Sharon Thomas \<SThomas@wef.org\>

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WEF Comments to Docket ID No. EPA-HQ-OW-2006-0656

WEF submits the attached comments to Docket ID No.
EPA--HQ--OW--2006--0656 on

the Draft Guidance for Implementing the January 2001 Methylmercury Water

Quality Criterion. If you have questions or can not open the attachment,

please contact Sharon Thomas at 703-684-2423 or sthomas@wef.org.

PS -- Thanks, Kellie!

![](media/image1.jpeg){width="1.0416666666666666e-2in"
height="1.0416666666666666e-2in"}

October 27, 2006

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

Water Docket

Environmental Protection Agency

Mailcode 4101T

1200 Pennsylvania Ave., NW

Washington, DC 20460

**RE: Notice of Draft Guidance for Implementing the January 2001**

**Methylmercury Water Quality Criterion**

The Water Environment Federation ("WEF") submits the following comments
on the above mentioned draft guidance published in the Federal Register
on August 9, 2006. Founded in 1928, the Water Environment Federation is
a not-for-profit technical and educational organization with members
from varied disciplines who work toward the WEF vision of preservation
and enhancement of the global water environment. The WEF network
includes water quality professionals from 76 member associations in 30
countries.

WEF supports the Environmental Protection Agency's (EPA) approach of
basing the water quality criterion for methylmercury on concentrations
found in fish and shellfish tissue rather than in the water column and
the overall intent of the draft guidance to assist states and tribes in
developing and implementing the January 2001 criterion. EPA is to be
commended for taking the initiative to publish a new type of criterion
and drafting guidance for public comment on its implementation. WEF
encourages EPA to allow for flexibility in the approach states and
tribes take to developing and implementing criteria in their permits and
to emphasize the use of robust data when developing criteria for a
waterbody.

**[Adaptive Management]{.underline}**

WEF has consistently stated in comments on issues related to water
quality (such as translating standards and criteria into permit limits)
that EPA should give flexibility to states and watershed stakeholders to
craft appropriate water quality goals, TMDLs, and implementation plans
that are watershed specific. This flexibility should allow for the
application of adaptive management approaches. WEF strongly supports
EPA's statement in the draft guidance that reinforces the importance of
adaptive implementation in improving water quality through the TMDL
program (page 80):

> EPA recommends that states and authorized tribes periodically review
> TMDLs during implementation to ensure that progress is being made
> toward achieving water quality standards. Such "adaptive
> implementation" provides the flexibility to refine and improve a TMDL
> as data is collected on the success of implementation activities.
> States may refine information on the contributions from sources, such
> as runoff from abandoned mining sites, sediment loading of
> mercury-laden sediments, or air deposition as data and modeling tools
> improve. Thus, states should consider the application of adaptive
> implementation in determining load allocations for these sources.
> Post-TMDL monitoring is an important tool for evaluating
> implementation success and, if necessary, making refinements in the
> TMDL.

**[Permitting Issues]{.underline}**

There is a need for clarification regarding the definition of sources
that "accept" wastewater containing mercury, specifically regarding
Publicly Owned Treatment Works (POTWs). In the draft guidance, EPA
suggests that, "for significant dischargers that use mercury in their
processes or accept wastewater containing mercury," stringent control
measures be imposed as permit conditions including numeric water
quality-based effluent limitations (WQBEL) for mass loading of mercury
(page 96). Even POTWs that accept only domestic wastewater from
residences will be receiving low levels of mercury because of its
ubiquitous nature. Consequently, all POTWs are likely to be included in
this category and potentially face the imposition of a burdensome
requirement. The application of these stringent permit provisions should
be limited to those POTWs that accept wastewater from sources that use
mercury as an additive or processing aid or use process additives that
contain mercury as an active ingredient. POTWs which receive low but
detectable levels of mercury from atmospheric and domestic sources
should not receive such WQBELS.

In the guidance, EPA puts forth the assumption that if fish tissue
concentrations are above the criterion, all sources with detectable
mercury levels in their discharge have "reasonable potential" to exceed
and must receive permit requirements. WEF does not think this is the
most rational approach to identifying which permittees need numeric
mercury limits. WEF is concerned about including all sources with
detectable mercury levels in the discharge. EPA recommends the use of
Method 1631, "to characterize the discharger's effluent for mercury from
all facilities for which the mercury levels are unknown and undetected"
(page 86). Experience with Method 1631 indicates that every discharge
will have detectable levels of mercury using this method. This means
that every discharger, regardless of how insignificant, will be
determined to have reasonable potential if discharging to a waterbody
with fish tissue levels exceeding the mercury criterion. This approach
is excessively restrictive, since state permitting authorities generally
have substantial discretion to determine whether discharges are
sufficiently significant to require permit limits. The requirement for
reasonable potential should be based on a reasonable definition of a
significant source of mercury to the waterbody.

EPA's recommended permit condition of a "numeric effluent limit for mass
loading of mercury established at the existing effluent level" for
"discharges that are not significant sources of mercury" (page 94) or
for "significant dischargers that do not use mercury and do not accept
wastewater containing mercury" (page 96) also concerns WEF. This mass
loading limitation would impose a burden on dischargers of
"background/domestic" loads of mercury that seek to expand their
discharges, since any increased discharge would invariably result in an
increase in mercury mass loading because it is ubiquitous. This would
specifically impact POTWs that experience an increase in throughput rate
as it expands to serve an increased population or works to reduce
overflows resulting in more treatment of wet weather flows. EPA needs to
insure that the final guidance explicitly provides reasonable
flexibility to allow some increased mercury loading in cases where it
will not have a significant impact on receiving water quality.

In the guidance, EPA encourages states to regard any increase in mercury
discharge as a "significant lowering of water quality" that triggers an
antidegradation review. Figure 8, "Procedures for addressing new sources
and new discharges" (page 100) shows that even if the fish tissue in the
receiving water does not exceed the mercury criterion, EPA expects that
a numeric limit would be imposed based on antidegradation requirements
for new sources and new dischargers. EPA should not require an
antidegradation review for every increased mercury discharge. This
decision should be left to the states and be based on their
antidegradation policies, which may include a de minis level below which
the increase is not considered sufficient to warrant use of the
antidegradation review process. Such flexibility is also needed because
of the inherent variability in low level mercury measurements using
Method 1631. The final guidance should make it clear that the data needs
to show a real increase rather than a "false" increase that is driven by
the inherent analytical variability.

**[Listing of Impaired Waters]{.underline}**

WEF supports the general policy that listing a waterbody as impaired
based on a fish or shellfish advisory is not required unless there are
data specific to that waterbody. As described in EPA (2003) *Guidance
for 2004 Assessment, Listing and Reporting Requirements Pursuant to
Sections 303(d) and 305(b) of the Clean Water Act*, the specific
criteria for determining impairment based upon tissue data include:

-   The advisory is based on fish and shellfish tissue data;

-   a classification below "Approved" (under the National Shellfish
    Sanitation Program) is based on water column and/or shellfish data;

-   the data are collected from the specific segment in question; and

-   the risk assessment parameters (e.g., toxicity, risk level, exposure
    duration, and consumption rate) of the advisory or classification
    are cumulatively equal to or less protective than those in the
    state's water quality standards.

It is important to note that the cited guidance does not require water
bodies with a fish consumption advisory to be listed unless there are
water body-specific data. Thus, statewide warnings regarding
mercury-contaminated fish based upon a subset of waterbodies do not mean
that all the state's waterbodies belong on the 303(d) list.

The Draft Implementation Guidance includes the statement that 303(d)
listings should include, "at a minimum, those waters where
waterbody-specific data that was the basis of a fish or shellfish
consumption advisory demonstrates nonattainment of water quality
standards." This implies that states have the discretion to list
waterbodies in the absence of specific data, using various monitoring
and modeling tools to support extrapolations from a relatively small set
of data. Given the wide variation in the biotic and abiotic factors
affecting mercury methylation and methylmercury bioaccumulation, it is
highly likely that such extrapolations will not be accurate. Most states
encompass a diversity of aquatic ecosystems such that statewide fish
advisories should not be the basis of 303(d) listing decisions for the
various waterbodies across the state. This should be made clear in the
draft implementation guidance.

**[Need for More Research]{.underline}**

The relationship between total mercury in effluents and methylmercury in
fish is still not clearly understood; therefore, it is not yet possible
to conclude that tissue levels will respond in a predictable manner to
reductions in mercury loadings. Sufficient uncertainty exists
surrounding the use of any of the approaches (national default
bioaccumulation factors (BAFs), bioaccumulation models, or site-specific
BAFs) that it is likely that permit limits derived from the fish-tissue
based criterion will be inconsistent within and among states and may not
achieve the desired reductions in fish tissue concentrations. WEF
recommends that EPA continue to update its guidance as more research and
information related to the relationship between mercury in effluent and
methylmercury in fish becomes available, and to facilitate information
sharing between states on how they are implementing the criterion.

The significance of a particular total mercury concentration in water,
and by extrapolation in an effluent, is highly uncertain. The major
challenge in developing methods for implementing the 2001 methylmercury
water quality criterion is the enormous variability in the site-specific
potential for mercury methylation and bioaccumulation. Among the
important factors that contribute to the variability in mercury
bioavailability and bioaccumulation are pH, dissolved organic carbon
(DOC), salinity, water flow (i.e., streams versus lakes, lake flushing
rate), temperature, redox potential, sulfide and sulfate, suspended
solids, nutrient loading, fish age and size, prevalence of wetlands and
forested land cover in the watershed, and concentration-dependent
demethylation. In addition, the distribution of fish-tissue mercury
concentrations within fish communities is affected by species, length
(or other measures of fish size or age), and portion of fish (whole
fish, fillet, etc.). These factors interact in numerous complex ways.
For example, the presence of sulfide inhibits methylation by reducing
mercury bioavailability, but the presence of sulfate stimulates
methylation by stimulating bacterial activity. Results from the
METALLICUS project indicate that mercury newly added to a lake system is
more rapidly methylated than in-situ mercury; however, over time this
added mercury appears to become less bioavailable for methylation.[^1]

**[Use of Approved Analytical Methods]{.underline}**

In the draft guidance, EPA states on page 42 that, "EPA believes that
the most appropriate methods for measuring compliance with the new or
revised methylmercury criteria are Method 1631 (mercury in water by cold
vapor atomic fluorescence spectrometry (CVAFS))." Based on this
assessment, EPA consistently recommends Method 1631 throughout the
document for all effluent and receiving water samples, giving the strong
impression that Method 1631 is the only valid or acceptable analytical
method, when in fact there are viable and less costly alternatives. WEF
agrees that low level clean/ultraclean methods of mercury analysis
should be used for water samples and that Method 1631 is an option;
however, the guidance should not appear to preclude other approved
methodologies when used with appropriate precautions and Quality Control
(QC).

Method 1631 is a difficult and costly analysis. One alternative is EPA
Method 245.7 (Mercury in Water by Cold Vapor Atomic Fluorescence) which
EPA proposed for approval in April of 2004 and presumably will be
formally approved in the near future. The validation testing of this
method has been completed and has been supported by the National
Association of Clean Water Agencies (NACWA) and others as an appropriate
and much less costly method than 1631. Detection levels for Method 245.7
are comparable to Method 1631, and once formally approved, Method 245.7
should be available to permittees, particularly for effluent samples.

Another EPA method (245.2) has been in use for decades (245.2 is an
automated version of 245.1). Improvement in technology in the past
several years has allowed the use of this \"old" method to attain
remarkably low detection levels. For example, using the Cetac Quick
Trace M7500 mercury cold vapor AA, the Boise City analytical laboratory
is generating mercury data with a detection level for effluent and
ambient water of 0.002 ug/L for low level samples. The lab has complied
with Discharge Monitoring Report -- Quality Assurance (DMR-QA) blind
performance samples and is generating quality data for much less cost to
the City than EPA Method 1631. Using EPA Method 245.2 allows the
laboratory to avoid many of the analytical problems with Method 1631,
such as the need for blank correction, the inability to treat standards
the same as samples, water vapor being a positive interference, and the
need to use the whole sample which prevents re-analysis of a sample.

WEF recommends that EPA make it clear in the draft guidance that EPA- or
state-approved analytical methods other than 1631 are appropriate and
can be used as long as they provide valid, reliable data with levels of
detection and quantitation that are below the levels of regulatory
concern.

If you have any questions or would like to discuss these issues further,
please contact Sharon Thomas, Senior Manager of Regulatory Affairs, at
703-684-2423. WEF appreciates your consideration of these comments and
looks forward to the opportunity to provide additional feedback.

Sincerely,

![](media/image3.png)

Tim Williams

Managing Director, Government Affairs

[^1]: Hintelman, H., R. Harris, A. Heyes, J.P. Hurley, C.A. Kelley, D.P.
    Krabbenhoft, S. Lindberg, J.W.M. Rudd, K.J. Scott, and V.L. St.
    Louis, 2002. Reactivity and mobility of new and old mercury
    deposition in a boreal forest ecosystem during the first year of the
    METAALICUS study. Environ. Sci. Technol. 36:5034-5040.