annually quantify actual emissions for purposes of calculating permit
fees. For those facilities subject to title V emissions reporting and/
or emissions quantification requirements, the EPA proposes that owners/
operators should use the same approaches to identify the emissions
sources of such facilities and to estimate and submit emissions data
under this subpart. Emissions sources at such facilities may include
portable sources (e.g., drill rigs), operation of units that, if on
land, would be stationary sources (e.g., boilers, control devices,
chemical processing equipment, refrigeration units), and marine vessels
(e.g., engines that power the movement of service vessels within 25
miles of an OCS source, and marine vessel engines used for other
purposes when stationary).
    In addition, the EPA proposes to require owners/operators of
facilities in Federal waters (as described above) to report all CAPs
when the PTE or actual emissions of one or more such pollutant exceeds
the reporting thresholds in Table 1A to Appendix A of this subpart.
This requirement is complementary to the previously described HAP
reporting requirements. For facilities meeting the CAP thresholds,
owners/operators would need to report all CAP pollutants and the
incidental CAP requirement would not be relevant to those facilities.
    Third, the EPA is assessing how these owners/operators should
report emissions data. In addition to meeting the other point source
reporting requirements under this subpart, the EPA proposes a
requirement for facilities operating in Federal waters to report
emissions using the Federal

waters region codes provided in the EPA electronic reporting system.
Because these Federal water regions are extremely large, the EPA
expects that most facilities will only operate within a single area,
but when portable facilities operate in multiple areas of Federal
waters, owners/operators would need to report those emissions
separately with different Federal waters region codes.
    Lastly, to support this proposed approach, the EPA further proposes
the definition of Federal waters to mean those waters over the ``Outer
Continental Shelf'' as defined in the Outer Continental Shelf Lands Act
(43 U.S.C. 1331(a)).
    The EPA also recognizes the possibility of duplicative reporting
related to any reporting that may be required by permits and/or for
assessing title V permit fees. To help avoid duplicative burden, the
EPA urges commenters to describe any duplicative burden that this
proposal may cause for emissions reporting.

C. Source Test Reporting

    To improve the data available to the EPA, States, and sources to
estimate emissions, the EPA proposes to require electronic source test
reporting (as first explained in section III.A.3 of this preamble) from
point sources for certain source tests. This action would require such
reporting for source tests already required to be performed, to help
improve emissions factors. An emissions factor is a key tool used in
the creation of emissions inventories, for example, to estimate air
pollutant emissions from a normally operating, point-source process or
activity (e.g., fuel combustion, chemical production). An emissions
factor relates the quantity of pollutants released to the atmosphere
from a process to a specific activity associated with generating those
emissions. For most application purposes, emissions factors are
intended to represent the average emissions for all emitting processes
of similar design and characteristics (i.e., the emissions factor
represents a population average). As such, emissions factors provide an
emission rate that may be appropriate for use by owners/operators of
facilities when site-specific source measurements of an emission
process are not available. While greater uncertainty is associated with
use of emissions factors as compared to site-specific source
measurements, it is nevertheless important to ensure that emissions
factors are high quality.
    EPA's most recent approach to develop emissions factors has been
prepared in response to a review of EPA's emissions factors program by
the National Academy of Sciences and EPA's Office of Inspector General.
In 2006, that review resulted in the Inspector General report
previously referenced in section IV.A.3 of this preamble. As described
in EPA's most recent documentation on emissions factor calculation
procedures,\41\ the EPA revised its emissions factor calculation
approach in response to that report. The EPA's emissions factor
procedures rely on direct measurement of releases from point source
processes or activities (i.e., a sample of the process emissions is
collected and analyzed). Hereafter, such measured emissions data from a
source will be referred to as ``source test data.'' EPA's progress on
improving emissions factors is limited to the available source test
data received by the Agency.
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    \41\ Recommended Procedures for Development of Emissions Factors
and Use of the WebFIRE Database, U.S. EPA, EPA-453/B-21-001,
November 2021, https://www.epa.gov/air-emissions-factors-and-quantification/procedures-development-emissions-factors-stationary.
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    As previously described in section IV.A.4 of this preamble, this
action proposes to require emissions reporting of annual total HAP from
owners/operators. The benefit of this HAP emission collection program,
however, depends on the quality of the annual emissions data reported
by owners/operators of facilities. The quality of the annual emissions
totals depends in part on the availability and quality of the emissions
factors, which in turn depend on the availability and quality of HAP
emissions source test data.
    While the Inspector General report highlighted the lower-than-
desired quality of published emissions factors, the EPA has thus far
been unable to revise many of these factors and continues to be limited
in part by the lack of source test data. This limitation remains
despite EPA's efforts to revise its regulatory framework of stationary
source emissions reporting to include electronic source test data
reporting as a component of industry-specific regulations included in
40 CFR parts 60, 61, 63, etc.\42\ The pace of progress on improving
these factors to date has been limited in part by the gradual nature of
adding industries and pollutants one regulation at a time. In addition,
since those regulations address specific pollutants and, in some cases,
allow for reporting of emissions of one pollutant (such as filterable
PM2.5) to serve as a surrogate for other pollutants (such as
specific HAP metals), sources do not always conduct tests for, and the
EPA does not receive data for, non-surrogate pollutants.
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    \42\ A complete list of regulations that require reporting to
CEDRI is available on EPA's website at https://www.epa.gov/electronic-reporting-air-emissions/cedri#list.
---------------------------------------------------------------------------

    In addition to the recommendations of the Inspector General Report,
States have long expressed their concerns with the many missing
emissions factors in addition to the low-quality emissions factors
included in EPA's AP-42 and WebFIRE emissions factor compilations.
These State concerns have been compiled and included in the docket for
this proposed action. Despite these concerns, these emissions factor
compilations largely remain a foundational piece of emissions
inventories. The States and the CAERS application use AP-42 and WebFIRE
emissions factor data to support owners/operators of facilities by
providing the emissions factors directly within the emissions
calculation tools used during emissions reporting. While owners/
operators are expected to use site-specific source test data to
calculate and report emissions when available and appropriate for that
use, the emissions factors are often the only emission rate information
available. Thus, improving the quality of the emissions factors is
central to improving emission inventory quality overall.
    With this proposed action, the EPA is seeking to improve emissions
factors to support improved emissions inventories via the proposed
collection of additional source test data. The EPA has recently
completed the updates to the WebFIRE system that automates most of the
emissions factor development processes described by the emissions
factor procedures document previously mentioned. As a result of these
efforts, the EPA issued its first set of revised emissions factors for
public review in November 2021.\43\ Now that the development procedure
infrastructure is largely completed, the EPA finds that increasing the
amount of source test data by obtaining information from the thousands
of emissions processes and hundreds of pollutants included for
stationary sources in the NEI is a logical progression in emissions
factor improvement. By improving emission factors, emissions estimates
are improved as well, supporting the needs for high quality data to
support EPA's regulatory and non-regulatory activities as described in
section IV.A of this preamble.
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    \43\ See https://www.epa.gov/air-emissions-factors-and-quantification/documentation-supporting-draft-and-final-emissions-factors.
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    To assess the feasibility of further collection of source test data
and gathering information to design the proposed approach, the EPA is

considering (1) whether source test data are readily available or could
be readily available, (2) how such data could be collected
electronically and efficiently, (3) which existing data would be of
interest to the agency, and (4) how to phase in any new reporting
requirements.
    The EPA is aware that direct measurements of facility or process
emissions are conducted for a variety of reasons, including
characterizing process emissions and/or control device performance,
assessing changes in process or control device operation on emissions,
and demonstrating compliance with Federal, State, local, or tribal air
regulations. Emissions testing may also be conducted as part of
performance evaluations such as relative accuracy test audits (RATAs).
Performance evaluations include linearity checks (which measure an
instrument's ability to provide consistent sensitivity throughout its
operating range) and routine calibrations of continuous emissions
monitoring system (CEMS) equipment, which provide emissions data much
more frequently than testing. Emissions data from CEMS are mostly used
for compliance purposes but can also be used for emissions factor
development. The reasons why such testing and evaluation occurs
includes both the CAP and HAP aspects of air quality planning and
implementation. Thus, these activities are conducted for a larger range
of pollutants than would be available from reporting required by
regulations under 40 CFR parts 60, 61, and 63, including those that
have been updated for electronic reporting and those that continue to
require testing and reporting by other means. Based on this
information, it appears to the EPA that additional unreported test data
are readily available.
    To aid owners/operators in planning and reporting the results of
emissions tests, the EPA developed the Electronic Reporting Tool (ERT),
and CEDRI. Further, the EPA has required their use in the revised
regulations previously described. The ERT is used by companies that
perform emissions testing for industrial sources and has been in use
for over 10 years. As the EPA has promulgated regulations to require
electronic reporting with the ERT, it has modified the ERT and CEDRI to
make sure that they support the source measurement methods required by
those regulations. As a result, the EPA has been collecting source test
data for selected pollutants from facilities regulated by those revised
rules for many years. The ERT and CEDRI collection infrastructure, in
addition to the recently implemented WebFIRE emissions factor
calculation procedures, will help ensure an efficient approach for data
collection and emissions factor development.
    Information collected by the EPA from the companies that perform
source measurements for industrial sources supports the idea that
electronic reporting for all pollutants via the ERT is commonly
supported by these companies. The EPA understands that it would be rare
to find any of these companies unfamiliar with the reporting via the
ERT. Some of our experience suggests that companies may find it more
difficult and more costly to prepare and submit reports in hard copy
(i.e., paper test reports) rather than reporting electronically, since
much of the data collection process has been made electronic.
    The EPA also is considering whether source test data should be
reported to the EPA directly by owners/operators or via the States.
States currently collect some test data as part of their implementation
of source permits and compliance, for example, when States require such
tests for their own reviews of emissions from stationary sources. Given
this current reporting, it is reasonable to expect that some States may
want to provide source test data to EPA. Such an approach might
parallel reporting that is currently done for CAP emissions and can be
done for HAP emissions. Including States in such reporting could have
the advantage of potentially meeting the needs of those States that
wish to be intermediaries or review the facility source test prior to
it being reported to the EPA for use in emissions factors.
    The possible disadvantage of States reporting the source test data
could be the added complexity that such an approach may cause. With the
existing CEDRI approach currently in place, States have a period during
which they may optionally review the source test results and advise the
EPA regarding the validity of the source test and any data quality
concerns that the State may have. In addition, when current EPA
regulations require source tests, they require that data to be reported
directly from owners/operators of stationary sources. Any difference
that might be proposed from that current approach could have a further
disadvantage of causing inconsistencies for owners/operators in how to
report source test data. Specifically, reporting under such an approach
could depend on whether the requirement to report for a pollutant and
process was under any finalized version of this proposed action or
under one of the other subparts of 40 CFR that require such reporting.
As a result of these significant disadvantages, the EPA expects that
any proposed action would be most efficiently and effectively
implemented through direct reporting of source test data to the EPA
from owners/operators and continuing to allow for State review and
comment.
    The EPA has additionally reviewed the requirements of the ERT to
ensure that the data collected with the ERT would be sufficient for the
purpose of generating emissions factors. To be able to use the source
test data for purposes of emissions factors, the EPA has identified
four additional types of information that are necessary to provide a
complete characterization of a unit's emissions in relation to its
operation. These are (1) the capacity of the unit being tested, (2) the
load of the unit during the testing period, (3) the level of activity
of the unit and operating conditions of the unit during the testing
period, and (4) process data (e.g., temperatures, flow rates)
pertaining to the unit and its control devices during the testing
period. All four of these are key components to ensuring emissions
factors appropriately represent unit operation. For example,
NOX emission rates from a unit operating at 50 percent load
using natural gas with 50 gallons per hour of ammonia injection differ
from a unit operating at 95 percent load using fuel oil with 75 gallons
per hour of ammonia injection. As a result, correctly computed
emissions factors from these separate modes could differ as well.
Without the full information, the EPA may not be able to discern the
differences in unit operation and incorrectly combine source test data,
which could lead to emissions factors erroneously assigned to certain
combinations of units, processes, and controls.
    As a result of these considerations, the EPA proposes to require
owners/operators of point sources to report performance test results
and performance evaluations that meet the following conditions: (1)
data would only be reported (under this proposed rulemaking) when they
are not otherwise reported to the EPA based on regulations listed at
https://www.epa.gov/electronic-reporting-air-emissions/cedri#list; (2)
the data are gathered to meet any other EPA or State requirement; (3)
the data are supported for reporting by CEDRI or an analogous
electronic reporting system; and (4) the results were not from a
project, method, device, or installation (or any component thereof)
that was produced, developed, installed, and used only for research
purposes. This final criterion

was added to avoid any potential conflict between the definition of
confidential data and the treatment of ``emission data'' in accordance
with 40 CFR 2.301. More information on the issue of confidential data
for this proposed action is available in section IV.H of this preamble.
    The EPA is seeking comment on these criteria. Specifically, the EPA
would be interested in knowing of examples of tests that meet these
criteria, but which do not meet the EPA's objective as described in
this section to support emissions factors. If such examples exist, the
EPA is further interested in suggestions of how to revise, or
supplement, the criteria to avoid collecting such information that does
not meet the objective of this section.
    Additional aspects of EPA's proposed approach to collect source
test data include the following. The proposed reporting, if finalized,
would be limited to include source tests and performance evaluations
beginning on the effective date provided in the final rulemaking. It
would require submission of data via CEDRI, including the four types of
information as previously noted: (1) capacity of the unit being tested,
(2) the load of the unit, in terms of percent capacity, during the
testing period, (3) the level of activity of the unit during the
testing period (e.g., input consumption rate, product consumption, heat
input, and/or output production rate), (4) operating conditions of the
unit during the testing period, and (4) process data such as
temperatures, flow rates, pressure differentials, pertaining to the
unit and its control devices during the testing period. The ERT would
need to be used when it supports the source test or performance
evaluation and, in other cases, a spreadsheet-based approach could be
required. Finally, each report would need to be submitted by the
scheduled date required by the State or Federal action motivating the
test. When no such date exists, the report would be required within 60
days of completing the source test or performance evaluation.

D. Reporting for Certain Small Generating Units

    With this proposed rulemaking, the EPA seeks to solve long-standing
challenges associated with emissions from certain types of intermittent
combustion sources. Interest in emissions and ozone formation on high
energy demand days (HEDDs) has led the EPA to consider collecting
information from sources that operate to offset electricity demand from
the electricity grid during these times. The EPA already collects
detailed data from EGUs through the Clean Air Markets Program, which
requires reporting of hourly data from CEMS as specified by 40 CFR part
75. In addition to these sources, other electricity units including
small generating units (less than 25 MW or otherwise not subject to
reporting under 40 CFR part 75 or the mercury air toxics NESHAP at
Subpart UUUUU of 40 CFR part 63) and backup generators (BUGs) are run
periodically both to offset grid-based energy needs at energy intensive
facilities and to generate electricity for the grid. These sources may
contribute significantly to tropospheric ozone on high-temperature days
in some areas, leading to public health concerns. As climate change is
expected to result in warmer summers, the use of this distributed
generation could increase. While such data are important to better
understand the environmental impacts of these sources, the EPA is not
currently collecting such data from States or owners/operators.
    Without data collection, EPA's understanding of these sources is
limited. First, the EPA lacks important details about intermittent
activity of these sources. For understanding ozone impacts, the EPA and
States have a compelling need to know when emissions occur on a finer
temporal resolution than typical annual emissions (i.e., which days).
Without such information, past studies \44\ have shown that efforts to
model HEDDs fail to fully characterize ozone formation on such days.
---------------------------------------------------------------------------

    \44\ Northeast States for Coordinated Air Use Management, High
Electric Demand Day and Air Quality in the Northeast, 2006. https://www.nescaum.org/documents/high-electric-demand-day-and-air-quality-in-the-northeast/final-white-paper-hi-electric-demand-day-06052006.pdf. Ozone Transport Commission, Stationary and Area Source
Committee, HEDD Workgroup, White Paper: Examining the Air Quality
Effects of Small EGUs, Behind the Meter Generators, and Peaking
Units during High Electric Demand Days 2016. https://otcair.org/upload/Documents/Reports/HEDD_Workgroup_White_Paper_Final_2016-11-10.pdf. Ozone Transport Commission, Stationary and Area Sources
Committee, Strategies to Reduce Emissions of Nitrogen Oxides on High
Electric Demand Days, 2017. https://otcair.org/upload/Documents/Meeting%20Materials/OTC_HEDD_Workgroup_Strategies_Whitepaper_Final_Draft_08282017.docx.
---------------------------------------------------------------------------

    Second, the EPA has reason to question the emission rates that
would be appropriate for estimating emissions from such sources.
Existing emission rates (i.e., emissions factors) for all units of any
type are based on emission source testing methods that are correctly
used during steady State operation of the emission unit to achieve
valid emission tests. By contrast, the operation of these intermittent
sources means that they are frequently turned on and off, which has an
unknown impact on the resulting emissions. As an illustration of the
issue, it is common knowledge that engines run more efficiently (thus
more cleanly) once they have warmed up. To the extent that units run
periodically spend more time in an inefficient State of operation, they
would be expected to have higher emissions rates. However, the impact
of such operation is not well understood, and the EPA is not aware that
it has been quantified.
    Over the past two decades, States and multi-jurisdictional
organizations have discussed with the EPA the possible importance of
intermittent sources on air quality. While some proposals have been put
forward to reduce the problem of emissions from these types of
intermittent units, the full understanding of the problem has been
limited based on lack of available data.
    In a 2017 publication, researchers from the University of
Wisconsin-Madison linked peak electricity demand to high levels of air
pollution.\45\ Using data collected from 27 States between 2003 and
2014, the researchers showed that the electricity used to power air
conditioners increased emissions of SO2, nitrogen oxides,
and carbon dioxide (CO2) by an average of almost four
percent for each pollutant per degree Celsius increase, above a certain
reporting threshold.
---------------------------------------------------------------------------

    \45\ Abel et al., Response of Power Plant Emissions to Ambient
Temperature in the Eastern United States, Environ. Sci. Technol.,
50, 10, 5838-5846, 2017. See also https://www.acs.org/content/acs/en/pressroom/newsreleases/2017/may/keeping-cool-in-the-summer-leads-to-increased-air-pollution.html.
---------------------------------------------------------------------------

    While they have received more attention in recent years, emissions
from these small generating units have been historically challenging to
track, a fact that has contributed to EPA's aim to understand and
improve the data in this sector. The EPA recognizes that emissions from
small generating units may increase as extreme weather and temperature
events are likely to become more frequent.\46\ Alongside this potential
rise in emissions are increases in public health risks from
tropospheric ozone formation, as well as nitrogen oxides and PM
emissions.
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    \46\ U.S. Global Change Research Program, Fourth National
Climate Assessment, Volume II, Impacts, Risks, and Adaptation in the
United States, Chapter 4: Energy Supply, Delivery, and Demand, 2018.
https://nca2018.globalchange.gov/.
---------------------------------------------------------------------------

    As a result of past investigations, some States have explored how
they can gather information about intermittent sources. For example,
the Maryland Department of Environmental Quality (MDEQ) requires that
Curtailment Service Providers (CSPs) provide data to the State under
COMAR <IP_ADDRESS>.

CSPs are entities that administer electricity demand response programs
by working with companies that use and generate electricity to decrease
electricity demand by deploying capacity from smaller units like BUGs
that can reduce demand from the electricity grid. The Maryland
regulation requires CSPs to report information about the units they
administer, including unit capacity, manufacturer, and model as well as
the types of fuel used and information about the days and hours of
operation. It also sets an exclusionary threshold based on output. It
excludes emergency stationary engines with an output less than 500
horsepower (hp) and excludes non-emergency stationary engines with an
output less than 500 hp that serve as a primary source of power for
agricultural equipment or industrial equipment. While this information
only partially addresses the needs for the State, discussions with MDEQ
identified that the information collected has helped the State
understand the scope of the intermittent unit emissions. This example
provides some evidence that partial data collection can inform the
larger temporal patterns in emissions associated with intermittent
sources.
    The EPA is also aware that federally enforceable regulations can
limit the ability of source operators to deploy older or more polluting
engines. Examples of such regulations include the NESHAP for
Reciprocating Internal Combustion Engines (RICE) in 40 CFR part 63,
subpart ZZZZ; the New Source Performance Standard (NSPS) for Stationary
Compression Engines in 40 CFR part 60, subpart IIII; and the NSPS for
Stationary Spark Ignition Engines in 40 CFR part 60, subpart JJJJ.
These rules define allowable emission rates and, as a result, limit the
types of sources that can be deployed. These rules do not restrict use
of units that meet the emissions standards, which can be deployed for
electricity generation during HEDD periods, and these rules do not
collect information that would help understand the impact of such
sources.
    The EPA also is considering the uncertainty associated with
emissions rates from units that are operated intermittently, as
previously described. This consideration is important because it
impacts whether the EPA would require reporting of emissions values
and/or other emissions data such as fuel use and unit types. If
emission values (i.e., mass of pollutants) were provided alone, then
whatever emissions rates were selected by data reporters would be the
basis for the emissions. In this case, the EPA would not be able to
adjust the emissions based on any improved emissions rate data that may
become available. Additionally, with emissions values alone, the EPA
would not be able to explore the impact of different emissions rates on
the ability of the data to better predict modeled air quality. Thus,
based on the limitations that would be imposed, the EPA is proposing to
collect information on fuel use or heat input and unit types.
    The EPA is considering all the factors described above and has
weighed the importance and long-standing need for the data to
understand ozone formation in some areas, the uncertainty associated
with emissions rates, and the potential burden of the various options
available. The EPA is considering the potential burden that could be
caused by requiring emissions or activity data reporting from States
from small generating units used to reduce electricity demand or meet
that demand during peak energy needs. Any requirements imposed on
States by this proposed action could in turn be imposed by States on
their sources for collection by the State and subsequent reporting to
EPA. The EPA also recognizes the great deal of uncertainty about units
associated with HEDDs and has included in this preamble one proposed
approach, one additional option, and 2 additional alternatives that the
agency is considering.
    Based on these considerations, the EPA is proposing requirements
for some States and certain owners/operators. First, the EPA proposes
that States would report facility inventory information (e.g., unit
characteristics) and daily fuel use or heat input data for units that
operate during the year at point sources (as defined by this proposed
action) and that meet specific criteria. Those criteria are (a) the
hourly or daily emissions and activity data from the unit are not
otherwise reported to the EPA, (b) the unit was operated to offset
electricity demand from the electricity grid, and (c) the unit is
located at a facility that operates on land. This approach is intended
to collect data for the appropriate units and avoid duplication with
any reporting done as part of other EPA requirements. By limiting
reporting to those small generating units for which hourly or daily
heat input data are not otherwise reported, EPA would ensure that data
reported to the EPA to comply with 40 CFR part 75 or other regulations
would not need to be re-reported under the AERR.
    Second, the EPA proposes to require owners/operators of facilities
located outside the geographic scope of States' implementation planning
authority to report for units at point sources that meet the same
criteria as the units that would be reported by States. For the
purposes of this preamble, the units covered by the proposed
requirement just described will be referenced as ``small generating
units''.
    Third, the EPA proposes a definition of small generating units to
mean ``any boiler, turbine, internal combustion engine or other unit
that combusts fuel on an occasional basis to generate electricity for
the electricity grid or for on-site use by a facility other than for
emergency use.'' Because the proposed reporting requirement would not
cover any units already reporting to the EPA and would cover units only
at point sources that are already being reported to EPA, the EPA does
not believe that the definition needs to specifically identify by size
which units are ``small,'' since larger units are presumably reporting
because of their size based on other regulations.
    The data elements that the EPA proposes would be reported include
identification of each small EGU used to offset electricity demand from
the electricity grid for a given year; the unit's rated capacity in hp
and kilowatts; the unit's manufacturer and model; the installation date
of the unit; source classification code (including the fuel type); and
for each day of operation: the emissions reporting period, reporting
period type as daily, date of activity, fuel used or heat input and
associated units of measure, and optionally the start hour and end hour
of operation. These small generating units would need to be reported to
reflect the data fields included in proposed Table 2A to Appendix A of
Subpart A and Table 2C to Appendix A of Subpart A. Finally, the EPA
proposes that this reporting would start with the 2026 inventory year
and that the deadline for such reporting would be one year and 15 days
after the year after the inventory year (e.g., the deadline for
reporting 2026 emissions would be January 15, 2028).
    Under these proposed requirements, States would have the
flexibility to either collect the data from the CSPs (where such
entities exist) or from the owners/operators of facilities that operate
small generating units. This implementation could include other
entities, such as large energy companies, that also have agreements
with other companies to deploy small generating units periodically
under certain circumstances. The EPA expects that collecting that data
from the CSPs or other types of companies with demand reduction
agreements would provide the lowest burden option for States.

Additionally, the EPA expects that the CSPs and other companies
aggregating demand side reductions could be in the best position to
gather from the owners/operators of small generating units the data
that needs to be reported as part of their normal operations. This
design could reduce burden because the number of CSPs and other
companies with demand reduction agreements within a State could be far
smaller than the number of facilities with small generating units that
operate in any particular year.
    The proposed requirements would require activity data for small
generating units in addition to the State's best estimate of annual
emissions for small generating units that are already required under
the current AERR and proposed to continue to be included under this
action. The EPA recognizes the challenges of estimating such emissions
based on the measurement challenges for startup/shutdown conditions
noted above regarding emissions factors.
    The EPA is proposing these requirements in part based on the idea
that by obtaining data from some of the small generating units (i.e.,
those operating at point sources as defined by this proposal), enough
information could be collected about temporal patterns to allocate
emissions from the remaining small generating units. Those other
emissions from small generating units are currently covered in the NEI
as part of the nonpoint county-total emissions based on overall State
fuel consumption and available emissions factors. Under the proposed
requirements, the EPA would collect more limited data from point
sources as defined and extrapolate that the temporal patterns apply to
the portion of nonpoint fuel combustion data associated with small
generating units.
    The proposed requirements have at least two limitations. First,
since the nonpoint fuel combustion emissions are based on standard
emissions factors, they may not accurately reflect startup/shutdown
related emissions from such units. Second, the proposed requirements
are incomplete because they limit the units required to be included to
only those units at point sources as defined by the proposed point
source definition in this action. Many BUGs and other units deployed
for demand reduction are located at retail establishments that are
unlikely to be major sources (because of low emissions) and are
specifically excluded from the definition of non-major sources by the
NAICS codes the EPA is proposing to be included in this proposal. Not
having all units would create two challenges: (a) the EPA would need to
determine with some other data source what portion of the nonpoint fuel
combustion should be temporally allocated based on the data collected
because this proportion may vary with each year in relation to
temperatures and the deployment of units for demand reduction; and (b)
the incomplete set of units also would not include the spatial detail
that would otherwise be achieved by having coordinates for all
individual units operated to meet peak energy needs.
    As part of the proposed requirements described above and to avoid
the associated limitations, the EPA is co-proposing and requesting
comment on one option and two alternatives. None of these options
addresses the limitation of emissions factors during startup and
shutdown, but they do either collect activity data from more units or
limit the data collection to reduce burden. The proposed requirements
described above are referenced below as the ``preferred alternative.''
    The EPA proposes an option to require a one-time collection from
all small generating units for a single year. The EPA is considering
including this ``One-time Collection Option'' in addition to the
preferred alternative and is also considering whether to use the One-
time Collection Option as the sole approach in any final action. To
accomplish the one-time collection, the EPA would require CSPs and
other operators or aggregators of small generating units (not States or
owners/operators of point sources) to report to the EPA the same data
elements as are described in the preferred option (i.e., the facility
inventory and daily fuel use or heat input) for either the 2024 or 2025
inventory year. The EPA would select which year in the final rule. The
deadline for such reporting would be October 31 the year after the
inventory year (e.g., for 2024 reporting, October 31, 2025).
    The One-time Collection Option would help the EPA to determine
whether and how to implement an annual reporting requirement, and it
could inform the development of some predictive model to avoid a need
for annual reporting. For example, a one-time study could allow for
correlation between the one-time data and other routinely available
data (such as temperature, fuel prices, and electricity prices), such
that the EPA could use such other data to calculate emissions from
intermittent generation for subsequent emission inventory years. A one-
time collection could also provide locations of units included in CSPs
to improve spatial allocation of nonpoint emissions to the model grid
cells for air quality modeling. In addition to providing more detailed
data, an advantage of a one-time collection requirement is that it
would have a lower burden on the CSPs than would an ongoing
requirement. The disadvantage of a one-time requirement is that a
correlation may not be found, and thus this rule would need to be
further revised, delaying the receipt of such information by the EPA
and States.
    The EPA is also co-proposing and requesting comment on two
alternative approaches that would replace the preferred alternative.
With Alternative D2, the EPA proposes to expand the preferred
alternative to require data from States for all small generating units
that are not otherwise reported to the EPA rather than only those at
point sources. Alternative D2 would not expand the point source
definition in a way that would require reporting of annual emissions.
Rather, Alternative D2 would require States to report the facility
inventory information, estimated annual emissions, and daily activity
data as described under the proposed approach, but only for small
generating units. Other point source requirements for facilities with
such units would apply only for those facilities that meet the point
source definition included in this proposal. For example, a retail
facility that is excluded because of its primary NAICS code for HAP
reporting and otherwise does not emit pollutants at levels required to
be reported as a point source would only need to be included in the
State report for the small generating units that operated during the
reporting year. If the EPA finalizes Alternative D2, the same State
deadlines for point source reporting would apply. Under this
alternative, no adjustment would be made for owners/operators of
facilities within Indian country. Alternative D2 has the advantage of
collecting more detailed data but the disadvantage of higher burden on
States and the entities from which they collect that data.
    Finally, the EPA is co-proposing and requesting comment on
Alternative D3, which would reduce burden on States relative to the
preferred alternative by requiring reporting about small generating
units from only those States that have ozone non-attainment areas and
those States linked to downwind non-attainment areas as would be
identified in whatever transport regulatory action has most recently
been promulgated by the EPA on January 1st of the emissions year. One
disadvantage of Alternative D3 is that the EPA does not currently have
data about whether the small generating units within non-

attainment areas are the only ones that are important in terms of
impacting air quality within non-attainment areas, because the EPA does
not have data on any such units irrespective of their location. In
general, the EPA is aware that emissions sources outside of non-
attainment areas can contribute to ozone within those areas, and small
generating units could be a type of source that could contribute. In
the preferred alternative, emissions data from small generating units
at all point sources would be collected, and the EPA could use that
information to determine which small generating units contribute to
higher ozone concentrations within non-attainment areas. The advantage
of Alternative D3 is that it would decrease the number of potential
States required to report from 50 to 23, the number with ozone non-
attainment areas, plus States linked to downwind non-attainment areas.
Alternative D3 would have the same requirements for the types of units
and the data fields to report as the preferred alternative but would
limit the States and owners/operators that would need to report.

E. Provisions for Portable and Offshore Sources

    As previously noted, the EPA intends for the NEI to include a
complete accounting of point sources that meet the emissions reporting
thresholds included in this proposed action. The current AERR does not
clearly address some atypical cases, which include portable facilities
(e.g., asphalt plants) and offshore sources (e.g., oil rigs, drilling
engines on barges, windfarm installation vessels) within State waters.
This action seeks to address both the definition of a portable facility
and to ensure that such sources are reported to the NEI.
    While portable facilities can move, they are not necessarily
considered with the nonpoint or nonroad mobile source portion of the
NEI. Under the current AERR, when these portable facilities meet the
point source reporting threshold, States can report them as point
sources without specific location information. In reporting portable
facilities, States use a placeholder county code of ``777'' to indicate
that those sources move around a State throughout the year. In this
way, no location coordinates are then required for reports of portable
facilities. The problem with the current approach is that the location
of emissions is not available for modeling the air quality impacts of
the source. If a portable source remains in a single location for a
long enough period, then it could conceivably have impacts on local air
quality and States. The EPA, States, and the public may, therefore,
benefit from location information to properly account for the facility.
    Some States are currently reporting atypical sources to the NEI,
but it is not clear that all such sources are being reported from all
States. Some of these facilities have emissions that exceed the point
source PTE CAP reporting thresholds, and with new HAP reporting
thresholds that may be adopted based on this proposed action,
additional portable facilities may need to be reported. A robust
offshore source inventory of drill rigs is available for facilities
operating in Federal waters under the jurisdiction of the Bureau of
Ocean Energy Management, and the EPA is proposing in section IV.A.B of
this preamble to collect data from facilities operating in Federal
waters under EPA jurisdiction. These facilities, however, do not
include facilities operating in State waters (e.g., oil platforms,
drilling engines on barges, construction activities, wind turbines).
Emissions from these sources should be reported by States as point
sources when such sources exceed the point source reporting thresholds.
Finally, reporting emissions for portable facilities requires a
specific treatment of county codes and location information, and the
requirements for that type of reporting are not explained in the
current AERR requirements.
    Based on these considerations, the EPA proposes to clarify that
both portable facilities and offshore facilities within State waters
should be considered when States determine which sources should be
reported to meet point source requirements of this proposed action. The
EPA also proposes to add a definition of portable facility to mean ``a
facility that does not have a fixed location such as an asphalt plant
or portable land or sea-based drilling rig.'' In addition, this action
proposes to include an explanation to use county code ``777'' to
reflect the lack of county specificity when such sources are moved
among counties over time. Facilities reported in this manner would
still need to be reported for their emissions within a State. This
proposal also includes an exception for the requirement of submitting
facility air centroid coordinates or for release point coordinates for
portable facilities.
    The design of this proposed action leaves open the possibility that
the owner/operator of a portable facility may need to report emissions
when the annual emissions of the facility exceed any of the emission
reporting thresholds used to define point sources. Two special cases
for reporting could arise from these scenarios. All cases that
reference operations within States and Indian country include
operations within any waters associated with those areas (e.g., State
waters).
    First, the EPA proposes that portable facilities operating solely
within Indian country where a tribe or State does not report CAP or HAP
emissions data would be required to report emissions and to designate
the tribe in which it operated using the EIS Tribal Code provided by
EPA. In this case, owners/operators of a portable source would follow
the same reporting requirements as for stationary facilities. For
example, this proposed requirement would mean that owners/operators of
portable sources would report CAP and HAP directly to EPA when neither
a tribe nor a State reports that emissions data.
    Second, the EPA proposes a requirement that portable facilities
operating across State and/or Indian country boundaries would report
directly to the EPA any emissions not reported by those States and/or
tribes. Relevant CAP or HAP emissions would need to be reported by
State and/or by tribe per other requirements of the rule. The EPA
proposes that owners/operators could optionally include the specific
time periods during which they operated in each region with their
emissions reports. This case includes both tribes that do not report
CAP or HAP and States that do not report HAP.
    This ``base alternative'' approach as just described would not
resolve the potential issue of portable facilities that remain in a
single location for a period that could impact local air quality. It
also does not resolve the temporal aspect of such emissions. The
information currently available to the EPA is that examples of such
sources are not widespread enough to warrant the additional complexity
associated with reporting a portable facility's emissions at multiple
locations and/or multiple time periods. However, the EPA continues to
seek information on the potential for portable facilities to adversely
impact local air quality, what type of information would be useful to
collect to better understand any air quality issues caused by such
sources, and how the EPA could most effectively collect information
from such sources.
    The 2017 NEI includes emissions reported by States from more than
1,300 portable facilities such as asphalt plants. While most of these
facilities are reported to emit actual emissions levels below the CAP
PTE reporting threshold, some of these facilities included significant
emissions for specific pollutants. For example, 41 portable facilities
have between 20 and 177 tons

of NOX, and 5 facilities have between 20 and 243 tons of
VOC. Two portable facilities contributed more than the proposed
emissions reporting threshold of Pb emissions (0.074 tons). While these
amounts are small nationally, they could significantly impact the local
air quality if the source was stationary for a significant period
within a year.
    Because the EPA recognizes that such portable sources, if
stationary for long enough, could be an important local source, the EPA
is proposing an option that may be included in the final rule, but is
not currently included in the base alternative. The EPA is proposing
that in addition to the base alternative, this ``Portable Definition
Option'' would include a categorization of portable facilities to put
them into two groups: (1) those that report as portable facilities as
in the base alternative and (2) those that report as stationary
sources. The EPA proposes that the two categories of portable
facilities would have different reporting requirements as follows.
Facilities would be defined as portable and required to report as
portable sources only for periods when the source remains within a 1-km
radius for fewer than 30 days. Facilities would be defined as
stationary and be required to report as a stationary point source when
the facility operates within a 1-km radius for 30 days or more. This
Portable Definition Option would require the point source report to
include the county identifier and coordinates of the centroid of its
operations during each time period. The EPA would provide additional
data formats that would support a requirement for States and owners/
operators to provide portable facility locations for each 30-day (or
more) period using the start and end dates of operation within a 1-km
radius (i.e., a single location could be provided associated with each
30-day period). The EPA urges commenters who have information about
such portable sources to comment about the advisability of EPA's
proposed requirements under the Portable Definition Option.
    The EPA is also considering Alternative E1, that would replace the
base alternative described above. Rather than require States to report
portable sources as point sources, Alternative E1 would require States
to report portable sources aggregated as county totals but include
monthly emissions rather than annual emissions as in the base
alternative. This alternative would allow States to track and aggregate
all such portable facilities but report only by county and month. While
the tracking of emissions from such sources would still be needed by
States on a facility-specific basis, this option reduces the reporting
complexity for States. For Indian tribes, this option would work in
conjunction with the additional proposed requirements described in
section IV.L of this preamble to report emissions from their boundaries
disaggregated by the portion of their lands overlapping each county.
This alternative would not be available to owners/operators. If the EPA
were to adopt Alternative E1 in any final action, the EPA proposes that
owners/operators would still be required to report as described in the
base alternative. The EPA urges commenters to provide their ideas on
the advisability of this alternative.

F. Reporting Deadlines for Point Sources

    In this proposed action, the EPA is proposing the dates by which
point source requirements would be required to be met for States and
owners/operators that are reporting emissions directly to EPA. We are
also considering the interaction between the two types of deadlines. In
this section, we discuss and propose State deadlines first followed by
deadlines for owners/operators.
1. Deadlines for States for Point Sources
    The current AERR requires States to report point sources by
December 31 of the year after the inventory year. Thus, for the 2020
inventory year, the current State deadline is December 31, 2021. In the
past, the EPA has used its enforcement discretion to allow States a 2-
week grace period to complete their emissions because of the holiday
season in which the current deadline occurs. In this action, the EPA
proposes to include what is now an unofficial grace period in the
current AERR deadline for the 2023 through 2026 inventory years by
setting the deadline to January 15 that occurs 1 year and 15 days after
the end of the inventory year. For example, the deadline would be
January 15, 2025, for the 2023 emissions inventory year. The EPA also
proposes a phase-in to earlier point source deadlines starting with the
2027 inventory year based on a variety of considerations described in
this section.
    While most States receive data from point sources between March and
October, most States do not start submitting point source emissions for
the previous year until December. As a result, any problems that the
States encounter in reporting their emissions in December often cannot
be resolved in time to meet the current AERR deadline. In more rare
cases, States have changed their software for handling emissions data,
and it is either not working properly or not completed in time for
States to meet regulatory deadlines.
    During the time between when States collect point source emissions
data and when it is submitted, the States' role is to perform QA on
emissions data, resolve any quality issues by having owners/operators
resubmit their emissions, format the data for submission to EPA, and
complete the EPA submission while resolving any QA errors sent by EIS.
States also assess fees on the owners/operators of point sources based
on emissions levels. The EPA is not aware of all the challenges that
States face to complete these tasks but is aware of some of them as
described next.
    States can have difficulty meeting any changes made to the EIS data
elements or formatting requirements. For example, even with 18 months
advanced notice, webinars, repeated reminders, and frequent newsletters
that included information about changes to the EIS data format for
controls, many States were left unaware of those changes as late as the
fall of 2021 when the data were due in just a matter of weeks. The EPA
recognizes that, even if States are working to ensure they meet any
changes to the reporting approach, they may have limited time and
resources to do so. States have also expressed concerns with their
information technology departments when those departments are
responsible for maintaining and revising State emissions reporting
systems.
    Despite the challenges meeting the existing deadline, the needs and
expectations for faster data turnaround continue to grow. While the
public has become accustomed to hourly updates on ambient air quality,
the emissions data lags years behind. The EPA's uses of the NEI all
benefit from more timely receipt of data because the EPA can then use
it to inform regulatory and non-regulatory analysis and decisions. With
the current AERR deadline, the States have 1 year to submit their point
source data, which is two-thirds or more of the time between the end of
the inventory year and the first NEI point source release. The EPA has
reduced the time it takes after receiving the data to combine State
data with other data sources, quality assure the data, and augment the
data to fill gaps or exclude flagged data that have not been addressed
by States. While EPA continues to streamline its point source data
processing efforts, only so much more improvement can be expected when
States take the majority of the overall time it takes to release the
inventory. By considering earlier State reporting deadlines, the EPA
hopes to

achieve further improvement in timeliness of the point source NEI.
    Other EPA emissions inventory programs collect data directly from
owners/operators, and their deadlines are earlier. For example, the TRI
program collects data for a given reporting year from owners/operators
by July 1 of the following year,\47\ releases a preliminary dataset by
the end of July, and publishes the National Analysis dataset a few
months later, typically mid- to late-October. The data are published
from TRI before the NEI data are even due to be submitted by States.
Another example is the GHGRP, which collects data from owners/operators
by the end of March and publishes its results by October or
November.\48\ While the States add value to the NEI reporting process
by reviewing emissions data from point sources, the current approach
requires more time than may be warranted.
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    \47\ The TRI deadline is described in 40 CFR 372.30(d).
    \48\ The GHGRP deadlines are described in 40 CFR 98.2(i).
---------------------------------------------------------------------------

    The current timing of the NEI is unsatisfactory to EPA, some
States, and the public. While everyone wants emissions data sooner, the
collection, review, and publication of data for the NEI takes time, and
resources are not always sufficient. Decisions and environmental
improvements based on new information are delayed when the data take
longer to produce.
    The disadvantages of less timely data have been known for years;
however, the EPA is aware that one of the root causes of the time
constraints have been resource limitations for the States. Until
recently, the EPA has not had a potential solution to aid States in
meeting their reporting requirements. By using CAERS for collecting
emissions data from owners/operators of point sources, States now have
a new option to assist in gathering, reviewing, and submitting high
quality emissions data more quickly.
    State efforts to report for the NEI involve four primary steps for
each inventory year: (1) configure a data reporting system; (2) support
owners/operators using the reporting system, including training; (3)
review data submitted by owners/operators for errors until owners/
operators resolve them; and (4) format data from the State system and
submit it to the EIS. CAERS can reduce burden for states because the
EPA makes sure that it is maintained with the latest AERR reporting
requirements, which greatly reduces the State burden for maintaining
the emissions reporting system. Since CAERS is integrated with the
latest QA checks and uses the latest available emissions factors
(including state-provided factors), States also can expect that data
collected with CAERS is more likely to use the best available emissions
estimation approaches. Finally, since CAERS converts and submits the
data to the EIS, States can expect that the burden of that part of
their role to be largely eliminated.
    In addition to the benefits of the existing CAERS approach for
States, the EPA intends to further integrate CAERS with the WebFIRE
database to provide direct access for owners/operators to the latest
emissions factors and emissions rates they have reported to CEDRI (this
would not change the public availability of the data in WebFIRE).
Because this proposed action would require owners/operators to report
certain source tests, this future CAERS advancement will streamline the
use of these data by owners/operators and States. Usually, these source
test data provide a better estimate of emission rates from facilities
than do average emissions factors more traditionally used by States in
their data systems. As a result, CAERS provides States a mechanism for
both improved timeliness and improved emissions data quality.
    While the need for more timely data is clear, the challenges for
States of any changes to an earlier deadline are significant. The EPA
is considering that any proposed change in deadlines would need to be
weighed against the time States would need to adapt to any new timing
requirements as well as any other changes finalized based on this
proposed action. While some States may have sufficient resources to
continue to report data using their own data systems, they may need to
change regulations and processes to adapt to an earlier deadline. The
EPA has heard from States that it can take 2-3 years to change their
emissions reporting regulations. Thus, States that must change those
regulations to meet an earlier deadline would need time to do so.
    Other States that choose CAERS to help augment their emissions data
collection and reporting approach may also need to change their
reporting requirements, and they would need sufficient time to migrate
from current processes to a CAERS-based approach. Depending on a
variety of factors, this process can take between 1 and 3 years.
    Based on these considerations, the EPA proposes to add 15 more days
to the point source reporting deadline through the 2026 inventory year.
The deadlines for point source reporting for the 2023 through 2026
inventories would be within 12 months and 15 days of the end of the
inventory year (e.g., for the 2022 inventory year, by January 15,
2024). This deadline and others are summarized below in section IV.S of
this preamble.
    The EPA additionally proposes to establish point source reporting
deadlines shorter than one year for inventory years 2027 and beyond. We
propose to do this through a phase-in of earlier deadlines. With the
preferred approach, the EPA proposes that for the 2027 through 2029
inventory years, States would report point source data to the EPA
within 9 months of the end of the inventory year (e.g., for the 2027
inventory year, by September 30, 2028). Then, starting with the 2030
inventory year and for every inventory year thereafter, States would be
required to report point source data to the EPA within 5 months of the
end of the inventory year (e.g., for the 2030 inventory year, by May
31, 2031). The EPA is proposing to collect this data sooner than the
current AERR requires because having more current data benefits EPA's
work. Further, many States already have their data collected from
owners/operators much earlier and submit it earlier than the current
AERR deadlines. Other States can adjust to collect data earlier so they
can report it earlier. CAERS could provide States an option for
assistance with such an adjustment.
    In addition to this preferred approach, the EPA seeks comment on
alternatives for phase-in of these earlier dates more gradually.\49\
Alternative F1 could provide for a slower phase-in of earlier point
source reporting deadlines. The EPA is considering that the inventory
year for the first deadline change could occur for inventory years 2028
or 2029. The EPA is considering that the second deadline change could
occur for inventory years 2031 or 2032.
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    \49\ Faster phase-in of earlier reporting dates is not under
consideration due to EPA resource and other implementation aspects
necessary to support states in joining CAERS.
---------------------------------------------------------------------------

    The EPA is also seeking comment on Alternative F2, which provides
alternative reporting dates for the earlier deadlines. The EPA urges
commenters to suggest alternative deadlines, provide rationale
supporting those other deadlines, or provide support for the deadlines
proposed. For the first deadline change (under the preferred approach,
starting for the 2027 inventory), the EPA is considering alternatives
of August 31 and October 31. For the second (and final) deadline
change, the EPA is considering

alternatives of April 1, April 30, and June 30.
    While the phase-in described in the preferred approach is the
fastest approach under consideration, the EPA urges commenters to
provide information and analysis if they believe such an approach may
be too rapid, and which of the alternative phase-in dates would work
better and why, or why the preferred approach is a good solution.
    In addition to the preferred approach and the alternatives on which
the EPA is specifically soliciting comment, the EPA will consider
appropriate combinations of phase-in timing as well as alternative
deadlines. The EPA urges commenters to suggest alternative combinations
of phase-in schedules and new deadlines if they believe that some other
combination is appropriate, provide information and rationale that
supports other combinations, or provide support for the preferred
alternative.
2. Annual Emissions Deadlines for Owners/Operators of Point Sources
    As previously described in this preamble, the EPA is proposing
annual emissions data reporting to the EPA from owners/operators of
point sources, which can be either for HAP alone for facilities within
States or both CAPs and HAP for facilities within Indian country and
Federal waters. Additionally, owners/operators of point sources within
Indian country may be required to report data for intermittent sources
of electricity generation under certain circumstances. The EPA proposes
deadlines for these requirements in this section.
    To explore the options for reporting by owners/operators, the EPA
is considering four factors: (1) the amount of time it takes to prepare
reports, (2) the availability of EPA's CAERS reporting system for each
annual reporting cycle, (3) other emissions reporting deadlines that
owners/operators must meet, and (4) coordination with State deadlines.
Consideration of these factors allows for a phase-in for owners/
operators that synchronizes with any phase-in of earlier deadlines for
States that may be finalized.
    First, the information an owner/operator needs to report emissions
is largely collected during the year of the emissions inventory. For
example, owners/operators keep track of their facility production rates
throughout the year, fuel usage, and other throughput and activity data
used to estimate emissions from each unit and process. For sources with
CEMS, throughputs and emissions are available within days. Source tests
performed during the year that would be required to be used under this
action can be completed and reported to the EPA within 60 days.
Emissions factors needed by sources are available on a continuous basis
through AP-42 and WebFIRE, through CAERS, or via a State reporting
system. For these reasons, the EPA expects that the data needed for
owners/operators to report emissions to the EPA would be available at
most within 60 days after the end of the inventory year.
    Second, the EPA has only been using CAERS for three emissions
inventory years. For each of these, the EPA has successfully met
objectives for including the States and associated owners/operators
expected for each reporting year. While this proposed action, if
finalized, is likely to greatly expand the adoption and use of CAERS,
the EPA expects that it can continue the success of past experiences
for future inventory cycles. The release date for CAERS for each
inventory year is expected to be between February 1 and February 28 of
the year after the inventory year.\50\ Thus, any deadlines that the EPA
would consider should need to leave sufficient time between the CAERS
release date and any due dates to accommodate owners/operators who
report directly to the EPA under any final action taken on this
proposal.
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    \50\ For the 2022 inventory year, the EPA released CAERS for
reporting on February 6, 2023.
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    Third, other EPA reporting program deadlines are also important to
consider from the perspective of owners/operations. For the GHGRP,
reports are due by March 31 of each year and for the TRI, reports are
due by July 1 of each year. The EPA understands that different owners/
operators could have different needs associated with any proposed
timing requirements in this action. Some owners/operators may
appreciate keeping the deadlines incremental, so that each requirement
could be met in turn. This approach would allow industry staff to
inform decision makers and report certifiers of the reports before they
are sent. Other owners/operators could prefer the idea of consolidating
reporting to multiple systems through CAERS, as well as consolidating
deadlines.
    Finally, the EPA is also considering the relationship of the data
being collected by each of the programs. The NEI program to relies on
GHG emissions from the GHGRP where such reporting is required. This
action does not propose allowing for owners/operators to voluntarily
report GHGs to the NEI program (though States could continue to report
them voluntarily). Therefore, the data connection between the GHGRP and
the NEI is limited to the facility characteristics as well as the
activity, such as fuel consumed, that may be used to estimate emissions
both of GHGs and of pollutants required under any final version of this
proposed action.
    The NEI program and the TRI program both collect emissions from
each program's unique list of chemicals. As previously described, to
meet programmatic needs, this action proposes to collect HAP emissions
for individual units, processes, and release points within facilities.
This proposed requirement is analogous to the current voluntary HAP
reporting by States for NEI. For reporting by owners/operators, the HAP
emissions estimated at the more detailed resolution for NEI could
inform the air emissions portion of the TRI reporting requirement. In
fact, the CAERS approach has recognized this potential connection
between NEI and TRI for HAP; therefore, the EPA designed TRI-MEweb to
access the emissions sums reported to CAERS for stack emissions and
fugitive emissions when preparing a TRI reporting. This connection
suggests that it may be beneficial to have an AERR deadline for owners/
operators be prior to the TRI reporting deadline.
    In addition to the other emissions reporting requirements, the EPA
recognizes potential benefits of coordinating reporting deadlines for
owners/operators with the proposed State reporting deadlines previously
described. This coordination is particularly relevant considering that
some States may choose to report HAP on behalf of owners/operators. The
available options are for owners/operators to report before States
submit data, at the same time, or after States' submissions. To address
this issue, we explore a complex but streamlined example envisioned by
this proposed action, whereby a State chooses to reduce its overall
burden by participating in CAERS for CAPs but not adopt HAP reporting.
In this case, owners/operators in that State would use CAERS to report
HAP emissions directly to the EPA and report CAPs to the State. We
expect that owners/operators would prefer to submit all their emissions
together, rather than have different deadlines for different
pollutants. With this example, the State would then need time to
quality assure the CAP emissions and resolve any concerns with owners/
operators. For this example to work, the owners'/operators' deadline
would necessarily need to precede the State deadline so that the State
would have sufficient time to perform its review prior to passing

the data along to EPA. While other examples exist, the EPA has been
unable to find another approach that addresses the needs for the
implementation options included in this proposed action.
    As previously described, this action also proposes a phase-in of
earlier deadlines for States. As a result, deadlines for owners/
operators would need to be adjusted in accordance with any changes to
State deadlines.
    Based on these considerations, the EPA is proposing a requirement
in which reporting from owners/operations would gradually increase. The
EPA would allow reporting to be optional in the first year and then
mandatory after that, as follows: Starting in the 2024 emission
inventory year, owners/operators of facilities could optionally submit
annual emissions data and any required daily fuel consumption for
specific units by May 31, 2025. This would allow those owners/operators
to report data directly to the EPA for any reason. The EPA additionally
proposes that for the 2025 inventory year, any owner/operator of a
point source that is located outside the geographic scope of the
State's implementation planning authority would be required to report
annual emissions data and any required daily fuel consumption for small
generating units by May 31, 2026. Other owners/operators could continue
voluntary reporting for the 2025 inventory year and then be subject to
mandatory reporting for the 2026 inventory year. This would allow for a
gradual increase in owner/operator reporting to ensure the CAERS system
can best support owners/operators through the process. This approach
would also allow the EPA to obtain data from sources within Indian
country sooner than it otherwise would to fill a current gap in EPA's
understanding of emissions.
    For the 2026 emissions inventory year, this action proposes that
all owners/operators subject to reporting for point sources would
complete submission of annual emissions and any required daily fuel
consumption for specific units to the EPA by May 31, 2027. This
requirement would apply both to point sources within Indian country as
well as point sources within States that have not been approved for
submission on behalf of owners/operators. Owners/operators within
States that have been approved to report HAP on their behalf would not
be subject to this proposed deadline (but rather to whatever deadline
is imposed by the State).
    The proposed May 31 deadline is earlier than the TRI reporting
deadline to address the relationship that exists between this proposed
action and existing TRI requirements. The EPA is considering that an
earlier date may not allow sufficient time for owners/operators to
transition to submitting reports directly to the EPA for some or all
their pollutants. In addition, for States that want to align their
requirements with this date to provide owners/operators reporting CAPs
to the State, the May 31 date provides States 7 months and 15 days to
complete their tasks and meet the January 15 reporting deadline
proposed for States for the 2024 and 2025 inventory years.
    Starting with the 2027 emissions inventory year and every year
thereafter, this action proposes that owners/operators of point sources
would complete submission of annual emissions and any required daily
fuel consumption for specific units by March 31 of the year following
the inventory year. The first date for meeting this requirement would
be March 31, 2031, for the 2030 inventory year. This earlier date
aligns with the second State earlier date phase-in to the proposed
State reporting requirements of May 31, 2031.
    The EPA is aware that some industries may, due to workload
concerns, have an interest in not aligning the proposed reporting
deadline from facilities with the GHGRP deadline of March 31. Though
the proposed approach described above would change the deadline for
owners/operators from May 31 to March 31, the EPA continues to evaluate
this proposed approach, and is requesting comment and additional
information on the expected impacts of that proposed deadline. The EPA
would also consider a later deadline for owners/operators that would be
either April 15, April 30, or May 15 of the reporting year. The EPA
urges commenters to describe additional considerations about which the
EPA may not be aware of to advise on a reporting deadline for the final
rule.
3. Summary of Reporting Deadlines and Phase-In Years
    Table 3 below provides a summary of the proposed point source
reporting deadlines for annual emissions of the preferred approaches
proposed in sections IV.F.1 and IV.F.2 of this preamble. These
deadlines would not apply to the collection of source test data. This
proposed phase-in approach is dependent on an assumed final
promulgation date prior to June 2024. If a final version of this
subpart were delayed beyond June 2024 or if comments on this proposal
lead to an approach for a final rule, the EPA may delay the phase-in of
earlier deadlines.

Table 3--Summary of Proposed Point Source Reporting Deadlines for Annual
                             Emissions Data
------------------------------------------------------------------------
                               Deadline in months after end of inventory
-----------------------------        year for reporting to the EPA
                             -------------------------------------------
            Phase                    States           Owners/operators
------------------------------------------------------------------------
Phase 1: 2022 through 2024..  12 months and 15      n/a.
                               days.
Phase 1: 2025...............  ....................  5 months (within
                                                     Indian country).
Phase 1: 2026...............  ....................  5 months (all
                                                     facilities).
Phase 2: 2027 through 2029..  9 months............  5 months.
Phase 3: 2030 and beyond....  5 months............  3 months.
------------------------------------------------------------------------

G. Point Source Reporting Frequency

    EPA is considering the frequency of point source reporting and is
proposing that point source reporting be done for the same sources
every year beginning with the 2026 inventory year. This proposed
approach would eliminate the reduced reporting requirements on interim
(non-triennial) years for point sources and would not affect the
frequency of reporting nonpoint or mobile sources.
    By way of background, the current AERR requires point source
reports from States for two categories of point sources: Type A and
Type B (Table 1A to Appendix A of this subpart). States must report
every year for Type A sources (which are point sources that exceed PTE
reporting thresholds of 250 tpy for most CAP and 2,500 tons for CO,
NOX, and SO2). No annual (i.e., only triennial)
reporting threshold exists specifically for Pb, but Pb emissions are
required to be reported annually when a source meets the PTE reporting

threshold for other pollutants above the Type A reporting thresholds.
States must report every third year for Type B sources, which have
lower reporting thresholds than the Type A sources. For parts of a
State in attainment for a relevant NAAQS, the criteria pollutant and
precursor PTE reporting thresholds for Type B sources are 100 tpy. For
CO, the PTE reporting threshold for Type B sources is 1000 tons/year,
and the Pb actual emissions reporting threshold is 0.5 tons. For
nonattainment areas with a Serious designation or above, lower
reporting thresholds for Type B sources exist for some pollutants,
depending on the NAAQS for which an area is in nonattainment. As
explained more below, the EPA is now proposing to do away with our
approach to distinguish between Type A and Type B sources.
    The current triennial approach, which was designed in part to
reduce burden on States, stems from the CAA section 182(a)(3)
requirement for ozone for which States must submit a revised inventory
no later than the end of each 3-year period after submission of their
SIP base year inventory required for Marginal nonattainment areas and
above. The EPA has continued this 3-year approach despite the expansion
of the NEI to include PM and optionally HAP and GHGs.
    The EPA has found that the inventory for each year is important and
useful to contribute to a variety of activities the EPA performs under
the CAA. Having more information every third year and less information
for other years has made it difficult for the EPA to effectively
utilize the NEI data for certain purposes such as evaluating emissions
trends, regulatory modeling, and non-regulatory modeling including
national efforts to estimate risks from HAP. As described in sections
IV.A.1 through IV.A.3 of this preamble, current HAP data needs to be
readily available for having accurate information to support technology
reviews and filling gaps in the MACT standards as per the LEAN decision
previous described. Additionally, EPA's AirToxScreen will have access
to more complete and current data to inform the public, support
prioritization of compliance activities, and to inform understanding of
risks faced by disadvantaged communities in support of various
environmental justice priorities.
    The EPA has also experienced challenges with the current approach
of more limited point source data on non-triennial years. For example,
the Great Recession occurred between December 2007 and June 2009. Real
gross domestic product did not regain its pre-crisis peak level until
the third quarter of 2011. Thus, the bulk of the impact on industrial
sources and reductions in their emissions occurred during 2009 and
2010, two years when the NEI collected only the Type A data. Thus, the
point source emissions inventory for those years did not reflect the
full extent of the impacts on emissions of the Great Recession.
    Similarly, impacts from the COVID pandemic started in 2020 (a
triennial inventory year in which we collected data from both Type A
and Type B sources) and has continued into 2022. The pandemic has
caused both activity decreases and facility closures for some
industries as well as increases in activity for other industries. Other
impacts to emissions-related activities caused by supply chain problems
and price changes to fuels that may also have impacted emissions. The
EPA anticipates that any potential impacts of the pandemic and
industrial recovery on emissions could only be partially captured under
the current AERR relying on Type A sources for non-triennial years.
    Because of greater data limitations for non-triennial years, the
EPA has traditionally tried to rely on the triennial NEI for regulatory
modeling of criteria pollutants, for example, for ozone transport
analysis or an RIA for a new NAAQS. However, using a triennial NEI has
not always been possible, because a modeling year is selected not only
based on the emissions inventory, but also on the meteorological
conditions that, in some years, lead to the formation of more ozone and
more exceedances of the ozone NAAQS. When the EPA updates a NAAQS or
transport rule and needs to perform an RIA and when States need to
develop SIPs, it is important to use a modeling year that exemplifies
the problem to be solved (e.g., a modeling year that models ambient air
above the level of the NAAQS). This year is not always a triennial NEI
year because of meteorological conditions and/or overly active fire
seasons. In fact, EPA's most recent regulatory modeling platform was
developed for 2016, which is not a triennial NEI year. A large amount
of additional coordination with the States and multijurisdictional
organizations was needed to refine the 2016 emissions to reflect 2016
for Type B sources that had not been reported to the NEI.
    For regulatory analysis of HAP in support of future technology
reviews under CAA 112(d)(6) and discretionary risk review, the EPA
needs the most currently available data. For these reviews, the data
need includes not only the actual emissions, but also the control
technologies and other changes made to industrial facilities and their
associated emissions rates for HAP. This is particularly important for
the Technology Reviews for which the EPA is responsible for conducting
periodically for each industry and in which the EPA considers
developments in practices, processes, and control technologies. The
emissions inventory data form the baseline emissions for Technology
Reviews, which are a key component of EPA's analyses of potential
control options, emissions reductions, and cost-effectiveness. The
latest data about the controls and technologies at the facilities,
provided by an emissions inventory, allow EPA to create a more
effective and credible review. About 25 sectors per year need to
undergo Technology Reviews each year, to meet the review schedule of
every 8 years. If a HAP reporting requirement is finalized, continuing
with a triennial approach would mean that the EPA would not always have
the most up-to-date information for the Technology Reviews. Current
limitations have required the EPA to conduct one-time efforts for
providing additional data that could have already been available via a
standardized NEI process.
    Annual HAP reporting will provide other benefits in addition to
those discussed above. For example, the EPA has recently committed to
providing annual updates of its air toxics data. The annual
AirToxScreen will provide updated emissions and risk information, to
both document the ongoing risks posed by some facilities and to provide
communities with the information they need to understand those risks.
The EPA intends to produce these updates annually to take advantage of
the best available data and to help inform emissions trends, ideally to
show progress in reducing risks to communities. Therefore, a triennial
approach to collecting point source data would reduce the effectiveness
of these efforts because all sources would not be updated on the same
timescale.
    Not only does the EPA have an interest in having the most current
information, but EPA's work with stakeholders has provided insights
into the challenges owners/operators face when EPA includes outdated
data in its NEI releases. For example, in the recent AirToxScreen
releases for 2017 through 2019, some commercial sterilizer facilities
had either ceased operating or installed additional controls to reduce
ethylene oxide emissions. During review of these data prior to release,
States and EPA regional office representatives heard from these
facilities and informed EPA that they

wanted the agency to use the more current data because emissions were
lower. Because these changes in operations had not occurred in the
historical years, rather than adjust the modeled concentrations and
risks in these historical years based on more current information, EPA
added notices on the website for each of these facilities to indicate
when operations ceased or when controls had been installed that would
reduce emissions after the year of the AirToxScreen release. Similarly,
when EPA used data that was several years old in support of regulatory
decisions, in cases when one-time information collections could not be
accomplished due to timing or other constraints, industry has commented
about EPA's flawed data and insisted that more current data be used.
With an annual approach for reporting emissions, the EPA could best
reflect emissions controls and lower emissions in the NEI data,
AirToxScreen, and regulatory assessments.
    Finally, as the EPA strives to best serve the public, EPA's ability
to receive updated and timely emissions data provides a foundational
piece of information needed to support many aspects of EPA's mission.
This need is already illustrated by other EPA emissions data
collections such as TRI, the GHGRP, and the Air Markets Program, which
all collect data annually using consistent criteria each year.
    As described, the EPA has identified several limitations with the
existing approach for which we receive more limited data 2 out of every
3 years. It is important to resolve those limitations as quickly as
possible to limit future impacts. The primary reasons for the triennial
approach were (1) the original CAA basis of the rule as previously
described, (2) the burden on States, and (3) the burden on the EPA to
create an NEI every year. Each of these reasons has less weight now
than it had for previous AERR revisions, as described in the following
paragraphs. At the time these decisions were made, the burden on
owners/operators was not considered; however, we are considering these
burdens now. Even with these additional burdens on owners/operators
considered, the EPA expects the benefits of the data collection to be
justified.
    Regarding the original CAA basis for ozone and triennial periodic
inventories, the EPA notes that inventories at least every three years
are necessary to administer the ozone nonattainment area RFP provisions
of section 182 (i.e., rate-of-progress, RFP, and milestone compliance
demonstration provisions). The EPA also notes that the timing of ozone
NAAQS nonattainment designations, which has implications for the
inventory year that a State may select for their baseline inventory for
the nonattainment area, does not necessarily align with the triennial
inventory years established in the AERR. Thus, the EPA has allowed
States to select the initial baseline inventory year (which serves as
the RFP baseline year) using either the most recent triennial year or
the year of the effective date of designation for that NAAQS. While
there may be valid planning reasons for States to choose a non-
triennial year, the practical ability for States to do this can be
constrained by the availability of adequate inventories during non-
triennial years. Moreover, with respect to the attainment demonstration
obligation, modeled attainment demonstrations for ozone and PM may
require base years other than triennial years to reflect meteorological
conditions conducive to the nonattainment problems faced by a State.
Thus, even though the Act requires a minimum triennial inventory
approach for ozone nonattainment areas, experience suggests that having
annually updated inventories provides benefits for criteria pollutant
implementation in addition to the other benefits that will occur.
Importantly, nothing in section 182 prohibits the EPA from requiring
updated inventories on a more frequent basis.\51\
---------------------------------------------------------------------------

    \51\ See CAA section 182(a)(3)(A), which states that ``No later
than the end of each 3-year period after submission of the inventory
under paragraph (1) until the area is redesignated to attainment,
the State shall submit a revised inventory meeting the requirements
of subsection (a)(1) of this section'' (emphasis added).
---------------------------------------------------------------------------

    Since the 2008 promulgation of the AERR, technology for data
collection and compilation has advanced significantly. Starting with
the 2008 inventory year, the EPA provided the EIS to collect data
electronically from States, and many States have developed their own
electronic reporting approaches. The EPA has further refined and
improved the EIS over time to provide additional QA, quality control
(QC), and summary information features for State and the EPA inventory
developers to help streamline the process and ultimately reduce burden
for both States and EPA's NEI program. In addition, the EPA developed
and released the CAERS application in 2019, which can support States
that wish to have a more modern and robust emissions reporting system
that meets AERR requirements. While the step of transferring State's
emissions collection and reporting systems to CAERS has an initial up-
front (though voluntary) burden, the longer-term information
technology, and programmatic efficiencies of sharing a reporting system
with the EPA and other States would be significant.
    Although the motivations and new developments described above build
a strong case for collecting the same point source data every year, the
EPA is considering some additional information in evaluating the
advisability of such an approach. This additional information includes
what States have been reporting for non-triennial years voluntarily and
the experiences of States that are already using CAERS for emissions
reporting.
    The EPA recognizes that States have reported voluntarily more
sources than required on non-triennial years. For the 2019 inventory
year, for which States were required to submit only Type A sources, 34
out of 82 State, local, and tribal agencies submitted roughly the same
number of point sources as they submitted for the 2017 triennial year.
This means that these States voluntarily submitted their triennially
required sources instead of the fewer sources required. Some
differences between years are to be expected because facilities open
and close. These submissions represented about 11,000 facilities out of
about 54,000 facilities submitted by agencies for either year, when
considering those facilities that reported NOX,
SO2, or VOC. Thus, because these 11,000 facilities represent
about 20% of the 54,000 total facilities, we estimate that the
incremental actual burden associated with requiring the same sources
every year is about 20 percent lower calculated on a per-facility basis
than it would be if these agencies were not already sending in such
data. These States would meet an annual point source requirement
without additional effort or burden (if the frequency change were the
only change).
    To build on the 2017 and 2019 analysis, we compared emissions
between 2017 and 2019 for those sources with 2017 emissions less than
Type A reporting thresholds and which had emissions in both 2017 and
2019. Sources that were not reported in both years were dropped. For
NOX the median emissions increase or decrease between 2017
and 2019 was less than 5 tons, which given the 100 tpy PTE reporting
threshold is a small difference. This suggests that many sources do not
change much from one year to the next. However, the NOX
changes for any one facility ranged from an 1,800-ton decrease to a
2,800-ton increase. In all, 672 facilities had emissions of 100 tons

or more in 2017 and more than a 25 percent increase or decrease in
emissions in 2019. Similarly, for SO2, the median change
between 2017 and 2019 was less than 1 ton, and the range of changes
were a 1,900 ton decrease and a 4,600-ton increase. There were 347
facilities with emissions of 100 tons or more in 2017 and more than a
25 percent increase or decrease in emissions in 2019. For some of the
uses of the NEI by the EPA and certainly for SIP inventories, the
magnitude of these changes can be impactful in local areas. Thus, the
EPA observes that including year-specific inventory data is important
to promoting the quality and use of the NEI for the purposes laid out
in sections IV.A.1 through IV.A.3 of this preamble and in this section.
    In discussions with States as part of the routine interactions
associated with creating the NEI and as part of ongoing outreach for
CAERS, State emissions inventory staff have volunteered the information
to the EPA staff that they collect these point sources because of State
regulations, and it is less work for them to report all the point
sources every year rather than taking extra steps to limit what is
reported in the non-triennial years. This response speaks to the
benefit (for the vast majority of States with annual reporting
regulations that include additional sources beyond those required by
the AERR) of streamlining, automating, and taking the same approach
each year.
    The EPA also is considering the experiences of States that are
already using CAERS for emissions reporting. Transitioning to CAERS for
these States has had its own one-time challenges, in part because the
system is new. Other than those initial challenges, however, the
States' experience using CAERS for the 2018 through 2020 inventory
years has been that their work is primarily focused on supporting
facilities and quality assuring data, rather than setting up their data
system or formatting data from the State system and submitting it to
the EIS.\52\ Since CAERS includes the QA checks in EIS for owners/
operators to get feedback and make corrections while reporting, once
the data has been accepted by CAERS, it largely can flow to the EIS
without much effort for States.
---------------------------------------------------------------------------

    \52\ See ``Georgia Partners with the EPA to Pilot Combined Air
Emissions Reporting System'' and ``From CHAOS to CAERS: Improving
Inventory Reporting Workflows in the District of Columbia,'' which
are both available in the docket for this proposal.
---------------------------------------------------------------------------

    Based on these considerations, the EPA proposes to change the
reporting thresholds so that they are the same for all years (EPA will
no longer distinguish between Type A and Type B sources). Further, the
EPA proposes implementation of this requirement to take effect the
first non-triennial year after promulgation of the final rulemaking for
this proposed rulemaking (expected to be 2027).
    The EPA is also considering whether the 2027 inventory year is too
soon for some States to implement changes that would enable them to
collect data from all point sources that otherwise would not be
reported until the 2029 inventory year. Thus, the EPA is considering
Alternative G2 to use the 2028 inventory year as the first year for
implementation of the same reporting thresholds every year. The EPA is
interested in comments about the feasibility of the base alternative of
a 2027 inventory year requirement (data would be due by September 30,
2028, under the preferred phase-in alternative described in section
IV.F.1 of this preamble) when compared to Alternative G2 that would use
a 2028 inventory year requirement (data would be due by September 30,
2029, under the preferred phase-in alternative).
    Irrespective of the implementation challenges for States, the EPA
is proposing that owners/operators within States not reporting on their
behalf would report annual emissions data for the same sources every
year beginning with the 2026 inventory year. As previously described,
the EPA is proposing that owners/operators operating facilities within
Indian country and Federal waters would report annual emissions data
for all applicable sources beginning with the 2025 inventory year. The
requirement for annual reporting by owners/operators is based on the
importance of year-specific data for many sources and EPA's ability to
implement CAERS for many new reporters. Nevertheless, the EPA is
interested in comments providing information and analysis about the
feasibility for sources to report directly to the EPA voluntarily for
the 2024 inventory year in two cases: (1) facilities that are within
the geographic scope of a State's implementation planning authority and
(2) all other facilities. In the first case, if there would be
unforeseen challenges for States or owners/operators in the case where
owners/operators are reporting HAP when the State is reporting CAPs, it
would be helpful for commenters to provide information on any such
challenges so the EPA can better evaluate the options it is considering
in this rulemaking.
    A provision of the current AERR in 40 CFR 51.35 provides States the
opportunity to submit Type B point sources over a 3-year period to
spread out their emissions inventory work rather than have a reporting
burden spike in the triennial years. For point sources, this existing
provision at Sec.  51.35(a)(2) says that States may ``collect data for
one-third of your sources that are not Type A point sources.'' That
provision continues by including ``Collect data for a different third
of these sources each year so that data has been collected for all of
the sources that are not Type A point sources by the end of each 3-year
cycle. You must save 3 years of data and then report all emissions from
the sources that are not Type A point sources on the triennial
inventory due date.'' The advantage of this provision is that States
can balance state workload. With the annual reporting for all sources
proposed in this action, the EPA is additionally proposing to remove
the provisions of 40 CFR 51.35 in the current AERR.

H. Clarification About Confidential Treatment of Data

    The existing requirements in the AERR include a statement about
confidential data at 40 CFR 50.15(d), which states ``[w]e do not
consider the data in Tables 2a and 2b in Appendix A of this subpart
confidential, but some States limit release of these types of data. Any
data that you submit to the EPA under this subpart will be considered
in the public domain and cannot be treated as confidential. If Federal
and State requirements are inconsistent, consult your EPA Regional
Office for a final reconciliation.'' This section of the current AERR
was intended to clarify that the data required to be reported to the
EPA under the AERR would not be treated as confidential by EPA.
    The context of this discussion and clarification on confidential
data and the NEI relates to EPA's intent to continue its current
practice of releasing point source emissions data on a regular basis.
Point source emissions data collected by the Agency will be available
to States and EPA staff via the EIS within months of its receipt. The
EPA expects to make such data publicly available via EPA's website
within the year after receipt. While some data fields may not currently
be published on EPA's website, the EPA provides that data upon request.
The EPA may change the composition of the data published, timing, or
method of any release of collected information without further notice.
    Since the provision in Sec.  50.15(d) of the current AERR was
promulgated, it has led to some confusion that the EPA is now seeking
to clarify with revisions.

For example, the EPA has received claims by States that, under the
current AERR, they do not need to report some data to the EPA because
the State considers that data entitled to confidential treatment. One
local air agency claimed that it could not report SCCs that describe
the emissions process to the EPA under the requirements of the AERR
because it claimed that information was confidential under State law.
Other agencies do not report the throughput data from their sources,
despite it being a required field currently in the AERR. The EPA's
understanding of the reasons for withholding such required data is that
States consider the throughput data to be confidential so the local
agencies cannot report it. The EPA recognizes that the existing wording
of Sec.  50.15(d) could be confusing and could contribute to the lack
of reporting for certain data elements. Nevertheless, the existing
language of Sec.  50.15(d) was not intended to allow States not to
submit certain data or to claim required data as entitled to
confidential treatment from EPA.
    To address this confusion and to articulate more clearly EPA's
position on confidentiality for all information States and owners/
operators are required to report under the AERR, the EPA proposes to
add language to clarify the classification of data collected under this
action. In addition, the EPA is proposing changes to clarify that those
parties required to report under this subpart cannot decline to report
certain data elements based on a claim that the data is entitled to
confidential treatment. Specifically, the EPA proposes to add the
determination that all data that parties are required to report under
the revised AERR, including the data from the additional categories
associated with emissions testing, is ``emissions data'' as defined at
40 CFR 2.301(a)(2)(i). As emissions data, the reported information is
not subject to confidential treatment in accordance with CAA section
114(c), which provides for the public disclosure of such information.
This proposed revision is intended to clarify that the EPA will not
treat any data reported to the EPA under this rule (including the HAP
data) as confidential in accordance with CAA requirements for emissions
data and that entities who are responsible for reporting cannot
withhold information based on claims of confidentiality.
    The EPA also proposes to amend 40 CFR 2.301 to clarify that
information the EPA collects through the AERR is emission data that is
not subject to confidential treatment. Within that subpart, Sec.  2.301
includes regulations governing certain information obtained under the
CAA. Section 2.301(a)(2)(i) defines the term emission data ``with
reference to any source of emission of any substance to air'' to mean
under paragraph (A) ``information necessary to determine the identity,
amount, and frequency, concentration, or other characteristics (to the
extent related to air quality) of any emission which has been emitted
by the source (or of any pollutant resulting from any emission by the
source), or any combination of the foregoing.'' In addition, the
definition is further established by Sec.  2.301(a)(2)(i)(B) to include
``[i]nformation necessary to determine the identity, amount, frequency,
concentration, or other characteristics (to the extent related to air
quality) of the emissions which, under an applicable standard or
limitation, the source was authorized to emit (including, to the extent
necessary for such purposes, a description of the manner or rate of
operation of the source).'' Lastly, Sec.  2.301(a)(2)(i)(C) further
defines emission data to include ``[a] general description of the
location and/or nature of the source to the extent necessary to
identify the source and to distinguish it from other sources
(including, to the extent necessary for such purposes, a description of
the device, installation, or operation constituting the source).''
    Also codified in Sec.  2.301(a)(2)(ii) are certain exceptions to
the general rule of paragraph (i) described above. This paragraph
elaborates that certain information ``shall be considered to be
emission data only to the extent necessary to allow the EPA to disclose
publicly that a source is (or is not) in compliance with an applicable
standard or limitation, or to allow the EPA to demonstrate the
feasibility, practicability, or attainability (or lack thereof) of an
existing or proposed standard or limitation.'' If these conditions do
not apply, then Sec.  2.301(a)(2)(ii)(A) excludes from the definition
of ``emission data'' any ``information concerning research, or the
results of research, on any project, method, device or installation (or
any component thereof) which was produced, developed, installed, and
used only for research purposes.'' Similarly, Sec.  2.301(a)(2)(ii)(B)
excludes ``[i]nformation concerning any product, method, device, or
installation (or any component thereof) designed and intended to be
marketed or used commercially but not yet so marketed or used.''
    With this action, the EPA is proposing to determine that all data
that would be required to be reported or optionally reported under the
proposed AERR revisions are emission data as defined by 40 CFR 2.301.
To support this proposed determination, the EPA has created a list of
the optional and required point source data elements for annual
emissions data and has identified the part of 40 CFR 2.301 that applies
to each element. The spreadsheet ``AERR point source data
elements.xlsx'' provides this information and is available in the
docket. Point source data elements are particularly relevant to
considerations of confidentiality since individual point sources are
owned by business interests and the data that the EPA collects is
highly detailed. Point source data are also the type of information
that has been claimed as confidential in the past.
    In addition to the list of point source data elements described
above, source test data collection included in section IV.C of this
preamble describes collection of source test data. The EPA proposes
that all required data elements for the ERT and such additional data
that owners/operators would need to include when reporting source test
data under this proposed action classify as emissions data. For
example, this action proposes to require load, process operation, and
parameter data, and all of these are necessary to develop emissions
factors. The EPA identifies these data elements as meeting the
definition of emissions data because they are, as per from 40 CFR
2.301(a)(2)(i)(B), ``other characteristics'' needed to provide ``a
description of the manner or rate of operation of the source'' that the
EPA needs ``to determine the identity, amount, frequency,
concentration, or other characteristics (to the extent related to air
quality) of the emissions.''
    For States, the emissions reporting requirement for annual total
emissions extends to all the types of sources listed under Sec.  51.15
of the proposed regulatory text. The data that would be required under
the proposed Sec.  51.15 includes totals of pollutants, activity
creating the emissions, characteristics of the sources, and in some
cases model input and documentation. States would be required to report
for point sources, aircraft and GSE, rail yards, nonpoint sources,
onroad mobile, nonroad mobile, and prescribed fires. States would be
able to optionally report wildfire and agricultural fire data. The EPA
is proposing to determine that all the required and optional data
fields, including those listed above, to be reported by States for all
these sources meet the definition of emissions data and, therefore, are
not subject to confidential treatment under the CAA.

Moreover, States would optionally be able to report wildfires and
agricultural fires.
    For example, the type of pollutants, magnitude of those pollutants,
and emission rates of a source all meet the definition of emission data
under paragraph 40 CFR 2.301(a)(2)(i)(A) as ``information necessary to
determine the . . . amount, . . . concentration, or other
characteristics (to the extent related to air quality) of any emission
which has been emitted by the source.'' In addition, data elements that
identify the source of any such emissions, such as the location, name,
industry codes, units, processes, release points, controls, and all
their characteristics all serve as ``information necessary to determine
the identity'' of such emission data as per the Sec.  2.301(a)(2)(i)(A)
definition. Many required data elements meet the definition of Sec.
2.301(a)(2)(i)(C) in that they ``identify the source and distinguish it
from other sources (including, to the extent necessary for such
purposes a description of the device, installation, or operation
constituting the source).'' Examples of data elements that meet this
definition in paragraph (C) include any data elements related to (1)
installation dates of units, processes, and controls; (2) effective
dates of use for units, processes, release points, and controls; and
(3) the throughput of each emission process for both annual reporting
and source test data reports. Many of the data elements about source
characteristics that meet the definition under Sec.  2.301(a)(2)(i)(A)
also meet the definition provided under Sec.  2.301(a)(2)(i)(C).
    This action proposes various requirements that relate to what
information is entitled to confidential treatment. First, this proposal
includes requirements through listing of data elements. Data elements
for annual reporting of point sources are listed in Tables 2a and 2b to
Appendix A of Subpart A to Part 51. The source test reporting that the
EPA proposes in section IV.C of this preamble requires use of the ERT;
therefore, this proposal contains those elements required to use ERT,
and additionally requires four data elements that would otherwise be
optional if we had relied only on the mandatory reporting requirements
of the ERT.
    The proposed determination that all data required to be reported by
the AERR are ``emissions data'' serves two purposes: (1) to re-state
and clarify EPA's position on the data that the current AERR is
collecting and would continue under any final action, and (2) to apply
to the newly added data fields the EPA is proposing to require (as per
section IV.I of this preamble). Therefore, this proposed
confidentiality determination is intended to apply to both the current
AERR and the proposed AERR revisions.
    There are some required data elements included in the proposed
requirement to use electronic reporting via the EIS, CAERS, and CEDRI
that do not meet the definition of emission data. These are data
elements that identify the individuals responsible for submitting such
data and their contact information. While this submitter information
does not meet the definition of emission data, the Agency is making a
final determination through this rulemaking that this contact
information does not meet the standard for confidential treatment under
5 U.S.C. 552(b)(4) and upon finalization of this rule, may be released
to the public without further notice to the submitter. These data
elements do not meet the definition of emission data, but also do not
meet the definition of information needing confidential treatment.
    Based on these considerations, the EPA proposes to determine that
all data elements collected by the AERR are emissions data not entitled
to confidential treatment, and thus that the EPA may release this
information to the public without further notice to the submitter upon
finalization of this rule. To implement this determination, the EPA
proposes to add paragraph (k) to apply to data required to be submitted
under 40 CFR 2.301.

I. Additional Point Source Reporting Revisions

    The EPA has identified new requirements for point sources, new
voluntary data elements, and various clarifications. New requirements
include both the formalization of special cases that have previously
been handled voluntarily and completely new required data elements.
Clarifications include those for existing requirements that will newly
be enforced by EPA data systems as well as clarifications for how to
report certain data.
1. Formalizing the Approach for Aircraft and Ground Support Equipment
    Over the past four or more triennial inventory years, the EPA has
developed a comprehensive inventory of all airports to support analyses
that may result in new regulations affecting emissions sources at
airports, including aircraft and GSE. These sources can additionally be
sources of HAP and impact communities, especially when the boundaries
of airports are close to housing, schools, and workplaces. Most
airports do not meet the emissions reporting thresholds for CAPs that
are in effect through this subpart, and many will not meet the
reporting thresholds for HAP proposed by this action. When stationary
sources at airports meet point source reporting thresholds, States
currently report emissions of stationary sources at airports (e.g.,
boilers) as stationary point sources, and this approach is unchanged by
this proposed action. However, other approaches are necessary for
aircraft and GSE to ensure a complete airport inventory.
    To date, the EPA has worked with States during previous triennial
emission inventory years through voluntary review of LTO data for all
airports. In past triennial inventory years, the EPA compiled and
distributed the LTO data for voluntary State review and accepted
comments and revisions to that data from States. The EPA estimated
emissions using the final LTO data as input to the Federal Aviation
Administration (FAA) Aviation Environmental Design Tool (AEDT).\53\
This model includes emissions from aircraft up to 3,000 feet from the
surface, and past guidance to States on airport emissions was to use
that same elevation as part of the ``point source'' emissions. The
resulting emissions data from aircraft and ground support equipment
using these methods provide a fallback estimate of emissions from these
sources at airports not reported by States.
---------------------------------------------------------------------------

    \53\ Aviation Environmental Design Tool website, https://aedt.faa.gov/.
---------------------------------------------------------------------------

    In assessing States' compliance with the provisions of the current
AERR, the EPA has previously accepted the States' provision of LTO data
as being sufficient to meet the point source requirements for those
airports that exceed the point source reporting thresholds. This
approach both reduces burden for States as well as provides the EPA
relevant information for use of the AEDT to estimate emissions. When
the NEI includes EPA-created emissions, the EPA and the public have
full transparency about how the data have been created including QA
steps. The approach also creates a consistent dataset for all airports
to use in QA of state-provided annual total emissions submitted, and it
allows the EPA to use the latest available AEDT version. This last
advantage allows the EPA to use AEDT updates that may be released by
the FAA after the State point source reporting deadline.
    Collection of LTO data provides the most advantage when used
consistently across all airports. While airport

emissions data provided by States is also useful, when LTO data are not
also provided, the EPA then lacks a consistent basis for comparing the
AEDT results it creates with the state-reported emissions. Furthermore,
without documentation provided about state-reported emissions, the EPA
does currently require the method by which the State estimated
emissions or performed QA, unless the EPA and the State incur the
further burden of follow-up outside the existing electronic reporting
process. The EPA has observed that implementing follow-up steps for
clarification is less efficient than using a process by which the
information is required from the outset.
    Given these considerations, the EPA is proposing distinct
requirements for reporting of aircraft and GSE data by States, which
differ from the more general point source requirements. This action
proposes in 40 CFR 51.15(b) to add two options for States to report
data for airports in triennial years: either (1) submit LTO activity
data for some or all airports within the geographic scope of the
State's implementation planning authority using formats provided by the
EPA and/or (2) review LTO data and annual emission totals provided by
the EPA, send comments on that data, and notify the EPA that the State
accepts that data. Under this proposed addition, States can choose one
of these two options for each airport for which they would be required
to report. The EPA additionally proposes that the deadline for
reporting activity data would be by September 30 of the year after the
inventory year, or 60 calendar days after the EPA provides airport data
to a State, whichever is later (i.e., for the 2023 inventory year, by
September 30, 2024, or later). This deadline and others are summarized
below in section IV.S of this preamble.
    In addition, the EPA is considering that there is a distinction
between emissions from stationary source units (e.g., boilers) at
typical point sources as compared to the emissions from aircraft and
ground support equipment. To the extent that an airport has emissions
sources other than aircraft and ground support equipment, and the
emissions from the airport exceed the point source reporting thresholds
included in this proposed action, those additional stationary sources
should be reported consistent with non-airport point source
requirements. For example, if a boiler is run at an airport for heating
and the total airport emissions cause the airport to meet the point
source reporting thresholds, then emissions from that boiler would need
to be reported under this proposed action. To clarify this point, the
EPA proposes that States must report stationary sources and qualifying
mobile sources as per IV.I.16 of this preamble (other than aircraft and
GSE) at airports.
    States may voluntarily submit annual total emissions for aircraft
and GSE for some or all airports. However, the EPA is proposing a
requirement that if a State chooses to report annual total emissions,
they would be required to: (1) use the latest airport emissions model
specific in the NEI plan, (2) submit all pollutants estimated by the
latest airport emission model, and (3) submit documentation that
describes how States used the model to estimate emissions and performed
QA steps.
2. Formalizing the Approach for Rail Yards
    Like airports, rail yards may sometimes meet the existing
definition of point sources under this subpart, and with this proposed
action including HAP emissions reporting thresholds described in
section IV.A.8 of this preamble, additional rail yards may be defined
as point sources for the AERR in the future. Rail yard data include
emissions from yard locomotive switchers and can include other
emissions sources if present. As with airports, the Agency's goal of
complete emissions is supported by a comprehensive inventory of
emissions associated with locomotives to support analyses that may
result in new regulations affecting these sources. Rail yards have also
been identified as important sources of HAP in some communities.\54\
For these reasons, the EPA has reviewed its approach for rail yard
emissions, which has many similarities to the airport approach.
---------------------------------------------------------------------------

    \54\ Spencer-Hwang, R., Montgomery, S., Dougherty, M.,
Valladares, J., Rangel, S, Gleason, P, Soret, S, Experiences of a
Rail Yard Community: Life is Hard, J Environ Health. 2014 Sep;
77(2): 8-17. Eiguren-Fernandez, A, Exposure to Rail Yard Emissions
and Possible Health Impacts on Adjacent Communities, Center for
Occupational and Environmental Health, Southern California Particle
Center, October 4, 2010, http://www.scientificintegrityinstitute.org/coehrail100410.pdf.
---------------------------------------------------------------------------

    EPA works with rail companies who voluntarily provide activity data
about rail yards for point sources and locomotive activity for nonpoint
sources. Emissions from both rail yards and locomotives are
interrelated, and a complete accounting of these sources and activities
would create a comprehensive and consistent emission inventory across
these activities. Accounting of rail yards cannot be only for those
that meet the definition of point sources because data from all rail
yards are needed to fully understand the locomotive emissions on rail
lines and achieve a complete inventory.
    In past triennial inventory years, the EPA provided the rail yard
data for voluntary State review and accepted comments and revisions to
that data from States. The EPA estimated emissions relying heavily on
collaboration with the Eastern Research Technical Advisory Committee
(ERTAC). The resulting emissions data for rail yards provided a
fallback estimate of emissions at rail yards not reported by States.
    In assessing States' compliance with the current AERR, the EPA has
previously accepted the States' provision of rail activity data as
being sufficient to meet the point source requirements for those rail
yards that exceed the point source reporting thresholds. This approach
both reduces burden for States as well as provides the EPA information
to estimate emissions. When the NEI includes EPA-created emissions, the
public has full transparency about how the data have been created
including QA steps. The approach also creates a consistent dataset for
all rail yards to use in QA of state-provided annual total emissions
submitted, and it allows the EPA to use the latest available emissions
estimation approaches.
    As with airports, the existing voluntary approach with States
provides the most advantage when used consistently across all rail
yards. This is true for the same reasons as for airports and to meet
EPA's interest in comprehensively understanding rail yard emissions to
best meet Agency goals.
    In the past, many States have not had an independent source of data
other than that provided by EPA. One approach for States to obtain that
data would be for States to require it from rail companies; however,
since rail companies operate across State boundaries, it is preferable
for these companies to work directly with a central coordinator like
the EPA and ERTAC. Nevertheless, nothing in the existing requirements
of this subpart or any proposed requirements of this action would
prevent States from collecting such information from rail companies if
such data were not otherwise available.
    Unlike the publicly available LTO data for airports, the current
rail yard approach for the NEI relies on voluntary reporting by a
limited number of existing rail companies. While this approach has
mutual benefit to both the EPA and those companies, it is nevertheless
a voluntary measure. Thus, in formulating the requirements under

this proposed action, the EPA is considering the possibility that rail
companies may not provide data voluntarily for one or more triennial
years. This exact situation has been experienced by the EPA for the
2020 triennial inventory. In this case, this proposed action must
consider that the EPA cannot offer States an option to reduce State
burden by compiling the rail yard activity when such data are not
provided by rail companies.
    Given these considerations, the EPA is proposing distinct
requirements for reporting of rail yard data by States, which differ
from the more general point source requirements. This action proposes
in Sec.  51.15(c) to add two options for States to report data for rail
yards in triennial years. States may either (1) submit rail yard
activity data and documentation for some or all rail yards within the
geographic scope of the States' implementation planning authority using