[Federal Register Volume 77, Number 112 (Monday, June 11, 2012)]
[Proposed Rules]
[Pages 34315-34326]
[FR Doc No: 2012-14153]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 122, 123, 124, and 125

[EPA-HQ-OW-2008-0667, FRL-9681-4]
RIN 2040-AE95

National Pollutant Discharge Elimination System--Proposed
Regulations to Establish Requirements for Cooling Water Intake
Structures at Existing Facilities; Notice of Data Availability Related
to Impingement Mortality Control Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of Data Availability.

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SUMMARY: On April 20, 2011, EPA published proposed standards for
cooling water intake structures at all existing power generating
facilities and existing manufacturing and industrial facilities as part
of implementing section 316(b) of the Clean Water Act (CWA). As a
result of that notice, EPA received extensive comments on its proposal.
These comments included a substantial amount of new information
accompanied by reports, studies and other documents often supplemented
with the substantiating data. In some cases, the materials may not have
included the underlying data supporting the documents' conclusions.
Consequently, in many circumstances, EPA contacted the commenters to
obtain the raw data underlying the documents for EPA's use in further
assessing its proposal. This notice presents a summary of the
significant new information and data EPA has received since proposal
and a discussion of possible revisions to the final rule that EPA is
considering that were suggested by the data and comments. EPA solicits
public comment on the data and possible revisions presented in this

notice and the record supporting this notice.

DATES: Comments must be received on or before July 11, 2012.

ADDRESSES: Submit your comments, identified by Docket No. EPA-HQ-OW-
2008-0667 by one of the following methods:
     http:www.regulations.gov: Follow the on-line instructions
for submitting comments.
     Email<EMAIL_ADDRESS>Attention Docket ID No. EPA-HQ-
OW-2008-0667.
     Mail: Water Docket, U.S. Environmental Protection Agency,
Mail Code: 4203M, 1200 Pennsylvania Ave. NW., Washington, DC 20460.
Attention Docket ID No. EPA-HQ-OW-2008-0667. Please include a total of
3 copies. In addition, please mail a copy of your comments on
information collection provisions to the Office of Information and
Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk
Officer for EPA, 725 17th St. NW., Washington, DC 20503.
     Hand Delivery: Water Docket, EPA Docket Center, EPA West
Building Room 3334, 1301 Constitution Ave. NW., Washington, DC,
Attention Docket ID No. EPA-HQ-OW-2008-0667. Such deliveries are only
accepted during the Docket's normal hours of operation, and special
arrangements should be made for deliveries of boxed information by
calling<PHONE_NUMBER>.
    Instructions: Direct your comments to Docket No. EPA-HQ-OW-2008-
0667. EPA's policy is that all comments received will be included in
the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Information that you consider to
be CBI or otherwise protected should not be submitted through
www.regulations.gov or email. The www.regulations.gov Web site is an
``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to EPA without
going through http://www.regulations.gov your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses.
    Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the Water Docket in
the EPA Docket Center, EPA/DC, EPA West, Room 3334, 1301 Constitution
Ave. NW., Washington, DC. The Public Reading Room is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The
telephone number for the Public Reading Room is<PHONE_NUMBER>, and the
telephone number for the Water Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For additional technical information,
contact Paul Shriner at<PHONE_NUMBER>; email<EMAIL_ADDRESS>For
additional economic information, contact Erik Helm at<PHONE_NUMBER>;
email<EMAIL_ADDRESS>or Wendy Hoffman at<PHONE_NUMBER>; email:
<EMAIL_ADDRESS>For additional biological information, contact
Tom Born at<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Supporting Documentation

A. Docket

    EPA has established an official public docket for this action under
Docket ID No. EPA-HQ-OW-2008-0667. The official public docket consists
of the documents specifically referenced in this action, any public
comments received, and other information related to this action.
Although a part of the official docket, the public docket does not
include information claimed as Confidential Business Information (CBI)
or other information for which the disclosure is restricted by statute.
For information on how to access materials in the docket, refer to the
preceding ADDRESSES section. To view docket materials, please call
ahead to schedule an appointment. Every user is entitled to copy 266
pages per day before incurring a charge. The Docket may charge 15 cents
for each page over the 266-page limit plus an administrative fee of
$25.00.

B. Electronic Access

    You may access this Federal Register document and the docket
electronically, as well as submit public comments, through the Web site
http://www.regulations.gov by searching for Docket ID No. EPA-HQ-OW-
2008-0667. For additional information about the public docket, visit
the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.

Table of Contents

I. Purpose of This Notice
    A. Summary of Proposed Rule for Existing Facilities
II. New Information Received Concerning Proposed Impingement
Mortality (IM) Requirements
    A. New Information Received
    B. Alternative Approaches Under Consideration
    1. Site Specific Approach for Reducing Impingement Mortality
    2. Closed-Cycle Recirculating Systems
    3. Measurement of Intake Velocity
    4. Impingement Mortality Limitations
    5. Credit for Existing or Newly Installed Technologies
    6. Facilities With Low Impingement Rates
    7. Species of Concern
III. General Solicitation of Comment

I. Purpose of This Notice

    On April 20, 2011, EPA published proposed standards for cooling
water intake structures at all existing power generating facilities and
existing manufacturing and industrial facilities as part of EPA's
implementation of its responsibilities under section 316(b) of the
Clean Water Act (CWA) (76 FR 22174). EPA received voluminous comments
and data submissions during the 90-day public comment period. After
many commenters requested additional time to review the proposal, on
July 20, 2011, EPA extended the comment period by an additional 30 days
(76 FR 43230).
    Along with the comments on the proposal, EPA also received more
than 50 documents containing new impingement and entrainment data. In
addition, after the comment period ended, EPA followed up with those
commenters whose comments referred to studies or summarized data in
their comments, but had not submitted the underlying studies or raw
data referenced in their comments. As a result, these commenters also
provided over 30 additional documents containing new impingement and
entrainment data. EPA is reviewing each of these roughly 80 documents
for possible use in developing the final

impingement mortality limitations. This notice makes these data
available and discusses the relevance of these data to the analyses
conducted by EPA. EPA solicits comment both on the information
presented in this notice and the record supporting this notice.
    EPA requested comment on all aspects of the proposed existing
facility rule, including specific solicitation of comments and data on
28 key issues (76 FR 22174, Section XI). EPA received more than 1,100
comment letters, several of which provided specific recommendations for
changes to the proposed regulatory language. Some of the suggested
revisions, if adopted, may help to address EPA's intent to greatly
reduce the damage to ecosystems while accommodating site specific
circumstances and providing cost effective options for compliance. Some
of these suggestions relate to the impingement mortality standard, and
are discussed in this notice along with accompanying new data.
    EPA notes that all data and options and issues discussed in its
proposal are still under consideration for the final rule. This notice
is intended to apprise the public of the new information, make this
information available for public review and provide an opportunity to
comment on the new information that the Agency will consider in making
its decisions for the final rule. However, EPA notes that the Agency is
not reopening the proposed rule for comment through this notice.

A. Summary of Proposed Rule for Existing Facilities

    The proposed rule would establish requirements under section 316(b)
of the Clean Water Act (CWA) for all existing power generating
facilities and existing manufacturing and industrial facilities that
withdraw more than 2 million gallons per day (MGD) of water from waters
of the U.S. and use at least 25 percent of the water they withdraw
exclusively for cooling purposes. The proposed national requirements,
which would be implemented through National Pollutant Discharge
Elimination System (NPDES) permits, would establish national
requirements applicable to the location, design, construction, and
capacity of cooling water intake structures at these facilities by
setting requirements that reflect the best technology available (BTA)
for minimizing adverse environmental impact. The proposed rule responds
to the remands of the Phase II existing facility rule and the existing
facilities portion of the Phase III rule from the U.S. Courts of
Appeals for the Second Circuit and Fifth Circuit. In addition, EPA
responded to the decision in Riverkeeper, Inc. v. EPA, 358 F.3d 174 (2d
cir. 2004) and proposed to remove from the Phase I new facility rule
the restoration-based compliance alternative and the associated
monitoring and demonstration requirements.
    The proposed rule provided significant flexibility in complying
with the proposed technology standards for impingement and entrainment.
For the proposal, EPA concluded that the best technology available for
reducing impingement mortality was modified travelling screens. Based
on this BTA technology, EPA proposed standards for impingement that
would require existing facilities to reduce impingement mortality. The
owner or operator of the facility would be able to choose one of two
options to comply with the impingement standard. Under the first
option, a numeric fish impingement mortality limitation, the owner or
operator would have to sample to measure fish mortality directly to
show it will meet the specified mortality performance standards. The
owner or operator could use any appropriate technology to meet the
standard. Under the second option, a velocity limitation, a facility
would have to demonstrate to the permitting authority that its maximum
intake velocity will not exceed 0.5 feet per second under specified
design conditions. Operation of its intake system in compliance with
these specified design conditions would become part of the facility's
permit requirements. EPA estimated that more than half of the
facilities that could be impacted by the proposed rule already employ
readily available technologies that are likely to put them into
compliance with the proposed standard.
    For entrainment, EPA proposed a site-specific determination to be
made by the Director based on local concerns and on the unique
circumstances of each facility. The proposed rule would establish
requirements for the owner or operator of a facility with actual intake
flows in excess of 125 MGD to conduct comprehensive studies, and for
all facilities to develop certain information as part of the permit
application. Under the procedures proposed to be established in the
proposal, the permit authority would determine the appropriate
technology to reduce entrainment mortality, if any, to be implemented
at each facility after considering site-specific factors.

II. New Information Received Concerning Proposed Impingement Mortality
(IM) Requirements

    EPA received a substantial number of comments on how the final rule
should address impingement mortality (IM). EPA based its proposed
national impingement mortality limitations on the performance of
modified traveling screens. And, as noted above, as an alternative EPA
proposed that a facility could demonstrate that either the design
intake velocity or the actual intake velocity at its operation was less
than 0.5 feet per second. Most of the commenters, including members of
the U.S. Congress, state and local elected officials, and industry
stakeholders, requested additional flexibility in complying with the IM
requirements.
    While the proposal would not specifically require the use of
modified traveling screens with a fish handling and return system to
meet the IM limits, some commenters interpreted the proposed rule as
requiring this. EPA's proposed IM limits are expressed as a monthly
average and an annual average. A facility could meet the limitation
through any technology it chose. In EPA's view, this approach is a more
flexible one than establishing a design standard (i.e., requiring a
specific technology) because it would allow facilities to choose a
compliance technology that best meets the individual facility
requirements dictated by site and other conditions. Further, such an
approach allows for innovation in meeting the national impingement
mortality limitations. EPA recognizes, however, that some regulated
entities may find a technology-based compliance option, rather than a
performance based approach, more attractive. Such an approach,
particularly the specification of pre-approved technologies, may offer
higher regulatory certainty, easier demonstration of compliance, and
may offer a less expensive alternative due to reduced monitoring
requirements associated with pre-approved technologies. Some commenters
viewed the proposed IM standard as overly stringent and requested that
EPA establish alternative IM requirements, including site-specific IM
requirements similar to those proposed for entrainment. Other
commenters provided data pertaining to the performance of technologies,
including modified traveling screens used as the basis for the IM
limitations.
    EPA reviewed all the performance data submitted. EPA is considering
these performance data in its evaluation of BTA, including likely
revisions to the IM annual and monthly numeric limits, different
approaches that may better streamline compliance, and additional
options that would better facilitate a demonstration of performance
that is equivalent to the proposed BTA. EPA

also received several comments that proposed alternative regulatory
approaches or provided specific alternative regulatory language. EPA is
also reviewing these comments and considering the alternative
regulatory approaches suggested. The data received and corresponding
issues are described in more detail in the following sections.

A. New Information Received

    As discussed in section I, EPA received more than 80 additional
documents containing impingement and entrainment data. In some cases,
the only data available was the facility name plus raw sampling data
for a number of different species of fish and/or shellfish. Other
documents focus on source water characterization data. EPA identified
more than 40 distinct sets of additional impingement sampling and
performance data from these documents. EPA is reviewing the data in
each of these documents for potential inclusion in EPA's evaluation of
an IM limitation. In light of these data and accompanying comments, EPA
is also reviewing the criteria it adopted for including a study in the
limit calculations. EPA's proposed criteria were described in Chapter
11 of the Technical Development Document (DCN 10-0004, EPA-HQ-OW-2008-
0667-1282).
    In addition to the new impingement and entrainment data, some
stakeholders suggested alternative regulatory frameworks for
impingement mortality. Under the proposed rule, a facility would be
permitted to adopt any technology it chooses so long as it will achieve
the required impingement limitation. Thus, a facility could demonstrate
the reductions in impingement mortality by either (1) increasing the
survival of those fish and shellfish that are impinged, or (2) by
reducing the fish and shellfish impingement rates in the first place.
EPA had concluded, based on the information it reviewed, that the
design standards pertaining to intake velocity would achieve the
impingement mortality limitations, and proposed such design criteria as
having met the impingement mortality limitation. Therefore, compliance
with intake velocity limitation would achieve full compliance with the
numeric impingement mortality limitations and no additional control
technology would be required.
    Several industry stakeholders stated that, despite EPA's best
intentions, the proposed rule applied a one-size-fits-all approach for
impingement mortality. While all of the suggested changes to the
proposal seek to provide additional flexibility through a variety of
approaches, most of the comments had several elements in common:
     Commenters suggested defining modified traveling screens
as a pre-approved technology or otherwise streamlining the NPDES
process for facilities using the candidate technology upon which BTA is
based. Thus, EPA would designate certain technologies or certain
conditions as complying with the impingement requirement;
     Providing a mechanism to identify other technologies that
perform comparably to modified traveling screens;
     Modifying the proposal so that facilities that have
already reduced the rate of impingement may obtain credit towards the
IM limit;
     Developing a more tailored approach to protecting
shellfish;
     Creating alternatives for facilities with very low
impingement levels or mortality rates; and
     Providing additional clarity on species of concern as it
pertains to demonstrating compliance with the IM limitations.
    In addition, as noted above, EPA also received a number of comments
suggesting that it adopt a site-specific approach to reducing
impingement mortality similar to the proposed approach for addressing
entrainment, rather than uniform national requirements for IM and a
site-specific approach for entrainment only. Should EPA decide to adopt
uniform national performance or technology based standards for IM, as
in the proposal, EPA is also considering a number of flexibilities,
such as the site-specific approach for measuring compliance with IM
limits detailed in section III.B.4 below. EPA also received requests to
meet with or hold conference calls with a number of stakeholders to
discuss each of these approaches. The stakeholders with whom EPA met
include the Utility Water Act Group (UWAG), the Clean Energy Group
(CEG), the Cooling Water Intake Structure Coalition, the Association of
Clean Water Administrators (ACWA), and Riverkeeper, as well as several
individual firms and companies. Documentation of these meetings may be
found in EPA's docket (11-6500). The following sections present the
data and suggested approaches EPA may use in developing the final rule.

B. Alternative Approaches Under Consideration

1. Site Specific Approach for Reducing Impingement Mortality
    EPA received a number of comments suggesting that it adopt a site
specific approach for both IM and entrainment, rather than uniform
national requirements for IM and a site-specific approach for
entrainment only. At proposal, EPA considered an approach that would
establish both impingement and entrainment mortality requirements on a
case-by-case basis taking into account the factors at a particular
facility, but did not propose such an approach based on its preliminary
determination at proposal that there are low cost technologies for
impingement mortality that are available, feasible, and demonstrated
for facilities on a national basis (76 FR 22174, Section VI.D.4). EPA
recognizes both advantages and disadvantages of uniform national
requirements. Such requirements would ensure a minimum level of IM
reduction at all facilities. Moreover, if the final rule provides
additional flexibility such as those measures discussed in Section
III.B.3, it is EPA's understanding, based on comments received and its
own technical analysis, that a substantial majority of the industry
would meet the IM limitations based on model technologies considered by
the Agency (see Section III.B.3 for more information). However, uniform
national requirements may also be challenging to implement on a
national level, given the wide range of facility types and intake
structure configurations covered by the rule. Commenters stated that in
some cases the technologies available for a particular site may not be
able to achieve the IM limitations. Commenters further stated that, in
certain circumstances, the costs of impingement technologies may be
unusually high due to site-specific factors. EPA is now considering
whether to adopt an approach that would allow establishment of
impingement controls on a site-specific basis either generally or
limited to those circumstances in which the facility demonstrated that
the national controls were not feasible. Under such an approach, the
facility could demonstrate to the Director that site-specific factors
warrant a site-specific BTA for both entrainment and IM. The
comprehensive study and other planning requirements could be enhanced
to include information that the permitting authority would use to
determine site-specific BTA for both entrainment and IM. The decision
criteria for choosing BTA would be the same for IM and for entrainment,
and EPA expects that permitting authorities and facilities would view
the two together in an integrated planning and decision making
framework. EPA requests comment on such an approach

and further information on why uniform controls should not be adopted.
2. Closed-Cycle Recirculating Systems
    EPA received a number of comments suggesting that a facility (or
intake) employing a cooling tower as a closed-cycle recirculating
system (CCRS) should be exempt from IM requirements. EPA did not
propose that a facility that fully employs cooling towers would
automatically meet the IM standards for a number of reasons. First, the
largest facilities with wet cooling towers still have the potential to
withdraw significant volumes of water; in some cases, 100 MGD or more
in makeup water alone. Second, at proposal, EPA did not provide an
additional alternative that specifically established cooling towers as
a pre-approved technology for complying with the IM limits because data
from EPA's industry questionnaire and site visits indicate that most
intakes providing cooling water to a cooling tower already met the
proposed intake velocity limitation of less than or equal to 0.5 feet
per second [DCN 11-6601].\1\ Further, based on the performance observed
in site visits and questionnaires, EPA anticipated that a properly
operated cooling tower installed as a retrofit would typically meet the
proposed intake velocity limitation alternative.\2\ Thus, EPA
anticipated all facilities employing wet cooling towers would already
meet the IM limitations. However, commenters pointed out that not all
facilities employing a wet cooling tower or some other CCRS as their
original technology (i.e., not a retrofit) would necessarily have been
designed to meet the 0.5 feet per second intake velocity threshold.
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    \1\ EPA also notes that the Phase I new facility rule requires
low intake velocity (0.5 feet per second) in addition to flow
reduction commensurate with closed cycle cooling.
    \2\ In a retrofit scenario, the facility's pre-retrofit intake
velocity would have been calculated for flow through multiple intake
screens. After the retrofit, the volume of water withdrawn is
significantly reduced, but is often still withdrawn through the same
number of screens, leading to a significantly reduced intake
velocity.
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    Third, EPA has found several instances where a cooling tower has
been installed but not operated to minimize the volume of water
withdrawn. For example, EPA found in site visits that cooling water may
be passed through a cooling tower to reduce the discharge temperature
of the water, but little or no water was recycled back to the facility
cooling system. In other words, the cooling tower was in place but
cooling water was used in a single pass mode, with overall water use
identical to a typical once-through cooling system, resulting in no
reductions in impingement or entrainment. Operation in this manner is
not feasible or in most cases even possible at a new facility because
the intake at a new facility is only sized for supplying make-up and
blowdown flows. Accordingly, in developing the existing facility
definition for CCRS in the proposed rule, EPA began with the Phase I
new facility rule definition of CCRS but added criteria to it in order
to clarify the meaning of minimized make-up and blowdown flows. EPA
proposed that a properly operated cooling tower is one that operates at
a minimum cycles of concentration of 3.0 for freshwater and 1.5 for
saltwater or brackish water. EPA solicited comment on this definition.
    EPA does not intend for facilities to install cooling towers solely
for the purpose of meeting the IM requirements. In fact, EPA expects
all facilities could comply with the proposed IM requirements without
relying on closed-cycle cooling. However, consistent with EPA's
position that flow reduction is strongly correlated to reductions in
impingement and entrainment,\3\ a properly operated cooling tower would
provide significant reductions in IM. An optimized cooling tower would
typically reduce water usage by 94.9 percent to 97.5 percent,
reflecting salt water and fresh water sources respectively. Thus, in
this case, such a cooling tower would exceed the level of performance
required by the proposed IM limitations.
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    \3\ See, e.g., 69 FR 41576, July 9, 2004, Section VII.C.1. A
reduction in flow leads to a corresponding reduction in impingement
and entrainment.
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    EPA is now considering a further alternative compliance provision
in the regulatory language that would allow the owner or operator of a
facility to demonstrate compliance with the fish impingement mortality
limitation though either defined technologies or studies that
demonstrate the impingement mortality reduction performance of
optimized travelling screens at a facility. This alternative could
include a provision that would deem a facility in compliance with the
IM limitations if the facility employed a CCRS (such as a wet cooling
tower) that minimizes water withdrawals. In addition, EPA received many
comments specific to the proposed definition of CCRS.
    Some commenters stated that while they may have been effectively
operating as closed-cycle units for many years, they have concerns with
their ability to comply with the new definition. We continue to look
closely at these comments. EPA may consider revising the definition of
CCRS to provide existing facilities flexibility in demonstrating they
already have a properly operated CCRS, such as a minimum level of flow
reduction or water usage, a minimum level of cycles of concentration,
and/or a narrative set of requirements demonstrating site-specific
minimized make-up and blowdown flows. We request additional comment and
supporting data, specifically including ways to define CCRS that
accommodates those existing CCRS systems that are properly operated.
EPA is also considering adopting the same definition of closed cycle
cooling for the existing facilities rule that it used for the new
facilities (and Phase II) rule. EPA acknowledges the argument that
requirements for existing facilities should not be ``more stringent''
than the comparable requirements for new facilities. Some commenters
have interpreted the proposed definition of closed cycle cooling to be
``more stringent'' than the definition used in the new facilities rule
because it places additional restrictions on how a facility must be
operated to be considered ``closed cycle.'' In the Phase II rule EPA
included as a compliance option a demonstration that the facility
``[has] reduced or will reduce [its] flow commensurate with a closed-
cycle recirculating system.'' EPA requests comment on using similar
language for a compliance option in this rule.
    Similarly, EPA is aware that a facility may obtain substantial flow
reductions due to partial CCRS systems, variable speed pumps, seasonal
operation, and other operational measures which result in reduced
impingement. For example, a facility that reduces intake flow by half
has reduced impingement by half; consequently, impingement mortality
has been reduced by 50 percent. EPA is therefore considering adding in
the final rule an opportunity for a facility to get credit for an
equivalent reduction in impingement mortality when it reduces its
intake flow (in comparison to a once-through cooling system). Thus, the
regulatory language could provide for submission of such information as
part of a performance study provided to the permit writer to
demonstrate compliance with the impingement mortality limitations.
Section 4 below describes how the credit for flow reductions could be
used to determine compliance with the IM limitations.
3. Measurement of Intake Velocity
    EPA proposed an intake velocity limitation corresponding to a
facility's design intake flow (DIF) as a design

standard for demonstrating compliance with the IM limitation. EPA's
record shows an intake velocity of 0.5 feet per second or lower
provides similar or greater reductions in impingement, and therefore
impingement mortality, than the BTA technology of modified traveling
screens. Therefore EPA proposed the intake velocity limitation as a
compliance alternative. EPA is aware that low intake velocity is
sometimes confused with velocity cap technologies, and EPA would like
to clarify that these concepts are not the same. Most velocity caps do
not operate as a fish diversion technology at low velocities, and in
fact are often designed for an intake velocity exceeding one foot per
second. Thus a velocity cap will not typically meet the low intake
velocity impingement mortality limitation. The velocity cap is located
offshore and under the water's surface, and uses the intake velocity to
create variations in horizontal flow which are recognizable by fish.
The change in flow pattern created by the velocity cap triggers an
avoidance response mechanism in fish, thereby avoiding impingement.
    The proposed velocity IM limitation is based on DIF, thus the
calculated velocity would reflect the maximum intake velocity as water
passes through the structural components of a screen, measured
perpendicular to the screen mesh. If the intake does not have a screen,
EPA assumes that in most cases the maximum intake velocity is
perpendicular to the opening of the intake.
    The following discussion explains how velocity would be determined,
and thus compliance with the intake velocity limitation demonstrated.
In general, EPA anticipates the first point of contact of the intake
with the source water is the likely point of compliance, and would be
the location for measurement of intake velocity. For example, some
intakes use a channel or canal to transport the water to the facility.
In those cases, the point of measurement is typically the channel or
canal entrance, and not at the screen face of the facility's forebay.
Similarly, if a facility employs a velocity cap, the point of
measurement is the velocity cap opening (as described above, most
velocity caps would not have a velocity low enough to meet the 0.5 feet
per second limitation, but some may).
    In the proposal, EPA clarified that DIF need not be the original
design of the facility. For example, redundant pumps, emergency service
water, and fire suppression systems could be excluded from a facility's
DIF. As an additional flexibility, EPA proposed to allow actual intake
velocity to be used to demonstrate compliance with the maximum intake
velocity requirement. In this case, the actual flow (i.e., volume)
across the screen surface area would be used to calculate the maximum
expected velocity through that screen. The proposed rule indicated that
the maximum velocity must be achieved under all conditions, including
during minimum ambient source water surface elevation and during
periods of maximum head loss across the screens or other devices during
normal operation of the intake structure.
    EPA received several comments regarding the velocity compliance
alternative. For example, some comments suggested that the requirement
to meet the intake velocity ``under all conditions'' was overly
conservative and may render this alternative technologically infeasible
and/or economically impracticable. These comments provided data
suggesting infrequent events with short durations can occur, during
which time the intake velocity could increase to a rate greater than
0.5 feet per second. Examples of such events might include variations
in river flows related to other uses of the water, weather related
variations (e.g., reduced or increased precipitation) or flow changes
related to dams. Some comments indicated these short duration events
would not result in measurable harm related to increased impingement.
Other comments point out that monitoring velocity at screens with low
levels of screen blockages (such as the maximum of 15 percent allowable
blockage presented in the proposed rule) is technically problematic
with standard \3/8\ inch mesh screens. It was further suggested that
changes to pressure or flow as a means of measuring velocity are often
indiscernible under such conditions. Industry comments also indicated
that, in general, debris fouling is minimized through typical
operations and maintenance procedures that must be performed to ensure
that cooling water flow is not disrupted. For example, a facility would
not allow conditions that could result in pump cavitations, other
damage to circulating water pumps and their related systems, or
anything else that could compromise cooling capabilities or affect
plant reliability.
    EPA also received comments suggesting that a direct velocity
measurement posed technical challenges. Some of these comments
suggested that EPA provide the flexibility to calculate velocity based
on other direct measurements, such as water depth, pressure
differential, and plant intake flow. Based on the comments and data
received in response to the proposed rule, EPA is actively considering
changes to the intake velocity compliance alternative, as described
below.
    Actual through-screen intake velocity can be measured directly.
However, after further discussion with vendors, EPA is aware that some
sites may have difficulty measuring through-screen velocity (DCN 11-
6602). EPA is considering rule language clarifying that velocity may be
calculated from a facility's actual intake flow rate (AIF), the screen
open face area, and the source water surface elevation at the time of
flow measurement. (If there is no screen, the opening of the intake is
the open face area.) The volumetric intake flow would be representative
of routine operations, and may not include periods of zero flow. As
with DIF, the point of measurement would be the point of first contact
with the source water (e.g., the canal entrance, velocity cap opening,
or shoreline screen face).
    To demonstrate compliance with the actual intake velocity criteria,
EPA expects that a facility would record the average monthly velocity.
This would be measured directly or calculated from the volumetric flow
and source water surface elevation measured no less frequently than
once per week reflecting normal operations. Such measurements would
already reflect current water levels; therefore a separate evaluation
of low flow conditions would be unnecessary. For example, low source
water elevation over a three month period would be represented in the
measured or calculated through-screen velocity and reflected in the
reported monthly values. However, it was not EPA's intention to
penalize a facility in the event of unusual and irregular conditions.
Thus, for example, in an unusual circumstance that causes the surface
elevation to be low for just one day, it may be acceptable that this
condition is not represented in the reported data because it does not
reflect conditions that are likely to have a lasting impact on aquatic
life. EPA solicits data on all of these assumptions and solicits
comment on making this clear in the final regulatory text or preamble
to the final rule.
    It is important to clarify that the velocity of water as it
approaches the screen, or even immediately adjacent to the screen, is
not equivalent to the through-screen velocity. The screen surface area
decreases the area through which a given volume of water has to pass,
therefore the velocity of the water increases as it passes through the
screen. Because the velocity compliance option functions in two ways--

protecting fish from injury due to being impinged on the screen's
surface, and allowing fish the opportunity to escape from the intake--
EPA proposed that the point of compliance must be the velocity through
the screen or intake structure and not at some point in front of the
screen. Velocity at other points near the intake can vary based on many
factors such as dead spots and hydraulic zones. However, as stated
above, EPA understands that there may be technical challenges in some
cases to measuring through-screen velocity. EPA will continue to
consider comments from the proposal on this issue and may modify the
monitoring requirements as appropriate.
    For the Phase I rule, EPA compiled data from three studies on fish
swim speeds and found that a velocity of 0.5 feet per second would
protect 96 percent of fish tested (66 FR 65256, December 18, 2001,
Section V.B.1.b.1). EPA recognizes that the flow directly in front of a
screen designed for 0.5 feet per second through-screen velocity will
always be lower than the velocity standard (it may be as much as half
the through-screen velocity in the case of a standard \3/8\ inch
screen). Therefore, EPA's proposed velocity standard as measured
through the screen surface already includes a margin of safety. This
potentially allows more fish to sense the change in velocity and invoke
an avoidance response before being impinged. Because the 0.5 feet per
second limit as a through-screen measurement already includes a margin
of safety, EPA's current view is that additional criteria regarding
screen blockage and related monitoring may be unnecessary. EPA solicits
comment on the data and possible changes to the rule language for the
intake velocity design standard to reflect such modifications.
4. Impingement Mortality Limitations
    EPA proposed two ways in which a facility could demonstrate
compliance with the impingement mortality limitations. The owner or
operator of the facility could conduct monitoring to show the specified
performance standards for impingement mortality of fish and shellfish
have been met through use of any appropriate best performing
technology, or they could demonstrate to the permitting authority that
the intake velocity meets the specified design criteria. The
performance standards for impingement mortality were proposed as
monthly and annual limitations in impingement mortality, measured as a
percent mortality not to be exceeded. These proposed standards were
applicable to all existing facilities with a DIF greater than 2 MGD.
EPA specifically solicited comments on how to give credit for existing
technologies, and using those site-specific adjustments to implement
the national uniform IM standard in a site-specific manner. The data
and comments on this approach will be further discussed in sections 4
and 5.
    As explained in the proposed rule, EPA applied four general
criteria when reviewing studies for acceptance in the impingement
analyses: (1) The data must be specific to the technology under
consideration; (2) impingement mortality must have been reported as an
absolute number or a percentage of impinged fish that were killed; (3)
the data must reflect technology performance that is representative of
conditions that exist under actual facility operations, and; (4)
reported values must be actual measurements, rather than estimates. EPA
based the proposed limitations on the performance of modified traveling
screens with a fish return system. Additional criteria were used to
select data as the basis for impingement mortality calculations. The
limitations were based on all life stages of fish collected or retained
in a \3/8\ inch sieve and held for a period of 24 to 48 hours to assess
latent mortality. Further, EPA rejected studies that did not evaluate
species typical of the location conducting the testing. At proposal,
EPA found four data sets at three facilities in New York State that met
these criteria; see Chapter 11 of the proposed Technical Development
Document (TDD) for more information (DCN 10-0004; EPA-HQ-OW-2008-0667-
1282).
    As described in section I of this notice, EPA received more than 80
documents and studies, several of which include impingement studies.
These additional studies represent facilities from a variety of
geographic regions and waterbody types, and include a broader
representation of species than those comprising the basis for the
proposed rule limitations. EPA solicits comment on recalculating the
impingement mortality limits using the new studies that meet EPA's
criteria as just described. EPA also solicits comment on whether such a
single monthly and annual limit could be sufficiently protective for
all facilities and also recognize site specific variations. In response
to the comments and data regarding fragile species and abundant
species, EPA may consider alternative procedures to determining the
limits, such as giving equal weight to each species instead of to the
total organism counts, or determining different limits for different
groups of organisms. Further, EPA has received several studies that
include counts of shellfish. EPA is considering whether the revised
limitation should include both fish and shellfish. Accordingly, EPA may
eliminate the specific requirement to employ technologies comparable in
performance to barrier nets in order to protect shellfish.
Alternatively, EPA is considering whether the need for additional
impingement controls for shellfish can be determined by the Director
based on site-specific assessments and consideration of the species of
concern for each facility.
    In addition, EPA received information suggesting one or more of the
acceptance criteria used to evaluate the studies for inclusion in EPA's
calculations were too stringent. For example, EPA received comments and
data concerning the holding time of 24 to 48 hours. Some studies
suggest that shorter holding times may still be sufficient for purposes
of determining latent mortality. Yet other information suggests
comparable performance with \3/8\ inch square mesh and \1/4\ by \1/8\
inch mesh,\4\ and therefore EPA solicits comment on including either
technology specification in the limit calculations. EPA is reviewing
these data and may revise the criteria as appropriate.
---------------------------------------------------------------------------

    \4\ Note EPA still intends to exclude data for fine mesh screens
to avoid confusion over the status of ``impinged entrainables'' (76
FR 22174, Section VI.B).
---------------------------------------------------------------------------

    Many commenters suggested that EPA should consider modified
traveling screens with a fish return as a pre-approved technology as
this technology forms the BTA basis of numeric limits. Alternatively,
comments suggested that EPA should streamline the permitting process
and reduce monitoring for facilities employing the candidate BTA
technology. Commenters went on to say if this technology is the
candidate BTA technology, then the proper design, installation,
operation, and maintenance should be deemed compliant with any limit
based on the technology.
    EPA still views properly operated, modified traveling screens as
BTA. Accordingly, EPA has concluded that an alternative compliance
option that would streamline the permitting process as well as provide
for reduced monitoring requirements may be appropriate for facilities
employing the model BTA technology. The BTA technology properly
operated according to best management practices would then be deemed
compliant with the IM standards. Under this approach, EPA might require
the facility to provide site-

specific performance data to identify the operational conditions that
would ensure that the technology is being operated appropriately. EPA's
current understanding suggests that two-years of data may be an
appropriate amount to make this determination. Note the biological
monitoring conducted as part of a performance study would not be used
to demonstrate compliance with the limit, but rather would be used to
help set operational parameters for the facility. The performance data
could consist of a two year study focused on the operational conditions
that optimize the proper design, installation, operation and
maintenance of modified traveling screens with fish return systems. A
facility could use relevant data already collected as part of the
study, or conduct a new two-year performance study. Once these
operational conditions have been identified, EPA would expect the
permit writer to incorporate these operational parameters as conditions
of the permit.
    The data from EPA's technical survey shows at least 79 percent of
existing power plants have traveling screens. EPA realizes not all
facilities could retrofit existing traveling screens to modified
traveling screens. In particular, the installation of a fish handling
and return system is not feasible at some facilities. However, EPA
expects the majority of those facilities currently employing traveling
screens would modify their traveling screens to comply with the IM
limitations. Therefore, EPA expects these same facilities could take
advantage of the reduced monitoring requirements and the streamlined
compliance associated with this alternative. Further, EPA's data show
15 percent of facilities meet the low intake velocity limitation.
Combining all of the IM limitation alternatives, EPA anticipates more
than 90 percent of the facilities could take advantage of design
standards rather than choosing to comply with the numerical IM
limitations if EPA adopted this approach. EPA expects some facilities
would explore innovative and creative approaches taking site-specific
characteristics of their facility into account to provide performance
comparable to the BTA technology, and EPA would maintain the numerical
IM limitation to provide for such flexibilities. EPA solicits comment
on providing this compliance flexibility and data on these assumptions.
    Under this approach, as long as the owner or operator of the
facility complies with the specified operational conditions, the
impingement mortality limitations would be deemed to have been met.
Subsequently, the owner or operator would not have to conduct any
biological monitoring to show compliance with the impingement mortality
limitations. In subsequent permit terms, and in the absence of major
changes to the operation of the intake structure or the biology of the
source water, EPA expects the Director would waive any further
requirement for a study or compliance monitoring for the facility. EPA
is considering modifying the regulations to provide specifically for
such a waiver. If EPA were to adopt these revisions in the final rule,
EPA would make corresponding changes to the permit application
requirements. EPA solicits comment on this alternative approach for
compliance with IM standards. The Agency also takes comment on the
appropriate level of data for assuring that the technology is operated
suitably to minimize adverse environmental impact. For example, EPA
solicits comment on whether some monitoring of operational parameters
should be required in lieu of biological monitoring, whether EPA should
specify some minimum set of operational parameters, or whether such a
determination is best left to the discretion of the permitting
authority.
    EPA also received comments regarding the need for separate
requirements to address entrapment. Some commenters indicated that the
requirements in the proposed rule would not be feasible to implement at
all facilities. EPA is considering these comments and requests specific
information on issues related to the feasibility of preventing
entrapment, including examples of where it is impractical or infeasible
to return entrapped organisms to the waterbody or prevent their
entrapment in the first place. EPA will consider this information as it
finalizes the rule.
5. Credit for Existing or Newly Installed Technologies
    EPA's objective in establishing the IM limitations is to minimize
adverse environmental impacts by ensuring that fewer aquatic organisms
such as fish and shellfish are killed by cooling water intake
structures. The limitations are based upon the model best technology
available which reduces impingement mortality of fish and shellfish. As
EPA's proposal noted, this model technology does not include, nor
account for, elements of impingement reduction technologies already
installed at some facilities. There are many cases where facilities
have installed and continue to operate technologies to reduce
impingement. These technologies may have been approved by the
appropriate permitting authorities, including required provision of
supporting studies and assessments of the impact of the plant on the
local aquatic environment. However, these technologies may not have
been designed in such a way that they would meet the proposed IM
requirements, particularly the monthly and annual IM numeric limits.
Further, the structure and design of the proposed rule IM numeric
limits make accounting for the benefits of these existing technologies
very difficult. For example, EPA received new information showing
diversion technology at one specific facility reduced impingement of
one or more species by more than 90 percent, and consequently, fewer
fish would have been killed as a result of impingement mortality.
However, the limitations are strictly based upon the performance of the
model technology and were derived by applying statistical methods to
observed data from facilities with the model technology.
    In the proposal, EPA intended that facilities would receive credit
for both pre-existing and/or newly installed technologies when
demonstrating compliance with the statistically derived IM limitations.
After reviewing the comments, EPA is providing additional discussion of
how reductions in impingement may be used to comply with the IM
requirements. In meeting EPA's overall objective, a facility should be
able to take credit for reducing the number of organisms killed by a
CWIS regardless of the technology used. If the alternative provision
were to provide credit for other technologies, the facility would need
some way to demonstrate that the technologies result in no more
impinged fish being killed than would have resulted from the model
technology (modified traveling screens) alone. With these alternative
provisions that EPA is considering, it is possible that a facility
might be able to meet the limitations by means other than installing
and operating the model technology. EPA examined the effect of
alternative provisions in demonstrating compliance with the annual
average limitation and the monthly average limitation.
    In establishing the IM limitations, EPA seeks to minimize
impingement mortality on an ongoing basis, each year, at a level that
is achievable for a facility. Both the annual average limit and monthly
average play an important role in ensuring that facilities optimize
performance of their technology. Compliance with the monthly average
limitation is demonstrated by comparing the average IM value from the
samples collected during each

month (or other 30-day period designated by the Director). At the end
of the 12-month period, the facility calculates the annual average as
the arithmetic average of the monthly averages during that period. The
facility would then compare its annual average to the annual average
limitation to demonstrate compliance.
    With the alternative provisions that the Agency is considering, a
facility would provide use data from long-term (e.g., 1-2 year)
performance studies and/or calculation baseline assessments to quantify
the impingement and/or IM reductions relative to what would be expected
from the model technology alone. Because monthly averages are used to
demonstrate compliance with both monthly average limitation and annual
average limitation (i.e., monthly averages are averaged to produce the
annual average), facilities would incorporate estimated reductions into
the monthly average IM percent calculations. To calculate an adjustment
using only data for a particular month (e.g., June) would require data
for a very long term, such as 4-years or more. EPA would not require,
nor recommend, this level of refinement in the calculations for two
reasons. First, EPA does not expect that many facilities would have
such long-term data available. Second, the calculations for each month
would require a different set of adjustments that would create
additional, unnecessary, complications for the facility and permit
authority. To simplify the adjustment procedures, a facility would
estimate the monthly reduction using the total reduction divided by the
number of months in the study. The facility then would use this
estimated monthly value to adjust the observed numbers of impinged fish
and killed fish in the IM percent calculations for each and every
month. Depending on the technology used, the reductions would be to the
number of impinged fish and/or number of impinged fish that do not
survive the holding time (``killed fish'').
    If the technology reduces impingement, the alternative provision
calculations would increase the number of the observed impinged fish by
the estimated number that would have been impinged without the
technology. The monthly average calculation then would compare the
observed number of killed fish to the larger total number of impinged
fish (i.e., the sum of observed and estimated number reduced by
technology). This comparison would result in a lower IM rate than the
unadjusted, observed value.
    The adjustments to the monthly average calculations, in turn,
affect the value of the annual average calculated by the facility,
because the facility's annual average is set equal to the arithmetic
average of the monthly averages. In other words, the facility's annual
average is solely based upon the values of the monthly averages. Thus,
when the monthly averages are adjusted downward by the alternative
provisions, the annual average also will be adjusted.
    The following example illustrates how the alternative provisions
would adjust for flow, location, and other technologies in
demonstrating compliance with the IM monthly average limitations. The
example uses values that simplify the calculations to better illustrate
the adjustments, and are not intended to reflect values that EPA
expects at any facility. To simplify the example further, the facility
has only fish and does not have shellfish in its source waters. EPA
also recognizes that facilities often examine the combined effect of
two or more technologies (e.g., deterrents and offshore location)
within a single study. In applying the alternative provision, the
facility could use the outcomes associated with the combined
performance of multiple technologies. However, for a more complete
example, EPA has chosen a hypothetical facility that examined each
change in a separate study.
    The hypothetical facility is located at an offshore location, has a
velocity cap, and installed variable speed drives. For the purposes of
this example, assume its permit requires that it collect samples once a
week and evaluate the impinged fish after 24 hours. The facility has
just completed sampling at the forebay each week during June, and has
identified the counts of the facility specific species of concern as
follows. The four samples had 1,500, 1,000, 500, and 1,000 impinged
fish, for a total of 4,000 impinged fish. During the 24-hour holding
period, 400, 100, 150, and 350 fish died, for a total of 1,000 dead
fish. The facility then calculated the forebay's IM as 25 percent,
using the equation provided in the proposed rule preamble (76 FR 22174,
Section IX.F.1) as follows:
[GRAPHIC] [TIFF OMITTED] TR11JN12.127

    To adjust the observed percent IM for its offshore location and
velocity cap, the facility first extracts information from its
previously conducted studies related to performance and calculation
baseline. For the offshore location adjustment, fish density and flow
data show the offshore location reduces the rate of impingement for all
species of concern by 30,000 fish annually, or, on average, 2,500 each
month (i.e., calculated as 30,000 fish divided by12 months). For the
velocity cap, performance data show the velocity cap reduces
impingement of fish and shellfish by 24,000 organisms annually, or a
monthly average of 2,000 organisms. Therefore, the facility has reduced
impingement of all species of concern, on average each month, by 4,500
organisms (i.e., sum of 2,500 for offshore location and 2,000 for
velocity cap). The facility then applies the reduction to the
denominator of the percent IM calculations as follows:

[GRAPHIC] [TIFF OMITTED] TR11JN12.128

    In summary, calculating percent IM at the forebay yields a 25
percent IM, and then applying the alternative provisions for other
technologies shows the effective percent IM is 12. Next, to adjust for
the variable speed drives, the facility has determined from engineering
and design calculations that the volume of cooling water flow has been
reduced by 11 percent. The volume of reduced flow multiplied by the
density of fish near the intake is calculated, and the facility
projects that the reduced flow excludes, on average for each month, an
additional 1,100 fish from impingement. Then the facility would apply
the reduction in impinged fish to the denominator, as follows:
[GRAPHIC] [TIFF OMITTED] TR11JN12.129

    This example is intended to illustrate how facilities would obtain
credit for existing technologies. While this example includes a
velocity cap, it does not imply that a velocity cap is the appropriate
technology for all facilities. EPA's data shows in most cases, a
properly located velocity cap alone would be sufficient to achieve the
limitations. In the case where a velocity cap (or any other technology)
alone would not be sufficient to meet the limitations, EPA expects that
each facility would identify and install a suite of cost effective
technologies to achieve the IM requirements (i.e., variable speed
drives in this example). EPA solicits comment on whether this approach
reasonably addresses commenters' request that EPA identify velocity
caps to be a pre-approved BTA for IM by appropriately taking into
account facilities' existing technologies in determining whether a
facility meets the proposed IM requirements. In summary, the
hypothetical facility would observe a 25 percent IM rate for June;
which would then be adjusted downward to 12 percent for its offshore
location and velocity cap; and then further adjusted downward to 10
percent for its flow reduction. The value that the facility would
report for compliance purposes would be the 10 percent value. At the
end of the 12-month monitoring period, the facility also would use the
10 percent value for that month with the other 11 adjusted monthly
values to calculate the annual average IM rate. In the final rule, EPA
may decide to include the equations for calculating IM and the
alternative provision in the rule language to provide additional
clarity. EPA solicits comment on how frequently a facility would need
to calculate credit for existing technology after the initial
demonstration.
    Comments from some Phase II facilities indicate facilities may have
already collected data and performed baseline calculations required as
part of the 2004 Phase II rule. While EPA identified considerable
challenges implementing calculation baseline in the 2011 proposed rule
(76 FR 22174, Section III.B.1), these commenters went on to suggest
that a facility should have the option to use these data and analyses
in demonstrating compliance with the IM limitations. In many cases
these data are sufficient to show their site specific impingement rates
as well as the performance of any technologies installed at their site.
Therefore, EPA is considering a provision that would allow existing
facilities to use data already collected as part of a site-specific
analysis of calculation baseline to demonstrate compliance with the
alternative provisions. EPA solicits comment on these data and possible
changes to the rule language for providing credit in reductions in
impingement calculations to demonstrate compliance with the annual
average and monthly average IM limitations.
    EPA recognizes that it may be challenging for a facility to
determine in some cases what its calculation baseline should be,
particularly if it has had a technology in place for many years. Thus
it may be difficult to establish precisely what the performance of a
technology is relative to a situation in which the technology was not
employed (a situation that may not have existed at the facility for a
long time). EPA is thus also considering identifying additional
technologies (which could include velocity caps) as satisfying the IM
performance standards without having to conduct the type of study and
calculation discussed in this example. EPA requests comment on this
approach, on what technologies could be deemed compliant under this
approach, and on what requirements or demonstrations would be
appropriate to establish the technology as a compliance alternative.
EPA also requests comment on whether the final rule should allow
permitting authorities to approve additional technologies as satisfying
the IM requirements, and if so, what specific demonstrations or
procedures would be appropriate for permitting authorities to use in
making such determinations.
6. Facilities With Low Impingement Rates
    EPA received data showing some facilities have very low impingement

rates. This is usually due to intake location for the specific
waterbody from which water is withdrawn for cooling, or the
implementation of other technologies. For example, EPA is aware of a
facility located on the inside bend of a large freshwater river which
seasonally employs large mesh barrier nets. The facility impinges an
average of several fish per month. In another case, the intake is
located downstream of a dam, and the fish avoid the cold water coming
from the dam. Recent data show the facility impinged one fish over two
24 hour periods. Under such low impingement rate conditions, technology
performance is unlikely to be meaningfully evaluated. Moreover, in
EPA's view, these facilities are not likely having an adverse effect on
aquatic life. It is probable that in most cases requiring additional
technology would not be necessary to further minimize adverse
environmental impacts.
    EPA has received several suggestions on how to establish
requirements for such facilities with very low impingement rates. One
suggested approach was to establish an exemption based on an annual
limit on biomass impinged. EPA found a small number of studies have
available performance data that are expressed as biomass, and the
amount of data within these studies are generally limited (see proposed
TDD, Chapter 11, Appendix B). Another approach that would be easier to
implement is to establish an annual limit on the absolute number of
fish that may be impinged. Facilities meeting this limit on the rate of
impingement would be deemed in compliance with the IM limitations, and
therefore would not be required to install additional technologies. In
other words, the existing technology in place would be deemed BTA for
that facility. Alternatively, if EPA were to consider the number of
fish killed (rather than as a percent of impinged fish) as a limitation
for the final rule, EPA might statistically model the data to derive
the limit, or EPA may select the minimum observed value (see TDD,
Chapter 11, Appendix D for further discussion of the methodology).
    Comments by some state agencies indicated concern that such an
approach does not fully consider the affected species. For example,
while the total number of impinged fish that die might be low, they
might all be species of concern, or may include a locally important
species under NOAA's NMFS conservation watch status. If EPA adopts this
approach, EPA might need to provide certain safeguards to ensure
adequate protection of specific fish populations.
    EPA is considering authorizing the permit writer to determine that
a facility using a given technology complies with the IM requirements
because it does not impinge greater than some absolute number of fish.
Such a provision would then authorize the Director to make a site-
specific determination that the facility is already employing BTA.
Under this approach, a facility impinging fewer than the specified
number of organisms might submit some minimum amount (e.g., two years)
of impingement rate or impingement mortality data, including a
demonstration that no threatened and endangered (T&E) or other
protected species are identified in the vicinity of the intake.
Additional factors the Director should consider might include any
impacts to significant recreational or commercial fisheries, a review
of locally important aquatic life such as those identified by NOAA's
NMFS regarding local or state conservation status of any species of
concern, value of impinged species, prevalence of nuisance or invasive
species, or other local conditions. The Director could then make a
determination that the very low impingement rate is BTA due to the
facility's existing technology. EPA solicits comment on the data and
approaches under consideration for facilities that already have very
low impingement rates. EPA also solicits comment on whether EPA should
identify in the final rule a specific upper limit on what could be
considered a very low level of impingement mortality, or if this should
be left to the discretion of the permitting authority. In addition, as
noted above, EPA is soliciting comment on recommendations it received
following proposal that EPA consider a regulation under which
impingement requirements (like entrainment requirements) would be
established on a site-specific basis. If EPA adopted the approach
proposed for entrainment, the permit writer could weigh site-specific
costs and benefits, among the factors being assessed, in the decision
whether to require further impingement controls. EPA also requests
comment on a hybrid approach under which the permittee could choose
among several compliance options that might include both meeting an IM
performance standard or requesting a site-specific determination of BTA
for both impingement and entrainment, if the benefits of meeting the
performance standard did not justify the costs on a site-specific
basis. This could be structured in a manner similar to the ``cost-
benefit variance'' that was included as a compliance option in the
final Phase II rule. EPA requests comment on all of these approaches.
7. Species of Concern
    In recognizing the variability in each facility's source water
characterization, particularly with respect to the specific species and
life stages of fish and shellfish, EPA proposed the IM standards should
be applied to site-specific species of concern. EPA intended this
provision to provide flexibility to the Director to focus the
technology based requirements on those species deemed important at a
given site. Some commenters indicated that many states have already
determined the species of concern as inclusive of forage fish, fragile
fish, and abundant representative indicator species. Therefore,
commenters indicated EPA's intended flexibility might not work.
    In this notice, EPA is clarifying the proposed rule approach to
species of concern is intended to allow the Director to prioritize
certain fish and shellfish in a site-specific manner. EPA generally
intended that the highly abundant, fecund forage fish species (such as
the clupeid species) would not be considered species of concern.
However, the Director could determine such species are species of
concern if they were considered: Important migratory or commercial
species; threatened or endangered; or of insufficient abundance in the
source water to support the growth and abundance of those species that
prey upon them. To provide the Director with the appropriate data to
make such a determination, and to avoid the unnecessary burden of
requiring a facility to comply with the IM limitations for all species,
EPA is considering a regulatory provision that would distinguish
representative indicator species (RIS) from the site-specific species
of concern. Under such an approach, a facility may be required by the
Director to monitor for those species identified as RIS, but the IM
limitations would only be applicable to the species of concern. The
species of concern would not necessarily include all RIS. EPA solicits
comment on the data and approaches under consideration here that best
address the variability in species and life stages of fish and
shellfish. Alternatively, EPA takes comment on the suggested addition
of defined species of concern, explicitly identifying those specific
species that are not subject to the IM limitations.

III. General Solicitation of Comment

    EPA encourages public participation in this rulemaking and requests
comments on this notice of data availability supporting the proposed
rule for cooling water intake structures.
    EPA invites all parties to coordinate their data collection
activities with the Agency to facilitate mutually beneficial and cost-
effective data submissions. Please refer to the FOR FURTHER INFORMATION
CONTACT section at the beginning of this preamble for technical
contacts at EPA.
    To ensure that EPA can properly respond to comments, the Agency
prefers that commenters cite, where possible, the paragraph(s) or
sections in the document or supporting documents to which each comment
refers. Please submit copies of your comments and enclosures (including
references) as specified in the ADDRESSES section at the beginning of
this preamble.

    Dated: May 31, 2012.
Nancy K. Stoner,
Acting Assistant Administrator, Office of Water.
[FR Doc. 2012-14153 Filed 6-11-12; 8:45 am]
BILLING CODE 6560-50-P