69864 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

1 69 FR 4652, January 30, 2004.

2 69 FR 12398, March 16, 2004.

SUMMARY: In this action, EPA is 

proposing to approve a revision to the 

Oregon State Implementation Plan and 

repeal rules which are no longer 

required by the Clean Air Act. The 

revision consists of the repeal of 

Oregon’s control technology guidelines 

for perchloroethylene (perc) dry 

cleaning systems. Perc is a solvent 

commonly used in dry cleaning, 

maskant operations, and degreasing 

operations. In 1996, EPA excluded perc 

from the Federal definition of volatile 

organic compounds for the purpose of 

preparing state implementation plans to 

attain the national ambient air quality 

standards for ozone under title I of the 

Clean Air Act. Emissions from perc dry 

cleaners continue to be regulated as 

hazardous air pollutants under the 

National Emissions Standards for 

Hazardous Air Pollutants.

DATES: Comments must be received on 

or before January 3, 2005.

ADDRESSES: Submit your comments, 

identified by Docket ID No. R10–OAR–

2004–OR–0001, by one of the following 

methods: 

• Federal eRulemaking Portal: http://

www.regulations.gov. Follow the on-line 

instructions for submitting comments. 

• Agency Web site: http://

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. 

• Mail: Colleen Huck, Office of Air, 

Waste and Toxics, AWT–107, EPA, 

Region 10, 1200 Sixth Ave., Seattle, 

Washington 98101. 

• Hand Delivery: Colleen Huck, 

Office of Air, Waste and Toxics, AWT–

107, 9th Floor, EPA, Region 10, 1200 

Sixth Ave., Seattle, Washington 98101. 

Such deliveries are only accepted 

during normal hours of operation, and 

special arrangements should be made 

for deliveries of boxed information. 

Please see the direct final rule which 

is located in the Rules section of this 

Federal Register for detailed 

instructions on how to submit 

comments.

FOR FURTHER INFORMATION CONTACT:

Colleen Huck at telephone number: 

(206) 553–1770, e-mail address: 

Huck.Colleen@epa.gov; or Donna 

Deneen at telephone number: (206) 553–

6706, e-mail address: 

Deneen.Donna@epa.gov, fax number: 

(206) 553–0110, or the above EPA, 

Region 10 address.

SUPPLEMENTARY INFORMATION: For 

further information, please see the 

direct final action, of the same title, 

which is located in the Rules and 

Regulations section of this Federal 

Register. EPA is approving the State’s 

SIP revision as a direct final rule 

without prior proposal because EPA 

views this as a noncontroversial SIP 

revision and anticipates no adverse 

comments. A detailed rationale for the 

approval is set forth in the preamble to 

the direct final rule. If EPA receives no 

adverse comments, EPA will not take 

further action on this proposed rule. 

If EPA receives adverse comments, 

EPA will withdraw the direct final rule 

and it will not take effect. EPA will 

address all public comments in a 

subsequent final rule based on this 

proposed rule. EPA will not institute a 

second comment period on this action. 

Any parties interested in commenting 

on this action should do so at this time. 

Please note that if we receive adverse 

comment on an amendment, paragraph, 

or section of this rule and if that 

provision may be severed from the 

remainder of the rule, EPA may adopt 

as final those provisions of the rule that 

are not the subject of an adverse 

comment.

Dated: October 29, 2004. 

Richard Albright, 

Acting Regional Administrator, Region 10.

[FR Doc. 04–26475 Filed 11–30–04; 8:45 am] 

BILLING CODE 6560–50–P

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 60 and 63 

[OAR–2002–0056; FRL–7844–8] 

RIN 2060–AJ65 

Proposed National Emission 

Standards for Hazardous Air 

Pollutants; and, in the Alternative, 

Proposed Standards of Performance 

for New and Existing Stationary 

Sources, Electric Utility Steam 

Generating Units: Notice of Data 

Availability

AGENCY: Environmental Protection 

Agency (EPA).

ACTION: Notice of data availability 

(NODA). 

SUMMARY: EPA issued a proposed Clean 

Air Mercury Rule (CAMR) under the 

Clean Air Act (CAA) concerning coaland oil-fired electric utility steam 

generating units (power plants) on 

January 30, 2004,1 and a supplemental 

proposal on March 16, 2004.2 The 

proposed CAMR represents the firstever Federal action to regulate mercury 

(Hg) from this source category. The 

proposed rule presents two primary 

alternative approaches to regulating Hg 

and nickel (Ni) from power plants. EPA 

received numerous comments on its 

proposed regulatory approaches, 

including comments on the modeling 

results EPA obtained using the 

Integrated Planning Model (IPM), which 

is a model that predicts how the power 

sector will respond to a particular 

regulatory approach, and comments 

addressing the speciation of Hg. EPA is 

currently evaluating those comments to 

determine how the new data and 

information received in the comments, 

as described below, may affect the 

benefit-cost analysis and regulatory 

options under consideration. Although 

we recognize that the public has access 

to the comments in the rulemaking 

docket, we are issuing the NODA, in 

part, because the Agency received over 

680,000 public comments, including 

almost 5,000 unique comments, and the 

comments present new data and 

information that are relevant to the two 

primary regulatory approaches 

addressed in the proposed CAMR.

We are also issuing the NODA to seek 

input on our benefits methodology, 

which has been preliminarily revised 

since the CAMR was proposed. An 

analysis of benefits and costs is 

consistent with principles of good 

government and the provisions of 

Executive Order (EO) 12866. Based on 

comments received on the proposal and 

in furtherance of our obligations under 

EO 12866, we have preliminarily 

revised our approach to analyzing the 

benefits of reducing Hg emissions from 

power plants, and we are seeking 

comment on that revised approach, 

which is described in Section III below. 

Some of the commenters suggested 

approaches that differ from EPA’s 

proposed revised benefits methodology. 

We identify those comments in Section 

III, as well as other comments that we 

received that provide analyses relevant 

to our refined benefits methodology.

DATES: Comments on the NODA must be 

received on or before January 3, 2005.

ADDRESSES: Comments on the NODA 

should be submitted to Docket ID No. 

OAR–2002–0056. Comments may be 

submitted by one of the following 

methods: 

• Federal eRulemaking Portal: http://

www.regulations.gov. Follow the on-line 

instructions for submitting comments. 

• Agency Web site: http://

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.

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69865

• Mail: Air Docket, Clean Air 

Mercury Rule, Environmental Protection 

Agency, Mail Code: 6102T, 1200 

Pennsylvania Avenue, NW., 

Washington, DC 20460. Please include a 

total of two copies. 

• Hand Delivery: EPA Docket Center, 

1301 Constitution Avenue, NW., Room 

B108, 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 on 

the NODA to Docket ID No. OAR–2002–

0056. The EPA’s policy is that all 

comments received will be included in 

the public docket(s) without change and 

may be made available online at http:/

/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 websites 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 email 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. 

Docket: All documents in the docket 

are listed in the EDOCKET index at 

http://www.epa.gov/edocket. 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 EPA Docket Center, EPA 

West, 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 Docket 

is (202) 566–1742.

FOR FURTHER INFORMATION CONTACT:

William Maxwell, U.S. EPA, Office of 

Air Quality Planning and Standards, 

Emission Standards Division, 

Combustion Group (C439–01), Research 

Triangle Park, North Carolina 27711, 

telephone number (919) 541–5430, email at maxwell.bill@epa.gov.

SUPPLEMENTARY INFORMATION: 

Outline: The information presented in 

this NODA is organized as follows:

I. Additional Information on Submitting 

Comments 

A. How can I help EPA ensure that my 

comments are reviewed quickly? 

B. What should I consider as I prepare my 

comments for EPA? 

1. Submitting CBI 

2. Tips for Preparing Your Comments 

II. Electric Utility Sector Modeling and Hg 

Speciation 

A. What is the relevant background? 

B. What are the specific issues relevant to 

electric utility sector modeling? 

1. Overview 

2. What is IPM? 

3. What specific comments did EPA 

receive on its IPM modeling in response 

to the January 2004 proposal and the 

March 2004 supplemental proposal? 

4. What are the areas of ongoing EPA 

research? 

C. Issues of Hg Speciation 

1. Overview 

2. What specific comments on Hg 

speciation did EPA receive in response 

to the January 2004 proposal and the 

March 2004 supplemental proposal? 

3. What are the areas of ongoing EPA 

research? 

III. EPA’s Proposed Revised Benefits 

Assessment 

A. What is the relevant background? 

B. How is EPA estimating reductions in Hg 

exposure associated with the CAMR? 

C. Step 1 of EPA’s Proposed Revised 

Benefits Methodology: Analyzing Hg 

Emissions from Other Sources 

1. Overview 

2. What specific comments did EPA 

receive on Hg emissions from other 

sources in response to the January 2004 

proposal and the March 2004 

supplemental proposal? 

D. Step 2 of EPA’s Proposed Revised 

Benefits Methodology: Analyzing Air 

Dispersion Modeling Capabilities 

1. Overview 

2. What specific comments did EPA 

receive on air dispersion modeling 

capabilities in response to the January 

2004 proposal and the March 2004 

supplemental proposal? 

E. Step 3 of EPA’s Proposed Revised 

Benefits Methodology: Modeling 

Ecosystem Dynamics 

1. Overview 

2. What specific comments did EPA 

receive on modeling ecosystem 

dynamics in response to the January 

2004 proposal and the March 2004 

supplemental proposal? 

F. Step 4 of EPA’s Proposed Revised 

Benefits Methodology: Fish 

Consumption and Human Exposure 

1. Overview 

2. What specific comments did EPA 

receive on fish consumption patterns in 

response to the January 2004 proposal 

and the March 2004 supplemental 

proposal? 

G. Step 5 of EPA’s Proposed Revised 

Benefits Methodology: How Will 

Reductions in Population-level Exposure 

Improve Public Health?

I. Additional Information on 

Submitting Comments 

A. How Can I Help EPA Ensure That My 

Comments Are Reviewed Quickly? 

To expedite review of your comments 

by Agency staff, you are encouraged to 

send a separate copy of your comments, 

in addition to the copy you submit to 

the official docket, to William Maxwell, 

U.S. EPA, Office of Air Quality Planning 

and Standards, Emission Standards 

Division, Mail Code C439–01, Research 

Triangle Park, North Carolina 27711, 

telephone (919) 541–5430, e-mail 

maxwell.bill@epa.gov.

B. What Should I Consider as I Prepare 

My Comments for EPA? 

1. Submitting 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 

information 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. 

2. Tips for Preparing Your Comments.

When submitting comments, remember 

to: 

a. Identify the rulemaking by docket 

number and other identifying 

information (subject heading, Federal 

Register date and page number). 

b. Follow directions—The Agency 

may ask you to respond to specific 

questions or organize comments by 

69866 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

3 69 FR 4652, January 30, 2004.

4The Agency also proposed standards of 

performance for oil-fired power plants that emit Ni. 

Although the Agency received several comments 

concerning its alternative proposals to regulate Ni 

from oil-fired power plants under CAA section 111 

and CAA section 112, those comments are not the 

subject of this NODA. This NODA instead focuses 

only on issues related to Hg.

5 69 FR 4652, January 30, 2004.

6 42 U.S.C. 7412(d). 7 69 FR 4706, January 30, 2004.

referencing a Code of Federal 

Regulations (CFR) part or section 

number. 

c. Explain why you agree or disagree; 

suggest alternatives and substitute 

language for your requested changes. 

d. Describe any assumptions and 

provide any technical information and/

or data that you used. 

e. If you estimate potential costs or 

burdens, explain how you arrived at 

your estimate in sufficient detail to 

allow for it to be reproduced. 

f. Provide specific examples to 

illustrate your concerns, and suggest 

alternatives. 

g. Explain your views as clearly as 

possible, avoiding the use of profanity 

or personal threats. 

h. Make sure to submit your 

comments by the comment period 

deadline identified.

II. Electric Utility Sector Modeling and 

Hg Speciation 

A. What Is the Relevant Background? 

On January 30, 2004, EPA issued a 

proposed CAMR under the CAA 

concerning power plants.3 That 

proposed rule presents two primary 

approaches to regulating Hg and Ni from 

power plants. Those approaches are (1) 

retaining the Agency’s December 20, 

2000, determination that regulating 

power plants under CAA section 112 is 

‘‘appropriate and necessary’’ and 

issuing final emission standards under 

CAA section 112(d); and (2) revising our 

December 2000 ‘‘appropriate and 

necessary’’ determination, removing 

power plants from the CAA section 

112(c) list, and issuing final standards of 

performance for coal-fired power plants 

using a ‘‘cap-and-trade’’ methodology.4

In response to the January 2004 

proposal and the March 2004 

supplemental proposal, we received 

over 680,000 public comments, 

including almost 5,000 unique 

comments. Among other things, the 

comments addressed how the power 

sector could respond to different levels 

of control on Hg emissions. In 

particular, we received comments on 

EPA’s IPM modeling results, including 

our modeling assumptions. We also 

received modeling analyses conducted 

by different commenters, some of which 

used models and/or assumptions 

different from EPA’s. Based on the 

importance of, and the level of interest 

in, these modeling analyses, this NODA 

summarizes the modeling analyses 

performed by commenters and solicits 

comment on the inputs and 

assumptions underlying those analyses 

and other issues related to benefit-cost 

analysis. 

We also received comments 

concerning the speciation of Hg. As we 

explained in the proposed rule, the 

degree to which emissions control 

devices can remove Hg depends, in 

large part, on the amount of each form 

(or species) of Hg present in the flue gas. 

The three relevant species of Hg are 

elemental Hg (Hg0), ionic or oxidized Hg 

(Hg∂2), and particulate Hg (Hgp).5 The 

Hg in the flue gas from a coal-fired 

utility unit consists of these three forms 

of Hg. Because of the importance of the 

relationship between Hg speciation and 

the level of Hg reduction achievable, we 

are seeking additional information on 

Hg speciation from coal-fired power 

plants to further inform our regulatory 

decision.

The comments concerning the impact 

of different levels of emissions control 

on the power sector and the speciation 

of Hg relate to both of the two proposed 

regulatory approaches described above. 

With respect to the CAA section 112(d) 

regulatory approach, the comments are 

relevant to whether EPA should adopt a 

CAA section 112(d) standard that is 

more stringent than the floor (i.e., a 

beyond-the-floor standard) and at what 

level such a standard should be set. In 

evaluating a beyond-the-floor standard 

under CAA section 112(d), EPA must 

consider cost, nonair quality health and 

environmental impacts, and energy 

impacts.6 With respect to the CAA 

section 111 regulatory approach, the 

comments are relevant to the level at 

which standards of performance should 

be set. Similar to the beyond-the-floor 

analysis under CAA section 112(d), EPA 

must consider cost, nonair quality 

health and environmental impacts, and 

energy requirements in defining the best 

system of emission reduction under 

CAA section 111.

We recognize that the public already 

has access to the comments submitted 

on the January 2004 proposed rule and 

the March 2004 supplemental proposal. 

However, because of the large volume of 

comments received on those proposals, 

we issue the NODA today to summarize 

and solicit comment on the new data 

and information presented in the 

comments that are relevant to benefitcost analysis and to the regulatory 

approaches under consideration. 

The Agency intends to make a final 

decision on its pending utility proposal 

by March 15, 2005. EPA is still 

considering the comments submitted on 

the proposal and supplemental proposal 

and evaluating which regulatory 

approach to pursue. 

B. What Are the Specific Issues Relevant 

to Electric Utility Sector Modeling? 

1. Overview. This section of the 

NODA addresses how the power sector 

is predicted to respond to different 

levels of emissions control. As we 

explained in the proposed CAMR, in 

designing regulatory programs for the 

electric power sector, it is important to 

consider (forecast) ways the power 

sector could respond to such programs. 

In the proposed CAMR, EPA provided 

a forecast of how the power generation 

mix in the United States (U.S.) would 

respond to a particular regulatory 

approach.7 In response to the proposed 

rule, several commenters provided their 

own forecasts of power sector response. 

In some cases, the regulatory scenarios 

modeled by commenters were the same 

or similar to those modeled by EPA. In 

these cases, we can better understand 

the importance of different input 

assumptions by comparing and 

contrasting the modeling performed. In 

other cases, the commenters modeled 

alternative approaches and provided 

information about the tradeoffs in 

regulatory design. The submitted 

modeling addresses regulatory 

alternatives that are both more and less 

stringent than our proposal. In all cases, 

the models are designed to predict a 

least-cost solution to meeting electricity 

demand, subject to the model input 

assumptions and constraints imposed. 

These constraints can include 

restrictions on the availability of 

specific control technologies. EPA is 

currently performing an evaluation of 

the modeling analyses submitted by 

commenters.

To aid in our decision-making 

process, we are seeking comment on the 

different input assumptions and 

constraints and the different modeled 

regulatory approaches as presented in 

the commenter’s modeling analyses 

described below. We also identify below 

our questions of particular interest 

concerning the new data and 

information presented in the comments.

2. What is IPM? EPA uses IPM, 

developed by ICF Consulting (ICF), to 

assess how the electric power industry 

will respond to various environmental 

policies affecting that industry. IPM is a 

dynamic linear programming model that 

can be used to examine air pollution 

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69867

8 69 FR 4652, January 30, 2004.

9 69 FR 12401, March 16, 2004.

control policies for Hg and other 

pollutants throughout the contiguous 

U.S. for the entire power system. IPM 

finds the least-cost solution to meeting 

electricity demand subject to 

environmental, transmission, reserve 

margin, and other system operating 

constraints for any specified region and 

time period. For a given control policy, 

IPM provides an electricity generator 

with various compliance options, 

including adding pollution controls, 

changing fuel type, and changing 

dispatch considerations. In addition, 

IPM provides information on fuel 

market interactions and impacts on the 

cost of electricity. 

Through licensing agreements with 

ICF, IPM is used by both public and 

private sector clients. EPA contracted 

with ICF to develop a version of IPM 

that EPA uses for its own power sector 

modeling. EPA has used IPM to model 

the nitrogen oxides (NOX) State 

implementation plan (SIP) call, the 

Clear Skies legislative proposal, the 

proposed Clean Air Interstate Rule 

(CAIR), and the proposed CAMR.8

Documentation for how EPA has 

configured IPM for pollution control 

analysis can be found at http://

www.epa.gov/airmarkets/epa-ipm.

Since it began using IPM as a power 

sector modeling tool, EPA has 

periodically reviewed and updated the 

assumptions and modeling capability of 

IPM. These updates have included the 

addition to IPM of the capability to 

model Hg emissions and Hg control 

costs. However, EPA recognizes that its 

Hg-related assumptions are more 

uncertain than sulfur dioxide (SO2)- and 

NOX-related assumptions due to limited 

information on controlling Hg from the 

power sector. This is because, although 

we have recent data on Hg emissions 

from the power sector, and some data on 

how the Hg speciation profile influences 

the ability to control Hg emissions, the 

electric power industry has much less 

experience implementing Hg controls 

than it does SO2 and NOX controls. 

Further, as described later in this 

NODA, the full impact of the mix of the 

various Hg species found in the flue gas 

on the level of control achievable 

continues to be investigated.9

As discussed further below, some of 

the commenters submitted analyses 

using IPM. EPA’s power sector 

modeling of the proposed CAMR CAA 

section 112(d) maximum achievable 

control technology (MACT) alternative 

using IPM 2003 is available in the 

docket in a memorandum titled 

‘‘Economic and Energy Impact Analysis 

for the Proposed Utility MACT 

Rulemaking’’ (OAR–2002–0056–0048). 

EPA’s power sector modeling of the 

proposed CAMR CAA section 111 

trading rule can also be found in the 

docket at OAR–2002–0056–0338 to 

–0344. 

3. What specific comments did EPA 

receive on its IPM modeling in response 

to the January 2004 proposal and the 

March 2004 supplemental proposal?

During the comment period, EPA 

received numerous comments related to 

the regulatory approaches outlined in 

the January 2004 proposal and the 

March 2004 supplemental proposal. 

EPA received specific comments on the 

power sector modeling results from the 

following commenters: Center for Clean 

Air Policy (CCAP) (OAR–2002–0056–

3447); Cinergy (OAR–2002–0056–4317 

and –4318); Clean Air Task Force 

(CATF), Natural Resources Defense 

Council (NRDC), et al. (OAR–2002–

0056–3459 and –3460); Edison Electric 

Institute (EEI) (OAR–2002–0056–2929, 

–4894, –4895, and –4896); and Electric 

Power Research Institute (EPRI) (OAR–

2002–0056–2578). 

Two of these commenters submitted 

the results of power sector modeling 

using a version of IPM and two 

commenters submitted analyses using a 

similar linear programming model. The 

CCAP submitted analyses of multipollutant control options for the power 

sector using a version similar to IPM 

2003 employing different assumptions 

about electricity demand growth and 

natural gas prices. Cinergy submitted 

analyses performed using a version of 

IPM operated by ICF that included 

Cinergy’s own unique modeling 

assumptions. The CATF submitted 

analyses on behalf of several 

environmental groups using EPA’s IPM 

2003. EEI submitted an analysis 

performed by Charles River Associates 

(CRA) using the Electric Power Market 

Model (EPMM; a linear programing 

model similar to IPM). The EPRI 

comments included the same EPMM 

analysis. The salient details of the 

individual analyses are described 

below. 

a. What were the results of CCAP’s 

power sector modeling? CCAP 

established a stakeholder policy 

dialogue on alternative designs of multipollutant legislative programs designed 

to control emissions from the power 

sector. Their analysis was performed 

using a version of IPM similar to EPA’s 

IPM 2003 with different assumptions 

about electricity demand growth and 

natural gas prices. Some modeling was 

conducted using EPA’s IPM 2002 

assumptions about demand growth and 

natural gas prices, and some modeling 

analysis was conducted using the 

Energy Information Administration 

(EIA) assumptions about demand 

growth and natural gas prices. 

CCAP sponsored a series of modeling 

runs to look at the costs and benefits of 

incremental changes in Hg cap levels 

and timing. The analysis was based on 

policy options similar to the Clear Skies 

proposal, using the same SO2 and NOX

caps and first phase Hg cap of 26 tons. 

Among the options analyzed, CCAP 

examined three scenarios that 

implemented incrementally more 

stringent Hg requirements in Phase 2: 

15-ton cap in 2018 (Clear Skies), 10-ton 

cap in 2015, and 7.5-ton cap in 2015. 

Although their comments included 

several other modeling runs, for 

comparison purposes EPA has 

summarized in Table 1 below CCAP’s 

model runs assuming EIA AEO2003 gas 

and growth assumptions. EPA notes that 

the term ‘‘total installed capacity’’ used 

in Table 1 includes all currently 

installed controls and control retrofits 

needed to meet the modeled policy. 

EPA also notes that CCAP’s results for 

the Phase 2 cap of 15 tons are taken 

from EPA’s analyses of the Clear Skies 

Act. CCAP recommended that EPA 

adopt a tighter Phase 2 cap for the 

proposed Hg trading rule, concluding 

that incremental changes in the timing 

and stringency of a Hg cap have, in 

CCAP’s opinion, relatively modest cost 

implications.

69868 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

TABLE 1.—SUMMARY OF CCAP POWER SECTOR MODELING

Hg phase 2 cap of 15 tons Hg phase 2 cap of 10 tons Hg phase 2 cap of 7.5 tons 

2010 2020 2010 2020 2010 2020 

Hg emissions ............ 25 tons ................ 18 tons ................ 21 tons ................ 13 tons ................ 19 tons ................ 11 tons. 

Annual costs ($1999) $3.3 billion .......... $6.7 billion .......... $4.3 billion .......... $6.8 billion .......... $4.6 billion .......... $7.1 billion. 

Present value (2005–

2025).

$64.5 billion $71.3 billion $75.0 billion 

Hg Marginal costs in 

2020.

$62,190/lb $75,190/lb $88,060/lb 

Total installed capacity: 

FGD ................... 179 GW .............. 228 GW .............. 171 GW .............. 223 GW .............. 174 GW .............. 220 GW. 

SCR ................... 173 GW .............. 229 GW .............. 173 GW .............. 214 GW .............. 173 GW .............. 213 GW. 

ACI ..................... 13 GW ................ 40 GW ................ 34 GW ................ 70 GW ................ 46 GW ................ 84 GW. 

b. What were the results of Cinergy’s 

power sector modeling? Cinergy used 

IPM to analyze the economic and 

environmental impact of potential CAIR 

and Hg policies. Cinergy used a version 

of IPM offered by ICF to its private 

sector clients. In addition, Cinergy 

provided their own modeling 

assumptions that differ from those used 

by EPA, including higher electricity 

demand growth, higher natural gas 

prices, different costs for subbituminous 

coal switching, higher costs for 

pollution control retrofits, and a higher 

discount rate. 

The scenarios modeled by Cinergy 

included a CAIR only scenario, ‘‘CAIR 

plus Hg trading’’ scenario, ‘‘CAIR plus 

EPA MACT’’ scenario, and ‘‘CAIR plus 

stringent MACT’’ scenario. The ‘‘CAIR 

plus stringent MACT’’ scenario has no 

subcategorization and a 0.88 pounds per 

trillion British thermal units (lb/TBtu) 

rate for all affected units, starts in 2008, 

and assumes that ACI is not 

commercially available until 2010. 

Results of the Cinergy analysis of Hg 

reduction scenarios are summarized in 

Table 2 below. Present value costs are 

for a 20-year period and assume a 7 

percent discount rate. Although 

Cinergy’s modeling assumed the 

availability of ACI, Cinergy raised 

concerns about the availability and 

performance of ACI in the 2008 to 2010 

timeframe. 

For the CAIR only scenario, Cinergy’s 

analysis projects a Hg co-benefit level in 

2010 of 38 tons. For the ‘‘CAIR plus Hg 

trading’’ scenario, the Cinergy analysis 

projected Hg marginal costs from 2010 

to 2020 to reach the safety valve price 

of $35,000/lb. Cinergy’s model also 

projected lower bituminous coal 

consumption, 25 percent higher 

subbituminous coal consumption, and 

10 percent higher lignite coal 

consumption when compared to EPA’s 

Hg trading results. For the ‘‘CAIR plus 

stringent MACT’’ scenario, Cinergy 

modeling concluded that, due to the 

lack of ACI controls, units had to switch 

to lower Hg coals, install flue gas 

desulfurization/selective catalytic 

reduction (FGD/SCR), or shut down in 

order to achieve compliance. In 

addition, Cinergy concluded that an 

unrealistic number of FGD/SCR were 

installed by 2008 in order to meet the 

MACT limit (about 10 gigawatt (GW) of 

FGD and 30 GW of SCR). The Cinergy 

analysis projected that units burning 

subbituminous and lignite coals would 

shut down for 2 years because no 

technologies would exist until 2010 to 

comply with stringent MACT emissions 

limits. Cinergy’s analyses predicted that 

natural gas- and oil-fired units would be 

operated to make up the generation 

short fall. This resulted in significant 

increases in power prices and fuel 

prices in the short term. Once ACI 

became available in the model in 2010, 

units installed such controls and started 

operating again.

TABLE 2.—SUMMARY OF CINERGY POWER SECTOR MODELING

Hg trading plus CAIR Proposed CAMR MACT plus CAIR Stringent MACT plus CAIR 

2010 2020 2010 2020 2010 2020 

Hg emissions ............ 32 tons ................ 26 tons ................ 33 tons ................ 30 tons ................ 9 tons .................. 9 tons. 

Present Value 

($2000) for 20 year.

$65 billion $64 billion $130 billion 

Total installed capacity: 

FGD ................... 150 GW .............. 200 GW .............. 160 GW .............. 180 GW .............. 180 GW .............. 180 GW. 

SCR ................... 150 GW .............. 160 GW .............. 140 GW .............. 170 GW .............. 165 GW .............. 175 GW. 

ACI ..................... 10 GW ................ 25 GW ................ 15 GW ................ 20 GW ................ 120 GW .............. 120 GW. 

* Note: No annual costs were provided by Cinergy in their comments. 

c. What were the results of CATF’s 

power sector modeling? CATF modeled 

two MACT scenarios with the assistance 

of ICF using EPA’s IPM 2003. The two 

scenarios modeled were: (1) EPA’s 

CAMR MACT alternative proposal in 

combination with EPA’s CAIR proposal 

(‘‘CAMR MACT plus CAIR’’), and (2) an 

‘‘Alternative Mercury Control 

Scenario.’’ In their comments, CATF 

states that their ‘‘Alternate Mercury 

Control Scenario’’ is consistent with 

EPA’s proposed ‘‘CAMR MACT’’

approach of basing subcategories on fuel 

rank; however, CATF notes that the 

emission rates used by EPA in its 

modeling do not represent what they 

believe to be MACT. The CATF states 

that their analysis is provided to 

‘‘demonstrate that more stringent Hg 

emission rates are feasible and highly 

cost-effective.’’

The alternative emission rates CATF 

evaluated are standards representing 90 

percent Hg reduction (measured as a 

reduction from the Hg content in the 

input coal) for bituminous-fired units, 

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69869

1.5 lb/TBtu for subbituminous-fired 

units, and 4.5 lb/TBtu for lignite-fired 

units. As stated in the CATF comments, 

the 90 percent level was specified for 

bituminous-fired units because the 

version of IPM used by CATF could not 

simulate Hg reductions any higher than 

90 percent through the use of retrofitted 

control technology. EPA notes, however, 

that IPM can model reductions greater 

than 90 percent through fuel switching, 

dispatch changes, or retirements. 

A summary of the CATF analysis of 

the EPA proposed ‘‘CAMR MACT plus 

CAIR’’ and ‘‘Alternative Mercury 

Control Scenario’’ plus CAIR is 

provided in Table 3 below. EPA notes 

that the term ‘‘total installed capacity’’

used in Table 3 below includes all 

currently installed controls and control 

retrofits needed to meet modeled policy. 

EPA further notes that EPA’s Base Case 

2003 projects about 115 GW of 

scrubbers and 116 GW of SCR by 2010.

TABLE 3.—SUMMARY OF CATF POWER SECTOR MODELING

CAMR MACT plus CAIR Alternative Mercury Control Scenario 

plus CAIR 

2010 2020 2010 2020 

Hg emissions .............................................................................. 26 tons ................ 23 tons ................ 12 tons ................ 12 tons. 

Annual costs ($1999) .................................................................. $5.7 billion .......... $7.1 billion .......... $8.4 billion .......... $7.7 billion. 

Total installed capacity: 

FGD ..................................................................................... 193 GW .............. 233 GW .............. 221 GW .............. 224 GW. 

SCR ..................................................................................... 145 GW .............. 177 GW .............. 172 GW .............. 174 GW. 

ACI ....................................................................................... 17 GW ................ 19 GW ................ 102 GW .............. 102 GW. 

* Note: No present value costs were provided by CATF in their comments. 

CATF concluded that the ‘‘Alternate 

Mercury Control Scenario’’ results in 

shifts toward more bituminous coal use 

(in 2020, about 7 percent from Base Case 

2003) and declines in subbituminous 

and lignite coal use (in 2020, about 27 

percent and 13 percent from Base Case 

2003, respectively). CATF projected a 

similar shift in reaction to EPA’s 

proposed ‘‘MACT plus CAIR’’ scenario 

(i.e., increase of about 5 percent for 

bituminous, decreases of about 24 

percent and 15 percent for 

subbituminous and lignite, 

respectively). In addition, CATF 

concluded that the ‘‘Alternate Mercury 

Control Scenario’’ reduces coal use in 

2020 by less than 1 percent compared to 

EPA’s proposed ‘‘CAMR MACT plus 

CAIR’’ scenario, to a level that would be 

about 6 percent above current (2001) 

electric power generation coal 

consumption. 

d. What were the results of EEI’s 

power sector modeling? EEI’s power 

sector modeling was performed using 

CRA’s EPMM model. As noted above, 

EPRI’s comments included the same 

CRA EPMM modeling analysis as EEI. 

Some of the EPMM modeling 

assumptions differ from those of EPA, 

including higher natural gas prices, 

higher electric growth demand, different 

Hg co-benefit assumptions for NOX and 

SO2 controls, and different costs and 

performance for ACI. The scenarios 

modeled by EEI include a CAIR-only 

scenario, ‘‘CAIR plus EPA MACT’’

scenario, and three ‘‘CAIR plus Hg 

trading’’ scenarios. EEI modeled two 

cases of the EPA-proposed Hg trading 

scenario with a 34-ton first-phase cap in 

2010 and a 15-ton second phase cap in 

2018. (Note that EPA did not propose a 

34-ton first-phase cap but, rather, took 

comment on the appropriate level of the 

Phase 1 cap.) One of EEI’s cases 

assumed a 2.5 percent annual 

improvement in variable operating costs 

for ACI, and the other did not include 

this assumption. EEI also modeled an 

alternative Hg trading scenario with a 

24-ton cap in 2015 and a 15-ton cap in 

2018, assuming 2.5 percent annual 

improvement in variable operating costs 

for ACI. Under this alternative option, 

early reduction credits can be earned 

and banked during the period 2010 to 

2014 through early application of Hg 

control technologies (e.g., ACI). To 

simulate early reduction credits, the EEI 

analysis set caps equal to co-benefits 

during this period. The co-benefits were 

defined as the Hg emissions from the 

comparable CAIR-only scenario, 39.9 

tons in 2010 and 2011, and 38.5 tons for 

2012 through 2014. 

Results of the EEI analysis of Hg 

reduction scenarios are summarized in 

Table 4 below. Present value costs in 

Table 4 are for 2004 to 2020 and assume 

an 8 percent discount rate, consistent 

with EEI’s analysis. For Hg trading 

scenarios, EPA notes that EEI projected 

emissions of 15 tons in 2020 appear to 

be an artifact of the grouping of the 2020 

run year with the model end run year 

of 2040. EPA maintains that, in a leastcost solution model like EPMM, the 

model would solve for the cap in the 

final run year grouping. Therefore, Hg 

emissions reported for trading scenarios 

in the table below are those projected 

for 2019, because EPA believes they 

better represent emissions in 2020, i.e., 

if 2020 had not been grouped with 2040. 

The Hg trading scenarios have been 

modeled without a safety valve.

EEI’s analysis also included 

information on projected technology 

retrofits. EEI notes in their comments 

that these projections reflect the 

quantities necessary to comply with the 

proposed rules and may not reflect what 

is feasible to retrofit or what is 

commercially available. EEI also noted 

in their comments, that although they 

modeled the availability of ACI at 90 

percent removal, the cost and 

effectiveness of ACI control technology 

remains uncertain, especially on 

subbituminous coal-fired units.

TABLE 4.—SUMMARY OF EEI POWER SECTOR MODELING* 

Proposed CAMR MACT plus 

CAIR 

Hg trading plus CAIR Hg trading plus CAIR (improved ACI costs) Alternative Hg trading plus 

CAIR (improved ACI costs) 

2010 2020 2010 2020 2010 2020 2010 2020 

Hg emissions** .... 32 tons ........ 30 tons ........ 34 tons ........ 24 tons ........ 34 tons ........ 24 tons ........ 37 tons ........ 23 tons. 

Annual costs 

($1999).

$4.4 billion ... $6.8 billion ... $2.5 billion ... $8.1 billion ... $2.5 billion ... $8.0 billion ... $2.6 billion ... $7.7 billion. 

69870 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

10See OAR–2002–0056–0043 and –0463.

TABLE 4.—SUMMARY OF EEI POWER SECTOR MODELING*—Continued

Proposed CAMR MACT plus 

CAIR 

Hg trading plus CAIR Hg trading plus CAIR (improved ACI costs) Alternative Hg trading plus 

CAIR (improved ACI costs) 

2010 2020 2010 2020 2010 2020 2010 2020 

Present value 

(2004–2020).

$27.8 billion $19.7 billion $19.1 billion $19.4 billion 

Hg marginal costs 

in 2020.

Not applicable $37,285/lb $32,536/lb $32,536/lb 

Total installed capacity: 

FGD .............. 153 GW ....... 180 GW ....... 128 GW ....... 192 GW ....... 128 GW ....... 193 GW ....... 129 GW ....... 195 GW. 

SCR .............. 134 GW ....... 153 GW ....... 120 GW ....... 148 GW ....... 121 GW ....... 148 GW ....... 121 GW ....... 148 GW. 

ACI ............... 67 GW ......... 67 GW ......... 16 GW ......... 107 GW ....... 16 GW ......... 112 GW ....... 16 GW ......... 112 GW. 

* EPRI comments submitted the same modeling analysis. 

** Emission results are presented for 2019. 

4. What are the areas of ongoing EPA 

research? EPA is in the process of 

evaluating the above comments and data 

and, as noted above, has developed 

certain preliminary reactions to the 

comments. We are seeking comment on 

certain aspects of the above modeling 

analyses. As demonstrated by the above 

summaries of the comments, estimates 

of the impact of Hg regulation on the 

power sector are sensitive to model 

input assumptions. To increase the 

accuracy of EPA’s power sector 

modeling as related to forecasting the 

power sector’s response to 

environmental regulatory programs, we 

are seeking comment and/or additional 

information to inform our regulatory 

decision. 

Moreover, since the January 2004 

proposal and the March 2004 

supplemental proposal, we have become 

aware of new information on the ability 

of sorbent injection technologies to 

remove Hg emissions from coal-fired 

power plants (e.g., results of ACI testing 

over a period of several months at 

Southern Company’s Plant Gaston, 

brominated activated carbon (B*PACTM) 

injection at Detroit Edison’s St. Clair 

Power Plant, etc.). To this end, the 

Agency is seeking updated information 

on issues that may be relevant to 

assessing the assumptions employed in 

our power sector modeling (e.g., 

removal efficiencies, capital and 

operating and maintenance (O&M) costs, 

timeline for commercialization, balance 

of plant issues, etc.). Specifically, we are 

interested in obtaining information on: 

a. In some of EEI’s analyses, EEI 

assumed a 2.5 percent annual 

improvement in variable operating costs 

for ACI. Is it appropriate for an 

economic forecast to assume an 

improvement in costs over time (such as 

through technology cost reductions or 

through future technology innovation), 

and, if yes, what level of improvement 

in costs should be assumed? 

b. Due to model size considerations, 

limited knowledge on achievable levels 

of Hg control, and limited knowledge on 

assessing the full impact of the Hg 

speciation profile on control, IPM has 

limited Hg control retrofit options. 

Currently, IPM assumes that Hg 

reductions are achieved only through 

use of SCR and FGD or ACI (with or 

without fabric filter). (EPA notes that Hg 

reductions in IPM can also be achieved 

through fuel switching, dispatch 

changes, and retirements.) Should other 

control options be considered in EPA’s 

power sector modeling (e.g., retrofit of 

fabric filters and electrostatic 

precipitators, pre-combustion controls, 

and the optimization of SO2 or NOX

controls)? 

c. To the extent commenters believe 

that control considerations other than 

those noted in the proposal or in the 

preceding paragraphs should be 

included in power sector modeling, EPA 

is seeking data on the timeline for 

commercialization, cost, balance of 

plant issues, and performance of such 

control options. 

d. CATF and Cinergy both modeled 

more stringent MACT-type options. 

However, CATF assumed that ACI 

would be available in 2005 for all coal 

types, while Cinergy assumed that ACI 

would be available in 2010 for all coal 

types for one MACT scenario modeled. 

(EPA notes that for Cinergy’s other 

modeled scenarios, including a MACT 

scenario, it assumed ACI would be 

available in 2005.) The year of 

availability for ACI is an assumption 

that appears to have made a large 

difference in the projected impacts of a 

MACT-type option. (Note that in a 

January 2004 white paper, we projected 

that ACI technology would be available 

for commercial application after 2010 

and that removal levels in the 70 

percent to 90 percent range could be 

achievable. This assumes the funding 

and successful implementation of an 

aggressive, comprehensive research and 

development program at both EPA and 

the U.S. Department of Energy (DOE). 

Such applications represent only the 

initiation of a potential national retrofit 

program, which would take a number of 

years to fully implement. Since release 

of the white paper, we have received 

numerous comments on technology and 

have additional test data. We are 

currently evaluating this new 

information.) 10 What assumptions for 

ACI availability are most appropriate? 

Specifically, what date of availability for 

ACI technology is appropriate to 

consider in a modeling analysis, at what 

quantities, for what coal types, and 

why?

e. EEI estimated that ACI would be 

less expensive per pound of Hg removed 

than EPA has estimated. In addition, 

Cinergy assumed higher capital costs for 

ACI than EPA in its modeled scenarios. 

Are EPA’s Hg control technology cost 

assumptions reasonable? Although EPA 

has information on the costs of ACI, 

EPA is seeking additional detailed data 

addressing the validity of the costs 

assumed for ACI. 

f. Analyses by commenters and EPA 

of Hg trading programs indicate that 

variations in the first phase cap level 

and timing impact when the final cap 

level will be achieved (i.e., the 

emissions reduction ‘‘glide path’’). 

Although banking in the first phase 

impacts the timing of achieving the 

second phase cap, it should not affect 

the cumulative Hg emissions reductions 

ultimately achieved under the program. 

EPA is seeking additional comment on 

the impact banking may have on the 

timing of achieving the second phase 

cap.

g. EPA received comments estimating 

the co-benefits of Hg reductions 

associated with implementation of the 

proposed CAIR (i.e., the level of Hg 

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69871

11See OAR–2002–0056–1268 and –1270. 12 69 FR 4672, January 30, 2004.

reductions realized as a result of 

compliance with the proposed CAIR). 

Cinergy estimates a co-benefit level in 

2010 of 38 tons as compared to current 

emissions of 48 tons. EEI estimates a cobenefit level in 2010 of 40 tons. Both 

groups modeled a 34-ton first phase cap. 

In light of these modeling analyses, EPA 

is seeking additional comment on the 

reasonableness of its current IPM 

assumptions co-benefit reductions. 

Emission modification factors (EMF) are 

one component of the estimated Hg cobenefits from the proposed CAIR. A 

comparison of co-benefit assumptions 

used in EPA and other modeling is 

provided in Table 5. We are also seeking 

comment on appropriate EMF.

TABLE 5.—HG REMOVAL ASSUMPTIONS FOR POLLUTION CONTROL EQUIPMENT

Name for control 

EPA 2003 EMFs CRA 2004 EMFs EIA EIA AEO2004 EMFs 

Bit EMF Subbit 

EMF 

Lignite 

EMF Bit EMF Subbit EMF 

Lignite 

EMF Bit EMF Subbit EMF 

Lignite 

EMF 

PC/CS–ESP ................................................... 0.64 0.97 1.00 0.65 0.80 0.90 0.64 0.97 1.00 

PC/CS–ESP/FGD ........................................... 0.34 0.84 0.56 0.40 0.65 0.65 0.34 0.73 0.58 

PC/CS–ESP/FGD–Dry ................................... 0.64 0.65 1.00 0.50 0.85 0.90 0.64 0.65 1.00 

PC/CS–ESP/SCR/FGD .................................. 0.10 0.34 0.56 0.15 0.65 0.65 0.10 0.73 0.58 

PC/FF ............................................................. 0.11 0.27 1.00 0.25 0.35 0.90 0.11 0.27 1.00 

PC/FF/FGD .................................................... 0.10 0.27 1.00 0.15 0.25 0.60 0.05 0.27 0.64 

PC/FF/FGD–Dry ............................................. 0.05 0.75 1.00 0.15 0.75 0.90 0.05 0.75 1.00 

PC/FF/SCR/FGD ............................................ 0.10 0.15 0.56 0.10 0.25 0.60 0.10 0.27 0.64 

PC/HS–ESP ................................................... 0.90 0.94 1.00 0.80 1.00 1.00 0.90 0.94 1.00 

PC/HS–ESP/FGD ........................................... 0.58 0.80 1.00 0.45 0.70 0.70 0.58 0.80 1.00 

PC/HS–ESP/FGD–Dry ................................... 0.60 0.85 1.00 na na na 0.60 0.85 1.00 

PC/HS–ESP/SCR/FGD .................................. 0.10 0.75 1.00 0.15 0.70 0.70 0.42 0.76 0.64 

Notes: PC: pulverized coal; CS–ESP: cold-side electrostatic precipitator; HS–ESP: hot-side electrostatic precipitator; FGD: flue gas 

desulfurization; SCR: selective catalytic reduction; FF: fabric filter; EMF: emission modification factor (% reduction = 1—EMF) EPA 2003 EMFs 

used by CATF and CCAP analyses; Charles River Associates (CRA) EMFs used in EEI analysis; AEO2004 EMF used in Energy Information Administration (EIA) modeling. 

h. More recent test data than were 

available at proposal on subbituminousfired units equipped with SCR indicate 

that SCR does not enhance the oxidation 

of Hg0 on such coals and, thus, does not 

provide for additional capture in a wet 

scrubber.11 Based on these test data, 

EPA is considering revising the EMF for 

subbituminous coal-fired units 

equipped with SCR and wet FGD in 

modeling for the final rule. For the EMF 

identified in Table 5 for such units, EPA 

recommends the use of the EMF control 

combination before a SCR is added (i.e., 

ascribe no additional control due to the 

addition of the SCR). Thus, EPA is 

considering making the following three 

changes to the subbituminous coal EMF 

used in IPM: for CS–ESP/SCR/FGD, use 

CS–ESP/FGD (0.84); for FF/SCR/FGD, 

use FF/FGD (0.27); and for HS–ESP/

SCR/FGD, use HS–ESP/FGD (0.80). EPA 

is seeking comment on these proposed 

EMF changes.

In addition, EPA notes that other 

recent test data (e.g., DOE- and EPRIsponsored testing on Hg controls) may 

be available that would influence EMF 

used in EPA modeling. EPA is seeking 

comment on the appropriateness of 

using other test data for EMF 

development and requests that 

commenters submit any test data that 

may be relevant. 

C. Issues of Hg Speciation 

This section addresses the issue of Hg 

speciation. As explained further below, 

we are seeking additional input on the 

species (or form) of Hg emitted in the 

flue gas, the percentage of each species 

emitted in the flue gas, and how those 

percentages in total (i.e., the speciation 

profile) affect the analysis of how the 

power sector could respond to different 

levels of emissions control. 

1. Overview. To quantify the relative 

contribution of Hg emissions from U.S. 

coal-fired power plants on total 

nationwide Hg deposition, the EPA 

initiated an Information Collection 

Request (ICR) in 1999 under the 

provisions of CAA section 114. During 

this data collection effort, incoming coal 

shipments for all coal-fired power 

plants in the U.S. were tested for Hg 

content (for calendar year 1999) and 

other selected coal properties (e.g., ash, 

sulfur and chlorine content, etc.). 

Additionally, during 1999, 81 power 

plants—chosen to be representative of 

the entire U.S. power plant sector—were 

tested for stack emissions of Hg using 

the Ontario-Hydro sampling method. 

The Ontario-Hydro method provided 

EPA with speciated Hg emissions (i.e., 

Hg0, Hg∂2, and Hgp) for these tested 

units. Data from these tests were then 

extrapolated to all domestic coal-fired 

power plants and used to generate a 

national total Hg emissions estimate for 

1999 (48 tons per year). These data were 

further used to provide a national 

estimate of emissions of the three forms 

of Hg as follows: Hg0—54 percent, 

Hg∂2—43 percent, and Hgp—3 percent. 

Plant-specific estimates based on these 

data were used in the IPM modeling 

activities discussed elsewhere in this 

notice. In general, eastern bituminous 

coals emitted the least amount of Hg0

(the species most difficult to control); 

followed by western subbituminous 

coals (e.g., Powder River Basin (PRB), 

etc.); and the northern and southern 

lignite coals. To this end, the 1999 ICR 

data collection effort provided EPA one 

of the most comprehensive databases 

available to date regarding Hg emissions 

from coal-fired power plants. 

In the proposed CAMR, EPA 

discussed the relevance and importance 

of characterizing the species of Hg 

emitted in the flue gas and solicited 

comment on that issue. EPA received 

significant public input as a result. As 

we and commenters have recognized, 

the form (or species) of Hg emitted in 

the flue gas affects the ability to control 

Hg emissions 12 and the form of Hg 

released from a stack affects the 

atmospheric fate and transport of Hg. 

The species of Hg, therefore, is relevant 

to assessing the costs associated with 

different levels of Hg emissions control.

2. What specific comments on Hg 

speciation did EPA receive in response 

to the January 2004 proposal and the 

March 2004 supplemental proposal? A 

number of comments were provided on 

69872 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

the importance of speciated Hg emission 

information and potential atmospheric 

transformations during the public 

comment period. Among these are 

comments or attachments submitted by 

the following: EPRI (OAR–2002–0056–

2578); Hubbard Brook Research 

Foundation (HBRF) (OAR–2002–0056–

2038); Southern Company (OAR–2002–

0056–2948); Subbituminous Energy 

Coalition (SEC) (OAR–2002–0056–

2379); and Utility Air Regulatory Group 

(UARG) (OAR–2002–0056–2922 and 

–2928). 

EPRI provided information (in Section 

A of their report) on plume-simulating 

chamber studies that indicate 

transformation of Hg species in the 

plume. This work was followed by 

studies to evaluate the speciation 

changes in actual power plant plumes. 

HBRF (in Section 3 of their report) 

provided comment on the validity of 

using an average speciation profile for 

all coal-fired power plants. SEC raised 

questions about the speciation profile 

for units burning a mix of coals. 

Southern Company and UARG 

indicated that, because the Hg 

speciation dictates the level of control 

that may be achieved with existing 

control equipment, different Hg 

emission limits must be established for 

the different coal ranks. 

3. What are the areas of ongoing EPA 

research? EPA is evaluating all of the 

comments on speciation that it received 

in response to the proposed CAMR. To 

further aid in our review of these 

comments, to supplement our existing 

1999 ICR database, and to aid in our 

decision-making process, EPA is seeking 

additional comment on the following 

areas.

a. We have received numerous 

comments on subcategorization by coal 

type and the speciation profiles 

resulting from the combustion of 

various coal types. We are seeking 

additional specific data and information 

on the speciation profiles of various 

types and blends of fuels. 

b. Commenters have questioned the 

appropriateness of using a standard (or 

average) speciation profile in modeling 

analyses conducted for all coal-fired 

power plants. The Agency is seeking 

comment on if/when a standard (or 

average) speciation profile should be 

used for either the CAA section 111 or 

CAA section 112 regulatory approach. 

c. Is it currently feasible, or will it be 

feasible within the compliance 

timeframes of the proposed rule, to 

accurately monitor a source’s Hg 

emissions by species? 

III. EPA’s Proposed Revised Benefits 

Assessment 

A. What Is the Relevant Background? 

Consistent with EO 12866, EPA 

included a benefits assessment in the 

proposed CAMR. EPA received 

comments on that assessment. Based on 

those comments and in furtherance of 

our obligations under EO 12866, we 

have preliminarily revised our proposed 

approach to analyzing the benefits 

associated with Hg emission reductions 

from power plants. We explain below 

our proposed revised benefits 

methodology. We also identify below 

comments received on the proposed 

CAMR that provide analyses or 

information relevant to our proposed 

revised benefits approach. We further 

identify those commenters that 

presented approaches that differ from 

our revised approach, as described 

below. We seek comment on our 

proposed revised benefits methodology 

and on the strengths and weaknesses of 

the analytical approaches presented in 

the comments to the extent they relate 

to our proposed revised benefits 

methodology. 

Although this section of the NODA 

addresses the benefits analysis that we 

must prepare for purposes of EO 12866, 

we recognize that the costs and benefits 

of reducing emissions are often interrelated. Thus, to the extent that we 

receive any comments or other 

information in the process of 

completing the benefits assessment for 

purposes of EO 12866 and to the extent 

that such information bears on the 

statutory factors relevant to setting 

either a beyond-the-floor standard for 

Hg under CAA section 112(d) or a 

standard of performance for Hg under 

CAA section 111, we intend to evaluate 

and consider that information as we 

make a final decision as to which 

regulatory approach to pursue. 

B. How Is EPA Estimating Reductions in 

Hg Exposure Associated With the 

CAMR? 

EPA’s proposed revised benefits 

analysis attempts to estimate the extent 

to which adverse human health effects 

will be reduced as a result of reducing 

Hg emissions from coal-fired power 

plants. Translating estimates of 

reductions in Hg emissions from coalfired power plants to health outcomes in 

humans is a function of a number of 

complex chemical, physical, and 

biological processes, as well as a wide 

variety of human behaviors and 

responses. 

The relevant events and processes 

include the following: 

• The magnitude and nature of 

current and forecasted Hg emissions 

from coal-fired power plants, as well as 

the magnitude and species of current Hg 

emissions from other sources, both 

domestic and international. 

• The physical transport of vapor and 

particle-phase Hg emissions in the air, 

as well as the chemical transformations 

that occur to Hg as it reacts with other 

chemical species in the atmosphere. 

• The deposition of inorganic Hg onto 

terrestrial and aquatic surfaces, and the 

transport of Hg from terrestrial systems 

to surface water bodies. 

• The biological, chemical, and 

physical processes that control the rate 

of methylmercury (MeHg) production in 

surface waters and aquatic sediments 

and the bioavailability of Hg to 

organisms. 

• The composition and complexity of 

aquatic food webs and species-specific 

factors such as diet composition, 

chemical assimilation efficiencies, and 

metabolism that affect the 

bioaccumulation of MeHg in fish. 

• The extent to which specific water 

bodies are used for a variety of fishing 

activities, either by individuals or 

commercially. 

• Different human fish consumption 

behaviors, including for specific 

subpopulations. 

• The human response to MeHg 

exposure. 

EPA’s proposed revised benefits 

methodology attempts to characterize, 

either directly or indirectly, each of the 

above events and processes. EPA 

specifically is seeking to estimate the 

reduction in exposure to MeHg 

associated with reducing Hg emissions 

from coal-fired power plants. We are 

seeking comment on our proposed 

revised benefits approach, as described 

below. As noted above, we are also 

seeking comment on the comments that 

we received that are relevant to our 

proposed revised benefits methodology. 

The following sections describe each 

of the steps of our proposed revised 

benefits methodology. Those steps can 

be categorized broadly as follows: 

• Quantify Hg emissions that are 

projected from U.S. coal-fired power 

plants under the Base Case and CAMR 

and then quantify Hg emissions that 

result from sources other than U.S. coalfired power plants. The power sector 

modeling described above and in more 

detail at http://www.epa.gov/

airmarkets/epa-ipm/ will assist in the 

quantification of Hg from U.S. coal-fired 

power plants. 

• Model the atmospheric dispersion, 

atmospheric speciation, and deposition 

of Hg. 

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69873

13Pacyna, J.M., E.G. Pacyna, F. Steenhuisen, S. 

Wilson. 2003. Mapping 1995 Global Anthropogenic 

Emissions of Mercury. Atmosph. Env., 37, p. 109–

117. 

14Seigneur, C., K. Vijayaraghavan, K. Loman, P. 

Karamchandani, C. Scott. 2004. Global Source 

Attribution for Mercury Deposition in the United 

States. Environ. Sci. Technol., 38, p. 555–569.

15The update of the 1999 NEI (1) updates 

emissions of criteria pollutants to 2001, (2) removes 

fugitive dust sources of Hg in the few States where 

the original 1999 NEI includes them, and (3) 

replaces the 1999 NEI estimates of 1999 Hg 

emissions from medical waste incinerators with 

more recent data on 2002 emissions. The original 

1999 NEI is posted at http://www.epa.gov/ttn/chief/

net/1999inventory.html. The 2001 criteria pollutant 

inventory for U.S. sources is available in EPA 

Docket ID No. OAR–2003–0053, and is the same as 

made available in the Notice of Data Availability for 

the Clean Air Interstate Rule (69 FR 47828, August 

6, 2004). The updated/modified 1999 U.S. Hg 

inventory and the Canadian inventory for all 

pollutants are posted at http://www.epa.gov/ttn/

chief/emch/invent/index.html.

16See http://www-as.harvard.edu/chemistry/trop/

geos/.

17See http://oaspub.epa.gov/eims/

eimsapi.dispdetail?deid=56181.

18See http://www.epa.gov/scram001/

tt22.htm#isc; http://www.epa.gov/scram001/userg/

regmod/isc3v2.pdf; and http://www.epa.gov/

scram001/7thconf/iscprime/useguide.pdf.

19See http://www.arl.noaa.gov/ready/

hysplit4.html.

20Amar, P., R. Bornstein, H. Feldman, H. Jeffries, 

D. Steyn, R. Yamartino, Y. Zhang. 2004. Review of 

CMAQ Model, December 17–18, 2003. See http://

hill.nccr.epa.gov/air/interstateairquality/pdfs/

PeerReview_of_CMAQ.pdf.

21Community Multiscale Air Quality (CMAQ) 

Model Documentation. See http://hill.nccr.epa.gov/

air/interstateairquality/pdfs/

CMAQ_Documentation.pdf.

22Byun, D.W., N. Moon, D. Jacob, R. Park. 

Linking CMAQ with GEOS–CHEM. See http://

hill.nccr.epa.gov/air/interstateairquality/pdfs/

GEOSCHEMforCMAQ_Description.pdf.

23U.S. EPA. February 1998. op. cit. pp. ES–16, 

ES–20, and 7–28.

24Cohen, M., R. Artz, R. Draxler, P. Miller, L. 

Poissant, D. Niemi, D. Ratte, M. Deslauriers, R. 

Duval, R. Laurin, J. Slotnick, J. Neetesheim, J. 

McDonald. 2004. Modeling the Atmospheric 

Continued

• Model the link between changes in 

Hg deposition and changes in the MeHg 

concentration in fish. 

• Assess the types and amounts of 

fish consumed by U.S. consumers and, 

from that, assess the resulting MeHg 

exposure. 

• Assess how reductions in human 

exposure to MeHg affects human health. 

C. Step 1 of EPA’s Proposed Revised 

Benefits Methodology: Analyzing Hg 

Emissions From Other Sources 

1. Overview. As stated in the proposed 

CAMR, Hg exposure is both a domestic 

and a global issue. From a domestic 

perspective, power plants are one 

source of Hg air emissions, but there are 

other domestic sources of man-made Hg. 

Mercury also enters the atmosphere 

from a variety of natural processes, 

including, for example, volcanic 

eruptions, groundwater seepage, and 

evaporation from the oceans.

EPA currently does not have an 

inventory of natural or re-emitted 

sources suitable for modeling purposes. 

EPA does, however, have inventories 

concerning man-made domestic and 

international sources of Hg. These 

inventories have been used over the past 

decade in air quality and air deposition 

modeling.13 14 They are important 

because the first step of EPA’s proposed 

revised benefits methodology is to 

quantify Hg emissions that result from 

sources other than U.S. coal-fired power 

plants. In particular, the inventories 

enable us to establish upwind and 

downwind boundary conditions to 

apportion exposure to non-natural 

domestic and international sources of 

Hg emissions.

The inventory sets that EPA currently 

is considering using include an update/

modification to the 1999 National 

Emissions Inventory (NEI) for all U.S. 

anthropogenic sources for criteria 

pollutants and for all U.S. 

anthropogenic non-power plant sources 

for Hg emissions, the 1995 Canadian 

criteria pollutant inventory for Canadian 

anthropogenic sources, and the 2000 Hg 

inventory for Canadian anthropogenic 

sources.15 EPA is also planning on using 

GEOS-CHEM for modeling boundary 

conditions representing the global 

background.16

EPA is also aware of research 

conducted by EPA and others (e.g., at 

Cheeka Peak, WA; Steubenville, OH; 

Mauna Loa, HI; Mt. Bachelor, OR; and 

Okinawa).17 That research, for example, 

provides important information about 

Hg fate and transport and relative 

domestic and international source 

contributions. The research also 

provides speciated high altitude 

atmospheric measurements of Hg. These 

measurements may improve our 

understanding of the atmospheric 

reactions that alter the chemical species 

of Hg in the atmosphere and that 

ultimately impact fate and transport of 

emissions originating in Asian countries 

and other international sources. This 

research is, therefore, directly relevant 

to the first step of our preliminary 

proposed revised benefits methodology, 

as it affects our ability to estimate the 

U.S. power plant contribution to total 

Hg deposition within the U.S. EPA is 

seeking comment on this step of its 

proposed revised benefits methodology.

2. What specific comments did EPA 

receive on Hg emissions from other 

sources in response to the January 2004 

proposal and the March 2004 

supplemental proposal? EPA received a 

number of public comments that are 

relevant to the issue of assessing Hg 

emissions from sources other than U.S. 

coal-fired power plants, including 

comments from the Center for Energy 

and Economic Development (CEED) 

(OAR–2002–0056–2256); EPRI (OAR–

2002–0056–2578); HBRF (OAR–2002–

0056–2038); National Mining 

Association (OAR–2002–0056–2434); 

TXU Energy (OAR–2002–0056–1831); 

and UARG (OAR–2002–0056–2922). 

Some of these comments employed 

different approaches for simulating 

boundary conditions for apportioning 

Hg exposure from domestic and 

international sources, and we are 

interested in obtaining public input on 

these alternative approaches and 

analyses. 

D. Step 2 of EPA’s Proposed Revised 

Benefits Methodology: Analyzing Air 

Dispersion Modeling Capabilities 

1. Overview. The second step of our 

proposed revised benefits methodology 

requires modeling the atmospheric 

dispersion, atmospheric speciation, and 

deposition of Hg. This is a critical step 

in our analysis because to evaluate the 

benefits of reducing Hg emissions from 

coal-fired power plants, we need to 

understand how Hg moves through the 

atmosphere and how it is ultimately 

deposited.

Over the past decade, EPA has used 

a variety of analytical and numerical 

simulation tools to project the 

atmospheric transport, chemistry, and 

deposition of both criteria (e.g., ozone, 

fine particles, etc.) and toxic (e.g., Hg) 

air pollutants. These models range in 

complexity from simple, one-layer 

Gaussian dispersion models (e.g., 

Industrial Source Complex (ISC3) 

model 18) to more complex, multi-layer 

Lagrangian puff-type trajectory models 

(e.g., Hybrid Single Particle Lagrangian 

Integrated Trajectory (HYSPLIT) 

model19), and finally to complex threedimensional (3–D) Eulerian grid models 

(e.g., Community Multiscale Air Quality 

(CMAQ) model 20 21 22

EPA and others have been using a 

suite of complex numerical models to 

assess the transport and fate of Hg 

emissions in the local, regional, and 

global atmosphere. In the Utility Report 

to Congress, EPA relied heavily on the 

ISC3 dispersion model to assess nearfield Hg deposition effects.23 The 

HYSPLIT model has also been used 

extensively in the Great Lakes and 

Chesapeake Bay watersheds to analyze 

source-receptor relationships for Hg 

deposition in these areas.24 The 

69874 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

Transport and Deposition of Mercury to the Great 

Lakes. Environ. Res., 95, p. 247–265.

25See http://remsad.saintl.com/.

26 ICF Consulting. August 5, 2004. EPA Region 

6—REMSAD Air Deposition Modeling in Support of 

TMDL Development for Southern Louisiana. Final 

Report. Prepared for EPA Region 6.

27See http://epa.gov/clearskies/

air_quality_tech.html.

28Bullock, O., K. Brehme. 2002. Atmospheric 

Mercury Simulation Using the CMAQ Model: 

Formulation Description and Analysis of Wet 

Deposition Results. Atmosph. Environ., 36, p. 

2135–2146.

29See http://www.mmm.ucar.edu/mm5/mm5-

home.html. 30See http://nadp.sws.uiuc.edu/mdn/.

31Lin, C-J., S.O. Pehkonen. 1999. The Chemistry 

of Atmospheric Mercury: A Review. Atmospheric 

Environment, 33, p. 2067–2079.

32Bloom, N.S. 1992. On the chemical form of 

mercury in edible fish and marine invertebrate 

tissue. Canadian Journal of Fisheries and Aquatic 

Sciences, 49, p. 1010–1017.

Regional Modeling System for Aerosols 

and Deposition (REMSAD),25 a 3–D 

Eulerian grid model, has been used in 

recent years for several State-based total 

maximum daily load (TMDL) 

assessments for Hg deposition to local 

watersheds.26 In addition, REMSAD was 

used to assess the depositional changes 

associated with the implementation of 

the Clear Skies Act of 2003.27

More recently, EPA and EPRI have 

applied 3-D Eulerian modeling 

platforms to assess both domestic and 

global Hg deposition, respectively. EPA 

has been evaluating the atmospheric 

transport, transformation, and 

deposition of Hg using the CMAQ 

model over four 1-month periods (two 

in 1995 and two in 2001) and over the 

entire year of 2001.28 CMAQ uses a 

‘‘one-atmosphere’’ approach and 

addresses the complex physical and 

chemical interactions known to occur 

among multiple pollutants in the free 

atmosphere. The spatial resolution (i.e., 

the ability to observe concentration or 

depositional gradients/differences) of 

the gridded output information from 

CMAQ is generally considered to be 

either 36 kilometers (km), 12 km, or 4 

km; however, to date, CMAQ results 

have only been developed for Hg 

modeling at the 36 km resolution. In 

simulating the transport, transformation, 

and deposition of pollutants, CMAQ 

resolves 14 vertical layers in the 

atmosphere, and employs finer-scale 

resolution near the surface to simulate 

deposition to both terrestrial and 

aquatic ecosystems. CMAQ transport is 

defined using a higher-order 

meteorological model, commonly the 

Fifth-Generation Pennsylvania State 

University/National Center for 

Atmospheric Research mesoscale model 

(MMM5) 29 (current modeling analyses 

are planning to use calendar year 2001 

meteorological data).

Currently, EPA is planning to use 

REMSAD and CMAQ for modeling the 

atmospheric dispersion, speciation, and 

deposition of Hg. EPA is specifically 

planning to use CMAQ version 4.4 with 

Hg with a horizontal resolution of 36 km 

and 14 vertical layers and REMSAD 

version 7.13 also with a horizontal 

resolution of 36 km and 14 vertical 

layers. As described above, EPA is 

planning to use the GEOS–CHEM global 

model for boundary conditions input to 

both REMSAD and CMAQ. EPA is 

seeking comment on its proposed use of 

REMSAD and CMAQ to evaluate how 

Hg moves through the atmosphere and 

how it will ultimately be deposited. 

An important aspect of the second 

step of our proposed revised benefits 

methodology is the evaluation of the 

REMSAD and CMAQ modeling. In 

evaluating modeling, we seek to 

compare the simulated results with 

ambient monitoring information to 

assess the quality of the modeled 

simulations. The Mercury Deposition 

Network (MDN) provides the only 

source of routinely available empirical 

domestic Hg deposition information. 

MDN is a collaborative network 

involving several organizations (e.g., 

United States Geological Survey 

(USGS), National Oceanic and 

Atmospheric Administration, EPA) and 

is part of the National Atmospheric 

Deposition Program (NADP) network of 

sites across the U.S.30 As of spring 2003, 

the MDN contained approximately 90 

sites across the U.S. and Canada, which 

provide measurements of wet 

deposition of total Hg, integrated over 

weekly intervals.

We recognize the need to complement 

the MDN wet deposition measurements 

with dry deposition measurements 

because it is not clear how significant 

dry Hg deposition is to total ecosystem 

deposition. Currently, there is no 

recognized field method for measuring 

dry deposition. State-of-the-art 

atmospheric models indicate that the 

rate of dry deposition of Hg can be of 

a similar order of magnitude as wet 

deposition. Although the current extent 

of the MDN is relatively limited—as 

compared to the extensive networks for 

ozone and fine particles—EPA believes 

that the MDN data are the best available 

to evaluate the predictive capabilities of 

regional- and national-scale models. The 

MDN was not developed to monitor 

deposition near large sources and is of 

limited use for evaluating near-field 

deposition from models. We are seeking 

comment on how to use the MDN or 

related information in evaluating the 

numerical modeling analyses discussed 

above.

2. What specific comments did EPA 

receive on air dispersion modeling 

capabilities in response to the January 

2004 proposal and the March 2004 

supplemental proposal? We received a 

number of public comments on the use 

of analytical and numerical models for 

assessing the impacts of the proposed 

regulatory programs on Hg deposition 

patterns. Among these are comments or 

attachments submitted by the following: 

CEED (OAR–2002–0056–2256); CATF, 

NRDC, et al. (OAR–2002–0056–3460); 

EPRI (OAR–2002–0056–2578); and 

UARG (OAR–2002–0056–2922). Some 

of these commenters suggested 

alternative approaches to assessing the 

atmospheric transport and deposition of 

Hg, and we seek comment on those 

approaches. 

E. Step 3 of EPA’s Proposed Revised 

Benefits Methodology: Modeling 

Ecosystem Dynamics 

1. Overview. In the above steps of our 

proposed revised benefits methodology, 

we seek to quantify changes in Hg 

deposition associated with Hg 

reductions from U.S. coal-fired power 

plants. The third step involves modeling 

affected ecosystems. As we explained in 

the proposed CAMR, the main route of 

human exposure to MeHg is through 

consumption of fish containing elevated 

levels of MeHg. Accordingly, to estimate 

the changes in human exposure to 

MeHg that may result from reductions 

in Hg emissions from U.S. coal-fired 

power plants, we must first quantify 

how changes in Hg deposition from U.S. 

coal-fired power plants (forecasted 

using the models described above) 

translate into changes in MeHg 

concentrations in fish. Quantifying the 

linkage between different levels of Hg 

deposition and fish tissue MeHg 

concentration is the third step of our 

proposed revised benefits methodology. 

To effectively estimate fish MeHg 

concentrations in a given ecosystem, it 

is important to understand that the 

behavior of Hg in aquatic ecosystems is 

a complex function of the chemistry, 

biology, and physical dynamics of 

different ecosystems. The majority (95 

to 97 percent) of the Hg that enters 

lakes, rivers, and estuaries from direct 

atmospheric deposition is in the 

inorganic form.31 Microbes convert a 

small fraction of the pool of inorganic 

Hg in the water and sediments of these 

ecosystems into the organic form of Hg 

(MeHg). MeHg both bioconcentrates and 

biomagnifies. In the environment this 

process is referred to as 

bioaccumulation. MeHg is the only form 

of Hg that biomagnifies in organisms.32

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69875

33Benoit, J., C.C. Gilmour, R.P. Mason, A. Heyes. 

1999. Sulfide controls mercury speciation and 

bioavailability to methylating bacteria in sediment 

pore waters. Environ. Sci. Tech., 33(6), p. 951–957. 

34Benoit, J.M., R.P. Mason, C.C. Gilmour, G.R. 

Aiken. 2001. Constants for mercury binding by 

dissolved organic matter isolates in the Florida 

Everglades. Goechim. Cosmochim. Acta, 65, p. 

4445–4451.

35Hammerschmidt, C.R. and W.F. Fitzgerald. 

2004. Geochemical controls on the production and 

distribution of mercury in near-shore marine 

sediments. Environ. Sci. Tech., 38(5), p. 1480–1486.

36 Description of EPA’s Mercury Maps model—

http://www.epa.gov/waterscience/maps/ and 

September 2001 Mercury Maps Peer Reviewed 

Final Report—http://www.epa.gov/waterscience/

maps/report.pdf.

Ecosystem-specific factors that affect 

both the bioavailability of inorganic Hg 

to methylating microbes (e.g., sulfide, 

dissolved organic carbon) 33 34 and the 

activity of the microbes themselves (e.g., 

temperature, organic carbon, redox 

status) 35 determine the rate of MeHg 

production and subsequent 

accumulation in fish. The extent of 

MeHg bioaccumulation is also affected 

by the number of trophic levels in the 

food web (e.g., piscivorus fish 

populations) because MeHg 

biomagnifies as large piscivorus fish eat 

smaller organisms. These and other 

factors can result in considerable 

variability in fish MeHg levels among 

ecosystems at the regional and local 

scale.

To analyze the link between Hg 

deposition and MeHg concentrations in 

fish in aquatic ecosystems across the 

U.S., EPA currently is considering using 

EPA’s Office of Water’s Mercury Maps 

(MMaps).36 MMaps, which has been 

peer reviewed by EPA scientists and is 

currently undergoing external peer 

review, provides a quantitative spatial 

link between air deposition of Hg and 

MeHg in fish tissue. The external peer 

review materials will be placed in the 

docket as soon as they are available. The 

MMaps model suggests that changes in 

steady-state concentrations of MeHg in 

fish will be proportional to changes in 

Hg inputs from atmospheric deposition 

if air deposition is the only significant 

source of Hg to a water body; and if the 

physical, chemical, and biological 

characteristics of the ecosystem remain 

constant over time. This model is best 

applied to ecosystems where 

atmospheric deposition is the principal 

source of Hg to a water body and 

assumes that the physical, chemical, 

and biological characteristics of the 

ecosystem remain constant over time. 

EPA recognizes that concentrations of 

MeHg in fish are not expected to be at 

steady state. We also recognize that the 

requirement that all other conditions 

remain constant over time inherent in 

the MMaps methodology is not likely to 

be met. We further recognize that many 

water bodies, particularly in areas of 

historic gold and Hg mining in western 

States, contain significant nonair 

sources of Hg. Finally, we recognize that 

MMaps does not provide for a 

calculation of the time lag between a 

reduction in Hg deposition and a 

reduction in the MeHg concentrations in 

fish.

Despite these limitations of this 

model, EPA is unaware of any other tool 

for performing a national-scale 

assessment of the change in fish MeHg 

concentrations resulting from 

reductions in atmospheric deposition of 

Hg. As with all other aspects of our 

proposed revised benefits methodology, 

we seek comment on the use of the 

steady-state linear relationship between 

air deposition and MeHg concentrations 

in fish (i.e., MMaps) and how the results 

of the application of this relationship 

should be interpreted to account for the 

inherent limitations described above. 

To supplement the MMaps 

methodology, EPA is currently pursuing 

a number of case studies examining Hg 

deposition and bioaccumulation of 

MeHg in fish tissue. Dynamic ecosystem 

scale models are being used to estimate 

ecosystem response times following 

reductions in atmospheric Hg 

emissions, and to explore the 

uncertainty around the proportional 

relationship used by the MMaps model. 

In this project, EPA is considering 

modeling eight case studies spanning a 

range of ecosystem types and 

characteristics in the Eastern and 

Midwestern U.S. Dynamic watershed, 

water body, and aquatic 

bioaccumulation models will be linked 

and applied to selected ecosystems, and 

sensitivity analyses will be run to 

provide a context for estimating the 

range in the magnitude and timing of 

changes in fish MeHg concentrations in 

response to declines in Hg deposition 

that expected as the result of regulation 

of power plants. More information on 

the models EPA is considering using in 

the case studies (WASP, GBMM, 

SERAFM, EFDC, WhAEM2000, BASS, 

E–MCM) can be found on the Council 

for Regulatory Environmental Modeling 

(CREM) Models Knowledge Base 

(www.epa.gov/crem) and the Web site 

for the Ecosystem Research Division of 

the Office of Research and Development 

(ORD) (http://www.epa.gov/athens/). 

In pursuing these case studies, EPA is 

seeking information on the strengths 

and weaknesses of different approaches 

for modeling the anticipated response of 

fish tissue MeHg concentrations to 

declines in deposition for a nationalscale benefits methodology. The case 

studies will help determine the 

potential magnitude of response of the 

MeHg concentration in fish in marine 

and freshwater systems if atmospheric 

deposition from power plants are 

reduced, and what the expected time lag 

will be before a response is observed in 

fish. To complement these case studies, 

EPA is interested in both empirical 

information collected from ecosystems 

across the U.S. or modeled scenarios 

that show the temporal dynamics of Hg 

in different ecosystems. 

The case studies will also help 

determine the effects of ecosystem 

properties other than total Hg loading 

on accumulation in organisms and 

suggestions for how such information 

should be incorporated into the 

exposure analysis. To complement these 

case studies, EPA is interested in both 

empirical information collected from 

ecosystems across the U.S. or modeled 

scenarios that show the effects of 

ecosystem properties other than total Hg 

loading on accumulation in organisms 

in different ecosystems and, 

specifically, on new knowledge related 

to factors affecting methylation and 

demethylation in a range of aquatic 

ecosystem types. 

Using the best-available scientific 

understanding of key processes, these 

case studies will provide estimates of 

average rates and a distribution of Hg 

methylation rates and MeHg 

bioaccumulation factors (BAF) in 

different aquatic systems (freshwater 

and marine) across the U.S. for use in 

modeling. EPA seeks comment on data 

and/or analytical tools that can be used 

to forecast methylation rates and 

bioaccumulation rates in aquatic 

ecosystems. 

These case studies should provide 

detailed information on time lag, 

important ecosystem properties other 

than deposition rates, Hg methylation 

rates, and Hg BAF that can be used to 

inform how the results of a nationalscale MMaps application should be 

interpreted. We are seeking information 

on the strengths and weaknesses of 

applying MMaps to modeling the 

anticipated response of fish tissue MeHg 

concentrations to declines in Hg 

deposition for a national-scale benefits 

methodology. Additionally, EPA 

intends to document these case studies 

in the electronic docket for the CAMR 

and to make this information available 

to the public on the ORD’s website as 

soon as possible.

There are two final issues on which 

we are seeking comment that are 

relevant to the third step in our 

proposed revised benefits methodology. 

First, MMaps is designed to simulate 

natural freshwater systems. We 

currently do not have an appropriate 

69876 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

37See OAR–2002–0056–2578, –2589, and –2593.

38H. Hintelmann, R. Harris, A. Heyes, J.P. Hurley, 

C.A. Kelly, D.P. Krabbenhoft, S. Lindberg, J.W.M. 

Rudd, K.J. Scott, V.S. St. Louis. 2002. Reactivity and 

mobility of new and old mercury deposition in a 

boreal forest ecosystem during the first year of the 

METAALICUS study. Environ. Sci. Tech., 36, p. 

5034–5040.

39U.S. EPA. August 2004. 2003 National Listing 

of Fish Advisories. Office of Water. EPA–823–F–

04–016. Additional information available at

http://map1.epa.gov/.

40U.S. EPA. November 2001. National Fish 

Tissue Study. EPA–823–F–01–028. See http://

www.epa.gov/waterscience/fishstudy/.

41U.S. Food and Drug Administration. Mercury 

in Fish: FDA Monitoring Program (1990–2003). See 

http://www.cfsan.fda.gov/frf/seamehg2.html.

method for assessing how a change in 

the deposition of Hg relates to a change 

in the concentration of MeHg in fish 

tissue in fish found in marine 

environments and/or farm-raised 

species. We recognize, however, that 

marine and farm-raised species 

comprise a large proportion of the fish 

consumed by the U.S. population and, 

likely account for a significant fraction 

of the overall exposure. We are aware 

that EPRI has submitted an analysis that 

assumes the changes in Hg deposition 

resulting from regulation of emissions 

from coal-fired power plants will have 

an effect on MeHg concentrations in 

estuarine and marine species (salt-water 

species) proportional to the reduction in 

global emissions.37 We are evaluating 

EPRI’s proposed approach, but are also 

seeking comment on other potential 

approaches for analyzing effects in saltwater marine fish populations.

Second, as noted above, MMaps does 

not account for the time lag that exists 

between reducing Hg deposition and 

reducing MeHg concentrations in fish. 

MMaps instead assumes that a change 

in Hg deposition immediately translates 

into a change in MeHg fish tissue 

concentration. We are evaluating other 

tools that will enable us to assess this 

time lag issue. In particular, we are 

aware of the Mercury Experiment To 

Assess Atmospheric Loading In Canada 

and the U.S. (METAALICUS) study, 

which was cited in a number of 

comments received by EPA on the 

proposed CAMR. In METAALICUS, 

newly deposited Hg appeared to be 

more available to bacteria to convert to 

MeHg than Hg that was in the system for 

longer periods of time (i.e., historically 

deposited Hg).38 These results suggest 

that lakes receiving the bulk of their Hg 

directly from deposition to the lake 

surface would see fish MeHg 

concentrations respond more rapidly to 

changes in atmospheric Hg deposition 

than lakes receiving most of their Hg 

from terrestrial runoff. These data also 

imply that systems with a greater 

surface-area-to-watershed-area ratio that 

receive most of their inputs directly 

from the atmosphere may respond more 

rapidly to changes in emissions and 

deposition of Hg than those receiving 

significant inputs of Hg from the 

catchment area. We emphasize that the 

METAALICUS experiment is ongoing, 

and conclusions are still being refined. 

We do not know whether the 

METAALICUS results, or ones similar, 

would be found in different ecosystems. 

We are especially interested in 

information that can be used to extend 

or extrapolate the results of the 

METAALICUS experiment to other 

freshwater systems, and information on 

Hg cycling and bioavailability in coastal 

and marine ecosystems.

2. What specific comments did EPA 

receive on modeling ecosystem 

dynamics in response to the January 

2004 proposal and the March 2004 

supplemental proposal? EPA received 

several comments addressing existing 

MeHg accumulation in fish and 

anticipated MeHg fish concentrations 

associated with reductions in Hg 

emissions from coal-fired power plants. 

Several groups submitted independent 

analyses of the changes in fish MeHg 

concentrations expected as the result of 

changes in Hg deposition. Among these 

are comments or attachments submitted 

by the following: Bad River Band of 

Lake Superior Tribe of Chippewa 

Indians (OAR–2002–0056–2118); 

Environmental Defense (OAR–2002–

0056–2878); EPRI (OAR–2002–0056–

2578, –2589, and –2593); HBRF (OAR–

2002–0056–2038); Northeast States for 

Coordinated Air Use Management 

(NESCAUM) (OAR–2002–0056–2887 

and –2890); and TXU Energy (OAR–

2002–0056–1831). We are seeking 

comment on the analyses provided by 

the commenters. 

F. Step 4 of EPA’s Proposed Revised 

Benefits Methodology: Fish 

Consumption and Human Exposure 

1. Overview. Step 4 in EPA’s proposed 

revised benefits methodology addresses 

the relationship between reductions in 

MeHg concentrations in fish tissue and 

reductions in human exposure to MeHg. 

Fish obtained through commercial 

sources or noncommercial fishing 

activities come from both saltwater 

environments (including estuaries, bays, 

and the open ocean), and freshwater 

rivers, streams, lakes, and ponds.

Consumption of fish is the primary 

pathway for human exposure to MeHg. 

The fourth step in our methodology 

requires both an assessment of MeHg 

concentrations in freshwater and 

saltwater fish and an assessment of 

human consumption patterns of such 

fish. In this regard, we have been 

evaluating several databases for 

estimating MeHg concentrations in fish 

and consumption rates of such fish. 

EPA’s ongoing freshwater fish study, 

among other things, incorporates 

information from EPA’s National Listing 

of Fish Advisories (NLFA), which 

contains approximately 80,000 samples 

of MeHg in fish tissue from both 

freshwater and saltwater species.39

These data are voluntarily submitted by 

State agencies to the EPA and provide 

extensive coverage for the Eastern half 

of the U.S. Although the method of 

collection can vary by State, the NLFA 

data generally represent a combination 

of data collected from areas of increased 

angling activity and areas of suspected 

contamination. To the extent that the 

NLFA data are concentrated in areas of 

suspected contamination, the MeHg 

concentrations in fish based on these 

data may be biased and overestimate 

exposure to anglers and their families. 

The potential existence of this bias 

reflects the varying data collection 

methodologies that are selected by each 

State.

To supplement the NLFA data, EPA is 

considering using the recently 

completed 4-year field study, entitled 

the National Study of Chemical 

Residues in Lake Fish Tissue, which is 

also referred to as the National Fish 

Tissue Study (NFTS). The database 

contains about 1,000 samples of 

freshwater fish from 500 different lakes 

across the U.S.40 The NFTS is a 4-year 

national screening-level freshwater fish 

contamination study. It is also the first 

national fish tissue survey to be based 

on a statistical (random) sampling 

design, and it will generate data on the 

largest set of persistent bioaccumulative 

and toxic chemicals ever studied in fish. 

The statistical design of the study 

allows EPA to develop national 

estimates of the mean concentrations of 

268 chemicals in fish tissue from lakes 

and reservoirs of the lower 48 States. 

EPA will conduct a quality assurance 

analysis on the data for each year of the 

study. Additional information 

concerning NFTS is available at http://

www.epa.gov/waterscience/fishstudy/.

For saltwater fish, there are fewer 

samples of fish tissue MeHg data, 

relative to freshwater information. EPA 

is considering the use of the Mercury in 

Marine Life database (available through 

the NLFA) that provides data on the 

level of Hg contamination in the 

estuaries and marine environments 

nationwide, and the U.S. Food and Drug 

Administration’s (FDA) database of 

MeHg concentrations in fish.41

Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 69877

42See http://water.usgs.gov/pubs/sir/2004/5199/.

43Center for Disease Control. National Health and 

Nutrition Examination Survey. National Center for 

Health Statistics. See http://www.cdc.gov/nchs/

nhanes.htm and http://www.cdc.gov/mmwr/

preview/mmwrhtml/mm5343a5.htm.

44Peterson, D.E., M.S. Kanarek, M.A. Kuykendall, 

J.M. Diedrich, H.A. Anderson, P.L. Remington, and 

T.B. Sheffy. 1994. ‘‘Fish Consumption Patterns and 

Blood Mercury Levels in Wisconsin Chippewa 

Indians.’’ Environmental Health 49(1):53–58.

45Hutchinson, R., and C.E. Kraft. 1994. ‘‘Hmong 

Fishing Activity and Fish Consumption.’’ Journal of 

Great Lakes Research 20(2):471–487.

46 66 FR 1345, January 8, 2001.

47National Academy of Sciences. July 2000. 

Toxicological Effects of Methylmercury. National 

Academy of Sciences/National Research Council; 

National Academy Press.

48 Yoshizawa, et al. 2002. ‘‘Mercury and the Risk 

of Coronary Heart Disease in Men.’’ New England 

Journal of Medicine; Nov. 2002; 347(22): 1755–60. 

49 Guillar, et al. 2002. ‘‘Mercury, Fish Oils, and 

the Risk of Myocardial Infarction.’’ New England 

Journal of Medicine; Nov. 2002; 347(22): 1747–54. 

50Salonen, et al. 1995. ‘‘Intake of Mercury from 

Fish, Lipid Peroxidation, and the Risk of 

Myocardial Infarction and Coronary Cardiovascular, 

and Any Death in Eastern Finnish Men.’’ American 

Heart Association, 1995.

51 ‘‘In general, the RfD is an estimate (with 

uncertainty spanning perhaps an order of 

magnitude) of a daily exposure to the human 

population (including sensitive subgroups) that is 

likely to be without an appreciable risk of 

deleterious effects during a lifetime.’’ See http://

www.epa.gov/iris/subst/0073.htm.

52National Academy of Sciences. July 2000. op. 

cit.

With the above information on MeHg 

concentrations in fish tissue in freshand salt-water fish, the next question is 

how do we compute exposures to 

affected populations? We recognize that 

our analysis must be based on MeHg 

estimates for fish that are typically 

consumed by the U.S. population. The 

NLFA contains samples that vary by 

size (i.e., several are taken from fish that 

are potentially consumable based on 

size, while other samples are taken from 

smaller fish that are not likely to be 

consumed) and by species. To estimate 

the MeHg content in fish species that 

are typically consumed, EPA is 

evaluating the application of the NLFA 

and NFTS data to a statistical model 

developed by Dr. Stephen Wente, USGS, 

the National Descriptive Model of 

Mercury and Fish Tissue (NDMMFT).42

The model uses statistical procedures to 

estimate a relationship between fish size 

and MeHg concentrations, while 

controlling for fish species, sampling 

method, location, and other factors. EPA 

intends to conduct a peer review of the 

application of this model to the NLFA 

and NFTS data and will place the 

appropriate materials in the docket 

when available.

We are also collecting information on 

fish consumption rates by different 

affected populations, particularly in the 

eastern half of the U.S. We recognize 

that many Americans consume seafood 

or freshwater fish; however, some 

subpopulations in the U.S. (e.g., Native 

Americans, Southeast Asian Americans, 

and lower income subsistence fishers) 

may rely on fish as a primary source of 

nutrition and/or for cultural practices. 

Therefore, they may consume larger 

amounts and different parts of fish than 

the general population and may 

potentially be at a greater risk to the 

adverse health effects from MeHg due to 

increased consumption/exposure. We 

intend to use the following 

consumption data to complete our 

analysis concerning the relationship 

between reductions in MeHg 

concentrations in fish tissue and 

reductions of human exposure to MeHg.

a. Women of childbearing age—the 

National Health and Nutrition 

Examination Survey (NHANES) 

provides information based on the 

women who participated in the study.43

b. Children—Exposure Factors 

Handbook and NHANES provide 

information. 

c. Subsistence fishers and ‘‘high-end’’

consumers (including, but not limited to 

Native Americans and Asian 

Americans)—The Exposure Factors 

Handbook provides information for 

subsistence Native American fishers; 

Journal articles (Peterson, et al., 1994; 44

Hutchinson, et al., 1994 45) provide data 

for specific subpopulations such as 

specific Native American tribes and the 

Asian American population (i.e.,

Hmong) located in the Eastern half of 

the U.S. Peterson, et al. (1994) assesses 

the fishing activity of the Chippewa in 

Minnesota and Wisconsin. Hutchinson, 

et al. (1994) assesses the fishing 

activities of the Hmong living in 

Minnesota, Wisconsin, and Michigan. 

Other studies exist for these 

populations, but they do not address 

consumption behavior in the Eastern 

half of the U.S. EPA is interested in 

additional information for subsistence 

anglers (freshwater and/or saltwater), 

and for Native Americans or Southeast 

Asian Americans living in the Eastern 

half of the U.S.

Finally, EPA notes that the Methyl 

mercury Water Quality Criterion, which 

establishes a MeHg fish concentration 

designed to be protective of human 

health, estimates fish consumption 

rates. EPA is seeking comment on 

whether the MeHg fish concentration set 

forth in the Water Quality Criterion or 

the fish consumption rates used in the 

Water Quality Criterion could be used 

for local, regional, or national 

assessments.46

2. What specific comments did EPA 

receive on fish consumption patterns in 

response to the January 2004 proposal 

and the March 2004 supplemental 

proposal? Several commenters 

identified existing fish consumption 

data, including: CATF, NRDC, et al.

(OAR–2002–0056–3460); EEI (OAR–

2002–0056–2929); EPRI (OAR–2002–

0056–2578); Forest County Potawatomi 

Community (OAR–2002–0056–2173); 

Minnesota Conservation Federation, et 

al. (OAR–2002–0056–2415); and 

Southern Environmental Law Center 

(OAR–2002–0056–4222). We are seeking 

comment on the usefulness of the data 

provided by the commenters. 

G. Step 5 of EPA’s Proposed Revised 

Benefits Methodology: How Will 

Reductions in Population-Level 

Exposure Improve Public Health? 

A variety of human health effects are 

associated with MeHg exposure. 

Published MeHg research suggests there 

may be neurological effects during fetal 

and child development, including 

intelligence quotient (IQ) decrements 

and more subtle effects on the ability to 

learn.47 Numerous studies suggest that 

fish consumption has a beneficial 

cardiovascular effect in adult males as a 

result of its n-3 fatty acids (e.g., Omega3 fatty acids, etc.). However, research 

also raises the possibility that MeHg in 

fish can reduce the cardioprotective 

effects of fish consumption in adult 

males.48 49 50

The state-of-the-science regarding 

neurodevelopmental effects in children 

has been more thoroughly evaluated and 

reviewed than that for other health 

effects. A review by the National 

Academy of Sciences (NAS), published 

in July 2000, concluded that 

neurodevelopmental effects are the most 

sensitive and well-documented effects 

of MeHg exposure. EPA subsequently 

established a reference dose (RfD) 51 of 

0.0001 milligrams per kilogram of body 

weight per day (mg/kg/day) derived 

from a neurodevelopmental endpoint 

based on the NAS review. NAS 

determined that EPA’s RfD ‘‘is a 

scientifically justified level for the 

protection of public health.’’ 52

The RfD was based on three 

epidemiological studies of prenatal 

MeHg exposure in the Faroe Islands, 

New Zealand, and Seychelles Islands. 

These studies examined 

neurodevelopmental outcomes through 

the administration of numerous tests of 

69878 Federal Register / Vol. 69, No. 230 / Wednesday, December 1, 2004 / Proposed Rules 

53Myers, et al. 2003. ‘‘Prenatal Methylmercury 

Exposure from Ocean Fish Consumption in the 

Seychelles Child Development Study.’’ The Lancet. 

Vol. 361; May, 2003. 

54Crump, et al. 1998. ‘‘Influence of Prenatal 

Mercury Exposure Upon Scholastic and 

Psychological Test Performance: Benchmark 

Analysis of a New Zealand Cohort.’’ Risk Analysis, 

18(6): 701–713. 

55 Grandjean. 1997. Cognitive Deficit in 7-YearOld Children with Prenatal Exposure to 

Methylmercury. Neurotoxicology, 19(6): 417–428.

56National Academy of Sciences. July 2000. op. 

cit. at 267.

57See http://www.epa.gov/ttn/ecas/regdata/

Benefits/mercuryworkshop.pdf.

cognitive functioning.53 54 55 These tests 

provided partial or full assessments of 

IQ, problem solving, social and adaptive 

behavior, language functions, motor 

skills, attention, memory, and other 

functions. NAS found that all three 

studies are ‘‘well-designed, prospective, 

longitudinal studies.’’ 56

EPA is considering using these three 

studies to conduct a benefits 

assessment. Specifically, EPA is 

considering focusing on IQ decrements 

associated with prenatal MeHg exposure 

as the initial endpoint for quantification 

and valuation of health benefits of 

reduced exposure to MeHg. This initial 

focus in IQ as the neurodevelopmental 

endpoint for quantification was 

supported by participants in a Hg 

neurotoxicity workshop held by EPA in 

November 2002.57 Reasons for focusing 

on IQ include the availability of 

thoroughly-reviewed, epidemiological 

studies assessing IQ and/or related 

cognitive outcomes suitable for IQ 

estimation; and the availability of wellestablished methods and data for the 

economic valuation of avoided IQ 

deficits. EPA recognizes that, although 

IQ is a good metric of the cognitive 

impacts of prenatal MeHg exposure, IQ 

is not a comprehensive measure of the 

neurodevelopmental effects of MeHg 

exposure.

To potentially support a benefits 

estimation, EPA is working with 

researchers from Harvard University to 

analyze whether data from the Faroe 

Islands, New Zealand, and Seychelles 

Islands studies on the relationship 

between prenatal MeHg exposure and 

neurodevelopmental outcomes can be 

integrated. The study is intended to 

estimate the relationship between the 

exposure to MeHg and decrements in 

full-scale IQ, based on all three studies. 

The Harvard study will likely assume a 

linear dose-response relationship. The 

Faroe Islands and Seychelles Islands 

studies did not conduct the complete 

battery of tests used to estimate fullscale IQ. Therefore, the study is 

designed to use the results from the tests 

administered to predict full-scale IQ. 

This analysis will be peer-reviewed and 

placed in the docket as soon as it is 

available. 

EPA is considering using a K-model to 

fit population-level dose-response 

relationships to the pooled data from 

the three studies. EPA is also 

considering, for the purposes of a 

national-level benefits assessment, to set 

K = 1, which assumes a linear 

relationship between exposure and 

effects. 

The practicality of using a linear (K = 

1) model is the primary reason that the 

Agency is considering use of such a 

model. A linear model would allow us 

to estimate the benefits of reductions in 

exposure due to power plants without a 

complete assessment of the other 

sources of exposure. Other models 

would require information on the joint 

distribution of exposure from power 

plants and other sources to estimate the 

benefits of reducing the exposure due to 

power plants, which would require 

much more precise information about 

consumption patterns than a K-model 

would require. 

EPA is seeking comment on all 

aspects of the methodology for 

estimating the relationship between 

reductions in MeHg exposure and 

improvements in health. In particular, 

we are seeking comment on the 

following: 

a. The focus on neurodevelopmental 

health of children. 

b. The selection of IQ as an endpoint 

for quantification of 

neurodevelopmental effects and 

whether it is an appropriate endpoint 

for benefits analysis for reduced 

exposure to MeHg. 

c. Whether other neurodevelopmental 

effects can be quantified and are 

amenable to economic valuation. 

d. Whether, and if so how, data from 

the Faroe Islands, New Zealand, and 

Seychelles Islands studies can be 

integrated for the purposes of a benefits 

assessment. 

e. The choice of the K = 1 model for 

the estimating the relationship between 

exposure and IQ and practical 

alternatives to that approach. 

f. The appropriateness and 

consistency of using a linear doseresponse model given the RfD 

established by EPA in 2001 (reflecting 

the NAS review in 2000), which 

assumes a threshold dose below which 

there is not likely to be an appreciable 

risk of deleterious effects during a 

lifetime.

List of Subjects 

40 CFR Part 60 

Environmental protection, 

Administrative practice and procedure, 

Air pollution control. 

40 CFR Part 72 and 75 

Environmental protection, Air 

pollution control, Electric utilities.

Dated: November 29, 2004. 

Stephen D. Page, 

Director, Office of Air Quality Planning and 

Standards.

[FR Doc. 04–26579 Filed 11–30–04; 8:45 am] 

BILLING CODE 6560–50–P

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service 

50 CFR Part 17

RIN 1018–AJ10

Endangered and Threatened Wildlife 

and Plants; Notice of Availability of the 

Draft Economic Analysis on the 

Proposed Designation of Critical 

Habitat for Allium munzii (Munz’s 

onion)

AGENCY: Fish and Wildlife Service, 

Interior.

ACTION: Proposed rule; notice of 

availability of draft economic analysis 

and reopening of public comment 

period. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce the 

availability of a draft economic analysis 

on the proposed designation of critical 

habitat for the federally endangered 

Allium munzii (Munz’s onion), and the 

reopening of the public comment period 

on the proposed rule to designate 

critical habitat for Munz’s onion. The 

comment period will provide the 

public, Federal, State, and local 

agencies, and Tribes with an 

opportunity to submit written 

comments on this proposal and its 

respective draft economic analysis. 

Comments previously submitted for this 

proposed rule need not be resubmitted 

as they have already been incorporated 

into the public record and will be fully 

considered in any final decision.

DATES: We will accept all comments and 

information until 5 p.m. on or before 

January 3, 2005. Any comments 

received after the closing date may not 

be considered in the final decisions on 

this action.

ADDRESSES: Written comments and 

materials may be submitted to us by one 

of the following methods: