United States
Environmental Protection
 Office of Water
EPA 820-F-16-006
     June 2016
Proposed Aquatic Life and  Aquatic-
Dependent  Wildlife  Criteria  for
Selenium  in California's  San  Francisco
Bay  and  Delta
EPA is proposing to revise the current federal Clean
Water Act (CWA) selenium water quality criteria
applicable to the salt and estuarine waters of the
San Francisco Bay and Delta to ensure that the
criteria are set at levels that protect aquatic life and
aquatic-dependent wildlife, including federally listed
threatened and endangered species.
CWA section 101(a)(2) establishes the national goal
that wherever attainable water quality should
provide for the protection and propagation offish,
shellfish, and  wildlife, and recreation in and on the
water. To protect aquatic communities from the
harmful effects of pollutants in surface waters,
states must adopt water quality criteria for
pollutants that are protective of such designated
uses in water bodies. EPA periodically publishes
national criteria recommendations for certain
pollutants under CWA section 304(a) for states to
consider using to protect aquatic life uses.
EPA promulgated the San Francisco Bay and Delta's
existing selenium criteria on the state's behalf in
1992 as part of the  National Toxics Rule (NTR), using
EPA's CWA section 304(a) recommended aquatic life
criteria for selenium at the time. However, the latest
science on selenium fate and bioaccumulation
                          indicates that the existing criteria are not protective
                          of aquatic life and aquatic-dependent wildlife in the
                          salt and estuarine waters of the San Francisco Bay
                          and Delta.
                          EPA determined that new or revised selenium
                          criteria in the salt and estuarine waters of the San
                          Francisco Bay and Delta are necessary to protect the
                          designated uses for these waters. Therefore, to
                          protect aquatic life and aquatic-dependent wildlife
                          in the San Francisco Bay and Delta from  the adverse
                          effects of selenium, EPA is proposing the criteria in
                          this rule using the best available science.

                          How EPA Derived the Proposed Selenium
                          Aquatic Life and Aquatic-Dependent Wildlife
                          In 2016, EPA published revised CWA section 304(a)
                          recommended criteria for selenium, based on the
                          latest science on selenium bioaccumulation and
                          toxicity (Final Aquatic Life Ambient Water Quality
                          Criterion for Selenium - Freshwater 2016, US EPA,
                          Office of Water, EPA 822-R-16-006). EPA considered
                          the methodology and information used to derive the
                          revised CWA section 304(a) recommended selenium
                          criterion, along with additional information specific
                          to the San Francisco Bay and Delta, in developing the
                          selenium criteria in this proposed rule.

Due to the introduction and population explosion of
an invasive clam species, Potamocorbula amurensis
(commonly known as Corbula), there has been a
rapid acceleration of selenium accumulation in the
food chain of fish and bird species in the San
Francisco Bay and Delta ecosystem. The species
most at risk in the estuary from selenium are clam-
eating fish and clam-eating bird species, and EPA is
proposing revised federal criteria to ensure
protection of these vulnerable species.
EPA is proposing selenium criteria in fish tissue (a
whole body criterion of 8.5 micrograms per gram
(u.g/g) dry weight (dw) and a muscle criterion of  11.3
u.g/g dw) and clam tissue (15 u.g/g dw), to reflect
biological uptake through diet, the predominant
pathway for selenium toxicity, and to address
reproductive toxicity. In order to facilitate
monitoring and regulation of pollutant discharges,
EPA is also proposing dissolved and particulate water
column selenium criteria of 0.2 u.g/L and 1 u.g/g,
respectively, that are designed to ensure the tissue
criteria are met.

Public Hearings on the Proposed Rule
EPA will hold public hearings on the proposed rule so
that interested parties may provide oral comments.
A virtual hearing will be on August  22, 2016 from
6:00 pm to 8:00 pm. The in-person hearings will  be
on August 23, 2016, one at 9:00 am and one at 2:00
pm, at  EPA's Region 9 Office: 75 Hawthorne Street,
San Francisco, CA 94105.

Where can I find more information?
Contact Erica Fleisig at (202) 566-1057,
Fleisig.Erica@EPA.gov or Diane Fleck at (415) 972-
3527, Fleck.Diane@EPA.gov. To access the proposed
rule, supporting documents, and more details on
how to make written comments and/or how to
register to make oral comments at a public hearing,
visit EPA's Water Quality Standards website at: