Current through Register Vol. 24-18, September 15, 2024
(1) The department
shall consider the following criteria to select a contaminant for developing a
SAL:
(a) Drinking water contributes to human
exposure to the contaminant.
(b)
The contaminant is known or likely to occur in public water systems at levels
of public health concern. Sources of occurrence information include, but are
not limited to:
(i) Washington state
department of agriculture;
(ii)
Washington state department of ecology; and
(iii) Monitoring results reported in
accordance with
40 C.F.R.
141.35.
(c) The contaminant has a possible adverse
effect on the health of persons exposed based on peer-reviewed scientific
literature or government publications, such as:
(i) An EPA health assessment such as an
Integrated Risk Information System assessment;
(ii) Agency for Toxic Substances and Disease
Registry toxicological profiles;
(iii) State government science assessment;
and
(iv) EPA guidelines for
exposure assessment such as the EPA exposure factors handbook.
(d) A certified drinking water lab
can accurately and precisely measure the concentration of the contaminant in
drinking water at and below the level of public health concern using
EPA-approved analytical methods.
(2) After consideration of the criteria in
subsection (1) of this section, the department may develop a SAL based on the
following:
(a) Evaluation of available
peer-reviewed scientific literature and government publications on fate,
transport, exposure, toxicity and health impacts of the contaminant and
relevant metabolites;
(b) An
assessment based on the most sensitive adverse effect deemed relevant to humans
and considering susceptibility and unique exposures of the most sensitive
subgroup such as pregnant women, fetuses, young children, or overburdened and
underserved communities; and
(c)
Technical limitations to achieving the SAL such as insufficient analytical
detection limit achievable at certified drinking water laboratories.
(3) The state board of health
shall consider the department's findings under subsections (1) and (2) of this
section when considering adopting a SAL under this chapter.
(4) Contaminants with a SAL.
(a) If a SAL under Table 9 of this section is
exceeded, the purveyor shall take follow-up action as required under WAC
246-290-320. For contaminants
where the SAL exceedance is determined based upon an RAA, the RAA will be
calculated consistent with other organic contaminants per WAC
246-290-320(6)
or other inorganic contaminants per WAC
246-290-320(3).
TABLE 9
STATE ACTION LEVELS
|
Contaminant or Group of Contaminants
|
SAL |
SAL Exceedance Based On: |
|
Per- and polyfluoroalkyl substances (PFAS)
|
|
PFOA |
10 ng/L |
Confirmed detection |
|
PFOS |
15 ng/L |
Confirmed detection |
|
PFHxS |
65 ng/L |
Confirmed detection |
|
PFNA |
9 ng/L |
Confirmed detection |
|
PFBS |
345 ng/L |
Confirmed detection |
(b)
If a system fails to collect and submit a confirmation sample to a certified
lab within ten business days of notification of the sample results, or as
required by the department, the results of the original sample will be used to
determine compliance with the SAL.
(5) The department shall consider the
following when developing a state MCL:
(a) The
criteria in subsection (1) of this section;
(b) Whether regulating the contaminant
presents a meaningful opportunity to reduce exposures of public health concern
for persons served by public water systems;
(c) The need for an enforceable limit to
achieve uniform public health protection in Group A public water systems;
and
(d) The need for an enforceable
limit to support source water investigation and clean-up of a contaminant in
drinking water supplies by responsible parties.
(6) In addition to the requirements in
subsection (5) of this section, the department shall:
(a) Meet the requirements of subsection (2)
of this section;
(b) Comply with
the requirements in
RCW
70A.130.010 to establish standards for
chemical contaminants in drinking water;
(c) Consider the best available treatment
technologies and affordability taking into consideration the costs to small
water systems; and
(d) Determine
that the probable benefits of the rule are greater than its probable costs,
taking into account both the qualitative and quantitative benefits and
costs.
(7) The state
board of health shall consider the department's findings under subsections (5)
and (6) of this section and follow the requirements under chapters 34.05 and
19.85 RCW when adopting a state MCL under this chapter.
(8) Upon federal adoption of an MCL, the
federal MCL will supersede a SAL or a less stringent state MCL, and the
associated requirements, including for monitoring and public notice. If the
federally adopted MCL is less stringent than a SAL or state MCL, the board may
take one of the following actions:
(a) Adopt
the federal MCL; or
(b) Adopt a
state MCL, at least as stringent as the federal MCL, using the process in
subsections (6) and (7) of this section.
