![](media/image1.png){width="1.7520833333333334in" height="0.875in"}
*Federal Water Quality Coalition*

November 2, 2006

EPA Water Docket (MC4101T)\
U.S. Environmental Protection Agency\
1200 Pennsylvania Avenue, N.W.\
Washington, D.C. 20460

Attention: Docket ID No. EPA-HQ-OW-2006-0656

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  **RE:**   **Comments on Draft Mercury Implementation Guidance**

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Dear Sir or Madam:

The Federal Water Quality Coalition (the Coalition) is submitting these
comments on the Draft Guidance for Implementing the January 2001
Methylmercury Water Quality Criterion (\"the Draft Guidance\"), issued
by the U.S. EPA (\"EPA\" or \"the Agency\") on August 9, 2006 (71
[Fed.]{.underline} [Reg.]{.underline} 45560).

The Coalition is a group of industrial companies, municipal entities,
agricultural parties, and trade associations that are directly affected,
or which have members that are directly affected, by regulatory
decisions made under the Federal Clean Water Act (the "CWA" or the
"Act"). The Coalition's members, for purposes of these comments, are as
follows: Alcoa, Inc., Alliance of Automobile Manufacturers, American
Chemistry Council, American Coke and Coal Chemicals Institute, American
Forest & Paper Association, American Iron and Steel Institute, American
Petroleum Institute, Asarco Incorporated, Chlorine Institute, City of
Fort Wayne (IN), City of Lafayette (IN), City of Superior (WI), Coeur
D'Alene Mines Corporation, Edison Electric Institute, General Electric
Company, Hecla Mining Company, Indiana Coal Council, Mid America
CropLife Association, National Association of Home Builders, Phelps
Dodge Corporation, Pharmaceutical Research and Manufacturers of America,
Rubber Manufacturers Association, Synthetic Organic Chemical
Manufacturers Association, Utility Water Act Group, Western Coalition of
Arid States, and Western States Petroleum Association.

Coalition member entities or their members own and operate facilities
located on or near waters of the United States. These facilities operate
pursuant to individual and/or general NPDES permits for discharges into
those waters. Many of the facilities will be subject to permit
requirements issued by their State agencies or EPA, based on the
requirements and recommendations set forth in the Guidance when it is
issued in final form. The Coalition therefore has a direct interest in
the matters addressed in the Draft Guidance, which is why we are filing
these comments.

The Coalition appreciates the opportunity to submit these comments, and
also appreciates the work that EPA has done on this Draft Guidance. We
have had several discussions with the Agency over the last several years
regarding mercury issues, including those addressed in the Draft
Guidance, and we have welcomed the opportunity to provide input as EPA
has developed its policies in this area. As a general matter, we believe
that it is highly important for EPA to issue guidance on how mercury
should be regulated under the CWA. States need to make regulatory and
permitting decisions, and clear, consistent guidance from EPA should be
very helpful in accomplishing those tasks. As for the substance of the
Draft Guidance, we support many of the key elements in the Draft
Guidance, including particularly the emphasis on the direct use of fish
tissue criteria and fish tissue data in making TMDL and permitting
decisions, and the focus on implementation of pollutant minimization
programs rather than numeric limits for point sources. There are other
aspects of the Draft Guidance that we believe should be improved and/or
clarified. Our thoughts and suggestions are provided in detail below.

A. GENERAL ISSUES

1.  We Support the Direct Use of Fish Tissue Criteria in TMDLs and
    Permitting. The BAF Approach Should Not Be Used..

EPA provides several methods that States can use to implement the
recommended fish tissue criterion. Draft Guidance at pp. 14-15. States
can use bioaccumulation factors (BAFs) to translate fish tissue levels
into water column concentrations, and then use existing regulatory tools
to derive TMDLs and permit requirements based on those water column
levels. However, EPA notes a number of concerns regarding use of that
method (Draft Guidance at pp. 12, 19, 22), and points out that States
can also use the fish tissue criterion directly to develop TMDLs and
permit requirements, without needing to translate fish tissue levels
into water column levels. That approach integrates the site-specific
effects of mercury speciation, transformation and bioaccumulation. We
support the "direct use of fish tissue" approach, particularly relative
to the alternative of using BAFs, which are extremely problematic. In
fact, we believe that the Draft Guidance should more strongly promote
the use of the "direct" approach and discourage use of BAFs. Our
concerns regarding use of BAFs are set forth in more detail in Section
A.4. below.

2.  EPA Should Increase the Emphasis on Methylmercury rather than Total
    Mercury.

EPA has, appropriately, recognized in the Draft Guidance that the form
of mercury that poses bioaccumulation risk, and that therefore should be
the focus of regulatory efforts, is methylmercury. Draft Guidance at p.
3. However, we remain concerned that the Agency has not sufficiently
emphasized collection and use of information on methylmercury levels,
rather than total mercury levels, whenever possible. For example, the
analysis of effluents is focused on total mercury (Draft Guidance at pp.
87-88, 94-96). While we understand the analytical and fate/transport
challenges as to methylmercury that lead to that approach, we believe
that it is very important to keep in mind that levels of total mercury
in effluents do not necessarily have a strong relationship to the levels
of methylmercury in fish in the waters that receive those discharges.
That caution needs to be factored in when the agencies are deciding on
the proper standards and the proper mix of controls to attain the
standards. Similarly, it may be easier to express TMDLs in total
mercury, rather than methyl, given the data collection challenges for
the methylated form, but that can lead to focus on the wrong sources,
and on wasteload reductions being mandated that do not actually result
in the needed reductions in methyl levels in fish. EPA should recommend
to the States that whenever possible, they should focus their evaluation
of water quality, source contributions, and other TMDL inputs on
methylmercury rather than the total form.[^1]

3.  EPA Should Recognize in the Guidance that the Relation between Total
    Mercury in Effluent and Methylmercury in Fish Needs to be Studied
    Further.

Implicit in the draft guidance is the recognition that some approaches
to implementing the water quality criterion for methylmercury would
necessitate the development of a relationship between methylmercury in
the water column and methylmercury in fish (i.e., the BAF), and the
relationship between total mercury in the water column (and in
wastewaters and stormwaters) and methylmercury in the water column
(i.e., total mercury to methylmercury translator). While the guidance
offers some suggestions for developing these relationships, it does not
speak to the real potential that in some, and perhaps many,
circumstances current scientific knowledge is insufficient to allow the
development of such relationships to the degree needed to support
defensible, economically responsible strategies for reducing
methlymercury concentrations in fish tissue. The guidance should
recognize deficiencies in the current science and potential need for
additional time for study by states prior to implementing control
strategies for methylmercury.

Sections 3.1.3.1 and 3.1.3.2 of the draft guidance (pp. 16-26 and 26-39
respectively) provide discussions concerning the translation of
methylmercury concentrations in fish tissue to methylmercury
concentrations in the water column and further to concentrations of
total mercury in the water column. From these discussions, it is clear
that EPA recognizes the complexity of factors affecting the fate of
mercury in the environment. In fact, the observation that these factors
are site-specific is one reason EPA cited in its rationale for issuing a
water quality criterion for methylmercury as a tissue concentration[^2].
However, in situations where States wish to reduce the level of
methylmercury in fish tissue, a sufficient understanding of
site-specific factors and processes concerning total and methylmercury
will be required to support responsible decisions for managing the water
body.

While the guidance offers a variety of suggestions regarding approaches
States might consider for relating total and methylmercury, the guidance
fails to recognize that the current state of the science will, in some
cases, lack the power to identify supportable relationships between
total mercury in the water column or in wastewater or stormwater
discharges and methylmercury in fish tissue. A complete review of the
relevant literature is outside the scope of these comments, but recent
work suggests that the methylation of mercury is a very complex process
that is only poorly understood at present. Methylation is generally
thought to be mediated by sulfur reducing bacteria, so factors unrelated
to the amount of total mercury present in a system may have a profound
effect on the observed relationship between mercury in sediments or
water and that found in fish. As an example, it has been observed that
the proportion of total mercury (Hg~T~) in the water column present as
methyl mercury (MeHg) can be lower in contaminated waters than in
pristine waters, and some researchers have even claimed an inverse
relationship between Hg~T~ and MeHg (Schaefer et al. 2004[^3]). In this
specific case, microbial processes were cited as the causal factor for
this counterintuitive observation. Other researchers have reported on
the significance of organic matter as a factor impacting methylation
and, in a study of mercury in the Moose Jaw River, Jackson (1986[^4])
concluded that methylmercury levels were not controlled by total mercury
concentrations, but were dependent on the abundance of organic matter
and planktonic algae. This is consistent with the work of Hammerschmidt
and Fitzgerald (2004[^5]), which suggested that Hg(II) can partition to
organic material, making it unavailable to methylating bacteria. More
recently, Lambertsson and Nilsson (2006[^6]) have also implicated the
presence of organic material (OM) as a factor controlling methylation in
estuarine systems, and their work led them to conclude that "the amount
of OM accumulated at the bottoms was the main factor affecting net MeHg
production, while the total amount of Hg had little or no influence on
the amount of MeHg in the sediment." Other research indicates that
iron-reducing bacteria may be as important as, or more important than,
sulfate-reducing bacteria in the mercury methylation process (Fleming et
al. 2006).[^7] A great deal of innovative work is currently underway
(e.g., the "METAALICUS" project[^8]) and these relationships may be
better understood in the future.

For the reasons discussed above, BAFs expressed as methylmercury in
tissue to total mercury in water are simply not supportable. BAFs must
be methylmercury in tissue to methylmercury in water, and even then will
require site specific data. As an example of how methylmercury in water
can be used to predict the concentration of total mercury in fish,
U.S.G.S. biologists developed a regression model that, after evaluating
all variables measured in studies of mercury in various watersheds
across the U.S., produced "best fit" (highest R^2^ value) equation for
predicting fish tissue mercury. The regression model included the
following variables: methylmercury levels in water, % wetland of the
water body, water body pH, and acid-volatile sulfide (Brumbaugh et al.
2001)[^9]. The single best predictor of fish tissue concentration (best
1-variable model) was methylmercury in water.

In the meantime, however, EPA should recognize in the draft guidance
that (a) today, it is not possible in all cases to quantify
relationships between total and methylmercury to a degree sufficient to
support economically responsible environmental management, and that (b)
it is likely that some sources of total mercury will have no impact on
methylmercury levels in local fish tissue.

4.  EPA Needs to be Consistent in its Discussion of Various Models.

EPA's draft guidance document discusses steady state models, dynamic
models and spatially detailed models, but is inconsistent in how it
discusses when these models may be used. For instance, on pp. 74-76),
EPA explains that different types of models fit different situations.
For example, when the factors affecting methylation of mercury vary
seasonally or around an average but stay the same from year to year, the
appropriate type of model is the dynamic model. Another type of model is
a BAF, which assumes a "constant proportionality." Where there are
seasonal changes in loadings, in phytoplankton concentrations or
abundance, or in many other factors, constant proportionality is not
attained, so use of this type of steady-state model would not be
appropriate. The third type of model is the sediment-based model, where
"a simplified steady state approach cannot simulate changes in mercury
concentrations in fish tissue due to external load reductions." This
third model type does not use a bioaccumulation factor.

However, earlier in the Draft Guidance, in § 3.1.3.1 (pp. 16-25), EPA
allows for regulatory actions based on bioaccumulation factors, but does
not appear to allow for sediment-based models. Also, EPA allows only for
steady-state bioaccumulation factors. This is indicated by the following
EPA statement: "Regardless of the type of model used, states' ...
methodologies should be consistent with the *Methodology for Deriving
Ambient Water Quality Criteria for the Protection of Human Health* ...
(section 5.6: National Bioaccumulation Factors for Inorganic and
Organometallic chemicals: USEPA 2000e) and *Technical Support Document
Volume 2: Derivation of National Bioaccumulation Factors* (USEPA
2003b)." Draft Guidance at p. 20. The technical documents cited by EPA
do not allow dynamic BAFs or allow sediment-based or other similar
models that are not predicated on BAF's (either steady state BAF's or
dynamic BAF's).

BAFs to estimate the propensity of mercury to bioaccumulate in
waterbodies, though simple to calculate, have scientific flaws (Reash,
R.J. 2002. An Evaluation of USEPA's Bioaccumulation Factor for Mercury:
A Regulated Industry Perspective. Abstract provided in U.S. EPA and
U.S.G.S -- Proceedings and Summary Report of the Workshop on the Fate,
Transport, and Transformation of Mercury in Aquatic and Terrestrial
Environments. EPA/625/R-02/005). Brumbaugh et al. (2001) noted a curious
finding that, for some watershed land-use categories, calculated BAF
values for largemouth bass were: 1) low when measured mercury levels in
fish were high, and 2) low when methylmercury concentrations in water
were high. In theory, BAF's should increase as the bioaccumulative
propensity of mercury (from water to fish tissue) increases. The low
solubility of inorganic mercury, variable and site-specific partitioning
of mercury species, and extended times necessary to reach equilibrium
and steady states are problematic for using a BAF approach to determine
confident estimates of the propensity to bioaccumulate. Therefore, EPA
needs to allow use of alternative models, and the Draft Guidance should
state a consistent approach as to when those models can or should be
used.

B. ASSESSMENT AND LISTING ISSUES

1\. We Support EPA's Recommendation for Use of Trophic Level-Weighted
Averages in Measuring Fish Tissue Levels. Data from One or a Few Species
Should Not Lead to Listing When That Average Does Not Exceed the
Criterion.

We support EPA's recommendation in Section 4.3 (Draft Guidance at p. 50)
that States use a trophic level weighting approach to compute an average
methylmercury concentration in fish tissue for comparison with the
methylmercury criterion. In the related discussion (Section 4.3.4), EPA
should clarify that fish consumption advisories for one, or even a few
species having geometric mean concentrations above 0.3 mg/kg, may not be
an adequate basis for 303(d) listing absent corresponding local fish
consumption data suggesting a risk level in excess of that embodied in
the criterion.

Section 4.3.2 of the Draft Guidance describes an approach for
calculating weighted average fish tissue values for each trophic level
and then applying local or default fish consumption distributions to
compute the average methylmercury concentration in fish tissue for a
stream (C~avg~ on p. 51). We support this approach, because it is a more
comprehensive assessment of fish tissue concentrations and exposure when
compared to some other procedures used by states. For example, some
states, including Idaho and Oregon, have included streams on their
303(d) lists as impaired for mercury when average tissue concentrations
for just one or a few species of fish have exceeded the criterion. This
approach does not imbed any analysis suggesting that fish consumption
patterns (local or default) present a risk in excess of that embodied in
the criterion. The problems with that policy are suggested by experience
in states that have shifted to a more sound approach. For example, in
Georgia, the Savannah River was originally included on the 303(d) list
as impaired for mercury. Once a full assessment was completed, the state
decided to delist that water body as impaired for mercury.

It is possible, and perhaps likely, that some state impairment listings
represent a degree of confusion concerning EPA's general interpretation
that fish consumption advisories demonstrate impairment of CWA section
101(a) "fishable" uses[^10]. As EPA is aware, the basis used by State
environmental or health agencies to support fish consumption advisories
varies widely between States and is rarely, if ever, developed solely on
the basis of a corresponding water quality criterion. Rather, such
advisories are often formulated to guide potential consumers, or subsets
of potential consumers (e.g., pregnant women), against the consumption
of excess amounts of certain species. For this and other reasons, it is
often difficult or impossible to contrast the potential risks associated
with the State issued fish consumption advisory with the risks embodied
in the methylmercury criterion as is suggested by EPA in the October
2000 guidance and the draft guidance[^11].

The Draft Guidance would be enhanced if EPA were to provide a more
forthright discussion of these difficulties and a recommendation that a
trophic level weighted average concentration, when used in conjunction
with local or default fish consumption patterns, is the [preferred
basis]{.underline} for comparison against the criterion. EPA should
further note that the co-occurrence of fish consumption advisories for
one or a small number of fish species for consumers (or subsets of
consumers) is not, by itself, justification for listing under CWA
section 303(d).

2\. We Support the Concept that Fish Data Older than 5 Years Should Not
Be Used for Listing Decisions Unless the State Considers Reliability and
Consistency with QA/QC Requirements.

In the Draft Guidance, EPA discusses the important concept of data age,
noting that if fish tissue data are more than 5 years old, the State
should consider reliability and consistency with quality
assurance/quality control requirements before using those data in
listing decisions. Draft Guidance at p. 53. We commend EPA for stressing
those important scientific concepts. Our experience has been that much
of the data that has been used for 303(d) decisions in the past has not
met basic data quality requirements, and this is particularly true of
data that was collected years ago. Since fish tissue data are not
routinely collected from every waterbody every year, data age and
quality are particular concerns, and they need to be considered
carefully before using older data in regulatory decisions.

3\. We Support the General Policy that Listing based on a Fish Advisory
is Not Required Unless Data are Specific to that Waterbody, but EPA
Should Not Give States Discretion to List based on Data from Other
Waterbodies.

In the Draft Guidance, EPA restates its existing policy concerning use
of fish advisories for 303(d) listing purposes - that a listing may not
be required unless the fish tissue data are specific to the waterbody
being evaluated for listing. Draft Guidance at p. 53. We support that
principle. Since listing a waterbody as impaired can carry substantial
consequences, a listing should not happen unless the State has actual
data showing that that particular waterbody is impaired - extrapolation
from "similar" waterbodies is fraught with uncertainty, and violates
basic concepts of fairness and due process. We are concerned, though,
with EPA's statement (also on p. 53) that even though a listing is not
required based on data from other waterbodies, the State has the
discretion to issue such a listing anyway. This is tantamount to saying
that even if the data supporting a listing, for whatever reason, are not
adequate from a scientific perspective, the State can list the waterbody
anyway, "just to be safe." That concept has no support in the statute,
EPA's regulations, or basic principles of our legal structure. A
waterbody either is or is not impaired. Data from other waterbodies
cannot legally be used as the basis for a listing when there is no
specific evidence that the waterbody being evaluated is actually
impaired. EPA cannot give the States the discretion to take an action
that is not legally authorized.

4\. EPA Should Clarify How States Should Use Data Below Detection
Levels.

The guidance document should provide a more complete discussion of
acceptable options, including an expanded list of references, for the
treatment of nondetects in data analyses that are likely to be relevant
to the assessment and management of compliance with the methylmercury
water quality criterion.

Recent literature has emphasized the importance of proper treatment of
nondetects in the analysis of left-censored water quality data (see
Helsel 2005a[^12] and 2005b[^13], for example). Simple substitution of
nondetect values with some fraction of the analytical detection limit
(e.g. 0, ½, etc.) can bias data analysis results.[^14] EPA recognizes
this possibility in Section 4.3.1 of the Draft Guidance in the context
of determining attainment with the methylmercury water quality
criterion. The Draft Guidance says (at pp. 49-50) that methods other
than substitution may be used, and some specific alternatives are
presented by reference to a 2001 EPA study (EPA 2001[^15]).

We find the existing discussion of nondetects (Draft Guidance at pp.
49-50) to be very limited, however, and believe that it should be
expanded to include other method references and other relevant analyses
that may require careful consideration of nondetects. Fish tissue data
may contain relatively few nondetects; however, nondetects will be much
more common for methylmercury analyses made in receiving waters,
stormwaters, and wastewaters. In section 7, which addresses NPDES
implementation and reasonable potential calculations, the 1991 Technical
Support Document for Water Quality-based Toxics Control (EPA 1991[^16])
is the only reference given for guidance on calculation methods. This
document does not describe the range of readily available approaches
currently used to analyze environmental data. Proper treatment of
nondetects may also be important in determining site-specific
methylmercury BAFs used to translate fish tissue methylmercury
concentrations to water column methylmercury concentrations (see section
3.1.3.1) and to studies of the ratio of methylmercury to total mercury
in receiving waters and effluent used in determining waste loads (see
Appendix A). A more thorough discussion of sources and application of
methods for the analysis of left-censored data will help users of this
document avoid bias resulting from inappropriate treatment of
nondetects.

5\. The Guidance Should be Made Consistent in How Fish Tissue Levels
Should Be Determined.

The Draft Guidance is inconsistent in how it recommends determining the
level of methylmercury in fish tissue for a waterbody. On page 21, EPA
states that the geometric mean of methylmercury levels in tissue over
several trophic levels should be used for developing national BAFs[^17]
^2^ However, on page 45, EPA recommends using only Trophic Level 4 as a
"conservative" approach because more mercury has been bioaccumulated in
Level 4. Then, on page 51, EPA refers to using the geometric mean of a
single trophic level, Level 3. Consistent with Section B.1. of these
comments, we believe that fish tissue data should be assessed across
trophic levels, and that EPA should therefore recommend that States
calculate the geometric mean over several trophic levels instead of
using data from just one level.

C. PERMITTING ISSUES

1\. We Support Use of PMPs Instead of Numeric Limits.

It appears that under the permitting structure in the Draft Guidance,
the preferred mechanism for addressing point source discharges (where
action by those sources is warranted) is through implementation of
pollutant minimization programs (PMPs), rather than through stringent
water quality-based effluent limits (WQBELs) at part-per-trillion
levels. Draft Guidance at pp. 90, 94-96. We strongly support this
choice. As EPA recognizes, the loadings from most point source
discharges of mercury are very small, particularly in comparison to
loadings from other sources, and stringent WQBELs would accomplish
little or nothing to improve water quality. Moreover, any such limits
would be set at levels that are near the detection limits of the current
analytical methods, in a range where the analytical variability is
significant.[^18] Further, the ability of control methods to comply with
these limits on a consistent basis is questionable at best. In contrast,
implementation of PMPs allows the sources, and the regulating agencies,
to focus instead on taking real, practical steps to minimize these
mercury discharges, in an iterative process, without posing any
significant impacts to water quality or to mercury levels in fish
tissue.

2\. EPA Should Revise its Assumption that Every Detectable Mercury
Discharge Has "Reasonable Potential."

EPA recommends in the Draft Guidance that if a State chooses to directly
implement a fish tissue criterion, without translating it to a water
column level, the State could find that a discharge has "reasonable
potential," and therefore impose control requirements in that
discharger's permit, if the fish tissue in the relevant waterbody
exceeds the criterion and the discharger has quantifiable levels of
mercury in its effluent. Draft Guidance at p. 86. We strongly disagree
with this blanket assumption that if fish tissue levels exceed the
criterion, every single discharger of mercury (which likely means most
dischargers, since our experience has been that mercury is present in
quantifiable levels in most water discharges, if for no other reason
than that it is present in most intake waters) needs to be subjected to
control requirements in order for the waterbody to eventually attain the
criterion. EPA does not impose such a requirement for other pollutants.
Instead, State permitting authorities are given a significant amount of
discretion in determining whether sources are significant enough to
merit imposition of permit limits. The States should be given that same
discretion in implementing the mercury fish tissue criterion.

3\. The Guidance Should Clarify How States Decide if Sources Are
"Significant."

In § 7.5.2, EPA recommends establishing different types of WQBELs
depending on whether the discharge is a "significant" source of mercury.
Section 7.5.2.1 explains that for a discharge to be considered
"insignificant," the loading of the point source (or cumulative loading
of all point sources) to the receiving water are expected to account for
a small or negligible component of the current total mercury loadings
and that, upon implementation of the permit's mercury minimization
program requirements, any further reductions from the point source(s)
would result in no discernable improvement in water quality. Draft
Guidance at p. 93.

We believe EPA should specify a more precise criterion for
"insignificant." We suggest that if an individual discharger is
responsible for less than 1% of the mercury loading to the waterbody,
once credits for mercury in the intake water are counted, then it should
be considered "insignificant."

We disagree with the suggestion that if the "cumulative" loading of all
point sources is significant, then each and every one of the point
sources is itself significant. There may be cases in which nine
dischargers to a waterbody contribute 99% of the "significant"
contribution. If a tenth discharger contributes only 1%, it should not
be considered "significant." This situation underscores the need for EPA
to work with stakeholders to define a reasonable approach, which
distinguishes those sources needing more active management (and likely
reductions) from those sources for whom that type of approach is not
needed or not appropriate.

4\. EPA Should Not Impose a Blanket Requirement for "Status Quo" Permit
Limits Based on Current Discharge Levels.

For insignificant sources of mercury (and for significant sources that
do not "use" mercury or accept wastewaters containing mercury), EPA
provides that in addition to PMP requirements, the States should also
impose a numeric mass limit at existing effluent quality (or an existing
limit, if more stringent). Draft Guidance at pp. 94, 96. We have several
concerns about this "existing effluent quality cap." First, we do not
see how this requirement can be justified under section 301(b)(1)(C) of
the CWA, which requires limitations "as necessary to attain water
quality standards." If these sources are not significant, then it is not
necessary to cap them at their existing levels in order to attain
standards; they could be allowed to increase by some amount without
endangering standards attainment in any way. In addition, we are
concerned that this "cap" would impose a severe burden on those
facilities that seek to expand their discharges to accommodate economic
growth or needed operational changes in order to survive in today's
marketplace. Since all wastewaters contain some level of mercury, any
increase in discharge flow will increase the mass discharge of mercury.
Since the "cap" would prohibit such increases, it would prevent those
dischargers from making the needed changes, even though these
dischargers are insignificant and the increases in their discharges
would make no appreciable difference in water quality. EPA needs to
provide flexibility in the requirements so as to accommodate these small
increases.[^19]

5\. EPA Should Clarify the Requirements for Source that "Use" Mercury.

For significant dischargers that "use" mercury in their processes, EPA
prescribes stringent control requirements, including numeric water
quality-based mass loading limits. Draft Guidance at p. 96. However, it
is not clear that the term "use" means in this context. Since many raw
materials for industrial processes contain small amounts of mercury, an
interpretation of "use" that covers these miniscule mercury levels in
raw materials would subject many dischargers to those stringent WQBELs,
even though they never intentionally purchase mercury, and even though
mercury plays no deliberate role in manufacture of their products. To
prevent this result, EPA should clarify that to "use" mercury in this
context means to "intentionally use mercury as an additive or processing
aid or intentionally use a process additive that contains mercury as an
active ingredient. 'Use' does not mean to use a processing aid or
additive that contains mercury as a contaminant."

6\. EPA Should Clarify the Requirements for Sources that Accept
Wastewaters Containing Mercury.

EPA also requires stringent WQBELs for significant dischargers that
accept wastewaters containing mercury. Draft Guidance at p 96. As with
the "use" of mercury, we are unclear what EPA means by this "accept"
term. This is a particular concern for municipal sewage treatment plants
(publicly owned treatment works, or POTWs), since given the ubiquity of
mercury in the environment, all wastestreams sent to POTWs, including
from residences, will contain some level of mercury. A literal
application of EPA's "accept wastewaters containing mercury" category
would mean that all POTWs would fall into that category. That result
simply makes no sense; it would subject municipal discharges to onerous
treatment requirements simply for accepting the wastewaters that they
are designed and built to accept. It would make more sense to apply
these requirements only to POTWs (and other facilities) that accept
wastewaters from sources that "use" mercury -- as "use" is defined in
Section C.6. of these comments.[^20]

7\. EPA Needs to Provide Appropriate Flexibility for Permitting of New
and Increased Discharges Containing Low Mercury Levels.

The Draft Guidance is vague as to the conditions under which States can
issue permits allowing increased or new discharges of mercury. For
example, the draft states that new sources and new dischargers with
quantifiable mercury levels must meet the requirements of 40 CFR
122.4(i) and antidegradation policy, but there is no explanation of what
that means, other than that one possible way to meet these tests may be
to demonstrate that other source reductions will offset the new or
increased discharge. Draft Guidance at p. 99. At another place in the
document (p. 102), EPA states that where fish tissue data exceed the
criterion, these sources would be subject to limits based on a TMDL, a
"TMDL-like analysis," or an offset. Given that virtually all of these
sources will be extremely small contributors of mercury loadings (and,
in many cases, contributing no more than was already present in their
supply water), we do not believe that these new or increased discharges
should be subject to extremely stringent limits, and certainly should
not be prohibited altogether simply because there is not another source
nearby from which one can obtain an offsetting reduction. Keeping in
mind that the primary focus should be attainment of standards, EPA
should enunciate a flexible policy that allows these discharges, subject
to reasonable control requirements, as long as issuing those permits
does not have a significant impact on standards attainment. For example,
one can readily envision a situation in which a discharger seeks a small
increase, or a new discharge that has low mercury levels, while that
same watershed will, over the next few years, experience much larger
reductions in mercury levels due to controls on other sources, including
national emission control requirements for air sources. In such a
situation, the watershed will continue making progress toward the
standard, and the small source should be allowed to discharge, within
reasonable limits.

8\. The Guidance Should Not Require Mercury Monitoring for All Sources.

The Draft Guidance requires that all dischargers perform some amount of
effluent monitoring for mercury, even if the fish tissue levels in the
waterbody are below the criterion and even if the mercury levels in that
effluent are not significant. Draft Guidance at pp. 86-88, 94-96. We do
not believe that this broad requirement is necessary or appropriate.
Monitoring for mercury using Method 1631 (and "clean hands" sample
collection techniques) is expensive and time-consuming. Moreover,
collection of data from every source, no matter how small, cannot help
but divert resources and attention from those sources that truly need to
be controlled in order for water quality to attain standards. For every
other pollutant, EPA has allowed State permitting agencies to exercise
some discretion in determining when effluent monitoring for particular
pollutants is necessary, based on factors such as the amount of the
discharge flow, the nature of the discharging facility, and the
characteristics of the receiving waterbody. States should have that same
discretion in making permitting decisions for sources of mercury.

9\. The Guidance Should Not Require Dischargers to Perform Fish Tissue
Surveys.

In situations where the fish tissue levels in a waterbody are not yet
known, EPA recommends that States require dischargers to conduct fish
tissue surveys. Draft Guidance at p. 89. We are concerned that
imposition of such a requirement is inappropriate, because it imposes an
obligation on regulated parties to do the work of the agencies. In
short, this requirement shifts the responsibility for conducting 305(b)
assessments from the regulatory agency to the regulated community. It is
certainly true that in some cases, dischargers may choose to cooperate
with agencies to collect fish tissue data, especially since it may be in
their interest to do so. However, that should not be required. Moreover,
it is not clear that States, or even EPA under Section 308, would have
legal authority to impose such a requirement. It is one thing to require
dischargers to submit information that has already been generated; it is
quite another to require them to go out in the field and affirmatively
generate new information. We would suggest that instead of imposing this
mandate, EPA instead encourage States to work with their stakeholders in
cooperative ventures to determine fish tissue levels in their
waterbodies.

10\. We Support Allowing States to Provide Intake Credits, but EPA
Should Allow Additional Flexibility in that Provision.

In the Draft Guidance, EPA indicates that States can use the "intake
credit" mechanism to address discharges whose mercury levels are due
totally or primarily to the mercury present in their intake water. Draft
Guidance at p. 103. We strongly support EPA's validation of this
important regulatory tool. As EPA is aware, many industrial facilities
use large amounts of water for cooling purposes. In addition, many
facilities take in large flows for use in their processes and
operations. These flows will inevitably contain small concentrations of
mercury, due to mercury's ubiquity in the environment. To impose permit
limits that require the dischargers to treat and remove those mercury
levels would be onerous, unfair, and legally unauthorized, given the
focus of CWA Section 402 on "addition" of pollutants, which is not
taking place in this situation. We also support EPA's explanation that
intake credits would be available in cases where the cooling process
results in small increases in concentration in the discharge, due to
evaporation and/or water loss. That increase, after all, does not
reflect any change in the mass loading of mercury. EPA should, however,
provide additional flexibility in the intake credits provisions of the
Draft Guidance, in at least one particular respect: to the extent that
dischargers are required to qualify for use of the credits provision by
periodic measurements of influents and effluents, we are concerned that
analytical variability could lead to a source losing its credits even
though it is not actually adding any pollutants to the effluent loading.
EPA needs to inform the States that in these circumstances, analytical
variability must be taken into account. Also, EPA should allow for other
ways for dischargers to show that they are not "adding" pollutants from
their operations, so that their State agencies can continue using the
credits provision in determining appropriate permit requirements.[^21]

11\. EPA Should Not Encourage States to Require Antidegradation Review
for Every Increased Mercury Discharge.

In addressing the application of antidegradation requirements to
increased discharges, EPA encourages States to regard any increase in
mercury used in a discharger's process or in wastewater accepted by the
discharger as a "significant lowering of water quality," requiring a
Tier 2 antidegradation review before the increase can be allowed. Draft
Guidance at p. 101. We have several concerns about this recommendation.
First, it infringes on an area that EPA has always left to State
discretion: the details of how they implement their antidegradation
policies. EPA has always made it clear that States are free to use
"trigger levels," which provide that increases below those levels are
insignificant and do not merit use of the antidegradation review
process. The only part of the Federal rules that applies a different
concept is the Great Lakes Initiative (GLI), which does not provide a
trigger level for mercury or other bioaccumulative compounds. However,
the GLI rules were issued under Section 118 of the CWA, which gives the
Agency additional authority that it does not otherwise possess.
Everywhere else, States are free to use trigger levels in their
antidegradation programs, and this concept should continue to apply to
mercury.

12\. We Support EPA's Encouraging States to Adopt Multiple-Discharger
Variances.

EPA encourages the States to consider using multiple-discharger
variances when a group of dischargers are in the same area or watershed
and the circumstances for issuing variances are the same. Draft Guidance
at p. 34. We support that recommendation. FWQC members have been very
involved in the development of these variances in several States,
including Ohio, Indiana, Michigan and Wisconsin. We believe that this is
a highly efficient and cost-effective way to address compliance problems
that affect large numbers of dischargers, while ensuring that progress
continues to be made toward eventual attainment of the standards.

[CONCLUSION]{.underline}

As stated earlier, the Coalition appreciates the opportunity to submit
these comments. We support many key elements of the Draft Guidance, and
we believe that with the changes suggested here, final guidance can be
issued that would be extremely helpful to the state agencies that issue
permits, develop TMDLs and take other actions related to mercury under
the CWA, as well as to the stakeholders that are affected by those
actions. We look forward to continuing to work with the Agency as it
finalizes this guidance and takes other mercury-related actions under
its CWA authorities. Please feel free to contact us if you have any
questions regarding the issues discussed in these comments.

Sincerely,

Fredric P. Andes

Coordinator

[^1]: EPA has not yet promulgated an approved analytical method for the
    measurement of methylmercury in water. There are two published
    methods: U.S. EPA Method 1630 and USGS Method OFR 01-445. EPA should
    move forward with the studies that are needed in order for Method
    1630 to be considered for approval under 40 CFR 136.

[^2]: Section 3.1.2.1, fifth bullet.

[^3]: Schaefer, J.K., Yagi, J., Reinfelder, J.R., Cardona, T.,
    Ellickson, K.M., Tel-Or, S., Barkay, T. 2004. Role of the bacterial
    organomercury lyase (MerB) in controlling methylmercury accumulation
    in mercury-contaminated natural waters. *Environ. Sci. Technol.*
    38(16): 4304-4311.

[^4]: Jackson, T.A., 1986. Methyl mercury levels in a polluted prairie
    river-lake system: seasonal and site-specific variations, and the
    dominant influence of trophic conditions. *Can. J. Fish. Aquat.
    Sci.* 43: 1873-1887.

[^5]: Hammerschmidt, C.R. and Fitzgerald, W.F. 2004. Geochemical
    controls on the production and distribution of methylmercury in
    near-shore marine sediments. *Environ. Sci. Technol.* 38(5):
    1487-1495.

[^6]: Lambertsson, L. and Nilsson, M. 2006. Organic material: the
    primary control on mercury methylation and ambient methyl mercury
    concentrations in estuarine sediments. *Environ. Sci. Technol.*
    40(6): 1822-1829.

[^7]: Fleming, E.J., Mack, E.E., Green, P.G. and Nelson, D.C. (2006).
    Methylation from Unexpected Sources: Molybdate-Inhibited Freshwater
    Sediments and Iron-Reducing Bacterium. Appl. Environ. Microbiol.
    Mercury 72(1): 457-464.

[^8]: see <http://www.biology.ualberta.ca/metaalicus/metaalicus.htm>.

[^9]: Brumbaugh, W.G., D.P. Krabbenhoft, D.R, Helsel, J.G. Wiener, and
    K. R. Echols. 2001. A National Pilot Study of Mercury Contamination
    of Aquatic Ecosystems Along Multiple Gradients: Bioaccumulation in
    Fish. Biological Science Report USGS/BRD/BSR-2001-009. U.S.
    Geological Survey, Columbus, Missouri. Accessible at
    http://www.cerc.usgs.gov/pubs/center/pdfDocs/BSR2001-0009.pdf

[^10]: As described in the October 24, 2000 guidance memo (referenced as
    USEPA 2000g) and discussed in Section 4.3.4 of the draft guidance.

[^11]: There are other concerns with States using fish consumption
    advisories as the basis for impairment listings, such as, for
    example, the lack of public notice and an opportunity to comment on
    potential advisories.

[^12]: Helsel, D.R. 2005a. Nondetects and data analysis: statistics for
    censored environmental data. John Wiley & Sons, Inc. 250 pp.

[^13]: Helsel, D.R. 2005b. More than obvious: better methods for
    interpreting nondetect data. Environ. Sci. Technol. 39: 419A-423A.

[^14]: Therefore, if this method is used, the fraction of the analytical
    detection limit substituted should be dependent on the distribution
    characteristics of the data and the assumptions on which the
    detection limit is based. Currie, L.A. Applied Radiation and
    Isotopes 61 (2004) 145-149.

[^15]: USEPA (U.S. Environmental Protection Agency). 2001. Robust
    Estimation of Mean and Variance Using Environmental Data Sets with
    Below Detection Limit Observations. U.S. Environmental Protection
    Agency, Office of Research and Development, Las Vegas, NV.

[^16]: USEPA (U.S. Environmental Protection Agency). 1991. Technical
    Support Document for Water Quality-based Toxics Control. EPA
    505/2-90-001. U.S. Environmental Protection Agency, Office of Water
    Enforcement and Permits and Office of Water Regulations and
    Standards.

[^17]: ^.14^ Page 21 of the draft guidance says that "EPA believes the
    geometric mean BAFs are the best available central tendency
    estimates of the magnitude of BAFs nationally, understanding that
    the environmental and biological conditions of the waters of the
    United States are highly variable."

[^18]: Because of these analytical challenges, EPA's focus should
    properly be on whether mercury levels can be reliably quantified,
    rather than whether they are detected. Accordingly, EPA should
    clarify that only effluents with "quantifiable" levels of mercury
    (i.e., levels that can be reliably quantified) should be subject to
    monitoring requirements, minimization requirements, or numeric
    limits.

[^19]: In addition, EPA should clarify that any "status quo" limits that
    are imposed should take into account normal variations in effluent
    loading, based on a valid statistical analysis.

[^20]: It may be that the source that "uses" mercury is subject to
    pretreatment standards that address the issue. In that case, the
    POTW should not necessarily be subject to additional requirements.

[^21]: In addition, EPA should provide additional flexibility in its
    policy regarding adjustment of "intake credits" to reflect removal
    of intake pollutants in the facility's water treatment systems.
    Pollutant levels that were present in intake water should not be
    required to be removed. To the extent that removal of intake
    pollutants is considered in establishing effluent limits, the
    permitting agency should carefully consider the feasibility of
    establishing these limits, given that this removal may be highly
    variable and difficult to measure. These concepts are reflected in
    the "intake credits" provisions of the Agency's Great Lakes
    Initiative rule, at 40 CFR 132, Appendix F, Procedure 5..E.3.b.