Offshore, segments 0806, 0807), dissolved oxygen and water clarity were
both found to be insensitive to changes in nutrients. In 2 segments in
Big Bend/Apalachee Bay (Fenholloway/Fenholloway Offshore, segments
0822, 0823) and 7 segments in Springs Coast (Crystal River/Crystal-
Homosassa Offshore/Homosassa River, segments 0812, 0813, 0833;
Chassahowitzka River/Chassahowitzka Offshore, segments 0810, 0811; and
Weeki Wachee/Weeki Wachee Offshore, segments 0808, 0809), dissolved
oxygen was found to be insensitive to changes in nutrients and there
was not enough available information to derive seagrass depth targets.
In Nassau River and St. Marys River, dissolved oxygen was found to be
insensitive to changes in nutrients and seagrass has not been
historically present. For all of these estuaries, proposed criteria
were derived that were protective of chlorophyll a concentrations
associated with balanced phytoplankton biomass.
    In the Lower St. Johns River, seagrass has not been historically
present, so proposed criteria were derived that were protective of
chlorophyll a associated with balanced phytoplankton biomass and
dissolved oxygen concentrations sufficient to maintain aquatic life.
For this system, EPA used the dissolved oxygen from the Site-Specific
Alternative Criteria, developed by FDEP and adopted for the marine
portion of the Lower St. Johns River, as an additional DO endpoint with
which to derive the proposed criteria to support dissolved oxygen
concentrations sufficient to maintain aquatic life.\195\ This DO
criterion, adopted as a water quality standard specific to this system,
was used as an alternative target to the daily water column average DO
concentration of 5.0 mg/L.
---------------------------------------------------------------------------

    \195\ FDEP. 2006. Site Specific Alternative Dissolved Oxygen
Criterion to Protect Aquatic Life in the Marine Portions of the
Lower St. Johns River Technical Support Document. Appendix L In:
FDEP. 2008. TMDL Report: Total Maximum Daily Load for Nutrients for
the Lower St. Johns River. Florida Department of Environmental
Protection, Tallahassee, FL.
---------------------------------------------------------------------------

    EPA considered several alternative approaches for deriving
estuarine numeric nutrient criteria, including approaches proposed by
the St. Johns River Water Management District for estuaries within
their jurisdiction (Lower St. Johns River, Mosquito Lagoon, Tolomato-
Matanzas estuary, Halifax River estuary, Indian River Lagoon, and
Banana River). While some of these approaches segmented Florida's
estuaries differently than the segmentation approach EPA is proposing,
all the alternative approaches used multiple biological endpoints and
analytical methods to determine the health of each system and derive
criteria. EPA solicits comments on the alternative approaches described
in more detail in the following sections. Additional details on these
approaches are provided in the TSD (Volume 1: Estuaries, Section 2).
(2) Alternative for St. Johns River Water Management District Waters
    The St. Johns River Water Management District (SJRWMD) submitted
proposed approaches to EPA for several estuaries within their
jurisdiction. These included the St. Johns River, Mosquito Lagoon,
Tolomato-Matanzas estuary, Halifax River estuary, Indian River Lagoon,
and Banana River. In general, SJRWMD proposed a weight of evidence
approach employing several analytical techniques to derive numeric
nutrient criteria for each of the systems. The following paragraphs
outline the methods proposed for each of these systems.
    The SJRWMD has proposed the use of the values for TN, TP, and
chlorophyll a for the Lower St. Johns River (LSJR) that have already
been developed as part of an existing TMDL to support designated uses
in the river. The LSJR is defined as the main stem segments of the
river between the juncture with the Ocklawaha River and the river mouth
at Mayport, with the marine portion occurring between Julington Creek
and the mouth. A SSAC was developed for DO in the marine portion of the
river. It was approved by EPA in 2006 and is in effect as a WQS. The
TMDL contains TN and TP protective loads in the freshwater portion of
the LSJR and a TN protective load in the saline portion of the LSJR.
These loads are set at a level necessary to achieve the marine DO SSAC
and protect the statewide standard for DO in the freshwater section.
The TMDL also contains a water quality target for chlorophyll a that is
intended to implement the State's narrative nutrient criterion.
    Similar to the modeling approach proposed by EPA for Florida
estuaries, TN, TP, and chlorophyll a criteria were derived for the LSJR
using linked watershed, hydrodynamic, and water

quality models. Non-point nutrient inputs from the watershed to the
river were determined for each sub-basin in the LSJR using the
Pollutant Load Screening Model (PLSM), estimates of atmospheric
deposition, and estimates of loading from tributaries and upstream.
Within the river, hydrodynamics were modeled using the Environmental
Fluid Dynamics Code (EFDC) model and water quality processes were
modeled using the U.S. Army Corps of Engineers Quality Integrated
Compartment Model (CE-QUAL-ICM), Version 2. The models were calibrated
for the period from January 1, 1995 to November 30, 1998. TMDL model
scenarios were assessed on an annual basis to determine if chlorophyll
a levels exceeded the chlorophyll a threshold of 40 [mu]g/L less than
10% of the time that was set as the water quality target to prevent
undesirable shifts in algal community composition.
    For Mosquito Lagoon, a suite of five approaches are considered to
develop a weight of evidence by which numeric nutrient criteria can be
developed. These approaches are based upon one of three relationships:
(1) The link between nutrients, phytoplankton growth (as shown by
chlorophyll a), and the trophic state of a system; (2) the link between
nutrients, phytoplankton growth (as shown by chlorophyll a), the
effects of phytoplankton on light attenuation in the water column, and
the light requirements of seagrasses; or (3) the connection between TP
and harmful algal bloom (HAB) occurrence. The first and primary
approach uses a reference period from 2004-2008 to calculate annual
median and maximum wet season medians of chlorophyll a, TN, and TP. The
reference time period was selected because the TN, TP, and chlorophyll
a observed during that period were low, the rainfall amounts during
that period were representative of typical rainfall over time, and the
Trophic State Index value for that time period was greater than 50,
which is considered to be ``good'' (mesotrophy to oligo-mesotrophy).
    The second approach draws upon an optical model linking chlorophyll
a to previously established light attenuation targets as a way to
predict annual median chlorophyll a in southern Mosquito Lagoon that
would be protective of seagrass and serve as a basis for criteria
derivation. A third approach derives a TP level that corresponds to
minimum ``bloom'' levels of the dinoflagellate Pyrodinium bahamense,
the common HAB species seen primarily in the southern Lagoon. A fourth
line of evidence applied to the Mosquito Lagoon is multivariate
geometric mean function regression models relating TN and TP to
chlorophyll a on an annual basis and during the wet season. The final
method is based on two general nutrient models.\196\ Targets for
chlorophyll a are set based on the reference period mentioned earlier
for the north and central segments and the optical model for the
southern segments. The reference method is used to derive the TN, TP,
and chlorophyll a criteria for the Mosquito Lagoon with the other four
methods providing supporting evidence. Two criteria magnitudes for TN,
TP, and chlorophyll a are presented; one an annual median value and the
other a wet season (July-September) median value.
---------------------------------------------------------------------------

    \196\ Steward, J.S., and E.F. Lowe. 2010. General empirical
models for estimating nutrient load limits for Florida's estuaries
and inland waters. Limnology and Oceanography 55(1):433-445.
Dettmann, E.H. 2001. Effect of water residence time on annual export
and denitrification of nitrogen in estuaries: A model analysis.
Estuaries 24(4):481-490.
---------------------------------------------------------------------------

    The approaches used for the Indian River Lagoon (IRL) and Banana
River Lagoon (BRL) are similar to those used for Mosquito Lagoon. The
approaches are based upon a weight of evidence relying on two general
ecological relationships: (1) The link between nutrients, phytoplankton
growth (as shown by chlorophyll a), and the trophic state of a system;
and (2) the link between nutrients, phytoplankton growth (as shown by
chlorophyll a), the effects of phytoplankton on light attenuation in
the water column, the light requirements of seagrasses, and the
previously established depth limit for seagrasses. The influence of TP
on HAB events is also discussed as an ancillary line of evidence. As a
first line of evidence loading limits are derived based on analyses
done for TMDLs in 2009. The loading limits were established using
regression models that regress seagrass depth limit targets against
loading of TN and TP.\197\ The second method used annual medians of
data from reference segments that meet desired depth thresholds
established by the TMDL analyses. The third approach relies upon an
optical model similar to the one described earlier for the Mosquito
Lagoon using data from 1996-2007. A model was built for each of the
sub-lagoons: The BRL, North IRL, and Central IRL (divided into
Sebastian and South Central reaches). An optical model is in
development for the North Central reach. The fourth approach also
applies two general models to data specific to the IRL and BRL.\198\
Where the Dettmann (2001) model could not be used to predict TN
concentrations, a TN:TP ratio for the given sublagoon was applied to
the TP limit to calculate TN limits. The fifth approach relies upon the
relationship between HAB occurrence and TP concentrations. Targets for
chlorophyll a are presented as a range of values established using the
optical model approach and the reference segment approach. Proposed TN
and TP loading criteria are based on the loading limits established
using the TMDL analyses. Primary proposed TN and TP criteria
concentrations are calculated based on the reference segment method.
Alternate criteria are proposed using a convergence of the
concentrations calculated by the reference segment method and general
models. Two criteria magnitudes are proposed, one for an annual median
and the other for a wet season (June-October) monthly maximum.
---------------------------------------------------------------------------

    \197\ Steward J.S., R.V. Virnstein, L.J. Morris, and E.F. Lowe.
2005. Setting Seagrass Depth, Coverage, and Light targets for the
Indian River Lagoon system, Florida. Estuaries 6:923-935.
    \198\ Steward, J.S., and E.F. Lowe. 2010. General empirical
models for estimating nutrient load limits for Florida's estuaries
and inland waters. Limnology and Oceanography 55(1):433-445.
Dettmann, E.H. 2001. Effect of water residence time on annual export
and denitrification of nitrogen in estuaries: A model analysis.
Estuaries 24:481-490.
---------------------------------------------------------------------------

    The SJRWMD proposed criteria for the Tolomato and Matanzas Estuary
(TME) using a weight of evidence approach and methods similar to those
used in the other estuaries. TN and TP concentrations and chlorophyll a
target concentrations are based on an approach that analyzes water
quality and estimated current loading during a reference period from
2000-2009. The period of reference was selected based on a desirable
TSI score (<50), rainfall amounts typical of average conditions, and
completeness of the data record. Criteria magnitudes are proposed as an
annual median or mean and a maximum wet season (June-September) median
or mean. The reference period approach of criteria derivation for the
TME is supported by an additional line of evidence using regression
analyses of chlorophyll a versus TN and TP. Target chlorophyll a values
are based on the reference period analyses. The general nutrient models
of Steward and Lowe (2010) and Dettmann (2001) are also used as an
additional method by which to estimate loading limits and
concentrations associated with those limits.
    The SJRWMD also derived proposed criteria for the Halifax River
Estuary. SJRWMD derived criteria using three methods. The first is a
reference condition based on the period from 2000-2008. This period is
selected because of the low TN levels compared

to the previous decade, the low chlorophyll a concentrations which are
consistent with chlorophyll a targets established for other estuaries
throughout the State, and the ``good'' trophic status shown by TSI
values less than 50. Concentrations are calculated using annual median
concentrations and maximum wet-season median concentrations (as the
highest monthly values from July-September) of TN, TP, and chlorophyll
a. Simple linear regressions are used as a second line of evidence to
calculate TN and TP criteria based on chlorophyll a targets established
by the reference period calculations. The general nutrient models of
Steward and Lowe (2010) and Dettmann (2001) are used as a final method
by which to estimate loading limits and concentrations associated with
those limits. Proposed loading and concentration criteria for the North
Halifax River Estuary are based on the loading and concentration
estimates of the general nutrient models, with estimates of loadings
from wastewater treatment facilities in the estuary removed to
represent reference conditions. The current estimated concentrations
(ca. 2004) of TN and TP based on the reference approach are proposed as
criteria for the South Halifax River Estuary. Target chlorophyll a
values for both segments are calculated using the reference period
approach.
    EPA is also considering the use of approaches outlined in Steward
et al. (2005) to derive criteria in Indian River Lagoon. In particular
EPA is considering using the depth of colonization within reference
segments as ``upper restoration depths'' and the highest value observed
for a specific segment as a minimum target for that segment. For more
information regarding the derivation of these criteria, please see the
TSD (Volume 1: Estuaries, Sections 2.18.9 (Indian River Lagoon), 2.19.9
(Halifax River), 2.20.9 (GTMP), and 2.21.9 (St Johns River)).
(3) Request for Comment on Proposed and Alternative Approaches
    EPA believes that the proposed approach for each estuarine system
is appropriate, scientifically defensible, and results in numeric
nutrient criteria that protect the State's designated uses to ensure
that nutrient concentrations of a body of water support balanced
natural populations of aquatic flora and fauna. EPA requests comment on
this system-specific approach and the resulting numeric nutrient
criteria. EPA also solicits additional available scientific information
that can be used to derive numeric nutrient criteria to provide
protection of fish consumption, recreation, and the propagation and
maintenance of a healthy, well-balanced population of fish and wildlife
and protect Florida's Class II and III estuarine waters from nitrogen
and phosphorus pollution.
    In addition, EPA requests comment on the alternative approaches
developed by the St. Johns River Water Management District for waters
under their jurisdiction. Specifically, EPA requests comment on the
scientific defensibility of these approaches, as well as whether
application of these approaches will result in numeric nutrient
criteria that will protect Class II and III estuarine waters in the
State of Florida. EPA also requests comment on promulgating the
alternative criteria in lieu of EPA's proposed criteria.
(b) Proposed Criteria Duration and Frequency (Estuaries)
    Aquatic life water quality criteria include magnitude, duration,
and frequency components. For EPA's proposed TN, TP, and chlorophyll a
criteria for estuarine waters, the criterion-magnitude values
(expressed as concentrations) are provided in Table III.B-1, the
criterion-duration (or averaging period) is specified as annual, and
the criterion-frequency is specified as a no-more-than-once-in-three-
years excursion frequency of the annual geometric mean. EPA is
proposing a criteria-duration of one year, in which sampled nutrient
concentrations are summarized as annual geometric means to be
consistent with the data set used to derive these criteria, which
relied on either annual average nutrient concentrations or annual
nutrient loading to the water body. EPA's proposed excursion frequency
of no-more-than-once-every-three-years is intended to minimize negative
effects on designated uses as it will allow water bodies enough time to
recover from occasionally elevated levels of nitrogen and phosphorus
concentrations.\199\ These duration and frequency components of the
criteria are identical to those finalized in EPA's rule for Florida's
lakes and flowing waters (40 CFR section 131.43), which will add
consistency to the implementation of these criteria with those
established in the previous rulemaking for upstream waters. Finally,
the 3-year evaluation period provides a sufficient representation of
average water body characteristics in the majority of cases, because it
balances both short-term and long-term variation, while not imposing
undue monitoring expectations. EPA requests comment on the frequency
and duration components of these criteria and whether the three
components of the criteria (magnitude, duration, and frequency) taken
in combination will ensure protection of the designated uses of these
waters.
---------------------------------------------------------------------------

    \199\ Boynton, W.R., J.D. Hagy, L. Murray, C. Stokes, and W.M.
Kemp. 1996. A comparative analysis of eutrophication patterns in a
temperate coastal lagoon. Estuaries 19(2B):408-421.
---------------------------------------------------------------------------

(c) Proposed DPVs (Estuaries)
    EPA is proposing a procedure to establish numeric TN and TP
criteria for streams in Florida to protect the downstream estuarine
water bodies that ultimately receive nitrogen and phosphorus pollution
from these streams. These numeric nutrient criteria, which EPA refers
to as Downstream Protection Values, or DPVs, would apply at each
stream's point of entry into the downstream water, referred to as the
pour point. However, as explained more fully in Section I.A, EPA does
not intend to finalize these DPVs if the district court modifies the
Consent Decree consistent with EPA's amended determination that numeric
DPVs are not necessary to meet CWA requirements in Florida. EPA
selected the pour point as the location to apply DPVs because the
downstream waters respond to the nutrient inputs from the pour point,
and all contributions from the network of flowing waters above this
point affect the water quality at the pour point. If the DPV is not
attained at the point of entry into the estuary, then the collective
set of streams in the upstream watershed does not attain the DPV, for
purposes of CWA section 303(d).
    The Agency is proposing a hierarchical procedure that includes four
approaches for setting TN and TP DPVs. EPA's intention in proposing the
four approaches is to provide a range of methods for the State to
derive TN and TP DPVs that reflect the data and scientific information
available. Water quality modeling is the most rigorous and most data-
demanding method, and will generally result in the most refined DPVs.
Water quality modeling is EPA's preferred method for establishing DPVs
and is listed first in the hierarchy. It is followed by less rigorous
methods that are also less data-demanding. Using a procedure from a
lower tier of the hierarchy requires less data, but also generally
results in more stringent DPVs to account for the uncertainties
associated with these less refined procedures. The methods available to
derive DPVs should be considered in the following order:
    1. Water quality simulation models to derive TN and TP values,

    2. Reference condition approach based on TN and TP concentrations
at the stream pour point, coincident in time with the data record from
which the downstream receiving estuary segment TN and TP criteria were
developed using the same data quality screens and reference condition
approach,
    3. Dilution models based on the relationship between salinity and
nutrient concentration in the receiving segment, and
    4. The TN and TP criteria from the receiving estuary segment to
which the freshwater stream discharges, in cases where data are too
limited to apply the first three approaches.
    All four approaches are briefly described in the following
discussion. A more detailed description of the approaches, as well as
the TN and TP DPVs that result from using each of the approaches, is
provided in the technical support document (Volume 1: Estuaries,
Section 1.6).
    EPA believes that the first approach, the use of water quality
simulation models, is the most refined method to define a DPV at the
stream's pour point that will support balanced natural populations of
aquatic flora and fauna in the downstream estuary. This approach may be
appropriate when water quality simulation models are available, such as
in the estuarine systems where mechanistic models were used to derive
criteria. The modeled nutrient loads entering the estuaries that result
in attainment of the biological endpoints within the estuaries can be
used to derive DPVs by computing the annual geometric mean TN and TP
concentrations that correspond with the modeled loads at the pour point
of each stream for each of the years 2002 through 2009. Because EPA
used coupled watershed and estuarine models to establish the estuary
criteria (in some locations), EPA is confident that the watershed
modeling provides concentrations that are protective of corresponding
estuarine biological endpoints. Therefore EPA selected the 90th
percentile from the distribution of annual geometric means of modeled
loads as the DPV to be consistent with the use of the 90th percentile
used to derive the criteria protective of the estuary using the
mechanistic models (Volume 1: Estuaries, Section 1.6).
    EPA is proposing the second DPV approach, a reference condition
approach, for estuarine systems where water quality simulation models
are not available, and where a reference condition approach is used to
derive estuary TN, TP, and chlorophyll a criteria. Since the downstream
estuary is supporting balanced natural populations of aquatic flora and
fauna during the reference condition period, the nutrient loads passing
through the pour points into the estuary during that same period should
be protective of the estuary. Therefore, EPA believes it would be
appropriate in these cases to derive reference condition-based DPVs
using water quality data at the pour point of the freshwater streams,
coincident in time with the data record from which EPA derived the
downstream estuary segment TN and TP criteria. EPA proposes that the
same data screens and reference condition approach be applied to the
pour point data as were applied to the estuary data when deriving DPVs
using this approach. This will prevent deriving a DPV using upstream
water quality data that coincided with a documented downstream impact
(e.g., CWA section 303(d) listing for nutrients in the estuary segment)
and ensure mathematical consistency between the DPVs and estuarine
criteria.
    EPA is proposing the third DPV approach for estuarine systems where
water quality simulation models are not available. For example, this
approach may be appropriate in the Indian River Lagoon, the Halifax
River, and the GTMP estuarine systems where EPA used statistical models
to derive the criteria protective of the estuary. In these areas, EPA
believes it would be appropriate to derive DPVs using dilution models
based on the relationship between salinity and nutrient concentration.
The concept is that the tidal mixing or dilution can be estimated from
the estuarine salinity. By plotting observed estuarine TN or TP versus
the estuarine salinity and fitting a linear regression, the TN or TP at
various levels of salinity can be determined. This regression model can
then be used to determine the TN or TP concentration at the pour point
that will ensure attainment and maintenance of the estuarine numeric
nutrient criteria concentration. The TN and TP DPV for the inflowing
canal or stream can be determined from the point on the regression line
having the same salinity as the pour point, which is by definition 2.7
psu.
    EPA's fourth proposed approach for establishing DPVs is to apply
the downstream receiving estuary segment TN and TP criteria as shown in
Table III.B-1 to the pour point as the DPVs. This is the simplest
approach and may be appropriate where data are too limited to apply the
first three approaches. As noted in Table III.B-1, Florida derived
numeric nutrient criteria for Clearwater Harbor, Tampa Bay, Sarasota
Bay, and Charlotte Harbor estuaries that can be found in Section 62-
302.532(a)-(d), F.A.C. Therefore, the applicable DPVs for those four
estuaries would be Florida's estuary criteria in Section 62-302.532(a)-
(d), F.A.C. if using this fourth proposed approach for establishing
DPVs.
    EPA believes the proposed approaches for deriving DPVs establish a
decision-making framework that is binding, clear, predictable, and
transparent. Therefore, EPA is proposing that DPVs derived using these
approaches do not require EPA approval under Clean Water Act section
303(c) to take effect.\200\ A DPV calculated under options 2, 3, and 4
may be more stringent than a DPV calculated using a water quality
model. These alternative options are intended to ensure that water
quality standards are not only restored when found to be impaired, but
are maintained when found to be attained, consistent with the CWA.
Higher levels of TN and/or TP may be allowed in watersheds where it is
demonstrated that such higher levels will fully protect the estuary's
WQS. To the extent that it is determined that the alternative option
DPVs for a given estuary are over-protective, applying a water quality
model as set out in EPA's option 1 would result in a more refined
definition of the DPV for that estuary.
---------------------------------------------------------------------------

    \200\ 65 FR 24641, 24648 (April 27, 2000).
---------------------------------------------------------------------------

    EPA believes that these proposed approaches to establish DPVs are
appropriate, scientifically defensible, and result in numeric values
that will ensure the attainment and maintenance of the downstream
estuarine criteria. EPA requests comment on these approaches. EPA also
requests comment on the alternative approach of finalizing the numeric
TN and TP DPVs that EPA calculated using these approaches (as provided
in Volume 1: Estuaries, Section 1.6 of the technical support document)
in place of the proposed approaches. Finally, EPA solicits additional
available scientific information that can be used to ensure attainment
and maintenance of the downstream estuarine criteria. Commenters who
submitted comments or scientific information related to DPVs for
estuaries during the public comment period for EPA's proposed inland
waters rule (75 FR 4173) should reconsider their previous comments in
light of the new information presented in this proposal and must re-
submit their comments during the public comment period for this
rulemaking to receive EPA response.

(d) Proposed Approach and Criteria for Tidal Creeks
    Tidal creeks are relatively small coastal tributaries that lie at
the transition zone between terrestrial uplands and the open estuary.
They are small sub-estuaries that exhibit a wide range of salinities
typical of larger estuaries, but on a smaller scale. Tidal creeks are
important spawning and nursery areas for aquatic life in adjacent
estuary and coastal systems. They typically receive freshwater flow
from streams and groundwater, similar to estuaries, but have less
developed drainage systems. Alternatively, some tidal creeks are
dominated by mangroves and other wetland vegetation with no freshwater
stream inputs, and serve as conduits for tidal water to enter and leave
wetland areas. Water quality and biological conditions are different in
tidal creeks compared to estuarine systems due to relatively small
drainage areas, narrow stream channels, shallow depths, and the
influence of adjacent marsh and mangrove habitats.
    EPA reviewed the available scientific information and has
determined that there are insufficient data and research at this time
to develop separate numeric nutrient criteria specifically for tidal
creeks. EPA, therefore, proposes to apply the TN and TP criteria
developed for either the adjacent freshwater or estuarine segments to
each tidal creek in Florida, depending on the tidal creek's salinity
levels. If the mean chloride concentration of the tidal creek is <
1,500 mg/L, EPA proposes to apply the TN and TP criteria from the
adjacent freshwater segment (as defined in 40 CFR 131.43).\201\ If the
mean chloride concentration of the tidal creek is > 1,500 mg/L, EPA
proposes to apply the chlorophyll a, TN, and TP criteria from the
adjacent estuary segment (as defined in Section III.B of this proposed
rulemaking). Alternatively, EPA requests comment on applying the more
stringent of the two sets of criteria, freshwater or estuarine, to
tidal creeks with varying salinity levels. For more information please
see the TSD (Volume 1: Estuaries, Section 3.1).
---------------------------------------------------------------------------

    \201\ EPA did not establish chlorophyll a criteria for
freshwater streams due to lack of available approaches to interpret
existing data to infer scientifically supported thresholds for these
nutrient-specific response variables in Florida streams.
---------------------------------------------------------------------------

    As a second alternative option, EPA could use the mean salinities
for each tidal creek to interpolate TN and TP concentrations between
freshwater and estuarine criteria from adjacent freshwater and
estuarine segments. TN and TP vary predictably along a salinity
gradient, allowing for this interpolation where salinity data are
available. The calculation EPA could use for this interpolation is
provided in the TSD (Volume 1: Estuaries, Section 3.1).
    EPA believes that the proposed approach for tidal creeks is
appropriate, scientifically defensible, and results in numeric nutrient
criteria that protect the State's designated uses and ensure that
nutrient concentrations of a body of water support balanced natural
populations of aquatic flora and fauna. EPA requests comment on the
proposed option and the alternative. EPA also requests additional
available scientific information that can be used to provide protection
for fish consumption, recreation, and the propagation and maintenance
of a healthy, well-balanced population of fish and wildlife to protect
Florida's tidal creeks from nitrogen and phosphorus pollution.
(e) Proposed Approach and Criteria for Marine Lakes
    Marine lakes are coastal lakes and ponds with groundwater or
intermittent surface water connections to marine water. They do not
have a permanent surface connection to tidal waters. They are small and
shallow, and generally round or elliptical in shape, as they were
formed from depressions that became isolated from marine waters by sand
and dune formation. Some marine lakes are stratified by a salinity
gradient where a freshwater layer at the surface is separated from a
denser saline layer below. Similar to inland lakes, marine lakes in
Florida are generally oligotrophic under undisturbed conditions with
low nitrogen and phosphorus concentrations and low productivity. Their
oligotrophic nature and stratification make them susceptible to the
adverse effects of nitrogen and phosphorus pollution. EPA analyzed the
data from over 50 marine lakes in Florida and found that chlorophyll a
responded to TN and TP in a similar fashion, based on color and
alkalinity, as freshwater inland lakes. Details and supporting
documentation are provided in the TSD (Volume 1: Estuaries, Section
3.2).
    EPA is proposing to apply the criteria developed for freshwater
inland lakes in EPA's December 6, 2010 rulemaking for Florida's lakes
and flowing waters (40 CFR 131.43) to protect the designated uses in
marine lakes since marine lakes have a similar trophic condition
expectation and chlorophyll a response to nutrient concentrations. The
criteria EPA proposes to apply to marine lakes are those found in 40
CFR 131.43 and replicated in Table III.B-2.

                    Table III.B-2--EPA's Proposed Numeric Criteria for Florida's Marine Lakes
----------------------------------------------------------------------------------------------------------------
                                                           EPA final       EPA final TN and TP criteria [Range]
   Long term average lake color \a\ and alkalinity        Chl[dash]a     ---------------------------------------
                                                        \b,*\[micro]g/L         TN mg/L             TP mg/L
----------------------------------------------------------------------------------------------------------------
Colored lakes \c\...................................                  20    1.27 [1.27-2.23]    0.05 [0.05-0.16]
Clear lakes, high alkalinity \d\....................                  20    1.05 [1.05-1.91]    0.03 [0.03-0.09]
Clear lakes, low alkalinity \e\.....................                   6    0.51 [0.51-0.93]    0.01 [0.01-0.03]
----------------------------------------------------------------------------------------------------------------
\a\ Platinum-cobalt units (PCU) assessed as true color free from turbidity.
\b\ Chl-a is defined as corrected chlorophyll, or the concentration of chl-a remaining after the chlorophyll
  degradation product, phaeophytin a, has been subtracted from the uncorrected chl-a measurement.
\c\ Long-term color > 40 PCU and alkalinity > 20 mg/L CaCO3.
\d\ Long-term color <= 40 PCU and alkalinity > 20 mg/L CaCO3.
\e\ Long-term color <= 40 PCU and alkalinity <= 20 mg/L CaCO3
* For a water body, the annual geometric mean of chl-a, TN or TP concentrations shall not exceed the applicable
  criterion concentration more than once in a three-year period.

    EPA believes that the proposed approach for marine lakes is
appropriate, scientifically defensible, and results in numeric nutrient
criteria that protect the State's designated uses and ensure that
nutrient concentrations of a body of water support balanced natural
populations of aquatic flora and fauna. EPA requests comment on the
proposed approach. EPA also solicits additional available scientific
information that can be used to provide protection for fish
consumption, recreation, and the propagation and maintenance of a
healthy, well-balanced population of fish and wildlife to protect
Florida's marine lakes from nitrogen and phosphorus pollution.

C. Proposed Numeric Criteria for Coastal Waters

1. Introduction
    EPA is defining coastal waters in this proposed rulemaking as
marine waters that start at the land margin and extend up to three
nautical miles from shore, with chloride concentrations greater than
1,500 mg/L, excluding estuaries. Unlike estuaries, which are typically
highly influenced by freshwater flows and can be organized within
boundaries, coastal waters are less confined, with open connections to
ocean waters, and have localized influences from freshwater sources
near the estuary/coastal boundary (i.e., estuary pass).
    EPA is proposing to derive chlorophyll a criteria for coastal
waters using satellite remote sensing, where possible. This approach is
possible for all coastal waters except those in the Big Bend Coastal
region. In the Big Bend Coastal region (waters offshore of Apalachicola
Bay, Alligator Harbor, Ochlockonee Bay, Big Bend/Apalachee Bay,
Suwannee River, and Springs Coast), seagrass beds and CDOM export from
rivers confound interpretation of satellite data and derivation of
chlRS-a. EPA's proposed approach and criteria for the Big
Bend Coastal region is discussed in Section III.B.
2. Proposed Numeric Criteria (Coastal Waters)
    EPA is proposing numeric chlorophyll a criteria, as measured by
remotely sensed numeric chlorophyll a (chlRS-a), for 71
segments in three coastal regions of Florida classified as Class III
waters under Florida law (Section 62-302.400, F.A.C.). A map showing
the locations of the coastal segments can be found in the TSD (Volume
2: Coastal Waters, Section 1.3). EPA's proposed coastal criteria are
listed in Table III.C-1.

                   Table III.C-1--EPA's Proposed Numeric Criteria for Florida's Coastal Waters
----------------------------------------------------------------------------------------------------------------
                                                 Coastal                                       ChlorophyllRS -
               Coastal region                  segment\+\         Approximate location        a\1\*  (mg/m\3\)
----------------------------------------------------------------------------------------------------------------
Panhandle..................................               1  Alabama border...............                  2.41
                                                          2  Pensacola Bay Pass...........                  2.57
                                                          3  .............................                  1.44
                                                          4  .............................                  1.16
                                                          5  .............................                  1.06
                                                          6  .............................                  1.04
                                                          7  .............................                  1.14
                                                          8  Choctawhatchee Bay Pass......                  1.23
                                                          9  .............................                  1.08
                                                         10  .............................                  1.09
                                                         11  .............................                  1.11
                                                         12  .............................                  1.18
                                                         13  .............................                  1.45
                                                         14  St. Andrews Bay Pass.........                  1.74
                                                         15  St. Joseph Bay Pass..........                  2.75
                                                         16  .............................                  2.39
                                                         17  Southeast St. Joseph Bay.....                  3.47
West Florida Shelf.........................              18  .............................                  3.96
                                                         19  Tampa Bay Pass...............                  4.45
                                                         20  .............................                  3.37
                                                         21  .............................                  3.25
                                                         22  .............................                  2.95
                                                         23  .............................                  2.79
                                                         24  .............................                  2.98
                                                         25  .............................                  3.24
                                                         26  Charlotte Harbor.............                  4.55
                                                         27  .............................                  4.22
                                                         28  .............................                  3.67
                                                         29  .............................                  4.16
                                                         30  .............................                  5.70
                                                         31  .............................                  4.54
                                                         32  .............................                  4.03
                                                         33  Fort Myers...................                  4.61
Atlantic Coast.............................              34  Biscayne Bay.................                  0.92
                                                         35  .............................                  0.26
                                                         36  .............................                  0.26
                                                         37  .............................                  0.24
                                                         38  .............................                  0.21
                                                         39  .............................                  0.21
                                                         40  .............................                  0.20
                                                         41  .............................                  0.20
                                                         42  .............................                  0.21
                                                         43  .............................                  0.25
                                                         44  .............................                  0.57

                                                         45  St. Lucie Inlet..............                  1.08
                                                         46  .............................                  1.42
                                                         47  .............................                  1.77
                                                         48  .............................                  1.55
                                                         49  .............................                  1.44
                                                         50  .............................                  1.53
                                                         51  .............................                  1.31
                                                         52  .............................                  1.40
                                                         53  .............................                  1.80
                                                         54  Canaveral Bight..............                  2.73
                                                         55  .............................                  2.33
                                                         56  .............................                  2.28
                                                         57  .............................                  2.06
                                                         58  .............................                  1.92
                                                         59  .............................                  1.76
                                                         60  .............................                  1.72
                                                         61  .............................                  2.04
                                                         62  .............................                  1.92
                                                         63  .............................                  1.86
                                                         64  .............................                  1.95
                                                         65  .............................                  2.41
                                                         66  .............................                  2.76
                                                         67  .............................                  2.80
                                                         68  .............................                  3.45
                                                         69  Nassau Sound.................                  3.69
                                                         70  .............................                  3.78
                                                         71  Georgia border...............                  4.22
----------------------------------------------------------------------------------------------------------------
\1\ ChlorophyllRS-a is remotely sensed calculation of chlorophyll a concentrations.
* For a given water body, the annual geometric mean of the chlorophyll a concentration shall not exceed the
  applicable criterion concentration more than once in a three-year period.
\+\ Please see TSD for location of Coastal Segments (Volume 2: Coastal Waters, Section 1.3).

    As discussed in Section III.A.1.b, EPA is not proposing TN and TP
criteria for Florida's coastal waters.
(a) Summary of Approaches
(1) Proposed Approach (Coastal Waters)
    EPA conducted a comprehensive review of water body-specific water
quality and impairment information as detailed in Section III.A.3.a.
EPA determined through this review that at most times, Florida coastal
waters appear to be supporting balanced natural populations of aquatic
flora and fauna. EPA removed data from criteria computations in the
limited instances where the Agency found that coastal waters were
listed on the State's CWA section 303(d) list to ensure the resulting
dataset was representative of times and locations that these waters
were supporting balanced natural populations of aquatic flora and
fauna. Therefore, EPA is proposing to use a reference condition
approach using data collected from satellite remote sensing of
chlorophyll a.
    To derive proposed criteria for coastal areas, EPA chose to use
chlRS-a measurements from the SeaWiFS satellite because it
had the longest and earliest historical record.\202\ From the satellite
measurements, screened to reflect conditions supportive of balanced
natural populations of flora and fauna, EPA calculated criteria as the
90th percentile of the annual geometric means of chlRS-a
values over the 1998-2009 period in each coastal segment (For a
discussion of EPA's selection of the 90th percentile to derive the
proposed coastal criteria, see Section III.A.3.a and the TSD (Volume 2:
Coastal Waters)).
---------------------------------------------------------------------------

    \202\ NOTE: SeaWiFS was replaced by MODIS and MERIS satellite
generated data. EPA has developed an approach that can utilize any
new satellite data sources for ongoing assessment purposes.
---------------------------------------------------------------------------

(b) Request for Comment on Proposed Approach
    EPA believes that the proposed approach for coastal waters is
appropriate, scientifically defensible, and results in numeric nutrient
criteria that protect the State's designated uses and ensure that
nutrient concentrations of a body of water support balanced natural
populations of aquatic flora and fauna. EPA requests comment on this
approach and the resulting numeric nutrient criteria. EPA also solicits
additional available scientific information that can be used to provide
protection of fish consumption, recreation and the propagation and
maintenance of a healthy, well-balanced population of fish and wildlife
and protect Florida's Class III coastal waters from nitrogen and
phosphorus pollution.
(c) Proposed Criteria Duration and Frequency (Coastal Waters)
    For EPA's proposed chlorophyll a criteria for coastal waters, the
criterion-magnitude values (expressed as concentrations) are provided
in Table III.C-1, the criterion-duration (or averaging period) is
specified as annual, and the criterion-frequency is specified as no-
more-than-once-every-three-years. EPA is proposing a criteria-duration
of one year, in which sampled chlorophyll a concentrations are
summarized as annual geometric means, to be consistent with the data
set used to derive these criteria, which relied on annual average
concentrations. EPA's proposed excursion frequency of no-more-than-
once-every-three-years is intended to minimize negative effects on
designated uses as it will allow water bodies enough time to recover
from occasionally elevated chlorophyll a

concentrations.\203\ These duration and frequency components of the
criteria are identical to those finalized in EPA's rule for Florida's
lakes and flowing waters (40 CFR 131.43), which will add consistency to
the implementation of these criteria with those established in the
previous rulemaking. Finally, the 3-year evaluation period provides a
sufficient representation of average water body characteristics in the
majority of cases, because it balances both short-term and long-term
variation, while not imposing undue monitoring expectations. EPA
requests comment on the frequency and duration components of these
criteria and whether the three components of the criteria (magnitude,
duration and frequency) taken in combination will ensure protection of
the designated uses of these waters.
---------------------------------------------------------------------------

    \203\ Boynton, W.R., J.D. Hagy, L. Murray, C. Stokes, and W.M.
Kemp. 1996. A comparative analysis of eutrophication patterns in a
temperate coastal lagoon. Estuaries 19(2B):408- 421.
---------------------------------------------------------------------------

D. Proposed Numeric Criteria for South Florida Inland Flowing Waters

1. Proposed Numeric Criteria (South Florida Inland Flowing Waters)
    For purposes of this proposal, EPA is defining ``south Florida
inland flowing waters'' as inland predominantly fresh surface waters
that have been classified as Class I or Class III in the South Florida
Nutrient Watershed Region, which encompasses the waters south of Lake
Okeechobee, the Caloosahatchee River (including Estero Bay) watershed,
and the St. Lucie watershed. This area contains more than 1,700 miles
(2,736 km) of canals, dikes, and levees that control the movement of
freshwater in south Florida. Some of the significant land management
units within south Florida include the Everglades Agricultural Area,
the Loxahatchee National Wildlife Refuge (Water Conservation Area 1),
Water Conservation Areas 2 and 3, Big Cypress National Preserve,
Everglades National Park, Biscayne Bay National Park, and the Florida
Keys National Marine Sanctuary. A map showing this region is provided
in the TSD (Volume 3: South Florida Inland Flowing Waters, Section 3).
    EPA is proposing that TN and TP DPVs be derived using the
approaches outlined in Section III.D.2 for 22 pour points in south
Florida, outside of the Everglades Protection Area (EvPA) and
Everglades Agricultural Area (EAA), where inland flowing waters
discharge into south Florida marine waters (Biscayne Bay, Florida Bay,
and marine waters on the southeast and southwest coasts). For south
Florida, EPA is proposing the use of DPVs to manage nitrogen and
phosphorus pollution in the inland flowing waters and protect the water
quality of estuaries and coastal waters downstream. Therefore, the
applicable numeric nutrient criteria for south Florida inland flowing
waters, outside the lands of the Miccosukee and Seminole Tribes, EvPA,
and the EAA, would consist solely of the south Florida marine water
DPVs. The calculated DPVs using the approaches in Section III.D.2 for
the 22 pour points are presented in the TSD (Volume 3: South Florida
Inland Flowing Waters, Section 2).
    The proposed approaches to derive DPVs that EPA is proposing for
south Florida inland flowing waters do not apply to flowing waters
(canals) within the EvPA or the EAA. There is an existing TP criterion
of 0.010 mg/L (10 ppb) that currently applies to the marshes and
adjacent canals within the EvPA (Section 61-302.540, F.A.C.). EPA
approved that TP criterion in 2005 as protective of the waters in the
EvPA. EPA's approval was upheld by the U.S. District Court in
Miccosukee Tribe of Indians of Florida, et al. v. U.S. EPA.\204\ For
this proposal, EPA has determined that the existing TP criterion
continues to be protective of the designated uses of the flowing waters
in the EvPA and that no additional numeric nutrient criteria are
necessary at this time for the EvPA. While the existing TP criterion
does not apply directly to the flowing waters of the EAA, EPA has also
determined that the TP criterion will serve to be protective of the
designated uses of the flowing waters in the EAA. Most of the water
flowing from the EAA currently passes through stormwater treatment
areas (STAs) that have been specifically constructed to remove
phosphorus from the water before it enters the EvPA. The waters
discharging from the STAs are subject to CWA discharge permits that
must include limits as stringent as necessary to meet the 10 ppb TP
criterion in the EvPA. Efforts to reduce phosphorus upstream of the
STAs (i.e., in the EAA) are currently underway to ensure the water
discharged from the STAs will meet the TP criterion in the EvPA. Based
on the combination of the actions that will be necessary to ensure that
waters from the EAA do not cause an impairment of the downstream waters
in the EvPA, EPA has determined that the existing TP criterion is the
only numeric nutrient criterion that is necessary to protect the
flowing waters of the EAA as well as the EvPA. Development of water
quality standards for the EvPA and restoration actions within the EAA
to attain the TP criterion have been and remain subject to the
oversight of two federal district courts. EPA believes its decision not
to propose additional numeric nutrient criteria for these areas is
appropriate given the ongoing restoration efforts in the Everglades.
For further information about ongoing EPA and FDEP actions related to
Everglades restoration see: (1) http://www.epa.gov/aboutepa/states/fl.html, and (2) http://depnewsroom.wordpress.com/hot-topics/everglades/.
---------------------------------------------------------------------------

    \204\ Miccosukee Tribe of Indians of Fla., et al. v. U.S. EPA,
No. 1:04-cv-21448 ASG, 2008 WL 2967654 (S.D. Fla. July 29, 2008).
---------------------------------------------------------------------------

2. Proposed DPVs (South Florida)
    EPA is proposing a procedure to establish numeric TN and TP
criteria for south Florida inland flowing waters to protect the
downstream marine waters that ultimately receive nitrogen and
phosphorus pollution from upstream sources. However, as explained more
fully in Section I.A, EPA does not intend to finalize these DPVs if the
district court modifies the Consent Decree consistent with EPA's
amended determination that numeric DPVs are not necessary to meet CWA
requirements in Florida. Like the DPVs that EPA is proposing to protect
estuaries in Florida, EPA is proposing the DPVs for south Florida
inland flowing waters that will apply at each stream or canal's point
of entry into the downstream south Florida marine water. If the DPV is
not attained at the pour point into the applicable marine water
segment, then the collective set of flowing waters, including canals,
in the upstream watershed does not attain the DPV, for purposes of CWA
section 303(d).
    The Agency is proposing a hierarchical procedure that includes four
approaches for setting TN and TP DPVs. These are the same approaches
EPA is proposing for the State to derive DPVs for Florida estuaries to
reflect the data and scientific information available. The methods
available to derive DPVs should be considered in the following order:
    1. Water quality simulation models to derive TN and TP values,
    2. Reference condition approach based on TN and TP concentrations
at the stream pour point, coincident in time with the data record from
which the downstream receiving marine water segment TN and TP criteria
were developed using the same data quality screens and reference
condition approach,
    3. Dilution models based on the relationship between salinity and

nutrient concentration in the receiving segment, and
    4. The TN and TP criteria from the receiving marine water segment
to which the freshwater stream discharges, in cases where data are too
limited to apply the first three approaches.
    EPA's intention in proposing the four approaches is to provide a
range of methods for deriving TN and TP DPVs that reflect the degree of
data and scientific information available. Water quality modeling is
the most rigorous and most data-demanding method, and will generally
result in the most refined DPVs. Water quality modeling is EPA's
preferred method for establishing DPVs and is listed first in the
hierarchy. Due to the highly modified and managed canal systems in
south Florida, EPA did not develop mechanistic models for the region,
however, EPA is including the option for use if mechanistic models are
developed for south Florida in the future. EPA's lead approach for
calculating DPVs in south Florida is the reference condition approach.
This approach is followed by less rigorous methods that are also less
data-demanding. Using a procedure from a lower tier of the hierarchy
requires less data, but also generally results in more stringent DPVs
to account for the uncertainties associated with these less refined
procedures.
    All four approaches are briefly described in the following
discussion. A more detailed description of the approaches, as well as
the TN and TP DPVs that result from using the lead approach, the
reference condition approach, is provided in the technical support
document (Volume 3: South Florida Inland Flowing Waters, Section 2).
    EPA believes that the first approach, the use of water quality
simulation models, is the most refined method to define a DPV at the
stream's pour point that will support balanced natural populations of
aquatic flora and fauna in the downstream marine water. This approach
may be appropriate when water quality simulation models are available,
such as in the estuarine systems where mechanistic models were used to
derive the criteria protective of the estuary.
    EPA is proposing the second DPV approach, the reference condition
approach, where a reference condition approach is used to derive TN,
TP, and chlorophyll a criteria in the downstream marine water, as the
lead approach for calculating DPVs in south Florida. Florida derived
numeric nutrient criteria for TN, TP, and chlorophyll a in south
Florida marine waters using a ``Maintain Healthy Conditions Approach,''
which derives criteria reflective of ambient water quality conditions
(Section 62-302.532, F.A.C.). This approach is akin to EPA's reference
condition approach, which is designed to develop numeric nutrient
criteria that are protective of applicable designated uses by
identifying numeric nutrient criteria concentrations occurring in
least-disturbed waters that are supporting designated uses. Since the
downstream marine water is supporting balanced natural populations of
aquatic flora and fauna during the reference condition period, the
nutrient loads passing through the pour points into the marine water
during the same period should be protective of the marine water.
Therefore, EPA believes it would be appropriate in these cases to
derive reference condition-based DPVs using water quality data at the
pour point of the freshwater streams, coincident in time with the data
record from which the downstream marine water segment TN and TP
criteria were derived. EPA proposes that water quality data used to
calculate DPVs at each pour point be screened to prevent the use of
upstream water quality data that coincided with a documented downstream
impact. This will prevent deriving a DPV using upstream water quality
data that coincided with a documented downstream impact (e.g., CWA
section 303(d) listing for nutrients in the marine water segment) and
ensure mathematical consistency between the DPVs and marine water
criteria.
    The third DPV approach is also available for south Florida marine
systems where water quality simulation models are not available. In
these areas, EPA believes it would be appropriate to derive DPVs using
dilution models based on the relationship between salinity and nutrient
concentration. The concept is that the tidal mixing or dilution can be
estimated from the marine water salinity. By plotting observed marine
water TN or TP versus the marine water salinity and fitting a linear
regression, the TN or TP at various levels of salinity can be
determined. This regression model can then be used to determine the TN
or TP concentration at the pour point associated with the average
marine water salinity that will ensure the attainment and maintenance
of the marine water numeric nutrient criteria concentration.
    EPA's fourth approach for establishing DPVs is to apply the
downstream receiving marine water segment TN and TP criteria to the
pour point as the DPVs. This is the simplest approach and may be
appropriate where data are too limited to apply the first three
approaches. Florida derived numeric nutrient criteria for south Florida
marine waters that can be found in Section 62-302.532(e)-(h), F.A.C.
Therefore, the applicable DPVs for those south Florida marine waters
would be Florida's criteria in Section 62-302.532(e)-(h), F.A.C. if
using this fourth proposed approach for establishing DPVs.
    EPA believes the proposed approaches for deriving DPVs establish a
decision-making framework that is binding, clear, predictable, and
transparent. Therefore, EPA is proposing that DPVs derived using these
approaches do not require EPA approval under Clean Water Act section
303(c) to take effect.\205\ A DPV calculated under options 2, 3, and 4
may be more stringent than a DPV calculated using a water quality
model. These alternative options are intended to ensure that water
quality standards are not only restored when found to be impaired, but
are maintained when found to be attained, consistent with the CWA.
Higher levels of TN and/or TP may be allowed in watersheds where it is
demonstrated that such higher levels will fully protect the marine
water's WQS. To the extent that it is determined that the alternative
option DPVs for a given marine water are over-protective, applying a
water quality model as set out in EPA's option 1 would result in a more
refined definition of the DPV for that marine water.
---------------------------------------------------------------------------

    \205\ 65 FR 24641, 24647 (April 27, 2000).
---------------------------------------------------------------------------

    EPA believes that these proposed approaches to establish DPVs are
appropriate, scientifically defensible, and result in numeric values
that will ensure the attainment and maintenance of the downstream south
Florida marine water criteria. EPA requests comment on these
approaches. EPA also requests comment on the alternative approach of
finalizing the numeric TN and TP DPVs that EPA calculated using these
approaches (as provided in Volume 3: South Florida Inland Flowing
Waters, Section 2 of the technical support document) in place of the
proposed approaches. Finally, EPA solicits additional available
scientific information that can be used to ensure attainment and
maintenance of the downstream south Florida marine water criteria.
Commenters who submitted comments or scientific information related to
DPVs for estuaries during the public comment period for EPA's proposed
inland waters rule (75 FR 4173) should reconsider their previous
comments in light of the new information presented in this proposal and
must re-submit their comments

during the public comment period for this rulemaking to receive EPA
response.
(a) Alternative Approach (South Florida Inland Flowing Waters)
    As an alternative to EPA's proposed DPV-only approach for south
Florida inland flowing waters, EPA developed protective instream TN and
TP criteria for Class I and III flowing waters (including canals and
streams) in three inland subregions in south Florida (Biscayne, Palm
Beach, and West) that are outside the lands of the Miccosukee and
Seminole Tribes, EAA, and EvPA. EPA's alternative criteria for south
Florida inland flowing waters are listed in Table III.D-1.

  Table III.D-1--EPA's Alternative Numeric Criteria for South Florida's
                          Inland Flowing Waters
------------------------------------------------------------------------
                                                        TN (mg/  TP (mg/
                       Subregion                           L)       L)
------------------------------------------------------------------------
Biscayne..............................................        2    0.052
Palm Beach............................................        2    0.052
West..................................................        2    0.052
------------------------------------------------------------------------

    EPA defined the boundaries of these three subregions based on
patterns in geology/soils, hydrology, and vegetation. EPA compiled data
for these subregions from IWR Run 40 and the South Florida Water
Management District's DBHydro database. EPA screened the data to
include freshwater locations and Class III waters, resulting in 4,758
daily averages with matched chl-a, TN, and TP data.
    Next, EPA chose to evaluate algal biomass, as indicated by
chlorophyll a concentrations, as a sensitive endpoint for numeric
nutrient criteria development. Nutrient pollution can increase biomass
of primary producers, especially algae, and have subsequent negative
impacts on recreation and aquatic life. The application of algal
biomass as an endpoint for criteria derivation in south Florida inland
flowing waters, including canals, might be appropriate given the
following observations: (1) Flow in these water bodies is frequently
reduced, leading to long residence times; (2) canopy cover is reduced
both naturally and through manipulation, reducing light limitation; and
(3) nutrient concentrations are elevated. Because both average
chlorophyll a concentrations and instantaneous chlorophyll a
concentrations (e.g. bloom conditions) can impact recreation and
aquatic life, EPA chose to derive TN and TP criteria to reduce the
likelihood of increased nuisance algal blooms by relating maximum
chlorophyll a to average annual chlorophyll concentrations. EPA defined
nuisance algal bloom conditions as concentrations above 30 [micro]g/L
using trophic state boundaries, user perception studies, and observed
impacts. EPA evaluated existing scientific literature on the frequency
of occurrence of chlorophyll a levels, and selected a 10 percent
occurrence of nuisance algal blooms as the maximum allowable frequency
to prevent impairment of recreation and aquatic life in the three south
Florida inland subregions.\206\
---------------------------------------------------------------------------

    \206\ Havens, K.E. and W.W. Walker. 2002. Development of a total
phosphorus concentration goal in the TMDL process for Lake
Okeechobee, Florida (USA). Lake and Reservoir Management 18(3):227-
238.
---------------------------------------------------------------------------

    EPA then used statistical models to derive TN and TP criteria to
limit the frequency of occurrence of nuisance algal blooms in these
waters, defined by chlorophyll a concentrations above 30 [micro]g/L.
The resulting TN and TP criteria represent the annual geometric mean of
TN and TP concentrations from flowing waters in each of the three
subregions that are associated with a 10 percent or lower frequency of
nuisance algal bloom occurrence. If EPA were to finalize this
alternative approach instead of EPA's lead approach, these TN and TP
criteria would apply throughout the flowing waters in each of the three
subregions, not just at the pour points. If criteria are calculated
using this alternative approach, DPVs for protecting downstream south
Florida marine waters will still be calculated using the hierarchical
approach in Section III.D.2, unless, as described more in Section I.A,
the district court modifies the Consent Decree consistent with EPA's
amended determination that numeric DPVs are not necessary to meet CWA
requirements in Florida. Additional details on this alternative
approach are provided in the TSD (Volume 3: South Florida Inland
Flowing Waters, Section 3).
(b) Request for Comment on Proposed and Alternative Approaches
    EPA believes that the proposed approach for south Florida inland
flowing waters is appropriate, scientifically defensible, and results
in the protection of south Florida inland flowing waters. EPA requests
comment on this approach. EPA also solicits additional available
scientific information that can be used to provide protection of fish
consumption, recreation and the propagation and maintenance of a
healthy, well-balanced population of fish and wildlife in south
Florida's Class I and III inland flowing waters from nitrogen and
phosphorus pollution.
    In addition, EPA requests comment on the alternative approach of
deriving instream criteria for south Florida inland flowing waters
outside of the lands of the Miccosukee and Seminole Tribes, EvPA, and
EAA. Specifically, EPA requests comment on the scientific defensibility
of this alternative approach as well as whether application of this
approach will result in numeric nutrient criteria that protect the
State's designated uses and ensure that nutrient concentrations of a
body of water support balanced natural populations of aquatic flora and
fauna.
    Commenters who submitted comments or scientific information related
to numeric nutrient criteria for south Florida inland flowing waters
during the public comment period for EPA's proposed inland waters rule
(75 FR 4173) should reconsider their previous comments in light of the
new information presented in this proposal and must re-submit their
comments during the public comment period for this rulemaking to
receive EPA response.

F. Applicability of Criteria When Final

    EPA proposes that the numeric nutrient criteria for Florida's
estuaries, coastal waters, and south Florida inland flowing waters
described in this rule be effective for CWA purposes 60 days after EPA
publishes final criteria, and apply in addition to any other criteria
for Class I, II, or Class III waters already adopted by the State and
submitted to EPA (and for those adopted after May 30, 2000, approved by
EPA). EPA requests comment on this proposed effective date.
    Additionally, EPA also requests comment on the alternative of a
delayed effective date, such as the 15-month delayed effective date
that EPA promulgated in the final inland waters rule. EPA subsequently
further extended the effective date of the 2010 rule to allow time for
FDEP to finalize and EPA to review Florida's own numeric nutrient
criteria rulemaking and reduce any administrative confusion and
inefficiency that should occur if Federal criteria took effect while
FDEP was finalizing or EPA was reviewing the State rulemaking.
Florida's newly-approved State WQS include a schedule for future State
rulemaking whereby they will develop numeric nutrient criteria for
additional estuaries by June 30, 2013 and again by June 30, 2015. If
Florida is on schedule toward adoption of protective and approvable
standards for their additional waters, EPA may consider delaying the
effective date of

its final rule to after June 30, 2015 to allow time for Florida to
finalize and EPA to review the State's numeric nutrient criteria.
    For water bodies that Florida has designated as Class I, II, and
III, any final EPA numeric nutrient criteria will be applicable CWA
water quality criteria for purposes of implementing CWA programs
including permitting under the NPDES program, as well as monitoring and
assessment, and establishment of TMDLs. The proposed criteria in this
rule, when finalized, would be subject to Florida's general rules of
applicability to the same extent as are other State-adopted and/or
federally-promulgated criteria for Florida waters. Furthermore, states
have discretion to adopt general policies that affect the application
and implementation of WQS (40 CFR 131.13). There are many applications
of criteria in Florida's water quality programs. Therefore, EPA
believes that it is not necessary for purposes of this proposed rule to
enumerate each of them, nor is it necessary to restate any otherwise
generally applicable requirements.
    It is important to note that no existing TMDL for waters in Florida
will be rescinded or invalidated as a result of finalizing this
proposed rule, nor will this proposed rule when finalized have the
effect of withdrawing any prior EPA approval of a TMDL in Florida.
Neither the CWA nor EPA regulations require TMDLs to be completed or
revised within any specific time period after a change in water quality
standards occurs. TMDLs are typically reviewed as part of states'
ongoing water quality assessment programs. Florida may review TMDLs at
its discretion based on the State's priorities, resources, and most
recent assessments. NPDES permits are subject to five-year permit
cycles, and in certain circumstances are administratively continued
beyond five years. In practice, States often prioritize their
administrative workload in permits. This prioritization could be
coordinated with TMDL review. Because current nutrient TMDLs were
established to protect Florida's waters from the effects of nitrogen
and phosphorus pollution, the same goal as EPA's numeric nutrient
criteria, the Agency believes that, absent specific new information to
the contrary, it is reasonable to presume that basing NPDES permit
limits on those TMDLs will result in effluent limitations as stringent
as necessary to meet the federal numeric nutrient criteria.

IV. Under what conditions will EPA either not finalize or withdraw
these Federal standards?

    Under the CWA, Congress gave states primary responsibility for
developing and adopting water quality standards for their navigable
waters (CWA section 303(a)-(c)). On June 13, 2012, FDEP submitted new
and revised WQS for review by the EPA pursuant to section 303(c) of the
CWA. On November 30, 2012, EPA approved the provisions of these rules
submitted for review that constitute new or revised WQS (see Section
II.F for additional information). Florida continues to have the option
to adopt and submit to EPA numeric nutrient criteria for any of the
State's Class I, Class II, and Class III waters that are not covered in
their June 13, 2012 submission to EPA, consistent with CWA section
303(c) and implementing regulations at 40 CFR 131. Although EPA is
proposing numeric nutrient criteria for Florida estuaries, coastal
waters, and south Florida inland flowing waters, if EPA approves
criteria that are legally effective under Florida law for any other
waters covered in this proposed rule as fully satisfying the CWA before
publication of the final rulemaking, EPA will not proceed with the
final rulemaking for those waters. Also, EPA will not proceed with
final rulemaking for numeric DPVs, provided that the district court
modifies the Consent Decree consistent with EPA's amended determination
that numeric DPVs are not necessary to meet CWA requirements in Florida
(see Section I.A for more information).
    Pursuant to 40 CFR 131.21(c), if EPA finalizes this proposed rule,
EPA's promulgated WQS become applicable WQS for purposes of the CWA on
their effective date unless or until EPA withdraws those federally-
promulgated WQS. Withdrawing the Federal standards for the State of
Florida would require rulemaking by EPA pursuant to the requirements of
the Administrative Procedure Act (5 U.S.C.551 et seq.). EPA would
undertake such a rulemaking to withdraw the Federal criteria if and
when Florida adopts and EPA approves numeric nutrient criteria that
fully meet the requirements of section 303(c) of the CWA and EPA's
implementing regulations at 40 CFR 131. If Florida adopts and EPA
approves nutrient criteria that meet these requirements for a subset of
waters, EPA would withdraw the Federal standards for that subset of
waters.

V. Alternative Regulatory Approaches and Implementation Mechanisms

A. Designating Uses

    Under CWA section 303(c)(2)(A), states shall adopt designated uses
after taking ``into consideration the use and value of water for public
water supplies, protection and propagation of fish, shellfish, and
wildlife, recreation in and on the water, agricultural, industrial and
other purposes including navigation.'' Designated uses ``shall be such
as to protect the public health or welfare, enhance the quality of
water and serve the purposes of [the CWA].'' (CWA section
303(c)(2)(A)). EPA's regulation at 40 CFR 131.3(f) defines ``designated
uses'' as ``those uses specified in water quality standards for each
water body or segment whether or not they are being attained.'' A
``use'' is a particular function of, or activity in, waters of the
United States that requires a specific level of water quality to
support it. In other words, designated uses are a state's concise
statements of its management objectives and expectations for individual
surface waters.
    In the context of designating uses, states often work with
stakeholders to identify a collective goal for their waters that the
state intends to strive for as it manages water quality. States may
evaluate the attainability of these goals and expectations to ensure
they have designated appropriate uses (40 CFR 131.10(g)). EPA's
regulations at 40 CFR 131 interpret and implement CWA sections
101(a)(2) and 303(c)(2)(A) to require that states adopt designated uses
that provide water quality for the protection and propagation of fish,
shellfish, and wildlife and for recreation in and on the water
(referred to as uses specified in section 101(a)(2) of the Act),
wherever attainable (40 CFR 131.2; 131.5(a)(4); 131.6(a),(f);
131.10(g),(j)). Where states do not designate uses specified in
101(a)(2) of the Act, or remove such uses, they must demonstrate that
the uses are not attainable consistent with the use attainability
analysis (UAA) provisions of 40 CFR 131.10, specifically 131.10(g). A
state may remove protection for a use specified in CWA section
101(a)(2) if it can show, based on a UAA consistent with 131.10, that
the use is not attainable. States may include waters located in the
same watershed in a single UAA, provided that there is site-specific
information to show how each individual water fits into the group in
the context of any single UAA and how each individual water meets the
applicable requirements of 40 CFR

131.10(g) for removing or modifying a use.
    EPA's proposed numeric nutrient criteria for estuaries, coastal
waters, and south Florida inland flowing waters will apply to those
waters designated by Florida as Class I (Potable Water Supplies), Class
II (Shellfish Propagation or Harvesting), and Class III (Recreation,
Propagation and Maintenance of a Healthy, Well-Balanced Population of
Fish and Wildlife). If Florida removes the Class I, Class II, and/or
Class III designated use for any particular water body ultimately
affected by this rule such that it is no longer designated as either
Class I, II, or III, and EPA approves such a removal because it is
consistent with CWA section 303(c) and regulations at 40 CFR 131, then
the federally-promulgated numeric nutrient criteria would not apply to
that water body. Only the water quality criteria associated with the
revised designated use would apply to that water body.

B. Variances

    A variance may be described as a time-limited designated use and
criteria that target a specific pollutant(s), source(s), water
body(ies) and/or water body segment(s). Variances constitute new or
revised water quality standards subject to the procedural and
substantive requirements applicable to removing a designated use.\207\
Thus, EPA may only approve a variance if it is based on the same
factors, set out at 40 CFR 131.10(g), that are required to revise a use
specified in CWA section 101(a)(2) through a UAA.
---------------------------------------------------------------------------

    \207\ In re Bethlehem Steel Corporation, General Counsel Opinion
No. 58. March 29, 1977 (1977 WL 28245 (E.P.A. G.C.)). USEPA. 1994.
Water Quality Standards Handbook: Second Edition. EPA-823-B-94-005a.
U.S. Environmental Protection Agency, Office of Water, Washington,
DC.
---------------------------------------------------------------------------

    Typically, variances are time-limited, but may be renewed.
Temporarily modifying the designated use for a particular water body
through a variance process allows a state to identify an interim
designated use and associated criteria to serve as the basis for NPDES
permit limits and certifications under CWA section 401 during the term
of the variance while maintaining the designated use and associated
criteria as the ultimate goal. A state should seek a variance instead
of removing or revising the designated use where the state believes the
designated use and associated criteria can be attained at some point in
the future. By maintaining the designated use, and associated criteria,
and by specifying a point in the future when the designated use will be
fully applicable in all respects, the state ensures that further
progress will be made in improving water quality and attaining the
ultimate goal.
    A variance may be written to address a specific geographic area, a
specific pollutant or pollutants, and/or a specific discharger. All
other applicable water quality standards not specifically modified by
the variance, including any other criteria adopted to protect the
designated use, remain applicable. State variance procedures, as part
of state water quality standards, must be consistent with the
substantive requirements of 40 CFR 131. Each variance must be submitted
to EPA as a revised water quality standard for review and approval or
disapproval pursuant to CWA section 303(c).
    For purposes of this proposal, EPA is proposing criteria that apply
to use designations that Florida has already established. EPA believes
that the State continues to have sufficient authority under 131.10 to
grant variances under its variance procedures to Class I, Class II or
Class III uses and associated criteria. For this reason, EPA is not
proposing a Federal variance procedure.

C. Site-Specific Alternative Criteria

    Site-specific alternative criteria (SSAC) are alternative values to
otherwise applicable water quality criteria that would be applied on a
watershed, area-wide, or water body-specific basis that meet the
regulatory test of protecting the water's designated use, having a
basis in sound science, and ensuring the protection and maintenance of
downstream water quality standards. SSAC may be more or less stringent
than the otherwise applicable criteria. In either case, because the
SSAC must protect the same designated use and must be based on sound
science according to the requirements of 40 CFR 131.11(a), there is no
need to modify the designated use or conduct a UAA. A SSAC may be
appropriate when additional scientific data and analyses can bring
increased precision or accuracy to expressing the concentration of a
water quality parameter that is protective of the designated use.
    In EPA's 2010 rulemaking for Florida's lakes and flowing waters
outside of the South Florida Nutrient Watershed Region, EPA promulgated
a procedure whereby EPA's Region 4 Regional Administrator may establish
a SSAC after making available the proposed SSAC and supporting
documentation for public comment (40 CFR 131.43(e)). This procedure
became effective for CWA purposes on February 4, 2011. Under this
provision, any entity, including the State, can submit a proposed
Federal SSAC directly to EPA for the Agency's review and assessment as
to whether an adjustment to the applicable Federal numeric nutrient
criteria is warranted. The Federal SSAC process is separate and
distinct from the State's SSAC processes in its water quality
standards.
    The current Federal SSAC procedure allows EPA to determine that a
revised site-specific chlorophyll a, TN, TP, or nitrate+nitrite numeric
criterion should apply in lieu of the generally applicable criteria
promulgated in the final rule for Florida's lakes and flowing waters
where that SSAC is demonstrated to be protective of the applicable
designated use(s). The promulgated procedure provides that EPA will
solicit public comment on its determination. Because EPA's rule
established this procedure, implementation of this procedure does not
require withdrawal of the associated federally-promulgated criteria for
the Federal SSAC to be effective for purposes of the CWA. EPA has
promulgated similar procedures for EPA's granting of variances and
SSACs in other federally-promulgated water quality standards.\208\
---------------------------------------------------------------------------

    \208\ See 40 CFR 131.33(a)(3), 40 CFR 131.34(c), 40 CFR
131.36(c)(3)(iii), 40 CFR 131.38(c)(2)(v), 40 CFR 131.40(c).
---------------------------------------------------------------------------

    As outlined in 40 CFR 131.43(e) and in the draft ``Technical
Assistance for Developing Nutrient Site-Specific Alternative Criteria
in Florida'' (June 2011), the process for obtaining a Federal SSAC
includes the following steps. First, an entity seeking a SSAC compiles
the supporting data, conducts the analyses, develops the expression of
the criterion, and prepares the supporting documentation demonstrating
that alternative numeric nutrient criteria are protective of the
applicable designated use. The ``entity'' may be the State, a city or
county, a municipal or industrial discharger, a permittee, a consulting
firm acting on the behalf of a client, or any other individual or
organization. The entity requesting the SSAC bears the burden of
demonstrating that any proposed SSAC meets the requirements of the CWA
and EPA's implementing regulations, specifically 40 CFR 131.11. Second,
if the entity is not the State, the entity must provide notice of the
proposed SSAC to the State, including all supporting documentation so
that the State may provide comments on the proposal to EPA. Third,
EPA's Region 4 Regional Administrator will evaluate the technical basis
and protectiveness of the proposed SSAC and decide whether to publish a
public notice and take

comment on the proposed SSAC. The Regional Administrator may decide not
to publish a public notice and instead return the proposal to the
entity submitting the proposal, with an explanation as to why the
proposed SSAC application did not provide sufficient information for
EPA to determine whether it meets CWA requirements or not. If EPA
solicits public comment on a proposed SSAC, upon review of comments,
the Regional Administrator may determine that the Federal SSAC is or is
not appropriate to account for site-specific conditions and make that
determination publicly available together with an explanation of the
basis for the decision.
    Since the SSAC provision in EPA's 2010 rule became effective,
numerous entities have contacted EPA regarding a possible interest in
obtaining a federal SSAC. However, following discussions with EPA, it
became clear that a different water quality standards mechanism, such
as a designated use change or variance, would be more appropriate in
their particular situation. On March 9, 2011, EPA received a SSAC
request from a pulp and paper mill that discharges to the Fenholloway
River. Since the SSAC was derived from data in a nearby reference
stream, the Econfina River, the TN and TP SSAC were requested to apply
to both the Econfina and Fenholloway Rivers. Additional information was
submitted by the requestor during 2011 and 2012 to address questions
posed by EPA. At this time, EPA does not have sufficient information to
move forward with proposing or establishing the TP or TN SSAC for the
Fenholloway and Econfina Rivers.
    EPA believes that there is benefit in extending this procedure for
EPA adoption of Federal SSAC that will adjust the numeric nutrient
criteria proposed in this rule. EPA is therefore proposing that a
similar procedure promulgated in 40 CFR 131.43(e) apply to estuaries,
coastal waters, and south Florida inland flowing waters. EPA requests
comment on the following proposed application of the SSAC procedure.
    To successfully develop a Federal SSAC for a given estuary, coastal
water, or south Florida inland flowing water, a thorough analysis is
necessary that indicates how the alternative concentration of TN, TP,
or chlorophyll a supports both the designated use(s) of the water body
itself, and provides for the attainment and maintenance of the WQS of
downstream water bodies, where applicable. This analysis should have
supporting documentation that consists of examining indicators of
longer-term response to multiple stressors, such as seagrass health, as
well as indicators of shorter-term response specific to nitrogen and
phosphorus pollution, such as chlorophyll a concentrations associated
with balanced phytoplankton biomass or sufficient dissolved oxygen to
maintain aquatic life.
    EPA is proposing seven approaches for developing SSAC for
estuaries, coastal waters, and south Florida inland flowing waters that
are similar to the four approaches EPA finalized in the 2010 rule for
Florida's lakes and flowing waters. The first five proposed approaches
are replicating the approaches EPA used to develop estuary, tidal
creek, marine lake, coastal, and south Florida inland flowing water
criteria, respectively, and applying these methods to a smaller subset
of waters or water body segments. To understand the necessary steps in
this analysis, interested parties should refer to the complete
documentation of these approaches in the Technical Support Document for
this proposed rule.
    The sixth proposed approach for developing SSAC is to conduct a
biological, chemical, and physical assessment of water body conditions.
A detailed description of the supporting rationale must be included in
the documentation submitted to EPA. The components of this approach
could include, but are not limited to, evaluation of: seagrass health,
presence or absence of native flora and fauna, chlorophyll a
concentrations or phytoplankton density, average daily dissolved oxygen
fluctuation, organic versus inorganic components of total nitrogen,
habitat assessment, and hydrologic disturbance. This approach could
apply to any water body type, with specific components of the analysis
tailored for the situation.
    The proposed seventh approach for developing SSAC is a general
provision for using another scientifically defensible approach that is
protective of the designated use. This provision allows applicants to
make a complete demonstration to EPA using methods not otherwise
described in the rule or its statement of basis, consistent with 40 CFR
131.11(b)(1)(iii). This approach could potentially include use of
mechanistic models or other data and information.

D. Compliance Schedules

    A compliance schedule, or schedule of compliance, refers to ``a
schedule of remedial measures included in a `permit,' including an
enforceable sequence of interim requirements * * * leading to
compliance with the CWA and regulations.'' (40 CFR 122.2, CWA section
502(17)). In an NPDES permit, Water Quality-Based Effluent Limitations
(WQBELs) are effluent limits based on applicable water quality
standards for a given pollutant in a specific receiving water (NPDES
Permit Writers Manual, EPA-833-B-96-003, December, 1996). EPA
regulations provide that schedules of compliance may only be included
in permits if they are determined to be ``appropriate'' given the
circumstances of the discharge and are to require compliance ``as soon
as possible'' (40 CFR 122.47).\209\
---------------------------------------------------------------------------

    \209\ Hanlon, Jim. USEPA Office of Wastewater Management. 2007,
May 10. Memorandum to Alexis Stauss, Director of Water Division EPA
Region 9, on ``Compliance Schedules for Water Quality-Based Effluent
Limitations on NPDES Permits.''
---------------------------------------------------------------------------

    Florida has adopted a regulation authorizing compliance schedules.
That regulation, Subsection 62-620.620(6), F.A.C., is not affected by
this proposed rule. The complete text of the Florida rules concerning
compliance schedules is available at https://www.flrules.org/gateway/RuleNo.asp?ID=62-620.620. Florida is, therefore, authorized to grant
compliance schedules, as appropriate, under its rule for WQBELs based
on EPA's federally-promulgated numeric nutrient criteria.

VI. Economic Analysis

    The CWA provides a comprehensive framework for the protection and
restoration of the health of the Nation's waters. EPA determined in
2009 that addressing the significant number of Florida waters impaired
by nitrogen and phosphorus required the establishment of numeric
nutrient criteria as part of Florida water quality standards adopted
under the CWA. State implementation of numeric nutrient criteria in the
proposed rule may result in an incremental level of controls needed for
compliance with CWA programs, or require them sooner than would occur
under current CWA programs. These controls include new or revised
National Pollutant Discharge Elimination System (NPDES) permit
conditions for point source dischargers and controls on other sources
of nitrogen and phosphorus (e.g., agriculture, urban runoff, and septic
systems) through the development of Total Maximum Daily Loads (TMDLs)
and Basin Management Action Plans (BMAPs).
    EPA conducted an analysis to estimate both the increase in the
number of impaired waters that may be identified as a result of the
proposed rule, and the potential annual cost of CWA pollution control
actions likely to

be implemented by the State of Florida and private parties to assure
attainment of applicable State water quality designated uses. It is
important to note that the costs of pollution controls needed to attain
water quality standards for nutrients for waters already identified as
impaired by the State (including waters with and without TMDLs in
place) are not included in EPA estimates of the cost of the rule. EPA's
analysis is fully described in the document entitled Economic Analysis
of Proposed Water Quality Standards for the State of Florida's
Estuaries, Coastal Waters, and South Florida Inland Flowing Waters
(hereinafter referred to as the Economic Analysis), which can be found
in the docket and record for this proposed rule. This analysis shows
that the incremental costs associated with the proposed rule range
between $239.0 million and $632.4 million per year (2010 dollars) and
monetized benefits may be in the range from $39.0 to $53.4 million
annually.

1. NRC Review of Phase 1 Cost Estimates

    On December 6, 2010 EPA published a final rule to set numeric
nutrient criteria for lakes and streams in Florida designed to protect
those waters for their State-designated uses, such as swimming,
fishing, or as drinking water sources (Phase 1 rule). EPA developed an
economic analysis to provide the public with information on potential
costs and benefits that may be associated with Florida's implementation
of EPA's rule. EPA's estimate of the annual costs of that rule ranged
from $135.5 to $206.1 million; stakeholder estimates of the same cost
categories ranged from $8 to $13 billion annually. While these costs
are not directly related to today's proposed rule, EPA determined that
an independent peer review of its economic analysis for the Phase 1
rule would provide important information on the disparity between EPA's
cost estimates and those of some stakeholders, and would be helpful to
inform and improve its analysis of today's proposed rule. Accordingly,
EPA requested the National Research Council (NRC) of the National
Academies to review EPA's economic analysis for the Phase 1 rule. The
NRC Committee completed its ``Review of the EPA's Economic Analysis of
Final Water Quality Standards for Nutrients for Lakes and Flowing
Waters in Florida'' in June. The Committee was charged with reviewing
and commenting on three specific areas:
    (1) EPA's assumption that only newly impaired waters should be
analyzed,
    (2) EPA's decision to estimate costs associated only with sources
affecting newly impaired waters, by sector, and
    (3) EPA's assumptions about levels of control by point and nonpoint
sources, including the use of variances and other flexibilities for
more cost-effective approaches and whether to implement reverse osmosis
and other stringent control technologies.
    NRC answered the first charge, agreeing with EPA's assumption that
only newly impaired waters should be analyzed. NRC also addressed the
second charge, but took exception with EPA's approach to not estimating
costs for unassessed waters or for septic systems affecting impaired
springsheds. NRC also suggested that EPA underestimated the affected
acres in agriculture. The Committee did not offer specific suggestions
for how to compute the increased acreage that should be analyzed.
However, on the cost side, they suggest including costs associated with
installation of regional treatment systems on agricultural lands.
    As for the third charge, the Committee largely addressed this by
examining the details of EPA's unit costs, including comments
suggesting ways in which EPA underestimated or overestimated costs. The
Committee did not directly address EPA's assumptions regarding the use
of SSACs, variances and use designations, except to propose an
alternative cost estimating framework based on predicting the future
time path of waters progressing through the stages of listing as
impaired, TMDL development, and BMAP implementation, with and without
the rule. The Committee generally concluded that EPA's cost estimates
were likely too low, while the stakeholder estimates were too high.
    In response to the NRC review, EPA has attempted to incorporate
many of the recommendations and suggestions made throughout the NRC
report including: Using the HUC-12 watershed unit of analysis;
analyzing potential costs for unassessed waters that could be
incrementally impaired; analyzing costs for each industrial plant
rather than extrapolating the results from a small sample; reviewing
actual experience from existing TMDLs to identify BMPs sufficient to
meet numeric targets; considering permeable reactive barriers for
septic systems and their installation costs; and considering
uncertainty in government expenditures. EPA has addressed these
recommendations and suggestions in this analysis of costs for the
coastal and estuary criteria.
    The NRC Committee also described an approach for EPA to consider in
analyzing the impacts of its numeric nutrients criteria rules by
tracing out two time-paths of costs and benefits: one time-path for the
baseline and one reflecting the proposed rule. The costs and benefits
of the proposed rule could then be analyzed as the present value of the
difference in the two time-paths of costs and benefits, respectively.
To execute this approach, EPA would need to model not just its
projection of the eventual controls that would be implemented under the
proposed rule, but its predictions of the prioritization of watersheds
that Florida would adopt to determine the timing of controls. NRC
suggested that EPA could engage external stakeholders in a
collaborative process to determine a collective set of assumptions to
use as part of this analytical approach (or at least to ``isolate and
possibly reconcile'' areas of disagreement). EPA acknowledges the merit
of this approach, and notes that it is consistent with EPA's intent
that its numeric nutrients criteria simply interpret Florida's current
narrative nutrient criterion, by providing the often time-consuming
first step of the science-based modeling necessary for developing a
TMDL. The ultimate effect of the EPA's proposal would be to improve the
efficiency and effectiveness of Florida's WQS program with regard to
nutrients. However, given the exigencies of the consent decree and the
timing of the NRC review, EPA determined that it was not possible to
adopt the NRC's alternative approach for this proposal. The NRC's
alternative approach was presented as a finding, rather than a
recommendation, because the NRC acknowledged that time and budget
constraints might render this approach unworkable for the current rule.
    Considering the exigencies, EPA took the approach of estimating
costs and benefits for a representative future year, using current
water quality data as a basis for projecting what incremental water
quality controls would need to be implemented during this future year
to meet the new criteria. An approach that compares two complete future
time-paths (with and without the proposed rule) requires taking the
difference between those two time-paths, discounting over time, and
summing in order to express the impacts in present value terms. In
contrast, EPA's approach identifies waters that would be newly
identified as impaired and the controls that would be needed to meet
the new criteria. EPA then annualizes the costs of these controls over
an appropriate time horizon. As such, the two approaches are not
directly comparable.

Nonetheless, EPA believes its approach sheds light on the costs and
benefits associated with its numeric nutrients criteria rules and
complies with the Executive Order requirements for conducting economic
analysis of regulations. As noted above, EPA has made significant
changes to its approach to address the NRC recommendations that are
applicable to it.

2. Baseline for Cost Analysis

    EPA is promulgating numeric nutrient criteria to supplement the
State of Florida's current narrative nutrient criteria. The incremental
impacts of the proposed rule are the potential costs and benefits
associated with implementation of the proposed numeric criteria,
including DPVs, for estuaries, coastal waters, and south Florida inland
flowing waters, above and beyond the costs associated with State
implementation of its current narrative nutrient criterion. The
baseline incorporates requirements associated with restoration of
already identified impaired waters, including waters for which TMDLs
are approved and waters for which TMDLs are not yet developed. Because
the numeric nutrients criteria proposed here interpret Florida's
existing narrative criterion, which is also the basis for existing
TMDLs, the analysis assumes that these TMDLs would be adopted as site-
specific criteria. Thus, there would be no additional costs or benefits
associated with the proposed rule for these waters. The baseline for
this analysis also includes EPA's previously promulgated numeric
nutrient criteria for Florida's lakes and flowing waters.
    For waters that the State of Florida has already identified as
impaired but for which it has not yet developed TMDLs, EPA expects that
the effect of this proposed rule will be to shorten the time and reduce
the resources necessary for the State of Florida to develop TMDLs and
BMAPs. For waters that the State of Florida has developed TMDLs, EPA
has looked at the proposed criteria to compare these to the target
loadings in the TMDLs and has not found a consistent pattern of
existing TMDLs being either more or less stringent than would be
required to meet the criteria proposed in this rule. For already
impaired waters and waters already under a TMDL, EPA assumed that no
additional controls on nonpoint sources to these waters would be needed
as a consequence of this rule. However, there may be an incremental
impact of the proposed rule for any point source dischargers to these
waters that have or may receive waste load allocations for just one
nutrient pollutant if those waters are not attaining criteria for the
other as a result of this proposed rule. These costs are included in
this economic analysis.
    For waters not currently impaired under the baseline, EPA uses
current water quality measurements to predict which waters would be
deemed unimpaired as a result of the proposed rule (and therefore need
not be analyzed for nonpoint source control costs). EPA acknowledges
that these conditions could change in the future. To the extent that
the experience in implementation of the proposed rule deviates from
these specific assumptions about the baseline, EPA's estimates of the
costs and benefits may be under- or overestimated. See Section 2 of the
Economic Analysis for a full description of the baseline. EPA requests
comment on its assumptions regarding the baseline.

3. Incremental Costs

    The likely effect of this proposed rule will be the assessment and
identification of additional waters that are impaired and not meeting
the numeric water quality criteria in the proposed rule. The
incremental impact of the proposed rule includes the costs for controls
on point and nonpoint sources, developing and implementing TMDLs to
attain the proposed criteria, and the monetary value (benefits) of the
resulting potential increase in water quality. The economic analysis
describes these potential incremental impacts of the proposed rule. It
is important to note that EPA took care not to include costs for the
estuarine and coastal marine waters contained in Florida's newly-
approved State WQS.
    To develop these estimates, EPA first assessed State control
requirements associated with current water quality, existing impaired
waters, and existing TMDLs, as well as existing regulations specific to
estuaries, coastal waters and south Florida inland flowing waters (the
baseline). EPA then identified the costs and benefits associated with
additional pollution controls to meet EPA's proposed numeric criteria,
beyond pollution controls currently needed or in place. To estimate
incremental costs to municipal and industrial dischargers, EPA gathered
publicly available facility information and data on potential control
technologies, and used Florida Department of Environmental Protection
(FDEP) point source implementation procedures to estimate the change in
WQBELs and treatment controls that could result from the proposed rule.
EPA assessed potential non-point source control costs by using publicly
available information and data to determine land uses near waters that
would likely be identified as impaired under the proposed rule. EPA
used current FDEP data on stormwater controls and Florida Department of
Agricultural and Consumer Services (FDACS) manuals to estimate costs of
implementing stormwater and agricultural best management practices
(BMPs) to attain the proposed numeric criteria. EPA also estimated the
potential costs associated with upgrades of homeowner septic systems
and potential government costs of developing additional TMDLs for water
identified as impaired under this rule. Finally, EPA qualitatively and
quantitatively described and estimated some of the potential benefits
of complying with the new water quality standards. Although it is
difficult to predict with certainty how the State of Florida will
implement these new water quality standards, the result of this
analysis represent EPA's best estimates of costs and benefits of the
State of Florida's likely actions to implement this proposed rule.
A. Incrementally Impaired Waters
    Compared to current conditions, potentially incrementally impaired
waters are those waters that exceed EPA's proposed criteria for which
FDEP has not already developed a TMDL or listed as impaired for
nutrients. To estimate incremental costs associated with attainment of
criteria, EPA first removed any waters for which the State of Florida
has already determined to be impaired or established a TMDL and/or
BMAP, because it considers these waters part of the baseline for this
analysis. BMAPs are iterative and are updated on a continual basis
until the TMDL targets are met. EPA assumes that controls will be
implemented through these mechanisms until the TMDLs are met. Although
additional costs to address baseline impairments may be needed in the
future (after this rule is promulgated), EPA does not believe that
these costs should be attributed to this proposed rule, but are instead
part of the baseline. As discussed above, the State of Florida is not
required to revise any existing TMDL as a result of this rule, and
WQBELs in NPDES permits that are consistent with an existing EPA
approved TMDL meet the requirements of the CWA. TMDL nutrient criteria
have been shown to be both more stringent and less stringent when
compared to criteria under this proposed rule and EPA has provided
SSACs as a mechanism to approve the standards in existing TMDLs and
BMAPs. Thus, EPA does not anticipate that this rule will result in
increased nonpoint source controls costs for

watersheds that already have an EPA-approved TMDL.
    After excluding waters already identified as impaired under
Florida's existing narrative criteria, EPA next identified estuarine
and coastal segments that do not meet the numeric criteria of this
proposed rule. EPA then assumed identified waterbodies (WBIDs \210\)
that overlap those segments may be identified as incrementally
impaired. EPA then identified the watersheds that contain or surround,
in the case of coastal waters, those incrementally impaired WBIDs.
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    \210\ WBID is a waterbody identification number assigned by
Florida, in order to delineate the boundaries of Florida's waters.
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    EPA analyzed FDEP's database of ambient water quality monitoring
data and compared monitoring data for each segment with EPA's proposed
criteria for TN and TP to identify incrementally impaired waters. EPA
compiled the most recent five years of monitoring data and determined
if there was sufficient data available to calculate more than one
annual geometric mean in a consecutive three year period. With
sufficient data, EPA calculated the annual geometric mean for each
segment identified by EPA segment boundaries, and identified waters as
incrementally impaired if they exceeded the applicable criteria in this
proposed rule. The results of this analysis are shown in Table VI(A).

               Table VI(A)(1)--Number of WBIDs Summary of Data Analysis for Proposed Criteria \1\
----------------------------------------------------------------------------------------------------------------
                                                                            Not currently impaired
                                                                              under the baseline
                                                                Baseline  --------------------------
                        Criteria type                           impaired       Data                     Total
                                                                  \2\       available     Data not
                                                                               \3\       available
----------------------------------------------------------------------------------------------------------------
Coastal.....................................................            0            5           68           73
Estuaries...................................................           42          121           95          258
                                                             ---------------------------------------------------
    Total...................................................           42          126          163          331
----------------------------------------------------------------------------------------------------------------
Source: FDEP IWR run 44.
\1\ Represents number of WBIDs, based on 10% of WBID area overlapping segments for which EPA is proposing
  numeric nutrient criteria.
\2\ On 303(d) list as impaired for nutrients or covered under a nutrient-related TMDL. EPA did not assess these
  waters further for attainment of the proposed criteria.
\3\ WBIDs in segments for which at least two geometric means in a consecutive three year period can be
  calculated based on having at least four samples in a given year, with one sample in winter and summer.

    Controls may also be needed to meet the proposed criteria in a
portion of the 163 WBIDs for which EPA does not have data if subsequent
data would indicate impairment. These 163 WBIDs are variously located
in the same watersheds as WBIDs that are baseline impaired or
incrementally impaired by this proposed rule, or in watersheds either
with no known impaired WBIDs or for which none of the WBIDs have
sufficient data to determine impairment status. Without additional
information about these waters, EPA determined the number of impaired-
though-unassessed waters as a range. As a low estimate, it is possible
that none of the unassessed waters would be impaired. Given the
targeting scheme for Florida's IWR data, these unassessed waters likely
have a lower probability of impairment than assessed waters, and zero
represents the lower bound. For the high end of the range, EPA
considered a proportional impairment rate of assessed waters. The
impairment rate of unassessed waters may be anywhere in between.
    While helpful in establishing the number of waterbodies that may be
incrementally impaired, the assumption of proportional impairment does
not produce information on location needed to estimate associated
costs. The majority of unassessed waters lie along the coast and in
close proximity to baseline impaired and impaired assessed waters.
Hence, for this analysis, EPA assumed that impairment in unassessed
waters would most likely be near baseline impairments and impaired
assessed waters, since the loads causing impairment in these assessed
waters could also affect the downstream unassessed waters. For coastal
waters and south Florida waters, EPA used GIS to locate waters within
or adjacent to the same watersheds associated with baseline impairments
and impaired assessed waters. For estuaries, the number of unassessed
waters estimated to be impaired (based on the assumption of
proportional impairment) would not fit within the same watersheds
associated with baseline impairments and impaired assessed waters.
Therefore, EPA used GIS analysis to identify a buffer around the
watersheds associated with baseline impairments and impaired assessed
waters that would just include the estimated number of impaired
unassessed waters. EPA found that a buffer size of 0.7 miles
encompassed the estimated number of impaired unassessed waters. A
smaller buffer (e.g., 0.5 mile) would not include enough unassessed
waters. A larger buffer (e.g., 1 mile) would include too many
unassessed waters. EPA then used this 0.7 mile buffer to identify the
associated incremental watersheds that may need nonpoint source
controls. EPA has estimated the acres of various land uses within these
watersheds and reported as the upper bound in the Additional Unassessed
Water column of Table VI(A)(2).

  Table VI(A)(2)--Summary of Land Use in Incrementally Impaired Watersheds for the Analysis of Costs Under the
                                                  Proposed Rule
                                                     [Acres]
----------------------------------------------------------------------------------------------------------------
                                                                           Additional
                 Land use type                   Assessed waters \1\  unassessed water \2\          Total
----------------------------------------------------------------------------------------------------------------
Agriculture...................................                15,312              0-22,828         15,312-38,140
Communications and Utilities..................                 3,337               0-3,315           3,337-6,652
Forest........................................               199,432             0-256,137       199,432-455,569
Industrial....................................                 2,025               0-6,703           2,025-8,729
Other.........................................                 9,276              0-11,306          9,276-20,582
Transportation Corridors......................                 9,177               0-3,636          9,177-12,813
Urban.........................................               128,787              0-86,508       128,787-215,295
Water.........................................               220,728             0-102,615       220,728-323,343
Wetlands......................................               196,545             0-322,355       196,545-518,899
                                               -----------------------------------------------------------------
    Total.....................................               784,619             0-815,403     784,619-1,600,022
----------------------------------------------------------------------------------------------------------------
\1\ Total acreage of 12-digit HUC watersheds surrounding the incrementally impaired WBIDs based on sufficient
  data, excluding watersheds for which EPA has already estimated a need for controls.
\2\ Acreage surrounding potential incrementally impaired unassessed waters not associated with baseline
  impairment or incremental impairment under the proposed rule based on sufficient data.

    The costs associated with the additional controls that would be
necessary in the watersheds not already included in the cost analysis
because of known incremental impaired waters will be included in the
remainder of this section.
B. Point Source Costs
    Point sources of wastewater must have a National Pollution
Discharge Elimination System (NPDES) permit to discharge into surface
waters. EPA identified point sources potentially discharging nitrogen
and phosphorus to estuaries, coastal waters, and south Florida inland
flowing waters by evaluating the Integrated Compliance Information
System-National Pollutant Discharge Elimination System (ICIS-NPDES)
database. EPA identified all facilities with any permitted discharge to
estuarine, coastal, and south Florida inland flowing waters with an
existing effluent limit or monitoring requirement for nitrogen or
phosphorus, as well as those with the same industry code as any point
source with an identified nutrient monitoring requirement. This
analysis identified 121 point sources as having the potential to
discharge nitrogen and/or phosphorus. Table VI(B) summarizes the number
of point sources with the potential to discharge nitrogen and/or
phosphorus.

            Table VI(B)--NPDES-Permitted Wastewater Dischargers Potentially Affected by Proposed Rule
----------------------------------------------------------------------------------------------------------------
                                                                       Major           Minor
                       Discharger Category                          Dischargers     Dischargers        Total
                                                                        \a\             \b\
----------------------------------------------------------------------------------------------------------------
Municipal Wastewater............................................              53              31              84
Industrial Wastewater...........................................              19              18              37
                                                                 -----------------------------------------------
    Total.......................................................              72              49             121
----------------------------------------------------------------------------------------------------------------
\a\ Facilities discharging greater than one million gallons per day or likely to discharge toxic pollutants in
  toxic amounts.
\b\ Facilities discharging less than one million gallons per day and not likely to discharge toxic pollutants in
  toxic amounts.

1. Municipal Waste Water Treatment Plant (WWTP) Costs
    EPA considered the costs of known nitrogen and phosphorus treatment
options for municipal WWTPs. Nitrogen and phosphorus removal
technologies that are available can reliably attain annual average
total nitrogen (TN) concentration of approximately 3.0 mg/L or less and
annual average total phosphorus (TP) concentration of approximately 0.1
mg/L or less.\211\ EPA considered wastewater treatment to these
concentrations to be the target levels for the purpose of this
analysis. The NRC suggested that there is uncertainty associated with
this assumption because dischargers to impaired waters typically
receiving WQBELs equal to the numeric water quality criteria (NRC,
2012; p. 48). However, procedures for determining appropriate WQBELs
include an evaluation of effluent quality and assimilative capacity of
the receiving water. Specifically for nutrients, EPA found no
implementation evidence in Florida to support the assumption that the
criteria would be adopted as end-of-pipe limits. Instead, based on the
State of Florida protocol \212\ and the examples from existing nutrient
TMDLs, EPA assumed for this analysis that state implementation of the
proposed rule will not result in criteria end-of-pipe effluent
limitations for municipal WWTPs.
---------------------------------------------------------------------------

    \211\ U.S. EPA, 2008, ``Municipal Nutrient Removal Technologies
Reference Document. Volume 1--Technical Report,'' EPA 832-R-08-006.
    \212\ Florida Department of Environmental Protection (FDEP).
2006a. TMDL Protocol. Version 6.0. Task Assignment 003.03/05-003.
---------------------------------------------------------------------------

    The NPDES permitting authority determines the need for WQBELs for
point sources on the basis of determining their reasonable potential to
exceed water quality criteria. To determine reasonable potential on a
facility-specific basis, data such as instream nutrient concentrations
and low flow conditions would be necessary. However, because most WWTPs
are likely to discharge nutrients at concentrations above applicable TN
and/or TP criteria, EPA assumed that all WWTPs have reasonable
potential to exceed the numeric criteria. The NRC supported this
assumption.
    For municipal wastewater, EPA estimated costs to reduce effluent

concentrations to 3 mg/L or less for TN and 0.1 mg/L or less for TP
using advanced biological nutrient removal (BNR). Although reverse
osmosis and other treatment technologies may have the potential to
reduce nitrogen and phosphorus concentrations even further, EPA
believes that implementation of reverse osmosis applied on such a large
scale has not been demonstrated.\213\ The NRC supported this assumption
(NRC, 2012; p. 46) but said that in some instances, treatment to levels
beyond the controls of advanced BNR would be required (NRC, 2012; p.
48). Such levels have not been required for WWTPs by the State of
Florida in the past, including for those WWTPs under TMDLs with
nutrient targets comparable to the criteria in this proposed rule. EPA
believes that should state-of-the-art BNR technology, together with
other readily available and effective physical and chemical treatment
(including chemical precipitation and filtration), fall short of
compliance with permit limits associated with meeting the new numeric
nutrient criteria, then it is reasonable to assume that entities would
first seek out alternative compliance mechanisms such as reuse, site-
specific alternative criteria, variances, and designated use
modifications. In addition, under a TMDL, FDEP could allocate greater
load reductions to nonpoint sources based on baseline contributions and
existing controls, thus resulting in fewer reductions required from
point source dischargers. EPA acknowledges that if its assumptions
about the availability of reuse, SSACs, variances and designated use
changes are incorrect, then the costs presented here are
underestimates.
---------------------------------------------------------------------------

    \213\ Treatment using reverse osmosis also requires substantial
amounts of energy and creates disposal issues as a result of the
large volume of concentrate generated.
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