also of central relevance.
    The EPA recognizes that there is a high degree of public interest 
in the final rule. The public had three opportunities to submit 
comments on the rulemaking, following the January 30, 2004, Notice of 
Proposed Rulemaking (NPR), the March 16, 2004, Supplemental Notice of 
Proposed Rulemaking (SNPR), and the December 1, 2004, Notice of Data 
Availability (NODA). EPA received, reviewed, and responded to thousands 
of documents. Thus, a robust public discussion of the rule has already 
occurred. Nonetheless, in the interest of ensuring ample opportunity to 
comment on all meaningful aspects of this important rule, we are 
granting reconsideration on certain issues and asking the public for 
additional comment. The issues for which we are granting 
reconsideration at this time, and for which we are soliciting comment, 
are discussed below.
    Our final decision on reconsideration for all the issues for which 
we are not granting reconsideration today will be issued no later than 
the date by which we take final action on the issues discussed in 
today's action.

IV. Discussion of Issues Subject to Reconsideration

A. Legal Interpretations

    In the final Section 112(n) Revision Rule, EPA explained, in 
detail, its interpretation of CAA section 112(n)(1)(A). Petitioners 
claim that many of the legal interpretations underlying the final 
Section 112(n) Revision Rule were not part of the proposal and, 
therefore, that they did not have an opportunity to comment on them 
during the designated comment period. They also contend that they did 
not have an opportunity to address EPA's application of its legal 
interpretations. At this time, EPA is opening for public comment 
several aspects of its legal interpretations and its application of 
those interpretations as provided in the final Section 112(n) Revision 
Rule.
    As explained in the final Section 112(n) Revision Rule, Congress 
treated Utility Units differently from other major and area sources and 
provided EPA considerable discretion in determining whether to regulate 
such units under CAA section 112. CAA section 112(n)(1)(A) provides:

    The Administrator shall perform a study of the hazards to public 
health reasonably anticipated to occur as a result of emissions by 
electric utility steam generating units of pollutants listed under 
subsection (b) of this section after imposition of the requirements of 
this Act. The Administrator shall report the results of this study to 
the Congress within 3 years after November 15, 1990. The Administrator 
shall develop and describe in the Administrator's report to Congress 
alternative control strategies for emissions which may warrant 
regulation under this section. The Administrator shall regulate 
electric utility steam generating units under this section, if the 
Administrator finds such regulation is appropriate and necessary after 
considering the results of the study required by this subparagraph.

    At this time, EPA grants reconsideration of its interpretation of 
the following terms and phrases in CAA section 112(n)(1)(A), and its 
application of those terms and phrases.
1. Hazards to Public Health Reasonably Anticipated To Occur as a Result 
of Emissions by Electric Utility Steam Generating Units
    We solicit comment on all aspects of EPA's interpretation of the 
above phrase as set forth in the final Section 112(n) Revision Rule and 
its application of that phrase. Although we seek comment on all aspects 
of EPA's interpretation and application of the above phrase, we clarify 
certain points below and identify certain threshold issues raised by 
petitioners on which we seek additional comment.
    As EPA explained in the final Section 112(n) Revision Rule, CAA 
section 112(n)(1)(A) does not define what constitutes ``hazards to 
public health reasonably anticipated to occur'' and EPA has the 
discretion to interpret those terms and, using its technical expertise, 
determine whether Hg emissions from

[[Page 62203]]

Utility Units pose such hazards. (See 70 FR 15997-98, 16023-25.) EPA 
also explained in the final Section 112(n) Revision Rule that CAA 
section 112(n)(1)(A) does not incorporate the requirements of CAA 
section 112(f), including, but not limited to, the two-part ample 
margin of safety inquiry set forth at 54 FR 38044 (September 14, 1989) 
(the benzene analysis), as referenced in CAA section 112(f)(2)(B). 
Accordingly, in evaluating ``hazards to public health reasonably 
anticipated to occur'' under CAA section 112(n)(1)(A), EPA is not 
subject to the requirements of CAA section 112(f). We are reiterating 
this point because the petitions exhibited some confusion in this 
regard.
    EPA also noted in the final Section 112(n) Revision Rule that even 
assuming, arguendo, that the health-based aspect of the two-part ample 
margin of safety inquiry under CAA section 112(f) applied to CAA 
section 112(n)(1)(A) (which EPA maintains it does not), EPA's 
conclusions would not have differed from the conclusion it reached in 
analyzing hazards to public health reasonably anticipated to occur 
under CAA section 112(n)(1)(A). In this regard, EPA examined the two 
steps in the ample margin of safety inquiry under CAA section 112(f) 
from a public health perspective and concluded that even ``if we were 
proceeding under section 112(f), we would likely conclude that CAIR, 
and even more so CAMR, not only protects public health, but does so 
with an ample margin of safety.'' (See 70 FR 16025.) EPA specifically 
solicits comment on the above-noted conclusion and EPA's analyses in 
this regard. (See also section IV.C of today's notice.)
    Finally, EPA specifically solicits comment on its interpretation 
that the relevant inquiry for assessing ``hazards to public health 
reasonably anticipated to occur'' under CAA section 112(n)(1)(A) is to 
focus on HAP emissions resulting from Utility Units. (See generally 70 
FR 15998.)
2. After Imposition of the Requirements of the Act
    We solicit comment on all aspects of EPA's interpretation of the 
above phrase as set forth in the final Section 112(n) Revision Rule and 
its application of that phrase. (See generally 70 FR 15998-99; section 
IV of the preamble to the final Section 112(n) Revision Rule.) Among 
other things, we solicit comment on EPA's reliance on CAIR in this 
regard.
3. Appropriate and Necessary After Considering the Results of the Study
    We solicit comment on all aspects of EPA's interpretation of the 
term ``appropriate.'' Among other things, we seek comment on EPA's 
interpretation of CAA section 112(n)(1)(A) as allowing EPA to consider 
environmental impacts of emissions from Utility Units in the 
``appropriate'' analysis, but only when EPA has already determined that 
hazards to public health are reasonably anticipated to occur as the 
result of utility HAP emissions. (See 70 FR 15997-98; section IV of the 
preamble to the final Section 112(n) Revision Rule.)
    We further solicit comment on EPA's application of its 
interpretation of the term ``appropriate.'' We specifically solicit 
comment on EPA's application of the term ``appropriate'' in the context 
of utility-attributable emissions alone, which reflects EPA's 
interpretation of CAA section 112(n)(1)(A).
    In their petitions, petitioners focus on EPA's alternative 
``appropriate'' argument. Specifically, in the final Section 112(n) 
Revision Rule, EPA explained that even examining the entire global pool 
of Hg emissions, as opposed to utility-only attributable Hg (as EPA has 
interpreted CAA section 112(n)(1)(A)), EPA would still conclude that it 
is not appropriate to regulate coal-fired Utility Units on the basis of 
the global Hg pool under CAA section 112. We seek comment on this 
argument. (See 70 FR 16028.)
    Moreover, we solicit comment on EPA's interpretation of the term 
``necessary,'' but only insofar as EPA has interpreted that term as 
involving an analysis of whether the alternative legal authority 
identified, if implemented, would result in effective regulation, 
including, for example, its cost-effectiveness and administrative 
effectiveness. (See 70 FR 16001.) We also solicit comment on EPA's 
application of this aspect of the term ``necessary.'' We are not 
soliciting comment today on EPA's interpretation of the term 
``necessary'' as involving an analysis of whether there is alternative 
authority under the CAA that, if implemented, would address hazards to 
public health associated with remaining utility-attributable HAP 
emissions.
    We further solicit comment on EPA's interpretation of the phrase 
``considering the results of the study'' and, in particular, that EPA 
is not foreclosed from examining relevant information that becomes 
available after the study. (See 70 FR 15999.) We also solicit comment 
on EPA's interpretation of CAA section 112(n)(1)(A) as authorizing EPA 
to revise a prior appropriate and necessary determination, where, as 
here, we believe that the December 2000 finding lacked foundation and 
that new information confirms that it is neither appropriate nor 
necessary to regulate HAP emissions from Utility Units under CAA 
section 112. (See 70 FR 16001.)
    EPA's interpretation of the above identified terms and phrases in 
CAA section 112(n)(1)(A) is set forth, in full, in the final Section 
112(n) Revision Rule and commenters should refer to that discussion in 
formulating any comments. In particular, commenters may want to review 
sections III, IV, V, and VI of the final Section 112(n) Revision Rule.
    EPA also specifically solicits comment on EPA's interpretation of 
CAA sections 112(n)(1)(A) and 112(c)(9), and its explanation as to why 
the requirements of CAA section 112(c)(9) do not apply to EPA's removal 
of Utility Units from the CAA section 112(c) source category list. (See 
generally section VIII of the final Section 112(n) Revision Rule.)

B. EPA's Methodology and Conclusions Concerning Why Utility Hg 
Emissions Remaining After Imposition of the Requirements of the CAA Are 
Not Reasonably Anticipated To Result in Hazards to Public Health

    In section VI of the final Section 112(n) Revision Rule, EPA set 
out a methodology for evaluating utility Hg emissions and deposition. 
That methodology, among other things, assesses the amount of utility-
attributable methylmercury (MeHg) levels in fish tissue and the amount 
of fish consumption and evaluates the resulting public health effects. 
EPA also set forth in section VI its conclusions based on that 
methodology. At this time, EPA is opening for public comment all 
aspects of this methodology and the conclusions EPA reached, as 
described and justified in section VI and the associated Section 112(n) 
Revision Rule technical support documents (TSD).
    EPA is also granting reconsideration with respect to materials 
included in the CAIR docket that EPA incorporated by reference into the 
docket for the final Section 112(n) Revision Rule, as they pertain to 
the methodology in section VI of the final Section 112(n) Revision 
Rule. We ask that anyone who comments on materials in the CAIR docket 
explain why their comments are pertinent to the issues on which we are 
granting reconsideration today.
    Many of the analytical tools (e.g., Community Multiscale Air 
Quality model (CMAQ), Mercury Maps (MMaps)) and data sources (e.g., 
emissions inventories, GEOS-CHEM global background, and fish tissue 
concentrations) relevant to the methodology described in section VI of 
the final Section 112(n) Revision Rule

[[Page 62204]]

were described in the NODA and the public, therefore, had an 
opportunity to comment on them previously. Nevertheless, EPA today 
grants the petitioners' request for an additional opportunity to 
comment on those analytical tools and data sources, including how they 
informed our final decision, as discussed in section VI of the final 
Section 112(n) Revision Rule. Among other things in Section VI, we 
solicit comment on EPA's treatment of the uncertainties in the analysis 
that support its determination that utility-attributable Hg emissions 
remaining after CAIR, and independently CAMR, are not ``reasonably 
anticipated to result in hazards to public health.''
    Although we are granting reconsideration on the entire methodology 
and our associated conclusions set forth in section VI of the final 
Section 112(n) Revision Rule, the following section of this preamble 
includes additional discussion concerning particular aspects of that 
methodology.

C. Detailed Discussion of Certain Reconsideration Issues Related to 
Coal-Fired Utility Units as Set Forth in Section VI of the Final 
Section 112(n) Revision Rule

    As explained in the prior section, EPA grants reconsideration of 
its methodology and conclusions contained in section VI of the final 
Section 112(n) Revision Rule. In this section, we provide additional 
information and discussion concerning specific aspects of the 
methodology described in section VI of the final Section 112(n) 
Revision Rule for which we are soliciting comment.
1. Modeling of Hg Deposition Changes That Result From Implementation of 
CAIR and CAMR
    The petitioners claim that EPA did not provide adequate notice of 
how EPA intended to use the CMAQ model or of the results from CMAQ 
model runs. In addition, some petitioners claim that EPA's reliance on 
the CMAQ model was flawed because (a) the model has not been used 
before for Hg modeling, (b) the model has not been peer reviewed, and 
(c) EPA conducted an inadequate performance evaluation. Other 
petitioners assert that CMAQ is not precise enough to estimate 
deposition for the purposes of the final Section 112(n) Revision Rule 
because the grid size is too large to investigate the possibility of 
utility hotspots. These petitioners add that CMAQ under-predicts wet 
deposition and that its dry deposition rates are inaccurate because 
there is no dry deposition monitoring against which to evaluate the 
model predictions. Petitioners add that EPA's averaging of the model-
predicted grid-cell-wide average deposition across all grid cells in a 
watershed obscures areas of higher deposition.
    Through the NODA, EPA solicited and received public comment on CMAQ 
and how EPA intended to use it generally, and responded to those 
comments in the final Section 112(n) Revision Rule. Even so, as noted 
above, in the interests of ensuring full opportunity for the public to 
comment, we grant reconsideration of EPA's use of CMAQ in its public 
health analysis, and solicit comment on the documentation for CMAQ and 
the substantive points raised by petitioners, in particular. In 
addition, we have developed additional information, summarized below, 
on some of the points raised by petitioners, and solicit comment on 
that information.
    a. Prior Use, and Peer-Review, of the CMAQ Model. The CMAQ model 
used in the Section 112(n) Revision Rule has been used for Hg modeling 
previously in model evaluation studies, although not to support a 
regulatory analysis. We solicit comment on the following information 
concerning peer review, some of which was included in the docket at the 
time of the final Section 112(n) Revision Rule, others of which we have 
added more recently in support of today's notice.
    The CMAQ model has been peer reviewed, as noted in section III of 
the ``Modeling TSD'' (Technical Support Document for the Final Clean 
Air Mercury Rule: Air Quality Modeling; OAR-2002-0056-6130).\3\ The 
CMAQ Hg module is primarily documented in the peer reviewed Atmospheric 
Environment journal article documented in the Modeling TSD (Bullock and 
Brehme, 2002). In addition the entire CMAQ model, including the Hg 
updates documented in the Modeling TSD, underwent further peer review 
in May 2005. A report containing the results of this peer review is 
available in the docket (and is also publicly available at https://
www.cmascenter.org).
---------------------------------------------------------------------------

    \3\ CMAQ Review Panel, 2004: Final Report Summary: December 2003 
Peer Review of the CMAQ Model. https://www.cmascenter.org/html/
CMAQ%20peer%20review%20final_CMAS-web.pdf, Carolina Environmental 
Programs, Chapel Hill, NC.
    CMAQ Review Panel, 2005: Final Report: Second Peer Review of the 
CMAQ Model. Carolina Environmental Programs, Chapel Hill, NC (http:/
/www.cmascenter.org).
    Byun, D., and K.L. Schere, 2005: Review of the Governing 
Equations, Computational Algorithms, and Other Components of the 
Models-3 Community Multiscale Air Quality (CMAQ) Modeling System. 
Applied Mechanics Reviews (in press).
---------------------------------------------------------------------------

    Concerns have also been raised over the exclusion of the State of 
Alaska (Healy Plant), the State of Hawaii (AES--Hawaii), and the U.S. 
Territories from the modeling analyses supporting CAMR. The primary 
reason for this exclusion is that the meteorological model (Mesoscale 
Meteorological Model, Version V, which drives the atmospheric chemistry 
simulation in CMAQ) does not include these remote areas in its current 
modeling domain. Thus, there is no available meteorological information 
to assess the transport, diffusion, and deposition from sources in 
these regions in the CMAQ modeling analyses.
    Moreover, EPA assessed the magnitude of emissions from coal-fired 
power plants in Alaska and Hawaii in the 1999 ICR data and determined 
that these plants emitted 0.0155 percent and 0.0162 percent, 
respectively, of the total 48 tons of Hg emissions in 1999. Given the 
magnitude and density of power plant emissions in the lower 48 States, 
and the conclusion stated in the final Section 112(n) Revision Rule 
that emissions in the lower 48 States, after the implementation of CAIR 
(and moreover CAMR), are not reasonably anticipated to result in 
hazards to public health, EPA does not reasonably anticipate that Hg 
emissions from units located in Alaska, Hawaii, and the U.S. 
Territories pose hazards to public health.
    b. CMAQ Model Evaluation. We solicit comment on the evaluation of 
the CMAQ model performance summarized in section VI of the Section 
112(n) Revision Rule and discussed more fully in section IV of the 
Modeling TSD. In particular, we seek comment concerning our conclusion 
that the model performance for CMAQ Hg deposition falls within what has 
been considered reasonable model performance for ozone and particulate 
matter model applications.
    Currently, there is no continuous measurement network for Hg dry 
deposition in part because there is no low-cost dry measurement method 
available for use in such a network. Thus, we are not able to evaluate 
model performance for Hg dry deposition by comparing model predictions 
to monitored observations. Nonetheless, we believe our use of CMAQ 
adequately accounts for Hg dry deposition.
    As discussed in the Modeling TSD, the best current scientific 
understanding is that wet Hg deposition and dry Hg deposition are 
roughly equal in magnitude. In a recent peer-reviewed journal article, 
Miller et al. (2005)

[[Page 62205]]

discuss in detail the state-of-the-science regarding monitoring wet and 
dry deposition in North America. In general, areas with high 
precipitation amounts may have more wet Hg deposition and areas with 
low precipitation amounts may have more dry Hg deposition. The total 
national CMAQ Hg wet deposition is roughly equal in magnitude to the 
total national dry deposition (see Modeling TSD) while CMAQ predicts 
more dry deposition in dry areas of the country and more wet deposition 
in wet areas of the country, as empirical evidence would support. 
(Miller, et al., 2005).
    c. Changes in Deposition Predictions. Petitioners state that the 
model predictions of higher Hg deposition rates in a 2001 scenario in 
which Utility Unit emissions are zeroed-out, compared to a 2020 
scenario in which Utility Unit emissions are reduced but not zeroed-
out, reveal the inaccuracies of the model.
    The 2001 utility emissions zero-out scenario results in lower Hg 
deposition than the 2020 with CAIR scenario in the high utility-
attributable Hg emissions area of the Ohio River Valley and western 
Pennsylvania. The CMAQ model predicts lower utility Hg deposition for 
the 2001 utility Hg emissions zero-out scenario than for the 2020 with 
CAIR scenario in the areas of highest utility Hg emissions.
    There are a few scattered small areas of the country where the 2001 
Hg deposition with utility Hg emissions zeroed-out are higher than the 
2020 with CAIR Hg deposition. However, these are in areas where local 
non-utility sources of Hg emissions have decreased between 2001 and 
2020. In the 2020 with CAIR scenario, not only are utility Hg emissions 
reduced from the 2001 scenario, but local non-utility sources of Hg 
emissions are also reduced from the 2001 scenario (see table 2 of the 
Modeling TSD). Thus, the reason that the model predicts higher Hg 
deposition in some scattered areas for the 2001 utility zero-out 
scenario, compared to the 2020 with CAIR scenario, is due to decreased 
Hg emissions from non-utility Hg emissions sources in the 2020 with 
CAIR scenario.
    d. Grid Cell Size and Averaging Across Grid Cells in a Watershed. 
Petitioners assert that averaging deposition within the 36 kilometer 
(km) grid cell, and averaging deposition across all grid cells within a 
watershed, results in imprecise estimates of the effects of Hg 
emissions on fish tissue in waterbodies. As explained in the final 
Section 112(n) Revision Rule and section 2.1 of the ``Effectiveness 
TSD'' in support of the final Section 112(n) Revision Rule (Methodology 
Used to Generate Deposition, Fish Tissue Methylmercury Concentrations, 
and Exposure for Determining Effectiveness of Utility Emission 
Controls, OAR-2002-0056-6301, OAR-2002-0056-6190), we believe that 
averaging Hg deposition within a grid cell, and then across all grid 
cells that comprise a watershed, is a reasonably accurate methodology 
to indicate the impact of Hg deposition on fish tissue levels in 
waterbodies within a given watershed.
    Processes operating at the watershed (8-digit hydrologic unit code 
(HUC)) level likely influence MeHg concentrations in fish at any given 
location within the ecosystem. As water moves through the watershed, Hg 
that has been deposited from the atmosphere will also move through the 
HUC. Fish living in the aquatic ecosystem can move as well. Some 
species migrate, while others may travel significant distances in large 
lakes and through river and stream networks while other species remain 
within smaller geographic areas. Therefore, there is additional 
geographic uncertainty associated with where the fish are exposed to Hg 
deposition. Additionally, many fishers visit numerous waterbodies to 
fish. Averaging to a larger geographic unit (U.S. Geological Survey 
(USGS) 8-digit HUC) representative of an ecosystem unit (watershed) 
helps us to avoid modeling false precision between the exposure of fish 
and the source of the deposited Hg, and fishing activity.
    Given all of these factors, averaging enables us to produce an 
accurate regional or watershed level picture of deposition. Thus, 36 km 
resolution CMAQ output, which is generally somewhat smaller than the 8-
digit HUC resolution, is an appropriate geographic resolution from 
which to analyze air deposition of Hg to the ecosystem, and averaging 
deposition across grid cells within a given watershed enables a 
watershed-level characterization of Hg.
2. EPA's Method for Determining How Changes in Utility-Attributable Hg 
Deposition Would Result in Changes in Concentrations of MeHg in Fish 
Tissue.
    Petitioners claim that the 1,633 sample sites for fish tissue MeHg 
levels are too few to adequately represent the millions of lake acres 
and river miles in the U.S. They also argue that the samples do not 
adequately represent the places where people regularly fish, and in 
particular that the geographic scope of sample sites is too limited. 
Petitioners also contend that EPA's elimination of small-sized fish 
samples resulted in too few sites for Virginia, Pennsylvania, Ohio, and 
certain other States, even though most of the utility-attributable Hg 
deposition occurs in these States.
    We solicit comment on the sufficiency of the sample site data set 
for the analytic purposes described in the final Section 112(n) 
Revision Rule, in particular the specific issues raised by the 
petitioners. In addition, we solicit comment on the additional 
information that we have developed, described below, which is pertinent 
to the concerns expressed by the petitioners, as noted above.
    We have re-examined aspects of the sufficiency of the fish tissue 
data set related to fish tissue concentrations and believes that 
because it is not realistic to directly sample, on a yearly basis, over 
40 million lake acres and 3 million miles of river, the issue is 
whether the available samples comprise a representative sample of U.S. 
waterbodies. As part of this evaluation, EPA examined the geographic 
area that a single sample represents.
    We have examined the similarity of sample sites within a particular 
geographic area. We define similarity in terms of variance, which is 
the average squared deviation of all values from the mean. The values 
are the levels of MeHg in fish tissue at the sample sites. We determine 
variance on the basis of all the values within particular geographic 
units.
    Our exploratory studies have found that samples taken from within 
the same watershed are reasonably similar to each other. They are more 
similar to each other than samples taken within larger geographic areas 
like States or the entire nation. EPA has examined whether samples 
continued to be more alike at the smaller geographic unit of a county. 
The samples are not greatly more alike within counties than they are 
within watersheds (which can contain several counties). Variance among 
fish tissue concentrations from across the nation is 0.21 parts per 
million (ppm). Average variance within States is 0.07 ppm. Average 
variance within watersheds is 0.053 ppm, and average variance within 
counties is 0.050 ppm.
    The difference between a geographic unit of analysis on the county 
level, compared to a watershed level is, 0.003 ppm in variance. This 
represents less than a 1 percent decrease in variance within the sample 
data, an amount which is quite small. Note that in the Effectiveness 
TSD, the average concentration is 0.43 ppm.
    The relatively small amount of variance within a watershed of 0.053 
ppm, compared to the average concentration of 0.43 ppm, and the 
comparability of the intra-watershed

[[Page 62206]]

variance with intra-county variance, supports EPA's use of the 
available fish tissue samples to adequately represent MeHg levels over 
a watershed.
    Applying this assumption of representativeness means that the fish 
tissue sample data are representative of all the rivers and lakes found 
within the watersheds in which they were taken. The set of fish tissue 
concentration samples used for the Effectiveness TSD covers 
approximately 24.5 percent of all the HUCs which, in turn, contain 50 
percent of lakes and 25 percent of river miles in the U.S. While EPA 
does recognize that there are HUCs from which no fish tissue samples 
have been taken, our sample set provides an adequate regional, 
watershed-level characterization.
    The adequate portrayal or characterization of concentrations in 
areas that have not been sampled can lead to more uncertainty in the 
analyses. The unavailability of predictive models to accurately 
estimate values of Hg concentrations in fish where no samples have been 
taken makes it difficult to quantitatively assess how representative of 
unsampled geographic locations the existing sample data set is. Thus, 
to assess the coverage of the available data set of fish tissue 
samples, we can examine how similar the data set is to other data 
resources that provide complete national coverage, and are believed to 
be related to fish tissue concentrations. Total air mercury deposition 
is one such data set.
    It is not unreasonable to assume that the fish tissue samples would 
have similar statistical characteristics to Hg deposition 
concentrations. In other words, if total Hg concentrations are 
dependent upon total Hg deposition, we would expect the distributional 
properties in each data set to be similar. The degree of similarity 
between the distributional properties of the two data sets (deposition 
and fish tissue concentrations) can be somewhat assessed by a visual 
comparison of the patterns shown in figures 2.9 and 3.4 of the 
Effectiveness TSD.
    Figures 2.9 and 3.4 graphically depict the cumulative distributions 
for the two data sets--Hg deposition and fish tissue concentration. A 
visual comparison of these two distributions reveals similar 
distributional properties. Both data sets show that small numbers of 
observations (samples/HUCs) have low values, while the majority of the 
data are within a tightly defined middle range, with the highest 
concentrations deviating further from the rest of the data, but small 
in numbers compared with the overall data set.
    While examining these data sets in this manner does not 
conclusively or quantitatively prove that new fish tissue samples would 
never be outside the statistical range of the existing distributions 
(minimum and maximum value), it does suggest that if air deposition and 
fish tissue concentrations have similar distributions, the fish tissue 
sample data set is representative of the total population of U.S. fish. 
Thus, the sample of fish tissue concentrations available to EPA for the 
Effectiveness TSD in support of the final Section 112(n) Rule analyses 
is adequate to reasonably characterize the range of potential health 
risks.
    In response to petitioners' argument that there are not enough 
samples in the West, we note that in the Effectiveness TSD, which 
focuses on examining the role coal-fired power plants play in Hg 
deposition and fish tissue concentration, the lower density of samples 
in the West is of comparatively little concern because of the low 
utility-attributable Hg deposition there. Figure 2.2 of the 
Effectiveness TSD shows that in the West, Hg deposition from power 
plants is less than 1 microgram per square meter ([mu]g/m\2\), while in 
the East, it can account for average HUC levels as high as 20 [mu]g/
m\2\. Although these data do not mean that the West is not of any 
concern, they do show that utility-related impacts are significantly 
lower in the West than in the East, and, therefore, they do not form a 
significant portion of the foundation of EPA's decision.
3. EPA's Approach to Estimating Utility-Attributable Exposure
    Petitioners provide substantive comments on certain aspects of 
EPA's decision regarding exposure pathways and health risks associated 
with Hg exposure. We provide further information below on some of the 
points they raise, and we solicit comment on this information.
    a. Exposure Pathways. The petitioners assert that EPA, by limiting 
its focus to one fish consumption pathway of Hg exposure--freshwater 
fish caught by recreational and subsistence fishers--failed to 
adequately evaluate four other fish consumption pathways for human Hg 
exposure: (a) Marine (saltwater) fish, (b) commercial freshwater fish, 
(c) fish produced through aquaculture, and (d) estuarine fish. 
Furthermore, the petitioners charge that EPA failed to explain the 
rationale for assessing these pathways qualitatively.
    Petitioners are correct that considering the total concentrations 
of MeHg in fish tissue resulting from all sources of Hg emissions 
(including global sources), marine fish present the primary source of 
Hg exposure to most persons living within the U.S. However, as 
explained in the final Section 112(n) Revision Rule, EPA has 
interpreted CAA section 112(n)(1)(A) as calling for an analysis of the 
hazards to public health reasonably anticipated to occur as the result 
of emissions by Utility Units. Thus, as explained in the final Section 
112(n) Revision Rule, the proper inquiry for purposes of CAA section 
112(n)(1)(A) is to examine the concentrations of MeHg in fish tissue 
that result from U.S. coal-fired power plant Hg emissions. As discussed 
in the final Section 112(n) Revision Rule, emissions of Hg from U.S. 
coal-fired power plants most significantly impact concentrations of 
MeHg in freshwater fish; thus, it was appropriate for EPA to focus on 
this pathway in the CAA section 112 rulemaking. Nonetheless, we 
recognize that other exposure pathways may still contribute to the 
total exposure from U.S. coal-fired power plant Hg emissions, and, 
thus, we explore them more fully below and in the ``Reconsideration 
TSD'' in support of the final Section 112(n) Revision Rule (Technical 
Support Document: Revision of December 2000 Regulatory Finding on the 
Emissions of Hazardous Air Pollutants From Electric Utility Steam 
Generating Units and the Removal of Coal- and Oil-Fired Electric 
Utility Steam Generating Units from the Section 112(c) List: 
Reconsideration). EPA solicits comment on all of these issues, 
comments, and analyses.
    Marine Fish Pathway. The petitioners argue that because utility-
attributable Hg deposits in areas where marine fishing occurs, human 
health impacts attributable to power plant Hg emissions should be 
reasonably anticipated, noting that a number of commercially important 
marine fish have relatively high Hg concentrations.
    In the Effectiveness TSD, EPA did acknowledge that marine systems 
could be affected by U.S. power plant Hg emissions, but concluded that 
based on the available science marine species do not appear to be 
significantly affected by Hg emissions from U.S. power plants. The 
actual quantification of this impact was not conducted because of the 
scientific uncertainty in modeling marine systems. (See Reconsideration 
TSD, section 2.) For today's action, EPA conducted an analysis using 
upper-bound assumptions, including the assumption of a proportional 
relationship between decreases in utility-attributable Hg deposition 
and decreases in MeHg fish tissue concentration. (See Reconsideration

[[Page 62207]]

TSD, section 3.) The conclusion of this analysis reinforces our 
conclusion to focus our previous quantitative analysis on self-caught 
freshwater fish, not marine fish. This conclusion is based on the small 
contribution of the U.S. power plant Hg emissions to open ocean 
environments. High-end consumers eating over 200 grams per day of a 
cross-section of marine fish would have an Index of Daily Intake (IDI) 
value of about 0.05.\4\ (See Reconsideration TSD, table 3.2.) Even if 
this high-end consumer exclusively ate marine fish with one of the 
highest utility-attributable MeHg concentration levels, the consumer 
would have an IDI value below one. (See Reconsideration TSD, table 
3.3.) Given that the IDI values for the marine fish pathway are 
significantly less than one for moderate consumption rates and less 
than one even for the extreme combination of high consumption rate of 
marine fish with high MeHg levels, EPA maintains that marine fish are a 
pathway of small concern when evaluating the health impact of Hg 
emissions from U.S. power plants.
---------------------------------------------------------------------------

    \4\ As described in the final Section 112(n) Revision Rule, the 
IDI is an index of exposure to Hg due solely to power plants. An IDI 
of 1 or greater indicates that an individual exposure to Hg from 
power plants is equal to or exceeds the EPA reference dose (RfD) for 
Hg due solely to utility-attributable Hg exposure. (See 70 FR 
16021.)
---------------------------------------------------------------------------

    Aquaculture Fish Exposure Pathway. The petitioners assert that our 
qualitative treatment of utility-attributable Hg exposure due to U.S. 
aquaculture fish was not adequate. EPA acknowledged in the 
Effectiveness TSD that we lacked ``sufficient information to 
characterize the impact of utility emissions on aquaculture'' due to 
the unique nature of the aquaculture pathway and gaps in the available 
data. By this statement, we meant that we were not able to provide a 
quantitative estimate then. Nor can we do so now. As explained in 
section 5 of the Reconsideration TSD, the concentration of MeHg in 
aquaculture fish is dependent on the MeHg content of the fish products 
fed to aquaculture fish. Thus, it is the location and type of the fish 
caught to make fish feed, as opposed to the location of aquaculture 
farms, that is relevant to assessing the utility-attributable 
concentration of MeHg in aquaculture fish. Furthermore, many of the 
commonly consumed aquaculture fish species (e.g., catfish) tend to have 
lower concentrations of MeHg than many of the commonly consumed marine 
fish, and the total amount of aquaculture fish consumed in the U.S. is 
substantially less than the total amount of marine fish consumed in the 
U.S.
    Having already concluded that an upper-bound estimate of utility-
attributable Hg exposure due to marine fish is small and that the 
utility-attributable Hg exposure due to aquaculture is smaller than for 
marine fish, we reasonably conclude that the utility-attributable Hg 
exposure due to aquaculture fish is minimal.
    Estuarine Fish Exposure. EPA believes that the state of the science 
currently does not support a national-scale quantitative analysis for 
this component of the exposure pathway. The studies cited as examples 
by the petitioners assumed a proportional relationship between declines 
in Hg deposition and declines in MeHg concentrations in estuarine fish. 
However, while such an assumption is supported for freshwater systems, 
it has not been endorsed by EPA or the scientific community as an 
appropriate method for characterizing the effects of Hg emissions 
reductions on MeHg estuarine fish concentrations. (See section 4.1 the 
Reconsideration TSD.)
    EPA finds that the available data indicate that the utility-
attributable exposure to Hg from estuarine fish and shellfish will 
likely be small relative to that from self-caught freshwater fish.
    We estimate that the total exposure from the entire global Hg pool 
(i.e., all Hg sources, including, but, not limited to power plants,) 
associated with consumption of estuarine and near-coastal fish is 
roughly one third of the exposure from all marine species. This 
fraction includes near-coastal fish caught on the Pacific Coast and 
other areas not significantly affected by U.S. power plants. This 
estimate of total Hg exposure from estuarine species is thought to be 
an upper bound because it is based on total Hg concentrations in 
shellfish rather than MeHg concentrations, the Hg species that is 
toxicologically most significant. (See section 4 of the Reconsideration 
TSD.)
    Of the Hg exposure associated with the consumption of estuarine and 
near-coastal fish, we estimate that the utility-attributable fraction 
is small. As described in section 4 of the Reconsideration TSD, utility 
deposition after CAIR, and even more so after CAMR, is small in the 
coastal areas, especially taking into account estuarine and near-
coastal fisheries on the West Coast. Finally, populated coastal regions 
like the Chesapeake Bay and Baltimore Harbor (Mason and Lawrence, 1999) 
will receive significant land-based (e.g., point source discharges) Hg 
inputs from wastewater effluents, municipal waste discharges, and 
historical Hg contamination that is slowly leaching from the watershed.
    Although we are not able to provide a national-scale quantitative 
estimate of the utility-attributable Hg exposure from the consumption 
of estuarine and near-coastal species of fish and shellfish, for all of 
these reasons we conclude that this exposure pathway is small relative 
to the self-caught freshwater pathway.
    Commercial Freshwater Fish Exposure Pathway. The petitioners raised 
concerns over the contribution of commercial freshwater fish to human 
Hg exposures. Specifically, the petitioners are concerned that the 
annual Great Lakes commercial freshwater fish harvest is 17 million 
pounds and EPA's air deposition modeling shows that relatively higher 
levels of utility-attributable Hg deposition, after CAIR and CAMR, 
occurs in the Great Lakes region.
    Freshwater commercial fish are not a significant exposure pathway 
because a total consumption of 17 million pounds/year (lb/yr) is small 
when compared to recreational freshwater fish consumption of 377 
million lb/yr (see section 6, Reconsideration TSD), or 22 times the 
Great Lakes' commercial haul.\5\ Further, even though utility-
attributable Hg deposition is comparatively higher around the Great 
Lakes and the regional watershed surrounding the Great Lakes as defined 
by the USGS, in comparison with the rest of the U.S., it is still only 
a small percentage of Hg deposition from all sources. Within small HUC 
cataloging units, the average percent of total Hg deposition that is 
attributable to power plants in these areas is approximately 14 percent 
in 2001. By 2020 after CAIR, this will decrease to approximately 8 
percent. After CAMR, utility-attributable deposition decreases further 
to approximately 7.5 percent. Thus, following the assumptions in MMaps, 
approximately 10 percent of the Hg in the fish found in this area is 
attributable to power plants.
---------------------------------------------------------------------------

    \5\ The Great Lakes commercial haul is 0.2 percent of the total 
commercial haul. The marine haul represents the most significant 
fraction of the total haul and is discussed elsewhere. (See 
Reconsideration TSD, section 6.)
---------------------------------------------------------------------------

    As described above, the commercial freshwater harvest is small 
compared to recreational freshwater consumption. Additionally, only a 
portion of the commercial freshwater harvesting area is affected by 
comparatively higher concentrations of utility-attributable Hg 
deposition in [mu]g/m2 (Lakes Michigan, Erie, and Huron), 
and the Great Lakes utility-attributable Hg deposition is not 
disproportionately higher than the immediately surroundings areas for

[[Page 62208]]

recreational freshwater harvest. All of these factors lead us to 
believe that the commercial freshwater fish exposure pathway is still 
expected to be small relative to the national recreational freshwater 
exposure pathway.
    Although we are not able to provide a national-scale quantitative 
estimate of the utility-attributable Hg exposure from the consumption 
of commercial freshwater species of fish, for all of the reasons 
discussed above, we conclude that exposure from this pathway is small.
    b. Joint Consumption. In order to examine utility-attributable Hg 
exposure from total fish consumption quantitatively, it would be 
necessary to have information on the distribution of consumption of 
each type of fish--recreational freshwater, commercial freshwater, 
recreational saltwater, etc--as well as utility-attributable MeHg 
concentrations (either sufficiently accurate or upper-bound) for each 
type of fish. If we were able to identify the consumption of each type 
of fish as well as utility-attributable MeHg concentrations for each 
type of fish, then the IDI values from each type of fish could be 
calculated and added together to arrive at a total IDI value. Currently 
no such data exists. While we are not able to develop a quantitative 
estimate, for the reasons described above and in the Reconsideration 
TSD, EPA maintains that self-caught freshwater fish consumption 
represents the most significant exposure pathway for the populations 
with the highest utility-attributable exposure.
    At any given total fish consumption rate noted in our analyses, 
introducing aquaculture, marine, or estuarine fish into the diet of a 
self-caught freshwater fish consumer necessarily implies reducing 
consumption of self-caught freshwater fish (e.g., in order to maintain 
the same total fish consumption rate). As discussed in previous 
sections, because power plants contribute more Hg to freshwater fish 
species than to any other fish species, such substitution implies a 
lower IDI than is associated with consumption of self-caught freshwater 
fish alone, supporting the assertion that self-caught freshwater fish 
consumption represents the pr