United States
Environmental Protection
\r ^1 # ^Agency

Office of Water
EPA 822-F-22-001
March 2022

Proposed Rule to Restore Protective Human
Health Water Quality Criteria in Washington


EPA is proposing a rule that would reinstate the
same science-based federal human health water
quality criteria to protect Washington's waters that
it withdrew in 2020, including waters where tribes
have reserved rights to fish. This rule would replace
the less stringent state criteria that EPA approved in
the prior administration.


Clean Water Act (CWA) section 101(a)(2) establishes
the national goal that water quality should provide
for the protection and propagation offish, shellfish,
and wildlife, and recreation in and on the water. EPA
periodically publishes national criteria
recommendations under CWA section 304(a) for
states to consider using to meet these CWA section
101(a)(2) goals. CWA section 303(c)(2)(B) requires
states to adopt numeric water quality criteria for all
priority pollutants for which EPA has published
criteria recommendations. When states designate
waterbody uses such as fish and shellfish harvesting
and drinking water supply, they must also establish
human health criteria (HHC) that protect people
from cancer and non-cancer effects of pollutants.

In August 2016, Washington submitted HHC to EPA
for review under the CWA, which EPA partially
approved and partially disapproved in November
2016. For the HHC that EPA disapproved, the Agency
promulgated federal HHC to protect Washington's
waters for use in fish and shellfish harvesting and
drinking water supplies. In response to a 2017
petition from several regulated entities, the Agency
reversed its prior partial disapproval of certain HHC

in May 2019. EPA then withdrew the federally
promulgated HHC in May 2020. The Agency's actions
in 2019 and 2020 are the subject of two legal

On June 30, 2021, the Court approved EPA's request
for the cases to be held in abeyance pending
voluntary reconsideration and rulemaking by the
Agency. EPA has concluded that its 2019 and 2020
actions related to Washington's HHC were not based
on a sound scientific rationale and were therefore
not protective of the applicable designated uses in

EPA's Recommended Approach to Derive

EPA derives HHC to protect against carcinogenic
effects using the following inputs: cancer slope
factor, cancer risk level (CRL), body weight, drinking
water intake rate, fish consumption rate (FCR), and a
bioaccumulation factor(s) (BAFs). For non-
carcinogenic and nonlinear carcinogenic effects, EPA
uses a reference dose in place of a cancer slope
factor and CRL, as well as a relative source
contribution (RSC), which is intended to ensure that
an individual's total exposure from all sources does
not exceed the criteria.

How EPA Derived the Proposed Criteria

To derive Washington-specific criteria, EPA is
proposing to use the same cancer slope factors, CRL
of one in one million (10~6), body weight, drinking
water intake rate, BAFs, reference doses, FCR of 175
g/day, and pollutant-specific RSCs that the Agency
used in its 2016 federal rule.

Scope of the Proposed Rule

EPA is proposing 141 HHC for 72 different pollutants
(70 organism-only criteria and 71 water-plus-
organism criteria) to protect the applicable
designated uses of Washington's waters. These
proposed federal criteria would supersede the HHC
that EPA disapproved in 2016 and later approved in
2019 (the "2019 Reconsidered HHC"). This rule
would not affect the federal HHC that EPA
promulgated for arsenic, methylmercury, or bis (2-
chloro-l-methylethyl) ether in 2016, which remain in
place for CWA purposes, nor Washington's HHC that
EPA approved in 2016. These proposed federal
criteria would apply only to waters under
Washington's jurisdiction.

Public Hearings and Soliciting Comments on
EPA's Proposed Rule

EPA welcomes comments concerning the proposed
rule and requests any additional information for
consideration by the Agency.

In addition to accepting written comments from the
public, EPA is offering two online public hearings on
the proposed rule so that interested parties may
provide oral comments. For details on how to submit
comments and/or attend an online public hearing,
visit: www.epa.gov/wqs-tech/federal-human-health-

Where can I find more information?

Contact Erica Fleisig at (202) 566-1057,
fleisig.erica@epa.gov or Lindsay Guzzo at (206) 553-
0268, guzzo.lindsay@epa.gov. To access the
proposed rule, Federal Register notice, and
supporting documents, visit EPA's Water Quality
Standards website at: www.epa.gov/wqs-