Technical Support Document for Conducting and Reviewing ... - Water

2. To assist EPA staff in reviewing state and tribal water quality standards (WQS)
submissions that contain site-specific criteria for ammonia (either from Appendix N of
the 2013 national ammonia criteria recommendations, or derived using EPA’s
Recalculation Procedure) and a demonstration that mussels are absent (i.e., do not occur)
at the site. 3
Development of this Document
In developing this document, EPA undertook several efforts to collect information on existing
mussel survey techniques, sampling methods, and data sources. EPA received information from
mussel experts in academia, industry, and government; state natural heritage programs; state fish
and game agencies, environmental protection agencies; and natural resource and conservation
agencies. Combined with a literature review, the information EPA received formed the basis for
the background and general content and scope of a draft Technical Support Document for
Conducting and Reviewing Freshwater Mussel Occurrence Surveys for the Development of Sitespecific
Water Quality Criteria for Ammonia. The draft technical support document (TSD) was
then sent to five independent external expert peer reviewers who were charged with answering
specific questions concerning the content, scope, completeness, and adequacy of this TSD. EPA
then revised the TSD to reflect the recommendations of the peer reviewers.
Information presented in this document neither represents an exhaustive list of available
techniques, sampling methods, and approaches for conducting mussel surveys nor recommends
an approach that states and tribes must undertake to make mussel presence/absence
determinations in support of site-specific criteria development for ammonia. Instead, this
document represents the information EPA compiled during its information collection efforts, and
the brief overview provided in this document is for informational purposes only. EPA is not
endorsing or directing states or tribes to use any particular method or approach, as states and
tribes choosing to utilize the Recalculation Procedure for ammonia have the flexibility to elect
any method they deem appropriate to demonstrate that mussels are absent on a site-specific basis
as long as the chosen method is scientifically defensible. However, based on information
acquired during the development of this document and the subsequent peer review, EPA believes
that much of the information provided below under “General Approach to Mussel
Presence/Absence Determinations” represent the key elements upon which states and tribes may
base an approach to support a scientifically-defensible rationale for their decision-making
processes. Consequently, EPA anticipates that approval of site-specific criteria may rely on the
inclusion of some or all of these key elements (or similar fact-finding information) in order to
provide the most transparent, high quality, and scientifically-defensible rationale for a decision
that aligns with the goals of the CWA.
3 Although this document is primarily intended to assist state and tribal water quality regulators with developing and
EPA staff with reviewing site-specific criteria for ammonia, EPA is fully aware that other parties may be interested
in pursuing site-specific water quality criteria development for ammonia and may also use the information in this
document to justify those decisions and situations where site-specific criteria might be appropriate. However, EPA
only considers the information submitted by the state or tribe when reviewing adopted state water quality criteria.
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