£%	United States
Environmental Protection
\r hI #* Agency
Office of Water
EPA 823-F-18-003
December 2018
Proposed Aquatic Life and Aquatic-
Dependent Wildlife Selenium Criterion
for California Fresh Waters
Summary
The Environmental Protection Agency (EPA) is
proposing to establish a federal Clean Water Act
(CWA) selenium water quality criterion for California
fresh waters that protects aquatic life and aquatic-
dependent wildlife. Elevated selenium levels can
contribute to the decline of fish and aquatic-
dependent birds, with the most severe toxic effects
being reproductive impairments.
Background
To protect aquatic communities from the harmful
effects of pollutants in surface waters, states must
establish criteria for their waters that are designated
for such uses. The EPA periodically publishes criteria
recommendations under CWA section 304(a) for
states to consider.
The EPA promulgated the State's existing selenium
criteria for certain waters on the State's behalf in
1992 as part of the National Toxics Rule (NTR), and
again in 2000 as part of the California Toxics Rule
(CTR) based on available science. In 2016, the EPA
published a revised recommended aquatic life
selenium criterion for freshwater based on the latest
scientific knowledge (see the EPA's Final Aquatic Life
Ambient Water Quality Criteria for Selenium -
Freshwater 2016 at:
https://www.epa.gov/wqc/aquatic-life-criterion-
selenium-documents).
In 2013, the Our Children's Earth Foundation and
Ecological Rights Foundation ("plaintiffs") sued the
EPA alleging in part that the EPA had failed to
establish selenium criteria in the CTR consistent with
the requirements of the CWA. In August 2014, the
EPA entered into a consent decree with the plaintiffs
that required the EPA to propose selenium criteria
for California fresh waters covered by the CTR to
protect aquatic life and aquatic-dependent wildlife
by November 30, 2018.
Overview of the proposed selenium
criterion
The EPA is proposing a chronic criterion for
California based on the EPA's current CWA 304(a)
recommended criterion for selenium. The proposed
selenium water quality criterion is comprised of
criterion elements offish tissue, bird tissue, and a
performance-based approach for translating the bird
and fish tissue elements into site-specific water
column elements.
The EPA is proposing selenium fish and bird tissue
elements because they reflect biological uptake
through diet, the predominant pathway for selenium
toxicity, and because they are most predictive of the
observed biological endpoint of concern,
reproductive toxicity.
Specifically, the EPA is proposing its recommended
2016 CWA section 304(a) selenium criterion for
freshwater with the addition of a bird tissue criterion

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element and the replacement of the 304(a) selenium
monthly average exposure water column criterion
elements with a performance-based approach. The
approach would be used by California to translate
the tissue criterion elements into protective water
column elements on a site-specific basis. This
performance-based approach maximizes the
flexibility for the State to develop water-column
translations specifically tailored to each individual
waterbody. Additionally, the performance-based
approach provides two methodologies for deriving
site-specific water column criterion elements: the
mechanistic modeling approach and the empirical
bioaccumulation factor (BAF) approach.
The EPA's proposed rule does not apply to California
waters where site-specific selenium criteria have
been adopted, nor does it apply to California waters
with selenium criteria promulgated in the NTR. In
other words, this proposal would not apply to the
San Joaquin River from Sack Dam to Vernalis, Mud
Slough, Salt Slough, the constructed and
reconstructed water supply channels in the
Grasslands watershed, surface waters that are
tributaries to the Salton Sea, nor the San Francisco
Bay and Delta.
Is the EPA soliciting comments on any
specific element of the proposed rule?
The EPA welcomes comments concerning any
component of the proposed rule and the EPA
requests any additional information for
consideration by the Agency. The EPA is also
specifically soliciting comment on the following:
The Draft Translation of Selenium Tissue
Criterion Elements to Site-Specific Water
Column Criterion Elements for California,
Version 1, August 2018 and how it has been
applied in this proposed rule.
Whether or not the EPA should include the
2016 CWA section 304(a) water column
criterion elements in addition to the
performance-based approach to translate
site-specific water column criterion elements.
Whether or not the EPA should include the
2016 CWA section 304(a) water column
criterion elements instead of including the
performance-based approach.
Whether or not the EPA should include two
criteria instead of one criterion; one criterion
to protect aquatic life designated uses and
the other to protect wildlife designated uses.
Public hearings on the proposed rule
The EPA is offering two online public hearings so that
interested parties may provide oral comments on
this proposed rule. The first public hearing will be on
Tuesday, January 29, 2019 from 9 AM - 11 AM PT.
The second public hearing will be on Wednesday,
January 30, 2019 from 4 PM - 6 PM PT.
Where can I find more information?
Contact Julianne McLaughlin at (202) 566-2542,
mclaughlin.julianne@epa.gov, Danielle Anderson at
(202) 564-1631, anderson.danielle@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
the online public hearings, visit the EPA's Water
Quality Standards website at:
https://www.epa.gov/wqs-tech/water-quality-
standards-establishment-numeric-criterion-
selenium-fresh-waters-california.

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