DEQ-CFW_00012418

Draft Best Practices Guide
Background: Water quality standards consist of designated uses, water quality criteria to protect these
uses, an anti -degradation policy to protect existing uses and high quality waters, and general policies
addressing implementation issues. National pollutant discharge system (NPDES)permits establish
discharge limits that are required to meet designated uses. When tech no logy -based effluent limits are
not sufficient to attain designated uses of a water body, water quality -based effluent limits (WQBELs)
are established in NPDES permits to control discharges of specific pollutants. VV{l8ELs may be used to
control pollutant discharges that cause, have the reasonable potential to cause, or contribute to an
excursion of a state water quality standard in receiving waters. WQBELs are numeric discharge limits
calculated on the basis of allocating the total allowable cumulative discharge of pollutants that will
achieve the water quality standard in -stream concentration. VVC\8EL5 include consideration of upstream
concentrations, effluent concentration and flow, and the flow ufthe receiving waters. State water
quality standard implementation procedures address these factors and are used by NPIDES permitting
authorities to develop permit limits. The implementation procedures may also include a dilution
allowance or regulatory mixing zone, to allow for mixing ofeffluents with receiving waters.
States establish water quality standards for aquatic life protection and human health protection; the
latter may consider protection of human health from exposure to pollutants through recreation,
drinking water, or fish consumption. If State has established water quality criteria for both aquatic life
and human health protection, the more stringent of the criteria are used to calculate WQBELs. Where a
specific numeric standard does not exist, permitting authorities may calculate a site -specific water
quality criterion based on an established interpretation of an applicable narrative water quality criterion
and use that numeric criterion to establish WQBELs. Alternatively, permitting authorities may use
indicator parameters to control pollutants ofconcern.
In cases where numeric human health criteria for specific pollutants are not found in State water quality
standards, information that may beused todevelop site -specific water quality criteria (and \NOBELu
based on those criteria) to protect drinking water include maximum contaminant level goals (MCLGs),
maximum contaminant levels (MCLs) and health advisories established under the Safe Drinking Water
Act; and health advisories using information under other statutes and regulations (e.8, human health
benchmarks for pesticides calculated from information developed under FIFRA; risk -based screening
levels calculated for use in CERCLA vemediation and removal programs). States may also consider the
acceptable risk level established for carcinogens under their water quality criteria for human health
protection. [Some examples where application of narrative criteria for development of WQBELs would
be/hasbeen useful include: nitrate, radionuclides, bromide, perch|orate, 1,4-dioxane, PFOA
(perf|uorooctanuioacid)]
Existing Requirements/
0 40 CFR §122'44 Establishing limitations, standards, and other permit conditions each
NPIDES permit shall include conditions meeting the following requirements when applicable.
o (d) Water quality standards and State requirements: any requirements in addition to or
more stringent than promulgated effluent limitations guidelines or standards under
sections 301,3&4,3O6,3O7,3l8and 4OSofC\WAnecessary to:
OEQ-CFVV_00012418

(1) Achieve water quality standards established under section 303 of the CWA,
including State narrative criteria for water quality.
(vi) Where a State has not established a water quality criterion for a specific
chemical pollutant that is present in an effluent at a concentration that causes,
has the reasonable potential to cause, or contributes to an excursion above a
narrative criterion within an applicable State water quality standard, the
permitting authority must establish effluent limits using one or more of the
following options:
o (A) Establish effluent limits using a calculated numeric water quality criterion
for the pollutant which the permitting authority demonstrates will attain an,I-'
maintain applicable narrative water quality criteria and will fully protect th(
designated use. Such a criterion may be derived using a proposed State
criterion, or an explicit State policy or regulation interpreting its narrative
water quality criterion, supplemented with other relevant information whi(
may include: EPA's Water Quality Standards Handbook, October 1983, risk
assessment data, exposure data, information about the pollutant from the
Food and Drug Administration, and current EPA criteria documents; or
• (B) Establish effluent limits on a case -by -case basis, using EPA's water quali
criteria, published under section 304(a) of the CWA, supplemented where
necessary by other relevant information; or
• (C) Establish effluent limitations on an indicator parameter for the pollutan
of concern, provided:
N (1) The permit identifies which pollutants are intended to be controlled
by the use of the effluent limitation;
N (2) The fact sheet required by § 124.56 sets forth the basis for the limit,
including a finding that compliance with the effluent limit on the
indicator parameter will result in controls on the pollutant of concern
which are sufficient to attain and maintain applicable water quality
N (3) The permit requires all effluent and ambient monitoring necessary t;
show that during the term of the permit the limit on the indicator
parameter continues to attain and maintain applicable water quality
standards; and
0 (4) The permit contains a reopener clause allowing the permitting
authority to modify or revoke and reissue the permit if the limits on th
indicator parameter no longer attain and maintain applicable water
quality standards. I
� NPDES Permit Writers' Manual (September 2018)—Chapter 6discusses development
ofWater Quality Based Effluent Limitations, primarily based on numeric water quality
criteria or Whole Effluent Toxicity (VVET) requirements to implement narrative criteria
where applicable.
� U.S. Environmental Protection Agency. 1991. Technical Support Document for Water
Quality -Based Towics Control (TSD).Technical guidance for assessing and regulating the
OEQ-CFVV_00012419

.i,ischarge of toxic substances to the waters of the US. Provides guidance to permittirl�-:4-
2uthorities on effluent characterization and wasteload allocation development,
2012 Edition of Drinking Water Standards and Health Advisories -
Human Health Benchmarks for Pesticides -The EPA has developed human health
benchmarks for approximately 350 pesticides to enable our partners to better
determine whether the detection of a pesticide in drinking water or source waters for
drinking water may indicate a potential health risk. This table includes benchmarks for
acute (one -day) and chronic (lifetime) exposures for the most sensitive populations
from exposure to pesticides that may be found in surface or ground water sources of
expected to be updated in Fall 2013 to include cancer risks for certain pesticides.
Regional Screening Levels for Chemical Contaminants at Superfund Sites -
was developed with DOE's Oak Ridge National Laboratory (ORNQ under an Interagency
Agreement as an update of the EPA Region 3 RSLTable, Region 6 HHMSSL Table and the
Region 9 PRG Table. Here you will find tables of risk -based screening levels, calculated
using the latest toxicity values, default exposure assumptions and physical and chemical
properties, and a calculator where default parameters can be changed to reflect site -
specific risks. Values are reported for cancer and non -cancer risk screening in specific
tables for various exposure routes, including tap water.
• Permit writers need to know the pollutants of concern and know the ambient criteria
they need to achieve. Withoug these the permit writer cannot write a limit.
• Where a state has a designated use for PWS but does not have appropriate WQC for
pollutants of concern the permit writer does not have a criteria against which to write a
permit
• States with narrative standards of addressing "toxics in toxic amounts" may be limited
by available narrative translators and could benefit from identification of those sources
of information that EPA would support.
• No definition has been made of how far downstream from an outfall a permit should
consider. This is likely to vary from site to site.
0 Permits may reach across state boundaries for considering drinking water intakes. The
w In order to ensure that permits consider downstream drinking water intakes, a clear
understanding of where they occur in relation to permitted facilities is necessary. No
such compilation of paired facilities currently exists.
OEQ-CFVV_00012420

set of models that would be considered satisfactory for state use.
• Current criteria are limited. There is a continuing need for new sources of acceptable
water quality values for states to consider, especially for emerging contaminants such as
cyanotoxins, perfluorinated compounds, pharmaceuticals and personal care products.
• Applicable water quality values for different averaging times other than chronic values
are needed.
Successes:
• PennmJvania'swater quality standards include the designated useofpub|iumater
supply for all surface waters statewide. The definition of public water supply indicates
that use shall be achieved after conventional treatment, which is defined as coagulation,
filtration and disinfection. Thus, standards for contaminants that are regulated under
Pennsy|vanie's Safe Drinking Water Act that would not be removed by conventional
treatment must be met a1the point ofintake toa public water supply. Permit writers
identify the nearest downstream public water supply intake and assure that surface
water quality criteria for human health/drinking water protection, MCLs and/or SMCLs
are achieved at the intake.
• West Virginia also has a statewide designation of water supply for all surface waters,
except those determined to be unsuitable because of insufficient flow or hydrologic
modifications. Concentrations ofpollutants identified aswater quality criteria to protect
the water supply use must be achieved within >6-nni|e above a water supply intake,
requiring the calculation of WQBELs if necessary to achieve these criteria.
Workgroup Recommendations: The workgroup recommends that the following steps be
1) The DVVprogram should develop a checklist for permit writers that include comprehensive list
ofcontaminants ofconcern under SDVVA. This should bedone onastate bystate basis, and
specialized lists could becreated for particular watersheds ofconcern.
Z) Using such achecklist, orstate-specific matrix ofcontaminants, permit writers could investigate
effluents for the presence of specific parameters for which the state has not adopted numeric
criteria, and establish limits using EPA'u3U4(a) criteria or an indicator parameter.
3) Auhared database between DVVand NPDES staff detailing location ofdrinking water intakes and
specific contaminants ofconcern atthose intakes.
4) Guidance should be developed to assist permit writers with conducting reasonable potential
analyses for parameters at the nearest downstream drinking water intake. The ambient induced
equation in EPA's Technical Support Documentfor Water Quality -based Toxics Control should be
used to calculate the concentration of an effluent at the drinking water intake.
OEQ-CFVV_00012421

5) If the state does not have a protocol for translating a narrative criterion, the DVVprogram and
the permitting program could collaborate indeveloping a protocol to protec1PVV8 intakes. [|f
there is no numeric or narrative standard, there is nothing for the permit writer to use to
conduct reasonable potential orset apermit |imit]
6) States should be encouraged to adopt public water supply standards where appropriate.
7\ Permit writers could calculate limits by back calculating from the intake. The permit
writer would need toknow the upper bound ofwhat the PVVScan take in. Then they
would need to use a model to protect to that amount at the intake point from an
upstream discharger with a margin of error built in that takes in frequency.
8) EPA should work with states to ensure that permit application requirements are being
met. Concurrently, effluent monitoring and reporting requirements can be imposed in
permits to better characterize any parameter of concern based on credible evidence.'
o Permitting Guidance for Surface Coal Mining Operations to Protect West Virginia's
Narrative Water Quality Standards
o Development of Regional ly-Based Interpretations of Tennessee's Narrative Nutrient
Criterion
/ See Bromide uaeparameter ofconcern letter Wthe 8fid-A(hntiustates dated August ]7.2O|3.EPA Region III
OEQ-CFVV_00012422