Texas, when other state-to-state consultations similarly failed to
result in additional controls. Often these comparisons were made
without regard to the specific facts, such as the magnitude of the
visibility impacts that Texas sources have on the Wichita Mountains in
Oklahoma in relation to the relative impact of the sources in those
other actions, or the overlooked cost-effective controls that were
available to Texas sources to address those impacts. Other commenters'
comparisons simply focused on the result without regard to the
substance: They noted instances where two other states consulted and
neither required additional controls, and concluded that Texas was
being treated unfairly.
    Commenters also argued that our proposed disapproval of Texas'
reasonable progress analysis was based on Texas' decision not to
undertake a source-by-source analysis of emission controls. The
commenters pointed to a number of other regional haze SIPs approved by
EPA where states had relied on analyses of the reasonableness of
controls for various source categories. The commenters claimed that
these examples demonstrate that we accepted analyses of source
categories in other states and that we should not, therefore,
disapprove Texas' reasonable progress analysis on the grounds that it
failed to look at controls on a source-by-source basis. These
commenters ignore the fact that Texas' reasonable progress analysis
was, in part, based on a source-by-source analysis. However, Texas set
that analysis aside in favor of comparing the combined costs of all
controls-- not those for specific source categories-- against its
calculation of the total visibility benefit. More importantly, however,
as we have explained elsewhere in this action, our objection to Texas'
approach to evaluating potential reasonable progress controls was not
grounded in whether it used a category or source-by-source analysis.
Rather, our disapproval of Texas' reasonable progress analysis is based
on the fact that its flawed methodology ignored cost-effective controls
that, as we demonstrated in our proposal, would result in significant
visibility benefits.
    Commenters also raise questions concerning our approval of regional
haze SIPs where states relied on implementation of CAIR or CSAPR to
satisfy BART. The commenters argue we repeatedly found that
participation in these trading programs also satisfied reasonable
progress obligations for these states. One commenter claimed it would
be illogical to find that CAIR or CSAPR was an appropriate substitute
for BART but to then require controls for reasonable progress. We noted
in 2005 that the determination that CAIR provided for greater
reasonable progress than BART did not answer the question of whether
more than CAIR would be required in a regional haze SIP.\146\ As we
have explained, we are not finalizing our proposal to rely on CSAPR to
satisfy the BART requirements for EGUs in Texas, and at this point it
is not certain what Texas' CSAPR budgets will be in the future.
However, the remand of the CSAPR budgets for Texas aside, we do not
agree that we have been inconsistent in our treatment of Texas. These
commenters ignore the meaningful differences between Texas and the
states cited. These include the significant impacts that point sources
in Texas have on the visibility at the Wichita Mountains in Oklahoma,
even after the projected reductions from CAIR/CSAPR, the availability
of cost-effective controls that would address the largest visibility-
impacting sources, the flaws in Texas' technical evaluation of the
reasonable progress and long-term strategy provisions, and the flawed
consultations between Texas and Oklahoma. We also note that Texas
itself did not rely on its participation in CAIR to satisfy the
reasonable progress requirements without further consideration of
controls on its EGUs. Rather, Texas considered controls on a
combination of EGUs and non-EGUs, but ultimately rejected them based on
a flawed analysis of the reasonableness of such controls.
---------------------------------------------------------------------------

    \146\ 70 FR 39104, 39143.
---------------------------------------------------------------------------

O. Modeling

    Comment: We received comments that we should have prepared a
modeling protocol and made it available for public/stakeholder review
and comment. The commenters state that a modeling protocol is required
by EPA modeling guidance.
    Response: EPA is not required to develop a modeling protocol and
take public comment on it. Our guidance and 40 CFR part 51 Appendix W
do not require us to develop a modeling protocol for our technical work
conducted to support review or rulemaking. We developed a workplan and
consulted with national experts at EPA HQ as needed to develop the
proposal that included modeling files, documentation of how the
modeling was conducted and results. We included all this information in
the materials for the proposal and took comment on all aspects of our
analyses and techniques.
    Comment: We received comments that our selection of the CAMx model
rather than CALPUFF is inappropriate and unjustified. The commenters
stated that we did not justify the use of CAMx to model visibility
impacts from individual sources and at large distances, and our use of
CAMx here is outside of the model's capabilities. Furthermore, these
commenters assert that our concerns regarding using CALPUFF are not
clear, and they have concerns that overprediction of impacts are also
present in CAMx and therefore do not justify the use of CAMx. These
commenters also state that we failed to consider and discuss bias and
uncertainty in the modeling results and instead relied on the model
predictions as definitive results.
    Response: We did include a number of reasons in our proposal and
Modeling TSD for our selection of the photochemical grid model CAMx
over CALPUFF. One of the primary reasons is we evaluated the Texas SIP
for reasonable progress and not BART, and the differences in the
purposes of these analyses supports the use of different models when
the resources are available to utilize a photochemical model.
Reasonable progress requires the evaluation of changes in emissions
from one or more facilities on visibility impairment at downwind Class
I areas, in order to properly account for chemical transformations of
those emissions, the model used must also include the other pollutants
in the airshed, for which CALPUFF is not as well suited. Reasonable
progress analyses typically look at the changes in visibility on the
20% worst days, and this evaluation was done by most states, including
Texas and Oklahoma, by utilizing a photochemical grid model (PGM) such
as CAMx or CMAQ and not CALPUFF. Therefore, our use of CAMx for
evaluation of additional potential controls is consistent with the
state's SIP submission.
    We also discussed our selection of CAMx vs. CALPUFF and included in
the Modeling TSD a number of references to performance analysis
comparisons between the two models. There are also many comparisons
available in journal articles and online that support using a
photochemical grid model (most of these comparison

studies are found in the Modeling TSD and the rest are in the docket).
Some of the references we provided in the proposal raised concern that
the use of CALPUFF could result in model over-prediction and other
model performance issues at the distances at which we were evaluating
most of the sources in our proposal. CALPUFF model results are used
directly, whereas photochemical grid model results such as those
achieved through use of CAMx are evaluated with Relative Response
Factors (RRFs) to help remove potential bias concerns. While no model
is free from bias issues, previous evaluations of the CENRAP databases
we used for our analyses have been evaluated and the CENRAP CAMx model
performance was considered adequate because the modeled outputs
compared well to past measured conditions. As discussed in the
following response, the only changes to the CENRAP basecase CAMx
modeling we made were to update both the CAMx model version used and
the chemical mechanism in order to use the best science and while
ensuring model performance was still acceptable.\147\
---------------------------------------------------------------------------

    \147\ Additional information is also included in the Environ
Memorandums for the 2002 and 2018 modeling, (TX166-010-08
Memo_TXHAZE_2002CAMx_ENV_29July2013, TX166-010-09
Memo_TXHAZE_2018CAMx 16Sept13), the FIP TSD, and in the modeling
section of our RTC document.
---------------------------------------------------------------------------

    In sum, there are many reasons for the selection of CAMx over
CALPUFF for the purposes of this rule making. CAMx is better suited for
evaluating the reasonable progress metric of improvement on the 20%
worst days. It is also better suited for evaluating multiple sources in
a complex airshed. In addition many references point to CALPUFF's
potential overprediction at the distances at issue here. Any bias
issues in CAMx are ameliorated by tethering the model to real
monitoring data, through the use of relative response factors generated
by modeling of base and future cases to predict future monitored
values.
    Comments: We received comments that we failed to perform a full
model performance evaluation and instead compared model results to the
CENRAP modeling results despite deviations from CENRAP's modeling
protocol. These commenters also assert that we failed to update the
modeled emission inventories or consider more recent emissions data,
such as the 2011 NEI and EPA's recent projected 2018 emission inventory
showing large reductions from the Mercury Air Toxics Standards Rule
(MATS). They state that recent monitor data are representative and
indicate that our modeling is not representative of anticipated future
conditions and was not considered during model performance evaluation.
    Response: We did not do a detailed model performance of the 2002
basecase because that had already been done by CENRAP. The only changes
we made in the 2002 basecase was to use a newer version of the CAMx
model and an updated chemical mechanism to utilize improvements in the
science for our analysis and decisions. As we discussed in our proposal
materials, these changes were not large and did not warrant a full
model performance evaluation. We did compare model results with
previous results and determined that model results were very similar
and deemed acceptable. It is not uncommon in the modeling community to
do some small updates such as we did and not perform a full updated
model performance analysis.
    With regard to comments that we should have performed a more
complete update of the inventory, a full emission inventory update for
all emission categories such as biogenic, mobile, non-road, area, and
point sources for 2002 and 2018 was well beyond the scope of our review
of the SIP submittal. Such an update was not necessary to evaluate
whether the modeling and analyses submitted with the original SIP could
have led to a conclusion that additional reasonable progress controls
are appropriate. Once our evaluation concluded that it could be
appropriate for some sources to be better controlled for reasonable
progress, we did do minor updates to evaluate the most recent emission
levels of EGUs in Texas for the ones being further evaluated for
potential controls in our 2018 emissions. Because of the additional
focus on these particular sources it was appropriate to use more up to
date emissions. We also used the most recent CAMx model version and
updated chemical mechanism that included improvements to the source
apportionment of single point sources and plume in grid algorithms to
use the most recent science for our evaluations.
    We evaluated the existing CENRAP 2002 and 2018 emission inventories
and whether to update parts of these emission inventories in 2018.
After our initial modeling analyses, we did update emissions for the
EGUs evaluated for potential controls to use recent actuals in the 2018
modeling, which were thought to better represent emissions from EGUs in
Texas based on comments from Texas and EGU owners.\148\ We also updated
the 2018 emissions for two other sources based on permitting and
additional controls. We considered updating the EGU inventory with the
emissions inventory from the modeling performed for the MATS
rulemaking. At the time of proposal, the best information available was
that no other major controls were planned to be installed on EGUs in
Texas for SO2 emissions in response to MATS, therefore using
the recent actuals that we used for 2018 emission rates (prior to any
potential reasonable progress controls) was the most reasonable
emission inventory to use in our further modeling.
---------------------------------------------------------------------------

    \148\ Texas comments on Draft IPM modeling conducted by EPA for
potential national rule making platform provided on June 26, 2014.
In this docket's materials as ``TCEQ comment letter to EPA on draft
modeling platform dated June 24, 2014 2018 EMP signed.pdf''
---------------------------------------------------------------------------

    Lastly, we disagree with the commenter that the SIP modeling and
our further evaluation of 2018 expected levels are not representative.
In fact, the recent ambient monitoring data at the IMPROVE sites in the
three Class I areas (2011-2013) are influenced by meteorology that has
lower than normal transport of pollution from sources in Texas when
compared to the base period on which projections are based (2000-2004)
and to the 30-year meteorology analysis of transport to the three Class
I areas (1984-2013). Thus, examining the 2011-2013 time period
overstates the progress that can be expected over long term. In
response to comments and information provided we conducted further
analysis to appropriately evaluate whether the base period was suited
for projections to 2018 and also an analysis of how the meteorology
accompanying the more recent monitoring data for 2011-2013 compared to
normal meteorology conditions. We further note that 2014 also was not
quite a normal year \149\ and likely similarly biased low for
visibility impacts at the Class I areas, but even so monitoring data in
2014 did increase compared to the 2011-13 data. Overall, we conclude
that our evaluation of 2002 and 2018 levels and the controls needed for
reasonable progress are based on representative periods and that recent
monitoring trends are not as representative and not expected to
continue if meteorology is more in line with 30-year climatological and
transport norms.
---------------------------------------------------------------------------

    \149\ Some preliminary analyses of meteorology and pollution
levels in 2014 indicated a higher frequency of cold fronts during
the summer of 2014 that led to cleaner air from the arctic mixing
with the air in the region and resulted in lower pollution build-up
and transport of pollution to Class I areas in Oklahoma and Texas.
---------------------------------------------------------------------------

    Comment: We received comments that CAMx is not the approved model
in 40 CFR part 51, appendix W for

modeling long-range transport for visibility.
    Response: Neither the regional haze regulations nor appendix W
requires the use of a specific preferred model for photochemical grid
modeling for visibility (regional haze), but we have approved the use
of regional scale photochemical grid models such as REMSAD and
CMAQ.\150\ CAMx is another regional scale photochemical grid model that
was utilized by the RPOs and states and approved by EPA. CENRAP
conducted its final CAMx source apportionment modeling for the regional
haze analysis to be utilized in consultations of its nine state members
in development of their SIPs. We approved most of these SIPs that
included modeling analyses using CAMx and CAMx is clearly acceptable
for evaluating long range transport for visibility. Texas also used
CAMx in its reasonable progress analysis. Furthermore, Texas used CAMx
to screen small groups of sources and individual sources as part of its
BART screening and we approved that approach in 2006/7,\151\ based on
modeling enhancements that Texas contracted to be developed to assist
in assessing single point source visibility impacts on visibility at
Class I areas. The visibility impact analysis we performed with CAMx is
commensurate with the work originally done by Texas in 2006/7 for its
BART screening. Overall, Appendix W gives us discretionary authority in
the selection of what models to use for visibility assessments with
modeling systems, and models such as CALPUFF, CMAQ, REMSAD, and CAMx
that have all been used for that purpose. In this specific situation we
determined that CAMx had the best scientific modeling approaches and
tolls and was best suited for the complex analysis that we needed to
perform.
---------------------------------------------------------------------------

    \150\ 40 CFR part 51, appendix W, Section 6.2.1 (e&f).
    \151\ EPA, TCEQ, and FLM representatives verbally approved the
approach in 2006 and in email exchange with TCEQ representatives in
February 2007 (see email from Erik Snyder (EPA) to Greg Nudd of TCEQ
Feb. 13, 2007 and response email from Greg Nudd to Erik Snyder Feb.
15, 2007).
---------------------------------------------------------------------------

    Comment: We received comments that our CAMx modeling significantly
overstates visibility impacts and improvements on which we based our
proposal. Commenters describe the ETEX and CAPTEX tracer studies and
conclude that the results of these studies prove that CAMx
overestimates visibility impacts by a factor of 3. These commenters
also claim that these results also show an overestimate in CALPUFF
results by a factor of 6 (ETEX) or a factor of 3 to 4 (CAPTEX). When
this factor of 3 over-prediction is taken into consideration,
commenters state, using the over-prediction amount to scale down
modeled visibility improvement from controls results in small
improvements and controls should not be required.
    Response: We disagree with the commenters' conclusion about the
ETEX and CAPTEX tracer studies and the relevance of these tracer study
analyses. The analysis provided allegedly indicating that CAMx
overestimates visibility impacts by a factor of 3 is an incorrect
interpretation and has flaws in the evaluation and conclusions. Details
on our technical evaluation and conclusions on why the commenters'
analysis is flawed is in the RTC document. We do not condone the
calibration of model results to try to adjust for potential
biases.\152\ Furthermore, the bias amount indicated by the commenter is
flawed and is based on limited sampling of model performance
evaluations that exist. As stated in a response above, our CAMx
modeling analysis utilized a technique called RRF that limits the
potential impacts of modeling performance issues since the modeling
results are used in a relative sense and absolute modeling values are
not directly used. Due to this and other reasons, we do not think that
the CAMx modeling overstates the impacts. In fact, several pieces of
information indicate the impacts may be underestimated (see modeling
section of the RTC document for full discussion and references). Some
information indicates that using Plume-In Grid may result in
underestimation of a source's impacts. As discussed previously, in
particular in the Cost versus Visibility Benefit and Modeling sections,
we also disagree that the impacts are small, and we do think the
impacts are large enough and the benefits of lowering emissions to meet
the FIP emission limits are great enough to require these reductions.
As discussed in a separate response to comment in this section, the
CALPUFF modeling submitted by the commenter had flaws and is not
appropriate even before they did their inappropriate scaling of
results.
---------------------------------------------------------------------------

    \152\ App. W, Section 7.2.9(a) ``. . . Therefore, model
calibration is unacceptable.''
---------------------------------------------------------------------------

    Comment: Commenters provided back trajectory data (72 hours, 500m)
using HYSPLIT \153\ and monitored data for 2002 and 2011-2013 for the
20% worst days for Big Bend, the Guadalupe Mountains, and the Wichita
Mountains. They conclude that these data show that only a small number
of back trajectories \154\ come from regions with sources being
analyzed and considered for controls. For Big Bend, the back-
trajectories submitted by the commenters show the majority of back-
trajectories coming from Mexico. For the Guadalupe Mountains, back-
trajectories also primarily came from Mexico and visibility impairment
is mostly due to natural sources. Back-trajectories for the Wichita
Mountains rarely come from sources that we are proposing to control.
---------------------------------------------------------------------------

    \153\ HYSPLIT is a model developed by NOAA to utilize national
meteorological modeling files to assess potential air transport.
    \154\ The HYSPLIT model is designed to utilize archived
meteorological fields to generate back trajectories. The model user
will pick a certain receptor (in this case one of the Class I Areas)
and a specific time (in this case an hour on the day when monitoring
indicated there was high visibility impairment) and then the model
will assess the meteorological fields and use the wind speed and
direction for previous hours to indicate a centerline trajectory of
where the air that was monitored was in the hours before the day and
time selected. In essence the product is usually a jagged curved
line with hourly wind vectors that traces back a centerline for a
number of hours (example 72 hours). The back trajectory is a
centerline of the wind and the model user has to keep in mind that
dispersion and mixing occur so there are areas on either side that
can contribute as well and the further back in time the back
trajectory is processed the wider the areas on either side of the
centerline that could have contributed becomes.
---------------------------------------------------------------------------

    Response: The commenters' back trajectory analysis for the base
period and 2011-2013 is flawed and did not follow the NOAA draft
guidance they cited and appropriate HYSPLIT modeling techniques.\155\
In addition, our evaluation, discussed in the modeling section of the
RTC document, shows that the 2011-13 time period is not representative
of climatological norms regarding the transport wind flows to the three
Class I areas. We also find that the base time period 2000-2004 was
more representative of climatological norms.
---------------------------------------------------------------------------

    \155\ NOAA is National Oceanic and Atmospheric Administration.
NOAA is the developer of HYSPLIT and has previously provided draft
guidance on the use of the HYSPLIT model.
---------------------------------------------------------------------------

    We reached these conclusions by performing our own HYSPLIT modeling
of a 30-year period (1984-2013) and concluded that in years with wind
flow patterns consistent with the climatological norms over that period
a significant number of days have back trajectories that did include
areas where the sources proposed for additional controls are located.
Furthermore our analysis of the 2011-13 period which was less
representative of normal pollution transport patterns also showed a
number of back trajectories went through or near the areas with the
sources being considered for controls. Therefore these back
trajectories do indicate the sources being considered

for control would be expected to reduce visibility impacts at the three
Class I areas.
    Our analysis of 30-years of back trajectories to assess whether the
2011-13 and 2000-2004 periods were within the climatological norm also
indicated that the base period (2000-2004) was more similar to the
climatological norm than the 2011-2013 period, so we conclude that
using the base period is more representative for projecting 2018
levels.
    In sum, the number of trajectories that go near the sources in
Texas is large enough to not rule them out from consideration for
potential control. In general, we have treated back trajectories as a
tool to potentially screen an area out if no trajectories go through an
area but if some trajectories go through an area then the area may be
evaluated further or, as in this case, the full analysis may rely on
more sophisticated tools such as CAMx.
    The commenter indicated that a number of back trajectories went
through Mexico but failed to mention that many of these also went
through Texas. Therefore, sources in Mexico and Texas could contribute
emissions to the visibility impairment at the Class I Areas. We have
concluded that the back trajectory data provided by the commenter do
not support their assertions that transport from the regions with those
sources we are controlling is rare. The data they have provided are
inconsistent with the guidance and general practices and are for years
that are not representative of normal climatological patterns with
respect to transport wind flow to the Class I areas. Furthermore, the
back trajectories submitted by the commenter do in fact show transport
from regions of Texas for some days. Our additional analysis identified
the normal wind patterns over a 30-year period and determined that
based on normal conditions, transport does occur from the regions in
Texas with those sources we are controlling.
    HYSPLIT is a meteorological transport model but does not assess the
dispersion of and impacts from pollutants from differing sources and
does not have chemistry to correctly assess the potential impacts of
secondary particulate matter. We used the CAMx model, which does
account for pollutants and utilizes atmospheric chemistry mechanisms to
calculate changes in visibility impacts from the proposed emission
reductions at specific sources. As discussed in a response to comment
above in this section, photochemical grid models such as CAMx are best
suited for this analysis and determination of the benefit of potential
emission reductions.
    Comment: Commenters submitted CALPUFF modeling for Coleto Creek
Unit 1 for 2004-2006. Results indicate that visibility impacts from the
facility are below the 0.5 dv subject to BART threshold. The commenter
states that tracer studies suggest CALPUFF overestimates visibility
impacts by a factor of 4.5 (on average) and adjusts the CALPUFF model
results down by this factor. The commenter concludes that Coleto
Creek's calibrated impacts are very small and any visibility benefit
from controls would be even smaller.
    Response: We have reviewed the CALPUFF modeling provided for Coleto
Creek Unit 1 and do not concur with the conclusions that Coleto Creek's
impacts are small. We have a number of concerns with the CALPUFF
modeling provided: (1) It utilizes the wrong years for modeling; (2)
the modeling does not comply with the original BART CALPUFF modeling
protocol that Texas and EPA approved; and (3) it uses some
inappropriate assumptions, including the calibrating of modeling
results based on limited analyses using other databases and locations
that are not directly comparable to assessing impacts from Coleto
Creek's units. The 0.5 dv threshold was utilized as a BART threshold,
but our action is for reasonable progress and the 0.5 dv threshold was
not set as an applicable threshold in the Regional Haze Rules for
reasonable progress (see response in the Cost versus Visibility Benefit
section of this document). We used a photochemical grid model which is
more scientifically robust than the CALPUFF modeling system and is more
appropriate for longer transport distances, such as the distances
between Coleto Creek and the Class I areas in Texas and Oklahoma. We
performed a multi-tiered analysis in order to identify the Texas
facilities with the largest impacts on visibility at Class I areas (in
Texas and Oklahoma) and Coleto Creek's facility did rank as one of the
largest impacting sources of the more than 1,600 sources considered in
Texas. As discussed in another response in this section, we do not
condone calibrating CALPUFF model output values. We discuss the
commenters' use of the tracer studies in the RTC document but their
analysis and conclusions are flawed and not representative of the
larger collection of information available that also is discussed in
more detail in the RTC document. In conclusion, based on our analysis
with CAMx, we think both the visibility impacts of the sources and the
benefits from the proposed emission reductions are large enough to be
beneficial for reasonable progress.
    Comment: Focusing on visibility impacts on the 20% worst days
ignores larger impacts from these sources and other sources on other
days. This approach is also inconsistent with CALPUFF modeling for BART
of the maximum impact from a source for comparison with a 0.5 dv
threshold. Consideration of impacts on other days will identify sources
for control analysis that will result in visibility improvement on
other days and make progress towards the goal of natural visibility
conditions.
    Response: Under the reasonable progress and long-term strategy
requirements of the Regional Haze Rule, the state or EPA in
promulgating a FIP must establish reasonable progress goals that
provide for improvement on the most impaired days, demonstrate that the
established goals are reasonable and develop coordinated emission
management strategies to achieve those goals. The most impaired days
are defined as the average visibility impairment for the 20% of
monitored days in a calendar year with the highest amount of visibility
impairment.\156\ Because the rule focuses on improving visibility on
the most impacted days, we believe it is reasonable and appropriate to
focus our analysis on sources that significantly impact visibility on
those 20% worst days. While we generally agree with the commenter that
this may ignore visibility impacts from sources that impact visibility
on days other than the most impaired days, visibility impairment on the
current 20% worst days will be reduced as a result of controls
implemented to address visibility impairment for this first planning
period, and we believe that in the future the most impaired days may
shift and be impacted by different sources. Analysis and development of
future regional haze SIPs for future planning periods can aim to
address those sources that impact any new set of most impaired days.
Furthermore, targeted reductions at those sources that significantly
impact the most impaired days will also result in improved visibility
on days outside of the most impaired days.
---------------------------------------------------------------------------

    \156\ This is the definition in the Regional Haze Rule, but it
contains an obvious typographical error. It should be interpreted to
mean that visibility on the most impaired days is defined as stated.
---------------------------------------------------------------------------

    CALPUFF modeling is used to provide estimates of the maximum
visibility impacts from a source based on maximum emissions and
simplified chemistry, irrespective of the relationship to the 20% worst
days. It is

possible that CALPUFF modeling of some of the subset of the 38 sources
identified based on Q/d that were not analyzed for additional controls
could show significant impacts on the maximum or 98th percentile day,
but our CAMx photochemical modeling (which includes all emissions
sources and has a realistic representation of formation, transport, and
removal processes of particulate matter that causes visibility
degradation) provides additional information that allows for the
identification of the sources with the greatest impacts on the 20%
worst days.
    Comment: EPA should have required additional controls on sources
beyond what we proposed in our FIP to assure even greater reasonable
progress. Certain controls are reasonable and consistent with the
proposed controls when impacts at Class I areas other than the Texas
Class I areas and the Wichita Mountains are considered. Some specific
facilities, such as Oklaunion and H.W. Pirkey, fall above the 0.3%
impact threshold for impacts at the Class I areas of interest and
should have been evaluated for controls. EPA evaluated controls for
Parish and Welsh but did not require controls despite significant
visibility benefit and reasonable costs.
    Response: We focused our control analysis on the Texas Class I
areas and the Wichita Mountains. As discussed in more detail elsewhere
in this action, we are disapproving portions of the Texas and Oklahoma
regional haze SIPs, including the Texas long-term strategy
consultation, the Oklahoma reasonable progress consultation, the
Oklahoma established reasonable progress goal for Wichita Mountains and
the Texas reasonable progress/long-term strategy analysis and
consideration of reasonable controls at Texas sources necessary to
establish the Texas and Oklahoma reasonable progress goals. In
developing a FIP to address the deficiencies in the Oklahoma and Texas
SIPs, we had to analyze the visibility impacts and the availability of
reasonable progress controls at Texas sources that impact visibility at
the two Texas Class I areas and the Wichita Mountains and establish
reasonable progress goals including consideration of an appropriate
reasonable progress control analysis for these areas. We expect New
Mexico, Arkansas, Louisiana, and Missouri to consider remaining impacts
from Texas sources on their Class I areas including the information on
visibility impacts from specific sources provided by our analysis, as
well as incorporate corrections and updates to emission reductions in
consultations and development of their regional haze SIPs for the next
planning period.
    We disagree with commenters and we note, as further detailed in our
RTC document, that when recent actual emissions and unit-level
visibility impacts are considered, the units at the facilities
identified by the commenters, such as Oklaunion and Pirkey, fall below
the percent of visibility impairment threshold we established to
identify units for additional control analysis. This threshold was
established to identify a reasonable set of units that had the greatest
visibility impacts for additional control analysis for this planning
period. We note that any increases in actual emissions at these
facilities in the future should be considered during development of the
regional haze SIP for future planning periods. In future planning
periods, as the facilities with the greatest impacts are controlled,
the percent of total visibility impairment due to these lower impact
facilities will increase and they in turn should be considered for
additional control.
    Considering the visibility benefits and costs, we disagree that we
should have required controls on units at Parish and Welsh. In
evaluating the cost of controls, we also weighed how effective the
reductions were in achieving visibility benefits. We considered the
anticipated visibility benefit in deciviews (for both a ``dirty
background'' and a ``clean background'') as well as the reduction in
extinction and the percentage of visibility impairment addressed by the
controls. Based on our evaluation of these visibility metrics within
the cost factor of the four-factor reasonable progress analysis, we
determined that additional controls on Parish and Welsh were not
required for reasonable progress for the first planning period. In the
FIP TSD and the proposed FIP, we note lesser visibility improvement
benefits at the three Class I areas for the W. A. Parish and Welsh
units compared to the benefits at other facilities that mainly impact
the Wichita Mountains. We also note that when considering the costs of
controls and the relative visibility benefit, the Parish scrubber
retrofits would be slightly more expensive with respect to $/ton but
would be much less effective in improving visibility at the Wichita
Mountains, when compared to the required controls at the Monticello or
Coleto Creek units. For the Welsh scrubber retrofits, the costs ($/ton)
would be approximately 50% greater than the cost of scrubber retrofits
at Monticello or Coleto Creek and would result in approximately 50%
less visibility improvement at the Wichita Mountains. We also
considered comments on cumulative visibility benefits of these controls
and determined that the cumulative visibility benefits of each new
scrubber at the Parish and Welsh units would be less than those at each
of the units where we proposed scrubber retrofits and less than that at
each of the units with proposed scrubber upgrades with the exception of
Limestone, at a cost significantly higher than the estimated cost of
scrubber upgrades. Similarly, the total cumulative visibility benefit
of controlling the three units at Welsh and the four units at Parish
would be less than half the benefit from all the required scrubber
retrofits or all the required scrubber upgrades, and at a greater
average $/ton cost.\157\ While controlling the Welsh and Parish units
would result in some additional cumulative visibility improvement,
based on our evaluation and weighing of the cost and consideration of
the visibility benefits of these controls at the Wichita Mountains, we
determined their individual projected visibility improvements do not
merit the installation of scrubbers at this time. We encourage the
State of Texas to re-evaluate this determination as part of its next
regional haze SIP submittal and we note that as the required controls
are implemented the significance of impacts and potential benefits from
the Parish and Welsh units will increase in terms of percentage of
extinction. As discussed in the modeling section of the RTC document,
we disagree with comments that this determination is inconsistent with
the determination to require controls at Tolk Station or with the
determination of required controls in other states for the purpose of
reasonable progress.
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    \157\ See TX-116-007-_33_Vis_modeling_summary.xlsx in the docket
to this action for visibility benefits of controls.
---------------------------------------------------------------------------

    We agree with the commenter that on a $/ton basis, scrubber
upgrades on Parish unit 8 are very cost-effective. However, the
visibility benefit and reduction in emissions from this control would
be very low when compared to all the other evaluated scrubber upgrades.
The estimated visibility benefit from upgrading the scrubber would be
an order of magnitude less than all the other evaluated scrubber
upgrades and not large enough to require as reasonable progress for
this planning period.
    Comment: EPA should have analyzed oil and gas sources and
NOX controls for certain point sources in Texas.
    Response: With regards to comments on additional controls for
NOX, as

discussed in the proposed FIP, we agree with Texas that the predominant
anthropogenic emissions impacting visibility are nitrate and sulfate
emissions, primarily from point sources.\158\ As described in more
detail in the FIP TSD, in our initial analysis we focused on point
sources and we identified facilities with the greatest potential to
impact visibility based on a Q/d analysis considering both
SO2 and NOX emissions. We then used photochemical
modeling to estimate the visibility impacts due to the emissions from
these facilities, considering SO2, NOX, and all
other emitted pollutants. Based on the results of that visibility
modeling, we identified a subset of facilities for additional control
analysis and determined that the visibility impacts due to these
facilities was almost entirely due to their sulfate emissions.
Therefore, we determined that to address the visibility impacts on the
20% worst days from these sources, it was only necessary to evaluate
sulfate controls for this planning period. Our analysis identified
those sources that had the greatest visibility impacts, which we then
further analyzed for controls. This analysis did not identify any
individual point sources (with the exception of the PPG Glass Works
facility) with significant visibility impacts due to NOX
emissions among the group of sources with the greatest visibility
impacts. We address our evaluation of NOX controls for the
PPG Glass Works in our RTC document.
---------------------------------------------------------------------------

    \158\ 79 FR 74838.
---------------------------------------------------------------------------

    Oil and gas emissions are the largest component of area source
emissions but are only part of the total NOX area source
emissions. Oil and gas sources that fall within the point source
category were considered in our initial Q/d analysis and photochemical
modeling used to identify sources for additional control analysis.
Similarly with regard to comments on controlling oil and gas sources,
visibility impacts from NOX emissions from area sources are
relatively small compared to impacts from point sources of
SO2 and NOX at the Class I areas impacted by
Texas emissions. Focusing on point source emissions of NOX
and SO2 captured those sources with the greatest impacts on
visibility and was a reasonable approach for this planning period.
    Comment: Visibility impairment from the ``Other 29'' sources not
analyzed for controls are still significant and additional controls
should be required. Furthermore, some of the ``1,600 +'' sources not
further analyzed collectively contribute to total visibility
impairment.\159\
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    \159\ ``Other 29'' refers to the facilities identified as having
the greatest potential to impact visibility based on the Q/d
analysis but were then eliminated from further analysis based on
photochemical modeling results. ``1,600 +'' refers to all point
sources in Texas from the TCEQ's 2009 point source inventory.
---------------------------------------------------------------------------

    Response: Our Reasonable Progress Guidance discusses the steps to
follow in identifying reasonable controls and establishing reasonable
progress goals. The key pollutants contributing to visibility
impairment at each Class I area should be determined. ``Once the key
pollutants contributing to visibility impairment at each Class I area
have been identified, the sources or source categories responsible for
emitting these pollutants or pollutant precursors can also be
determined. There are several tools and techniques being employed by
the RPOs to do so, including analysis of emission inventories, source
apportionment, trajectory analysis, and atmospheric modeling'' (page 3-
1). As discussed in more detail in our proposal and in a separate
response to comment in the modeling section of the RTC document, we
determined that it was reasonable to focus our analysis on point
sources of SO2 and NOX.\160\ This was based on
review of emissions and source apportionment results indicating that
these sources were most responsible for anthropogenic contributions to
visibility impairment. We then used a Q/d analysis to identify those
sources with the greatest potential to impact visibility based on
emissions and distance. Additional analysis using photochemical grid
modeling was then completed to estimate the visibility impact from
those sources. Based on consideration of facility level and estimated
contributions to visibility from units at the modeled facilities, we
identified those sources that had the greatest visibility impacts to
analyze for additional controls. We agree with the commenter that
collectively the ``Other 29'' sources and ``1,600+'' sources contribute
a sizeable percentage of the total visibility impairment. However, on
an individual basis, these point sources have lower contributions and
smaller potential for visibility improvements relative to the nine
facilities evaluated for additional controls. For example, the proposed
controls on only 7 facilities address 5.8% of the total visibility
impairment at the Wichita Mountains, while controls on all of the
``Other 29'' sources would address 4.4% of the total visibility
impairment. Consistent with our guidance, we identified those key
pollutants and sources with the greatest impact on visibility
impairment for this first planning period. We also note that the
``Other 29'' includes impacts from San Miguel and the PPG Glass Works
facility that were considered for additional controls, and the JT Deely
units that are scheduled to shutdown in 2018.
---------------------------------------------------------------------------

    \160\ 79 FR 74838.
---------------------------------------------------------------------------

    The Regional Haze Rule requires the identification of reasonable
progress controls and the development of coordinated emission control
strategies in order to make reasonable progress towards the goal of
natural visibility conditions. Faced with a very large and unwieldy
universe of sources, we followed our guidance and chose an approach
that focused on the portion of the universe of Texas sources that
contributed the greatest impact to visibility impairment, by
establishing a threshold of 0.3% contribution to total visibility
impairment on a unit basis for this planning period, thereby
identifying a reasonable set of units at nine facilities to analyze for
additional controls.\161\ Our four-factor analysis concluded that
controls on units at seven of the nine facilities analyzed for
additional controls were required. As these controls are implemented,
the percentage impact from those facilities not controlled will become
larger (on a percentage basis) and will be analyzed in future planning
periods. In other words, some of the ``Other 29'' will be identified as
the greatest impacting sources and should in turn be analyzed for
additional reasonable progress controls in a future planning period.
This methodology can be used as a consistent procedure to identify
facilities for additional control analysis in this and future planning
periods and would ensure continuing progress towards the goal of
natural visibility conditions. The USDA Forest Service commented that
``the methodology and metrics that EPA used are the most comprehensive
seen to date for any SIP/FIP in the country that we have reviewed, and
should serve as a model for future efforts to consider the contribution
and/or potential benefits of individual sources to visibility.''
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    \161\ As discussed elsewhere, San Miguel has already upgraded
its scrubber and therefore it was not included in our modeling
analysis of additional controls and not included among the nine
facilities discussed here. In our FIP, we are finalizing our
determination that San Miguel maintains an emission rate consistent
with recent monitoring data.
---------------------------------------------------------------------------

    Comment: We received comments on the methodology used to identify
sources for analysis. Commenters stated that our analysis, beginning
with a Q/d analysis and the use of a 0.3% of total impairment threshold
for identifying

sources for additional analysis was arbitrary, capricious, or improper.
In addition, commenters contend that the Q/d analysis selects the wrong
sources because it does not consider stack parameters or meteorology.
Other commenters suggested that all 38 facilities identified as having
the greatest potential to impact visibility by the Q/d analysis should
have undergone a four-factor analysis. We also received comments that a
lower threshold should have been used, that the threshold was applied
inconsistently, and that the 0.3% threshold screened out sources that
have a significant visibility impact and should have been evaluated for
controls.
    Response: We disagree with the commenters' assertion that our
analysis, beginning with a Q/d analysis, was arbitrary, capricious, or
improper. As explained below and elsewhere in this document, our
complete analysis identified those sources with the greatest visibility
impacts at the Wichita Mountains and the Texas Class I areas based on
consideration of a source's emissions, location, and modeled visibility
impairment. Once identified, we performed additional control analysis
on these sources to determine through the four-factor analysis if
controls were available and cost-effective.
    As we discuss at length in the FIP TSD and in our RTC document, we,
states (including Texas) and RPOs (including CENRAP) have used a Q/d
analysis to identify those facilities that have the most potential to
impact visibility at a Class I area based on their emissions and
distance to the Class I area. These identified facilities could then be
considered for further evaluation to estimate visibility impacts, and
then undergo the reasonable progress analysis for determination of
reasonable progress controls. The BART guidelines \162\ discuss
identifying sources with the potential to impact visibility based on a
Q/d approach consistent with the method followed in this action.
Furthermore, this approach has also been recommended by the FLMs' Air
Quality Related Values Work Group (FLAG) \163\ as an initial screening
test to determine if an analysis is required to evaluate the potential
impact of a new or modified source on air quality related values (AQRV)
at a Class I area. In the Texas regional haze SIP, the TCEQ relied on a
Q/d approach as one of the initial steps to identify sources for
additional analysis.\164\ We used a similar Q/d approach to identify 38
sources, from the more than 1,600 point sources in Texas that had the
most potential to impact visibility due to their location and size. In
other words, we started by looking at every point source in Texas \165\
and narrowed the field to a much smaller subset of sources with the
most potential to impact visibility based on their emissions and
location. This approach is a widely used method as an initial step to
evaluate a facility's potential to impact air quality and identify
those sources with large enough emissions close enough to a receptor to
need additional analysis. Using this methodology, we considered every
point source in Texas and narrowed the list to a much smaller list of
facilities with the greatest potential visibility impacts based on just
emissions and distance.
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    \162\ See 40 CFR part 51, appendix Y, section III (How to
Identify Sources ``Subject to BART'')
    \163\ Federal Land Managers' Air Quality Related Values Work
Group (FLAG), Phase I Report--Revised (2010) Natural Resource Report
NPS/NRPC/NRR--2010/232, October 2010. Available at http://www.nature.nps.gov/air/Pubs/pdf/flag/FLAG_2010.pdf.
    \164\ TX RH SIP Appendix 10-1. ``The group of sources was
further reduced to eliminate sources that are so distant from any of
the ten Class I areas that any reduction in emissions would be
unlikely to have a perceptible impact on visibility. The list was
restricted to those sources with a ratio of estimated projected 2018
base annual emissions (tons) to distance (kilometers) greater than
five to any Class I area.''
    \165\ The Texas point sources are defined as industrial,
commercial, or institutional sites that meet the reporting
requirements of 30 Texas Administrative Code (TAC) Sec.  101.10.
Permitted point sources in Texas are required to submit annual
emissions inventories. The data are drawn from TCEQ's computer-based
State of Texas Air Retrieval System (STARS). Annual emission data
from 2009 were utilized to calculate the Q/D value for all point
sources with reported emissions in Texas. 2009 emissions data
available in the docket as ``2009statesum.xlsx''
---------------------------------------------------------------------------

    Following the Q/d analysis, we took the additional step of using
photochemical modeling, utilizing CAMx with Plume-In-Grid (PiG) and
Particulate Source Apportionment Tagging (PSAT). As the commenter
states, the Q/d analysis does not take into account stack parameters,
meteorological conditions, or chemistry. Given the large geographic
distribution of sources and distances to the Class I areas, we
recognized that it was highly likely that only a subset of these 38
facilities would have the greatest visibility impacts on downwind Class
I areas once meteorology and transport conditions, atmospheric
dispersion, chemistry, and stack parameters were taken into
consideration, as CAMx with PiG and PSAT can do. We determined it was
appropriate to use photochemical modeling to assess the visibility
impact from those sources identified by our Q/d analysis. In the same
way that Q/d is used as an estimate of the potential visibility impact
due to emissions and distance, the photochemical modeling aims to
estimate the visibility impacts albeit in a much more refined manner
that accounts for chemistry and meteorological conditions. We also note
that some RPOs and states used a combination of back trajectory
analysis, source apportionment modeling results, and Q/d as a more
refined approach to identify sources for additional control analysis
for reasonable progress.\166\ Our modeling results indicated that a
subset of the 38 facilities were the primary contributors to visibility
impairment at each Class I area. The results of this modeling were used
to verify our initial identification of sources and further eliminate
sources from a full four-factor analysis based on facility-level
impacts and consideration of estimated unit level impacts, as described
in detail in the FIP TSD.
---------------------------------------------------------------------------

    \166\ To select the specific point sources that would be
considered for each Class I area, VISTAS first identified the
geographic area that was most likely to influence visibility in each
Class I area and then identified the major SO2 point
sources in that geographic area. The distance-weighted point source
SO2 emissions (Q/d) were combined with the gridded
extinction-weighted back-trajectory residence times. The distance
weighted (Q/d) gridded point source SO2 emissions are
multiplied by the total extinction-weighted back-trajectory
residence times (Q/d * Bext-weighted RT) on a grid cell by grid cell
basis and then normalized. See VISTAS Area of Influence Analyses,
2007 available in the docket for this action.
---------------------------------------------------------------------------

    There are a number of different approaches used by states in
identification of sources for reasonable progress evaluation but these
approaches usually centered around the general premise of evaluating
the biggest sources and the biggest impacts on visibility. As we
explain in the FIP TSD, we considered the visibility modeling results
in a number of ways to determine a reasonable approach to identify
those sources with the largest impacts for additional analysis for
controls for this planning period. We examined the model results for
extinction and percent extinction of the modeled facilities as well as
estimated impacts based on more recent actual emissions. We considered
both facility level and unit level impacts. We concluded that any unit
with an estimated impact greater than 0.3% would be further evaluated.
We believe that using a percent impacts approach is appropriate because
of its linkage to the reasonable progress concept. For example, a
source that has a smaller absolute impact on a relatively cleaner area
but a higher percentage impact might be considered for control so that
the cleaner area can potentially make progress. We used the 0.3%
threshold only as a way to identify a reasonable

set of sources to evaluate further. At this point, the resulting
reasonably broad set of sources served as a starting place from which
to further analyze individual source impacts in the second round of
modeling, and balance them against any cost-effective controls that
could be identified.
    In summary, our analysis properly identified the sources in Texas
with the greatest individual visibility impacts for additional control
analysis. Commenters are incorrect in their assertion that the
visibility impacts from the identified sources are miniscule, or that
we started our analysis with the wrong sources. Starting from the
entire universe of Texas point sources, we systematically eliminated
those facilities that had less potential to impact visibility based on
careful consideration of emissions, location, and finally modeled
visibility impacts. After identifying those facilities with the
greatest visibility impacts, we performed the four-factor analysis to
evaluate whether reasonable progress controls were available and cost-
effective.
    Comment: We received comments that EPA established the deciview as
the required metric for establishing and tracking progress towards the
reasonable progress goal. EPA's use of extinction or percent extinction
and establishment of thresholds is arbitrary, capricious, illegal and
without precedent.
    Response: We disagree with the commenters that our use of metrics
other than deciviews for certain purposes is contrary to regulations.
The commenters fail to distinguish between the metrics used to describe
overall visibility conditions at a Class I area and the metrics that
can be used to describe the visibility impairment due to an individual
source, group of sources, a state's sources, or some other portion of
the visibility impairment at a Class I area. In describing the overall
visibility conditions at a Class I area, we established the deciview as
the principle metric. This applies to the calculation of current,
baseline, and natural visibility conditions at a Class I area, as well
as the reasonable progress goals established as the visibility
condition goal for the Class I area at the end of the current planning
period. We agree with the commenters that the use of the deciview
metric is required in a number of places within the rule that discuss
overall visibility conditions and assessing progress towards meeting
the desired visibility conditions. Specifically, the state must (1)
establish reasonable progress goals expressed in deciviews (40 CFR 51.
308(d)(1)); (2) determine the uniform rate of progress in deciviews (40
CFR 51.308(d)(1)(i)(B)); and (3) determine the baseline and natural
visibility conditions expressed in deciviews and the number of
deciviews by which baseline conditions exceed the natural conditions
(40 CFR 51.308(d)(2)). Consistent with these requirements, we
calculated the baseline and natural visibility conditions, the uniform
rate of progress, and the number of deciviews by which baseline
conditions exceed the natural conditions in deciviews for Big Bend and
the Guadalupe Mountains, as well as established reasonable progress
goals for the Wichita Mountains and the Texas Class I areas in
deciviews.
    The deciview metric provides a scale that relates to visibility
perception and therefore is useful in assessing the overall visibility
conditions that are being or will be perceived at the Class I area. The
commenters cite to several actions and the Regional Haze Rule where the
benefits of using the deciview metric are discussed, however this is
only discussed in the context of overall visibility conditions, such as
determining current or natural visibility conditions. This is very
different from the fraction of visibility impairment attributable to a
source or group of sources. We note that in the final Regional Haze
Rule, we do in fact mention the use of light extinction as another
metric that states may choose to use.
    There is no requirement to use the deciview metric in describing
the visibility impairment due to a source or group of sources as part
of the analysis required for identifying reasonable controls under
reasonable progress. In describing how to identify sources or source
categories responsible for visibility impairment, our guidance \167\
provides states with considerable flexibility to utilize various tools
and techniques that would necessarily involve the use of various
metrics other than deciviews. Many states and RPOs, including Texas and
CENRAP, relied on a Q/d analysis, described and discussed in depth in
separate responses to comments and in our proposed FIP, to identify
sources for additional control analysis. The Q/d analysis relies on an
annual emissions divided by distance metric, not deciviews. The VISTAS
RPO relied on a metric derived from Q/d and residence-time, not
deciviews.\168\ Some states relied on a simple analysis of emissions to
determine which sources should be analyzed.
---------------------------------------------------------------------------

    \167\ Guidance for Setting Reasonable Progress Goals Under the
Regional Haze Program, U.S. EPA, OAQPS, June 1, 2007, page 3-1
    \168\ VISTAS Area of Influence Analyses, 2007, available in the
docket for this action.
---------------------------------------------------------------------------

    When assessing the various contributions to visibility impairment
due to either source categories or pollutant species from other states
and international sources, Texas routinely relied on light extinction
and percent of total visibility impairment metrics. For example,
Chapter 11 of the Texas regional haze SIP describes the contributions
due to sulfate, nitrate, and other pollutants on the 20% worst and 20%
best days at the Guadalupe Mountains and Big Bend in terms of light
extinction (inverse megameters, Mm-\1\). Similarly, the
extinction metric is used by Texas (see section 11.2.3 of the Texas
regional haze SIP) to assess the level of impact on other Class I areas
from Texas sources. Texas also used the extinction metric to determine
which states significantly impact the Texas Class I areas, applying an
impact extinction level threshold of 0.5 Mm-\1\ from all
sources in a state as a threshold for inviting a state to consult.\169\
Source apportionment modeling performed by the RPOs was utilized by
every state to assess the various contributions to visibility
impairment at their Class I areas in terms of light extinction and
percent contribution to total light extinction. The CENRAP PM source
apportionment tool (CENRAP PSAT tool) utilized by all CENRAP states,
including Texas and Oklahoma, to review the results of the source
apportionment modeling provides results in two ways: Light extinction
(inverse megameters) and percentage of total extinction. In our action,
we also utilized the methodology and metrics used by the RPOs to
evaluate the source apportionment results, the only difference being
that our source apportionment modeling provided information on
visibility impacts from individual sources instead of source
categories, or regions/states. In the FIP TSD, we provide information
on visibility impacts from the individual sources in terms of
extinction, percentage of total extinction, and in deciviews.
---------------------------------------------------------------------------

    \169\ See Texas Regional Haze SIP Appendix 4-1: Summary of
Consultation Calls
---------------------------------------------------------------------------

    We evaluated the information in terms of light extinction and
percentage of total impact to identify a reasonable subset of sources
with the largest visibility impacts to analyze for additional controls.
Because the overall visibility conditions at different Class I areas
can vary greatly, particularly Class I areas in the Eastern U.S.
compared to Class I areas in the Western U.S., we determined that it is
not enough to consider just the magnitude of extinction from a
facility; we must also

consider the percentage of total impairment metric at each Class I
area. As we state in the FIP TSD, ``We believe that using a percent
impacts approach is appropriate because of its linkage to the RP
concept. For example, a source that has a smaller absolute impact [in
terms of extinction] on a relatively cleaner area but a higher
percentage impact might be considered for control so that the cleaner
area can potentially make progress.'' Using the percentage of total
visibility impairment metric allows us to somewhat normalize the
extinction differences between Class I areas so that we can utilize the
same approach at each Class I area and identify a reasonable set of
sources to analyze that if controlled would result in meaningful
visibility benefits towards meeting the goal of natural visibility at
every Class I area. For every Class I area to have the opportunity to
reach the natural visibility goals, it is necessary to identify the
sources or source categories that significantly impact visibility,
identify available controls and analyze whether those controls are
reasonable. Had we established a strict threshold based on extinction,
we would have had to establish a different threshold for each Class I
area. Using a percentage approach, such as the 0.3% of total visibility
impairment on a unit basis we used in this action, results in
identification of a subset of sources that includes those sources with
the greatest visibility impacts at each Class I area. As stated by the
USDA Forest Service in its supportive comments, the use of this
methodology and metrics, including the use of a small percentage
threshold on the 20% worst days is linked to the concept of reasonable
progress. We believe it could serve as the model for future efforts to
consider the contribution and potential benefits of individual sources
to visibility. After identifying which sources to analyze for
additional controls based on the percentage impact on a unit basis, we
determined which controls were reasonable based on consideration of the
four factors, including comparison of cost to the anticipated
visibility benefit (deciview improvement, extinction, percentage of
total extinction, and the percentage of the total impact from Texas
point sources addressed by the control).
    Comment: We received comments on the method we used to adjust CAMx
results. Commenters stated that we developed a linear relationship
between emissions and extinction and then adjusted CAMx modeled
extinction linearly with emissions to match proposed controlled
emission levels. The commenters stated that the relationship between
emissions and light extinction is not linear and that interactions
between nitrate and sulfate create a complicated relationship. The
commenters cited to the CAMx user guide which they claim supports that
the relationship is non-linear. In contrast, Earthjustice said that our
approach was reasonable.
    Response: We disagree with the comments that the methodology used
to estimate visibility benefits from control level emissions was
unjustified or unreasonable, and agree with Earthjustice that our
approach was reasonable. The linear relationship we developed to
extrapolate extinction due to controlled emission rates was a
reasonable approach in our technical analysis.
    We agree with the commenters that, in general, the relationship
between downwind concentrations and emissions can be complicated and
non-linear due to complex chemistry, including the fact that reductions
in sulfur emissions can result in an increase in ammonium nitrate. Each
modeled emission scenario took this complex chemistry into account in
estimating the visibility impacts for that scenario. We estimated
control efficiencies for a high and low control case scenario that
would span the range and give a reasonable approximation of emission
reductions of potential controls and maximize the number of data points
available to estimate the visibility benefit due to a reduction in
emissions.\170\ Using the unit level High and Low modeled visibility
impacts and the 2018 facility level modeling described in the FIP TSD,
we examined the relationship between the various levels of emissions
from a modeled site and the modeled visibility impact at each Class I
area. For each facility and Class I area, the available modeled data
were linear with high correlation and the modeled emission levels were
relatively close to the estimated control levels examined. Therefore we
used the linear fit to extrapolate the anticipated visibility impact/
benefit from a given level of emission/control.\171\ We agree that
small perturbations relative to the model inputs can be approximated as
linear. However, as discussed in more detail in our response to this
comment in the RTC document, we disagree with the commenters that we
extended the linear treatment to large variations, and we note errors
in the commenters' assessment of the differences between modeled and
required control levels. The variations between the modeled High
control levels and the control levels required in the FIP are
relatively small. This is a small perturbation from the modeled levels,
a small difference in estimated extinction benefit from the modeled and
required control level, and does not impact our overall decisions on
the significance of visibility benefits from the required controls. We
agree with Earthjustice that the small level of uncertainty in the
visibility benefit from these controls introduced by the linear
extrapolation does not impact the overall conclusions. In every case,
the required control level emissions are the same or less than the high
control level modeled, and the visibility benefits from controls at the
required control level will be the same or more than those modeled at
the high control level. Therefore, the high level modeled visibility
benefits can be seen as a lower bound and even these support our
decision.
---------------------------------------------------------------------------

    \170\ See FIP TSD at A-54 for a more detailed description
    \171\ See the file, ``Vis modeling summary.xlsx'' in the docket
for this action for our calculations and estimates of visibility
benefits from the examined levels of controls.
---------------------------------------------------------------------------

    Comment: We also received comments on the calculation of a deciview
impact or improvement based on natural ``clean'' background conditions
and the estimated visibility impacts/improvement based on recent actual
emissions rather than projected 2018 emissions. The commenters contend
that the use of natural background overstates the estimated visibility
benefit from the proposed controls and that these adjustments based on
recent actual emissions and natural background artificially increase
projected visibility improvement from the proposed controls. The
commenter states that the use of ``natural conditions'' is contrary to
the regulations, inconsistent with agency precedent, and arbitrary and
capricious and that the analysis does not address the relevant legal
issue and is not rationally connected to the final decision (i.e. what
is a reasonable progress goal for 2018).
    Response: We disagree with the commenter that the use of ``natural
conditions'' is contrary to the regulations, inconsistent with agency
precedent, and arbitrary and capricious. We disagree with the commenter
that the analysis does not address the relevant legal issue and is not
rationally connected to the final decision (i.e., as defined by the
commenter as what is a reasonable progress goal for 2018). The Regional
Haze Rule requires that we identify reasonable controls based on
consideration of the four statutory factors and establish a reasonable
progress goal that reflects the

anticipated amount of visibility improvement from implementation of
those controls in additional to all other ``on the books'' controls.
Specifically, Sec.  51.308(d)(1)(i)(A) requires consideration of the
four factors and a demonstration of how these factors were taken into
consideration in selecting the visibility goal. We analyzed the time
necessary for compliance, energy and non-air environmental impacts, the
remaining useful life, and the costs of compliance including
consideration of the anticipated visibility benefits of specific
controls on individual units. As discussed in depth below, in
considering the anticipated visibility benefits from individual
controls, it was appropriate to consider estimated benefits on a
``clean'' or ``natural'' background.
    In the FIP TSD, we discuss the need to estimate visibility benefits
using both a ``clean'' and ``dirty'' background: \172\
---------------------------------------------------------------------------

    \172\ See our FIP TSD, page A-39.

The deciview improvement based on the 2018 background conditions
provides an estimate of the amount of benefit that can be
anticipated in 2018 and the impact a control/emission reduction may
have on the established RPG [reasonable progress goal] for 2018.
However, this estimate based on degraded or ``dirty'' background
conditions underestimates the visibility improvement that would be
realized for the control options under consideration. Because of the
non-linear nature of the deciview metric, as a Class I area becomes
more polluted the visibility impairment from an individual source in
terms of deciviews becomes geometrically less. Results based solely
on a degraded background will rarely if ever demonstrate an
appreciable effect on incremental visibility improvement in a given
area. Rather than providing for incremental improvements towards the
goal of natural visibility, degraded background results will serve
to instead maintain those current degraded conditions. Therefore,
the visibility benefit estimated based on natural or ``clean''
conditions is needed to assess the full benefit from potential
---------------------------------------------------------------------------
controls.

    In considering the visibility benefits of potential controls, we
considered deciview improvements as well as the reduction in extinction
and percent extinction. By definition, the ``clean'' background
analysis using natural conditions eliminates the impact from all other
anthropogenic sources, domestic and international. This approach is
aimed at assessing the full potential visibility benefit of controls.
It is not reasonable to only assess the visibility benefit of controls,
the value of installing a control in the immediate future that will
permanently reduce visibility impacts from a source, in such a manner
that is dependent on the current level of emissions or impact from
other sources or other countries. For example, in considering only the
estimated visibility benefit from controlling Big Brown using a
``dirty'' background, an increase in visibility impacts from Mexico
emissions or emissions from another Texas point source would result in
a decrease in the visibility benefit in deciviews from installing
controls on Big Brown, making controls appear less beneficial. By using
a metric that is independent of all other emission sources (``clean''),
we avoid this paradox that the dirtier the existing air, the less
likely it would be that any control is required. This was also
explained in the preamble to the final Regional Haze Rule and
Guidelines for BART Determinations.\173\ The use of ``clean''
background is necessary to assess the full potential benefit from
controls and does not overstate the visibility benefit.
---------------------------------------------------------------------------

    \173\ Using existing conditions as the baseline for single
source visibility impact determinations would create the following
paradox: The dirtier the existing air, the less likely it would be
that any control is required. This is true because of the nonlinear
nature of visibility impairment. In other words, as a Class I area
becomes more polluted, any individual source's contribution to
changes in impairment becomes geometrically less. Therefore the more
polluted the Class I area would become, the less control would seem
to be needed from an individual source. We agree that this kind of
calculation would essentially raise the ``cause or contribute''
applicability threshold to a level that would never allow enough
emission control to significantly improve visibility. Such a reading
would render the visibility provisions meaningless, as EPA and the
States would be prevented from assuring ``reasonable progress'' and
fulfilling the statutorily-defined goals of the visibility program.
Conversely, measuring improvement against clean conditions would
ensure reasonable progress toward those clean conditions. 70 FR
39124.
---------------------------------------------------------------------------

    Our use of ``clean'' background is also consistent with the
methodology used by Texas for BART visibility analysis, which also
relied on CAMx photochemical modeling with source apportionment. The
TCEQ utilized this approach in assessing the visibility impacts from
individual sources and groups of sources to determine their
significance for BART screening. As detailed in the screening analysis
protocol developed by TCEQ and reviewed by us, ``The source's HI [haze
index] is compared to natural conditions to assess the significance of
the source's visibility impact. EPA guidance lists natural conditions
(bnatural) by Class I area in terms of Mm-\1\
(EPA, 2003b) and assumes clean conditions with no anthropogenic or
weather interference. The visibility significance metric for evaluating
BART sources is the change in deciview (del-dv) from the source's and
natural conditions haze indices.'' \174\
---------------------------------------------------------------------------

    \174\ Texas Regional Haze SIP, Appendix 9-5, ``Screening
Analysis of Potential BART-Eligible Sources in Texas'' at 2-11,
emphasis added.
---------------------------------------------------------------------------

    We disagree with the commenter that our use of the ``natural
background'' metric is contrary to regulations. As we discuss in a
separate response to comment concerning the legality of the extinction
and percent extinction metrics, the commenter fails to distinguish
between the required metric used to describe overall visibility
conditions at a Class I area at a given point in time and the range of
metrics that can be used to describe the visibility impairment due to
an individual source, group of sources, a state's sources, or some
other portion of the visibility impairment at a Class I area. As
explained above, it is necessary to consider the visibility benefit of
controls on a ``clean'' background basis to assess the full benefit
from potential controls.
    The use of natural background is also supported by our previous
action on North Dakota's regional haze SIP and the associated Eighth
Circuit Court decision. The full text of our determination in North
Dakota is: \175\
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    \175\ 76 FR 58627.

    In addition to evaluating the four statutory factors, North
Dakota also considered the visibility impacts associated with the
control options for each RP source. However, in modeling visibility
impacts, North Dakota used a hybrid cumulative modeling approach
that is inappropriate for determining the visibility impact for
individual sources. As with the modeling North Dakota conducted for
its NOX BART analysis for MRYS [Milton R. Young Station]
Units 1 and 2 and LOS [Leland Olds Station] Unit 2, the approach
fails to compare single- source impacts to natural background. While
there is no requirement that States, when performing RP analyses,
follow the modeling procedures set out in the BART guidelines, or
that they consider visibility impacts at all, we find that North
Dakota's visibility modeling significantly understates the
visibility improvement that would be realized for the control
options under consideration. Accordingly, we are disregarding the
modeling analysis that North Dakota has used to support its RP
---------------------------------------------------------------------------
determinations for individual sources.

    The Eighth Circuit Court's decision affirmed our position that the
use of degraded, or dirty background, was not consistent with the CAA.
The relevant section of the 8th Circuit Court's decision on this point
reads: \176\
---------------------------------------------------------------------------

    \176\ North Dakota v. EPA, 730 F.3d 750, 766 (8th Cir. 2013).

Although the State was free to employ its own visibility model and
to consider visibility improvement in its RP

determinations, it was not free to do so in a manner that was
inconsistent with the CAA. Because the goal of section 169A is to
attain natural visibility conditions in mandatory Class I Federal
areas, see 42 U.S.C. 7491(a)(1), and EPA has demonstrated that the
visibility model used by the State would serve instead to maintain
current degraded conditions, we cannot say that EPA acted in a
manner that was arbitrary, capricious, or an abuse of discretion by
disapproving the State's RP determination based upon its cumulative
---------------------------------------------------------------------------
source visibility modeling.

    The use of natural background conditions to assess visibility
benefits of individual controls, as we have done here in this action,
is consistent with the goals of the CAA. As to the comment that we
adjusted the modeled results by updating the baseline uncontrolled
emissions for each unit based on SO2 emissions data for
2009-2013, this was a necessary step to assess the visibility benefit
of controls relative to the visibility impairment due to future
anticipated emission levels at these units without the required
controls. Comparison of 2018 CENRAP projected emissions to recent
actual emissions showed that a number of facilities have actual
emissions that are much higher than CENRAP 2018 modeled emissions.\177\
For instance, Big Brown, Sandow, and Martin Lake actual emissions were
all significantly higher than 2018 CENRAP modeled rates, with Martin
Lake having over 90% more SO2 emissions than projected by
CENRAP for 2018. Both Pirkey and Oklaunion had much smaller actual
SO2 emissions than projected. As we discuss in the FIP TSD,
we believe that recent actual emissions are more representative of
anticipated future emissions at the sources evaluated than the CAIR
projections developed in 2006 and adopted by CENRAP. The CENRAP
modeling was based on an IPM (Integrated Planning Model) that estimated
EGU future emissions in 2018 including reductions for CAIR across the
eastern half of the United States. This analysis was conducted in 2006
and projected that Texas would be a purchaser of SO2
credits, and that not much high level control would be placed on Texas
EGU sources. Given the length of time between 2006 when the IPM
analysis was conducted, and 2013 when we were conducting this analysis,
we had some concern that these projections could be off for the EGUs in
Texas. Information available also indicates that SO2 credits
are much cheaper than originally projected, therefore more credits may
have been used in lieu of emission reductions. We also weighed the
technique that Texas has used in estimating emissions from EGUs for
future years (including 2018) in ozone attainment demonstration SIPs in
DFW and HGB. For these photochemical modeling analyses with CAMx, Texas
has relied upon the recent CEM data that is also included in CAMD's
databases in conjunction with information on recently permitted EGUs
for estimating the emissions to model for EGUs in Texas in 2018 as
these overall EGU emission levels are already near levels projected
under CAIR Phase II control such that further emission reductions are
doubtful in the absence of some new requirements.
---------------------------------------------------------------------------

    \177\ See Table A.4-2 of the FIP TSD for a comparison of recent
actual emissions to CENRAP 2018 projected emission levels.
---------------------------------------------------------------------------

    The actual SO2 allowances for Texas under CSAPR are not
much different than the CAIR Cap for Texas, so large additional
reductions over current emission levels were not expected. However,
because we had earlier projected with IPM that controls for MATS may
generate the installation of additional scrubbers in Texas that could
potentially result in further SO2 reductions, we again
investigated this possibility. Texas recently submitted comments to us
on a more recent IPM projection that was at the time intended by EPA to
be part of a new modeling platform for national rule making.\178\ In
these comments and comments from several EGU owners in Texas, the
assertion was that no significant amount of additional SO2
controls are expected due to compliance with MATS. The comments also
pointed out that, as some of our cursory research had also indicated,
no large SO2 control projects were planned at most of the
sources we were evaluating. Therefore, based on Texas' recent comments
and other information, we concluded considerable uncertainty exists as
to whether any further reductions of SO2 will occur beyond
current emission levels as a result of compliance with MATS or CSAPR.
Overall this information supports looking at recent actual emissions to
represent future emission levels in 2018.
---------------------------------------------------------------------------

    \178\ TCEQ comment letter to EPA on draft modeling platform
dated June 24, 2014. `2018 EMP signed.pdf'.
---------------------------------------------------------------------------

    In summary, this adjustment from CENRAP 2018 to the baseline
calculated from recent actual emissions was not an ``artificial
adjustment'' and was necessary to account for the large difference
between specific unit-level emissions in the 2018 CENRAP emissions and
a baseline more representative of anticipated future emission levels in
2018. We estimated and presented the estimated visibility benefit of
controls based on both the CENRAP 2018 projected emission levels and
emission levels consistent with recent actual emissions data. The
results considering the 2018 CENRAP emissions baseline were also needed
to provide a comparison with the Texas regional haze SIP and an
estimate of the change from the 2018 CENRAP modeled reasonable progress
goal to a new reasonable progress goal including the controls required
in the FIP. The visibility benefit of individual controls calculated
based on the CENRAP 2018 emissions baseline represents the additional
level of visibility benefit from controlling individual units,
consistent with the assumptions/emission projections in the Texas
regional haze SIP.
    Comment: EPA's methodology to estimate revised reasonable progress
goals for Big Bend, the Guadalupe Mountains, and the Wichita Mountains
is without precedent and is not supported by the record. The commenters
also state that the revised reasonable progress goals are incorrect
because they do not account for reductions in Oklahoma emissions.
    Response: We disagree with the comment and believe we took a
reasonable approach to estimate the change in overall visibility
impairment anticipated due to the required controls and provided all
calculations for review. We also disagree with the commenter's
description of how the states estimated the reasonable progress goals.
While our guidance suggests that reasonable progress goals should be
established by modeling all existing and reasonable controls, in
practice all RPOs including CENRAP completed the modeling early in the
process. The 2018 CENRAP modeling was completed before any states had
completed their BART and reasonable progress determinations. In many
cases, the 2018 projection included an assumption of BART level
controls and ``on the book'' controls. Once final BART determinations
and reasonable progress determinations were completed, the RPO did not
go back and remodel to reassess the reasonable progress goals. In our
proposed action in Arkansas,\179\ as well as our actions in Arizona
\180\ and Hawaii,\181\ the modeled reasonable progress goals were
adjusted based on a methodology of scaling of visibility extinction
components in proportion to emission changes. We noted that although we
recognize that this method is not refined, it allows us to translate

the emission reductions achieved through the FIP into quantitative
reasonable progress goals, based on modeling previously performed by
the RPOs. However, in this case, our analysis using CAMx modeling and
source apportionment, provided a somewhat more refined means to
estimate the visibility benefit from specific individual controls on
the 20% worst days in 2018. While there is limited precedent for
adjusting the RPO calculated reasonable progress goals to account for
emission reductions achieved in a FIP or revised SIP, we took a
reasonable approach based on the information available. We adjusted
each reasonable progress goal established by Texas or Oklahoma for 2018
by the amount of visibility benefit anticipated from all scrubber
upgrades estimated by our modeling analysis based on CAMx source
apportionment modeling.\182\ In estimating the deciview visibility
benefit in 2018 compared to the CENRAP modeled 2018 reasonable progress
goals, we considered reductions from 2018 CENRAP emissions levels and
2018 ``dirty'' background conditions. We believe that this is a
reliable estimate of the amount of visibility benefit anticipated from
controls (e.g., 0.14 dv for the Wichita Mountains) beyond the projected
2018 CENRAP reasonable progress goals. We then simply adjusted the
reasonable progress goals established by the state by the amount of
visibility benefit anticipated from the additional controls.
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    \179\ 80 FR 18944, 18997.
    \180\ 79 FR 52420, 52468.
    \181\ 77 FR 31692, 31708.
    \182\ As discussed elsewhere in this document, while the
required scrubber retrofits will provide for additional visibility
improvement at the Class I areas that we consider necessary for
reasonable progress towards natural visibility conditions, we do not
anticipate these controls to be implemented until after 2018.
---------------------------------------------------------------------------

    As discussed above, we adjusted the CENRAP modeled reasonable
progress goals to translate the emission reductions required in this
FIP for Texas sources into quantitative reasonable progress goals. We
note that the CENRAP modeling included an assumption for anticipated
BART reductions for Oklahoma sources. We considered the comment
concerning consideration of the reductions required by the BART FIP in
Oklahoma in setting the 2018 reasonable progress goals and we believe
these assumptions are a reasonable approximation of the anticipated
BART reductions in Oklahoma at this time, considering the uncertainty
of the timing of the reductions for some of the sources and the
uncertainty in the final control scenario chosen by the operator to
meet the requirements. The required enforceable emission limits in the
Oklahoma and Texas FIPs remedy the deficiencies in the SIPs and our
finalized reasonable progress goals properly consider the visibility
benefits anticipated by those required emission reductions.
    Unlike the emission limits that apply to specific reasonable
progress sources, the reasonable progress goals are not directly
enforceable. Rather, the reasonable progress goals are an analytical
tool used by EPA and the states to estimate future visibility
conditions and track progress towards the goal of natural visibility
conditions.
    Comment: EPA's proposal provides no basis for disapproving Texas'
and Oklahoma's reasonable progress goals for the 20% best days and
fails to provides analysis of the part of the reasonable progress goals
addressing the ``best'' days.
    Response: We disagree with the comment. Our basis for disapproving
the relevant reasonable progress goals for the 20% best days arises, as
was noted in our proposal, from our determination that the analysis
developed by Texas to evaluate reasonable progress controls was flawed
and additional controls are necessary for the first planning period.
Finalizing requirements for additional controls, as we now accomplish
with our final rule, makes ``visibility on these days better than Texas
projects,'' as we noted in our proposal.183 184 The
submitted reasonable progress goals for the 20% best days did not
consider reductions from the reasonable controls, so they cannot be
approved. We understand the comment to request a quantitative
assessment of the projected visibility conditions for the 20% best
days. These calculations have been completed and add to our position
that visibility will be better than Texas projects. These numbers,
following the same methodology that we employed with the 20% worst
days, are summarized in the table provided in the introduction section
of the document.
---------------------------------------------------------------------------

    \183\ 79 FR 74843.
    \184\ ``No degradation,'' as distinctly needed for the 20% best
days, is ensured because added controls do not significantly impact
the 20% best days and would serve only to improve visibility on
these days. Even so, what we provide as the 20% best day reasonable
progress goals for 2018 (i.e., the ``least impaired days'') for Big
Bend, Guadalupe Mountains and Wichita Mountains numerically differ
from the numbers that Texas had submitted by very small amounts. By
the design of 40 CFR 51.308(d)(1), improvements for the most
impaired days provide a more vital benchmark for progress that may
be made.
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P. Interstate Visibility Transport

    We received comments opposing our proposed disapproval of the
visibility protection portion of the interstate transport requirements
in Texas infrastructure SIP submittals for the ozone, PM2.5,
NO2, and SO2 NAAQS (CAA 110(a)(2)(D)(i)(II)).
Among the adverse comments were the following: The requirements for
infrastructure SIPs in CAA section 110(a)(2)(D)(i)(II) only contain
structural, rather than substantive, requirements. Disapproving Texas'
infrastructure SIPs conflicts with the differing deadlines for NAAQS
SIP submittals and regional haze SIP submittals. Texas submitted
separate SIPs to address the visibility prong of interstate transport
for the 1997 ozone, the 2006 PM2.5, the 2008 ozone, the 2010
SO2, and the 2010 NO2 standards and EPA failed to
evaluate these submittals in its proposed disapproval. CAA section
110(a)(2)(D)(i)(II) is pollutant specific, and, because EPA finds that
Texas' SIP is inadequate to protect visibility only because it does not
contain certain limitations on SO2 emissions, EPA should not
disapprove for the other NAAQS at issue. The CAA's visibility
protection requirement is narrower than the requirement for reasonable
progress and requires only provisions necessary to prevent interference
with control measures included in another state's plan to achieve a
visibility standard. The CAA limits EPA's authority to require one
state to adopt binding emission limits for the benefit of another
state, citing EME Homer City.
    We disagree with the comments for several reasons. Section
110(a)(2) specifies the substantive elements that infrastructure SIP
submissions need to address, as appropriate, for EPA approval.\185\ EPA
has disapproved portions of such SIPs for failure to comply with the
interstate visibility transport requirements section
110(a)(2)(D)(i)(II) for various other states. See 78 FR 46142, July 30,
2013 (Arizona); 77 FR 14604, March 12, 2012 (Arkansas); 76 FR 52388,
August 22, 2011 (New Mexico); 76 FR 81728, December 28, 2011
(Oklahoma). By contrast, in many other SIP actions across the country,
we have allowed states to rely on their approved regional haze plan to
meet the substantive requirements of the visibility component of
section 110(a)(2)(D)(i)(II) because the regional haze plan achieved at
least as much emissions reductions as projected by the RPO modeling.
See 76

FR 34608, June 14, 2011 (California); 79 FR 60985, October 9, 2014 (New
Mexico); 76 FR 36329, June 22, 2011 (Idaho); and 76 FR 38997, July 5,
2011 (Oregon). We gave limited disapproval to the Texas regional haze
SIP based on its reliance on CAIR. CAIR provided limits on emissions of
SO2 and NOX. SO2 is a precursor for
PM2.5. NOX is a precursor for ozone and for
PM2.5. NO2 is a component of NOX. With
CAIR no longer in effect, Texas may not rely on its regional haze SIP
to ensure that emissions from Texas do not interfere with measures to
protect visibility in nearby states. We recognize that CAA section
110(a)(2)(D)(i)(II) is pollutant specific; nevertheless, ozone,
PM2.5, NO2, and SO2 or their
precursors could interfere with visibility protection. Because Texas
has not demonstrated that its SIP submittals ensure that Texas
emissions would not interfere with measures required to be included in
the SIP for any other state to protect visibility, we are disapproving
these SIP submittals.
---------------------------------------------------------------------------

    \185\ See September 13, 2013 EPA guidance memo ``Guidance on
Infrastructure State Implementation Plan (SIP) Elements under Clean
Air Act Sections 110(a)(1) and 110(a)(2)'', http://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sept_2013.pdf.
---------------------------------------------------------------------------

    As discussed in this action, the D.C. Circuit Court in EME Homer
City recently issued a decision upholding CSAPR but remanding without
vacating a number of the Rule's state emissions budgets, including
those for Texas. The CSAPR remand did not affect our reasons for
proposing to disapprove portions of Texas' SIP submittals that address
CAA provisions for prohibiting air pollutant emissions from interfering
with measures required to protect visibility in any other state for the
1997 PM2.5, 2006 PM2.5, 1997 ozone, 2008 ozone,
2010 NO2, and 2010 SO2 NAAQS. However, the remand
did affect our proposal to rely on CSAPR to help address our FIP
obligation for interstate transport of air pollution and visibility
protection. Therefore, today's action does not finalize the portion of
our proposed FIP that would have relied on CSAPR to satisfy Texas'
visibility transport obligations with respect to the aforementioned
NAAQS. We will address the visibility transport requirements for Texas
in a future rulemaking once the issues surrounding the partial remand
are resolved.

Q. Disapproval of the Oklahoma and Texas Reasonable Progress Goals

    We received numerous comments on our proposed disapproval of the
reasonable progress goals selected by Texas and Oklahoma for their
respective Class I areas and the recalculated reasonable progress goals
we proposed. Some comments were in support of our proposed disapproval
of the state's reasonable progress goals and our proposed recalculated
reasonable progress goals. However, a majority of the comments raised
objections to our proposed action on the reasonable progress goals.
These commenters raised numerous issues in support of their objections
to our proposal, including that recent monitoring data from IMPROVE
monitors indicates the Class I areas are already meeting the new
reasonable progress goals we proposed without the need for the
additional controls we proposed, that there have been significant
SO2 and NOX emissions reductions in Texas since
the baseline period, that our proposed disapproval of the state's
reasonable progress goals had no technical or legal basis, and that we
inappropriately recalculated the new reasonable progress goals we
proposed.
    Below we present a summary of our responses to the more significant
comments we received that relate to our proposed action on the
reasonable progress goals for Texas and Oklahoma Class I areas. See our
RTC document for a more in-depth presentation of the comments we
received and our responses to them.
    Comment: Our proposed disapproval of Oklahoma's reasonable progress
goals for the Wichita Mountains is proper and required by the CAA, as
the record is clear that control measures satisfying the four
reasonable progress factors are available for some of the largest
sources of visibility impairment at the Wichita Mountains. Our proposed
finding that Oklahoma and Texas did not adequately consult with each
other regarding the impact of Texas sources on Oklahoma's Class I area
is also proper because in order to engage in meaningful consultation,
an upwind state such as Texas must provide impacted states with
sufficient technical information detailing the visibility impacts of
individual sources and the feasibility and cost-effectiveness of
control measures on those sources. A downwind state such as Oklahoma
should request the adequate information when it is not provided by the
upwind state and must take a hard look at this information and request
that upwind states require the control measures that satisfy the four
factors laid out in the statute for making reasonable progress. We
support the EPA's conclusions as to what constitutes a proper and
meaningful consultation under the regional haze program and support the
EPA's proposed disapproval of Oklahoma's reasonable progress goals and
finding that the consultations between Oklahoma and Texas were
inadequate.
    Response: We appreciate the commenter's support of our
interpretation of what constitutes an adequate consultation that
satisfies the Regional Haze Rule requirements. We also appreciate the
commenter's support of our proposed disapproval of Oklahoma's
reasonable progress goals for the Wichita Mountains and our finding
that the consultations between Oklahoma and Texas to address the
impacts of Texas sources on the Wichita Mountains were not adequate and
did not meet the regional haze requirements. We are finalizing as
proposed our disapproval of several of the requirements with regard to
Oklahoma's establishing of reasonable progress goals for the Wichita
Mountains, including our finding that the consultations between Texas
and Oklahoma to address Texas' impacts on the Wichita Mountains were
not adequate and did not meet the Regional Haze Rule requirements.
    Comment: EPA should withdraw its proposed FIP and instead fully
approve the regional haze SIPs submitted by Texas and Oklahoma because
the SIP submitted by Texas fully complies with the statute and all
regulatory standards and therefore there is no legal or technical basis
for EPA's proposed FIP. On every level, EPA's proposal exceeds the
agency's authority under the CAA and EPA's regional haze regulations.
    Response: We disagree with the commenter that there is no legal or
technical basis for our proposed FIP, that the proposed FIP exceeds our
authority under the CAA and the regional haze regulations, and that the
SIP submitted by Texas fully complies with the statute and regulatory
requirements. The CAA and Sec.  51.308(d)(1) provide how to determine
what constitutes reasonable progress for each planning period and
specify the requirements related to establishment of the reasonable
progress goals for each Class I area. In particular, both the CAA and
the Regional Haze Rule require states to consider four factors when
setting reasonable progress goals: The costs of compliance, time
necessary for compliance, energy and non-air quality environmental
impacts, and the remaining useful life of potentially affected
sources.\186\ The Regional Haze Rule also requires that in establishing
the reasonable progress goals, states must consider the uniform rate of
progress and the emission reduction measures needed to achieve it for
the period covered by the implementation plan. In addition, because the
reasonable progress goals selected by Texas and Oklahoma provide for a
rate of improvement slower than the

uniform rate of progress, the Regional Haze Rule requires the states to
demonstrate why their reasonable progress goals are reasonable and why
a rate of progress leading to natural visibility conditions by 2064 is
not reasonable.\187\ As discussed in more detail in our proposal and in
the RTC document associated with this final action, Texas did not
satisfy several of the requirements at Sec.  51.308(d)(1) with regard
to setting reasonable progress goals for its own Class I areas, most
notably the requirement to reasonably consider the four statutory
reasonable progress factors and the requirement to adequately consider
the emission reduction measures needed to meet the uniform rate of
progress. Texas also did not satisfy the consultation requirements at
Sec.  51.308(d)(3)(i) to address its impacts on the Wichita Mountains.
Oklahoma also did not satisfy certain requirements under Sec.
51.308(d)(1) with regard to setting reasonable progress goals for the
Wichita Mountains, including the requirement to adequately consult with
other states that may reasonably be anticipated to cause or contribute
to visibility impairment at the Wichita Mountains and the requirement
to adequately consider the emission reduction measures needed to meet
the uniform rate of progress. Therefore, we disagree that the Texas and
Oklahoma SIPs fully comply with the statutory and regulatory
requirements and that our FIP exceeds our authority under the CAA. We
are finalizing our proposed disapproval of Texas' and Oklahoma's
reasonable progress goals and the controls we proposed under reasonable
progress for sources in Texas.
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    \186\ CAA Section 169A(g)(1), 42 U.S.C. 7491(g)(1). 40 CFR
51.308(d)(1)(i)(A).
    \187\ 40 CFR 51.308(d)(1)(ii).
---------------------------------------------------------------------------

    Comment: EPA does not take issue with Oklahoma's four-factor
analysis, but nevertheless proposes to reset Oklahoma's reasonable
progress goals based on its reasonable progress analysis for Texas
sources. EPA also finds it necessary to disapprove Oklahoma's
reasonable progress goals because they did not include the emission
reductions from the Oklahoma SO2 BART FIP and the revised
BART SIP for the AEP units that were subsequently promulgated. However,
EPA's proposed SIP does not correct this error either.
    Response: The comment that we disapproved the reasonable progress
goals for the Wichita Mountains because they do not include the
emission reductions from the SO2 BART FIP and the revised
BART SIP for the AEP units that have subsequently been promulgated is
taken out of context and does not fully capture the rationale for our
disapproval. We are disapproving the reasonable progress goals for the
Wichita Mountains because they do not account for emission reductions
from reasonable measures at Texas sources. We stated in the proposal
that the reasonable progress goals selected by Oklahoma for the Wichita
Mountains do not include the level of reductions necessary to meet the
requirements under 40 CFR 51.308(e) for BART. We further explain that
``BART is a component of developing the reasonable progress goals, and
the reasonable progress goals are inadequate because BART controls were
not adequately considered. We note this deficiency is addressed by our
Oklahoma BART FIP and the revised Oklahoma BART SIP.'' \188\ The
visibility modeling developed for CENRAP and used by Oklahoma in
support of its SIP revision submittal assumed SO2 reductions
from the six BART sources that Oklahoma subsequently did not secure
when making its BART determinations for these sources. We believe that
the BART limits in our Oklahoma BART FIP \189\ have adequately
addressed the deficiency. We also provide in our proposal additional
reasons for disapproving the reasonable progress goals, stating
``Oklahoma's consultations with Texas were flawed, which prevented
Oklahoma from adequately developing its reasonable progress goals for
the Wichita Mountains,'' and, because Oklahoma's consultations with
Texas were flawed, Oklahoma did not adequately demonstrate that the
reasonable progress goals it established were reasonable based on the
four statutory factors under Sec.  51.308(d)(1)(ii).\190\ Comments
regarding how we calculated the reasonable progress goals for the
Wichita Mountains, Big Bend, or the Guadalupe Mountains, and our
consideration of emission reductions from BART requirements in Oklahoma
are addressed in a separate response to comment.
---------------------------------------------------------------------------

    \188\ 79 FR 74871, 74872.
    \189\ 76 FR 81728.
    \190\ 79 FR 74872.
---------------------------------------------------------------------------

    Comment: EPA's proposed disapproval of Texas' reasonable progress
goals and its substitution with new reasonable progress goals in the
proposed FIP is based on EPA's flawed interpretation of what the CAA
requires for ``reasonable progress goals.'' This action is based on the
EPA's conclusion that ``reasonable progress'' must be determined based
on source-specific cost of controls even though such a requirement did
not exist in the statute, the Regional Haze Rule, or the guidance
available in 2009. The Texas 2009 regional haze SIP established
reasonable progress goals for both Big Bend and the Guadalupe Mountains
that provide for visibility improvement for the most impaired days over
the period of the SIP and ensure no degradation in visibility for the
least impaired days over the same period. The EPA agrees the SIP meets
these requirements and also agrees that the TCEQ considered the four
statutory factors in establishing the reasonable progress goals for its
Class I areas in accordance with the Regional Haze Rule. Furthermore,
the four statutory factors in and of themselves do not determine the
reasonableness of the goals for the planning period. The Regional Haze
Rule, in 40 CFR 51.308(d)(1)(iii), requires the EPA to evaluate whether
the state's goal for visibility improvement provides for reasonable
progress based on a demonstration of which the four statutory factors
are only one element. Therefore, EPA's proposed disapproval of Texas'
reasonable progress goals and its proposed new reasonable progress
goals is flawed.
    Response: We disagree that our proposed disapproval of Texas'
reasonable progress goals is based on a flawed interpretation of what
the CAA requires for reasonable progress goals. As we discuss in our
responses to other similar comments, we believe that our evaluation of
cost, including visibility benefits, on a source-specific basis was an
appropriate and reasonable interpretation of the analysis required in
this instance, in order to determine what, if any, level of control for
Texas sources constituted reasonable progress for this planning period.
    We agree that Sec.  51.308(d)(1) requires more than just the
consideration of the four factors in the establishment of the
reasonable progress goals. Also, although we agree Texas conducted an
evaluation of the four reasonable progress factors, we determined that
that evaluation was flawed. Texas did not fully satisfy the
requirements under Sec.  51.308(d)(1) related to the evaluation of the
four reasonable progress factors and establishment of the reasonable
progress goals for the two Texas Class I areas. We note that Sec.
51.308(d)(1)(iii) provides that in determining whether the State's goal
for visibility improvement provides for reasonable progress towards
natural visibility conditions, the Administrator will evaluate the
demonstrations developed by the State pursuant to paragraphs (d)(1)(i)
and (ii). Thus, we are specifically directed to judge the quality of a
state's submission of these key parts

of its reasonable progress goals development, which we found to be
flawed. In particular, as we discussed in detail in our proposal, we
disagree with the set of potential controls identified by Texas and how
it analyzed and weighed the four reasonable progress factors under
Sec.  51.308(d)(1)(i)(A) \191\ and we further proposed to disapprove
Texas' reasonable progress goals under Sec.  51.308(d)(1)(ii).\192\ For
the reasons given in the proposal and affirmed in this final action, we
cannot approve Texas' reasonable progress goals. In this action, we are
finalizing our disapproval of Texas' reasonable progress goals for Big
Bend and the Guadalupe Mountains and we are establishing new reasonable
progress goals for these Class I areas, as discussed in our proposal.
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    \191\ 79 FR 74838.
    \192\ 79 FR 74843.
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    Comment: EPA fails to take into consideration the TCEQ's 2014 Five-
Year Regional Haze SIP Revision or the effects of early action or
emission reduction accomplished or to be accomplished by other EPA
programs before imposing additional requirements beyond the state
submitted SIPs. Considering that the visibility improvements of these
programs have not yet been quantified, and the gradual progress
anticipated in establishing such a long-term goal, EPA should be
patient and not take such aggressive action in overriding reasonable
state SIPs and imposing additional controls.
    Response: We stated in our proposal that the TCEQ submitted the
first five-year report in March 2014, but we are not including our
analysis of that SIP revision within this action.\193\ The five-year
progress report is a requirement that is separate from the regional
haze SIP required for the first planning period, and it has separate
content and criteria for us to review. We therefore believe we are not
obligated to consider or take action on the five-year progress report
at the same time we take action on the regional haze SIP for the first
planning period. Even so, we acknowledge that recent monitoring data
from IMPROVE monitors indicate that the more recent five-year average
measurements of visibility extinction at Texas and Oklahoma Class I
areas on the 20% worst days contained in the progress report are lower
(i.e., indicate better visibility conditions) than the numerical
reasonable progress goals we are establishing for these Class I areas.
This issue is addressed in detail elsewhere in this final action and in
the RTC document.
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    \193\ 79 FR 74864.
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    We disagree with the commenter's contention that we should not
impose additional controls on Texas sources and instead approve the
Texas regional haze SIP and the remaining portion of the Oklahoma
regional haze SIP because there may be potential visibility
improvements that have not yet been quantified, resulting from early
actions and emission reductions accomplished or expected to be
accomplished through other EPA programs. If it is determined based on
the demonstrations developed pursuant to Sec.  51.308(d)(1)(i) and (ii)
that there are reasonable and cost-effective controls available that
would provide for reasonable progress, the statute and regional haze
regulations do not allow for a delay in requiring these controls to
allow time for the quantification and consideration of possible future
visibility improvements. Therefore, we are finalizing our proposed
disapproval of Texas' and Oklahoma's reasonable progress goals and are
finalizing the control requirements we proposed for Texas sources under
the reasonable progress and long-term strategy reasonable progress
requirements.
    Comment: The regional haze program tasks states with determining
what is reasonable progress toward elimination of man-made visibility
impairment, along with specific progress milestones (10-year planning
and SIP revisions, with program reviews in the middle of the 10-year
planning periods). The regional haze program contemplates gradual
visibility improvements along a ``glide path'' that considers the 2064
goal, and does not require immediate reductions that exceed
``reasonable progress'' as determined by the state based on the four
statutory factors. Thus, it neither requires nor authorizes the
frontloading of extensive control requirements.
    Response: The commenter's contention concerning reasonable progress
is premised on the assumption that the emissions reductions that are
part of the state's long-term strategy and upon which its reasonable
progress goals are based do in fact constitute reasonable progress. The
determination of what constitutes reasonable progress must be made
pursuant to Sec.  51.308(d)(1). Based on its analyses under Sec.
51.308(d)(1), a state (or EPA in the context of a FIP) may determine
that a greater or lesser amount of visibility improvement than what is
needed to get on the glide path is what constitutes reasonable
progress.\194\ As discussed in our proposal and within this action, we
disagree with the set of potential controls identified by the TCEQ as
having the greatest impact on visibility on the three Class I areas and
how it analyzed and weighed the four reasonable progress factors in a
number of key areas.\195\ Therefore, we proposed to disapprove Texas'
reasonable progress goals for its Class I areas and conducted our own
analysis of the four reasonable progress factors to fill in the
regulatory gap that would be created by our disapproval action. We are
replacing Texas' flawed reasonable progress analysis with our own and
are finalizing the cost-effective reasonable progress controls we
proposed on the small number of Texas point sources that have the
greatest visibility impacts on the Class I areas of interest.
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    \194\ 64 FR 35732.
    \195\ 79 FR 74838.
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    Comment: Texas' four-factor analysis and its reasonable progress
goals were reasonable and within the state's broad discretion, and are
supported by recent monitoring data showing the reasonable progress
goals will be met for Oklahoma and Texas Class I areas without the
additional controls EPA proposed for Texas sources. The most recent
five-year (2009-2013) averages of visibility monitoring data from
IMPROVE monitors indicates that visibility impairment at the Guadalupe
Mountains, Big Bend, and the Wichita Mountains, are lower than both the
2018 reasonable progress goals proposed by the states and the more
stringent 2018 reasonable progress goals proposed by EPA. The Texas
five-year regional haze progress report issued in 2014 includes a
projection of further reductions of haze-forming SO2 and
NOX emissions from point sources through 2018. Therefore,
the commenter concludes that it is expected that visibility
improvements observed through 2013 for Big Bend, the Guadalupe
Mountains, and the Wichita Mountains will continue and that the 2018
reasonable progress goals that EPA proposes will be met without the
further emission controls EPA proposes. These current data also show
that Wichita Mountains is projected to meet the EPA approved uniform
rate of progress for Oklahoma, and the Guadalupe Mountains is projected
to meet the EPA-proposed uniform rate of progress by 2018, without the
emission controls that EPA is proposing. Yet EPA ignores these actual
conditions in developing its reasonable progress goals and in
concluding that its reasonable progress goals are more reasonable. EPA
has no authority to require further controls from Texas sources and
should

withdraw its FIP and approve the Texas SIP.
    Response: These comments are predicated on two false tests: (1) If
a Class I area meets its uniform rate of progress, or (2) if subsequent
monitoring shows a Class I area meets its reasonable progress goals, it
is automatically relieved of any obligation to address the reasonable
progress and long-term strategy requirements in Sec.  51.308(d)(1) and
(3).
    We discuss elsewhere in this final action that, while we agree that
the Regional Haze Rule requires states to consider the uniform rate of
improvement in visibility when formulating reasonable progress goals,
we disagree that a state's consideration of the uniform rate of
progress and establishment of reasonable progress goals that provide
for a slightly greater rate of improvement in visibility than would be
needed to attain the uniform rate of progress is all that is needed to
satisfy the reasonable progress goal requirements in the Regional Haze
Rule. We also disagree that the Regional Haze Rule requires additional
analysis only when a state establishes reasonable progress goals that
provide for a slower rate of improvement than the uniform rate of
progress. Even when recent data from IMPROVE monitors indicate that
visibility conditions in the Class I area are better than the
established reasonable progress goals and/or that the area may be
projected to meet the uniform rate of progress by 2018, the state must
still address the requirements under Sec.  51.308(d)(1) and (d)(3)(i)
in evaluating controls for additional sources and in establishing
reasonable progress goals for its Class I areas.
    With regard to the assertion that Texas' five-year regional haze
progress report projects SO2 and NOX emissions
from point sources to continue to decline through 2018 (with
corresponding visibility improvement trends at the three Class I
areas), Texas' five-year regional haze progress report is pending
evaluation as a SIP revision, and we intend to take action on it in a
future rulemaking. We note that the portion of the Texas' five-year
regional haze progress report referred to by the commenters \196\
compares actual annual emissions from 2002 through 2011 against a
linear change between 2002 actual emissions and the 2018 CENRAP modeled
emissions and concludes that emissions from 2002 to 2011 have trended
downward better than or as predicted in the CENRAP modeling
projections. However, we noted in our proposal that the CENRAP
projected visibility impacts in 2018 from Texas point sources, and EGUs
in particular, are significant. As noted in our proposed rulemaking,
based on information provided by the TCEQ in materials other than the
progress report, we do not expect large additional emission reductions
of SO2 in Texas between 2013 and 2018 under Federal programs
and the SIP as submitted.\197\ We have not seen evidence in support of
something different. Furthermore, emissions from some of the Texas EGUs
that we are requiring controls for and that impact visibility at the
three Class I areas the most, are still above the emission level
projected in the 2018 CENRAP modeling. We are not aware of any upcoming
controls or changes in operation to suggest that future actual
emissions at these specific sources will decrease to those predicted
levels.
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    \196\ 2014 Texas Five-Year Reasonable Progress Report, p 4-10,
figure 4-2.
    \197\ TCEQ comment letter to EPA on draft modeling platform
dated June 24, 2014.
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    We also remind the commenters that even with the controls we are
requiring for Texas EGUs under our FIP, additional reductions would be
needed for visibility conditions to meet or exceed every uniform rate
of progress goal in 2018 as calculated by us in our proposal. For
example, current conditions at the Wichita Mountains (based on 2009-
2013) is 21.2 dv. Additional reductions would be needed for the area to
meet the uniform rate of progress goal of 20.01 dv in 2018.
    Comment: The SO2 emissions from Luminant's units, for
which EPA proposed controls, have steadily trended downward over the
first planning period, further underscoring the effectiveness of the
measures relied on in Texas' SIP and the unreasonableness of EPA's
proposed FIP. From 2009 to 2014, SO2 emissions from
Luminant's Big Brown, Martin Lake, Monticello, and Sandow Unit 4 were
reduced by 27%. The SO2 emissions for the first quarter of
2015 are sharply lower--approximately 57% lower than the first quarter
of 2009 and about 44% lower than the first quarter of 2014. The data
unequivocally show that SO2 emissions at Luminant's units
are trending down, and thus there is no basis for EPA's proposal.
    Response: The annual and quarterly SO2 emissions data
for Luminant's facilities for 2009-2015 demonstrate that, although
there has been an overall downward trend in annual SO2
emissions during this time period, there has not been a downward trend
in SO2 emissions during Quarter 3 for the six-year period
for which full data are available. Except for the years 2011 and 2012,
when total SO2 emissions for Quarter 3 were either sizably
higher or lower compared to the other years during the 2009-2014 time
period, emissions for Quarter 3 remained relatively unchanged during
this six year period. This is significant because Quarter 3 corresponds
to the summer months and many of the 20% worst days, which is what the
reasonable progress goals are based on, typically occur during the
summer months. Emissions reductions during the fall and/or winter
months reduce annual emissions, but will not lead to improved