65FR31681 Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California, Part 3/4
robop...@us.govnews.org
Posting-number: Volume 65, Issue 97, Page 31681, Part 1
[[Page 31698]]
of mercury in certain water bodies in California. EPA supports the use
of this information to develop site-specific criteria for mercury.
Further, if a California water body is impaired due to mercury fish
tissue or sediment contamination, loadings of mercury could contribute
to or exacerbate the impairment. Therefore, one option regulatory
authorities should consider is to include water quality-based effluent
limits (WQBELs) in permits based on mass for discharges to the impaired
water body. Such WQBELs must be derived from and comply with applicable
State water quality standards (including both numeric and narrative
criteria) and assure that the discharge does not cause or contribute to
a violation of water quality standards.
d. Polychlorinated Biphenyls (PCBs) Criteria
The NTR, as amended, calculated human health criteria for PCBs
using a cancer potency factor of 7.7 per mg/kg-day from the Agency's
IRIS. This cancer potency factor was derived from the Norback and
Weltman (1985) study which looked at rats that were fed Aroclor 1260.
The study used the linearized multistage model with a default cross-
species scaling factor (body weight ratio to the \2/3\ power). Although
it is known that PCB mixtures vary greatly as to their potency in
producing biological effects, for purposes of its carcinogenicity
assessment, EPA considered Aroclor 1260 to be representative of all PCB
mixtures. The Agency did not pool data from all available congener
studies or generate a geometric mean from these studies, since the
Norback and Weltman study was judged by EPA as acceptable, and not of
marginal quality, in design or conduct as compared with other studies.
Thereafter, the Institute for Evaluating Health Risks (IEHR, 1991)
reviewed the pathological slides from the Norback and Weltman study,
and concluded that some of the malignant liver tumors should have been
interpreted as nonmalignant lesions, and that the cancer potency factor
should be 5.1 per mg/kg-day as compared with EPA's 7.7 per mg/kg-day.
The Agency's peer-reviewed reassessment of the cancer potency of
PCBs published in a final report, PCBs: Cancer Dose-Response Assessment
and Applications to Environmental Mixtures (EPA/600/P-96/001F), adopts
a different approach that distinguishes among PCB mixtures by using
information on environmental processes. (The report is included in the
administrative record of today's rule.) The report considers all cancer
studies (which used commercial mixtures only) to develop a range of
cancer potency factors, then uses information on environmental
processes to provide guidance on choosing an appropriate potency factor
for representative classes of environmental mixtures and different
pathways. The reassessment provides that, depending on the specific
application, either central estimates or upper bounds can be
appropriate. Central estimates describe a typical individual's risk,
while upper bounds provide assurance (i.e., 95% confidence) that this
risk is not likely to be underestimated if the underlying model is
correct. Central estimates are used for comparing or ranking
environmental hazards, while upper bounds provide information about the
precision of the comparison or ranking. In the reassessment, the use of
the upper bound values were found to increase cancer potency estimates
by two or three-fold over those using central tendency. Upper bounds
are useful for estimating risks or setting exposure-related standards
to protect public health, and are used by EPA in quantitative cancer
risk assessment. Thus, the cancer potency of PCB mixtures is determined
using a tiered approach based on environmental exposure routes with
upper-bound potency factors (using a body weight ratio to the \3/4\
power) ranging from 0.07 (lowest risk and persistence) to 2 (high risk
and persistence) per mg/kg-day for average lifetime exposures to PCBs.
It is noteworthy that bioaccumulated PCBs appear to be more toxic than
commercial PCBs and appear to be more persistent in the body. For
exposure through the food chain, risks can be higher than other
exposures.
EPA issued the final reassessment report on September 27, 1996, and
updated IRIS to include the reassessment on October 1, 1996. EPA
updated the human health criteria for PCBs in the National Toxics Rule
on September 27, 1999. For today's rule, EPA derived the human health
criteria for PCBs using a cancer potency factor of 2 per mg/kg-day, an
upper bound potency factor reflecting high risk and persistence. This
decision is based on recent multimedia studies indicating that the
major pathway of exposure to persistent toxic substances such as PCBs
is via dietary exposure (i.e., contaminated fish and shellfish
consumption).
Following is the calculation of the human health criterion (HHC)
for organism and water consumption:
[GRAPHIC] [TIFF OMITTED] TR18MY00.013
Where:
RF = Risk Factor = 1 x 10<SUP>-6
</SUP>BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-day
WC = Water Consumption = 2 l/day
FC = Fish and Shellfish Consumption = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200
the HHC (<greek-m>g/l) = 0.00017 <greek-m>g/l (rounded to two
significant digits).
Following is the calculation of the human health criterion for
organism only consumption:
[GRAPHIC] [TIFF OMITTED] TR18MY00.014
Where:
RF = Risk Factor = 1 x 10<SUP>-6
</SUP> BW = Body Weight = 70 kg
q1* = Cancer slope factor = 2 per mg/kg-day
FC = Total Fish and Shellfish Consumption per Day = 0.0065 kg/day
BCF = Bioconcentration Factor = 31,200
the HHC (<greek-m>g/l) = 0.00017 <greek-m>g/l (rounded to two
significant digits).
The criteria are both equal to 0.00017 <greek-m>g/l and apply to
total PCBs. See PCBs: Cancer Dose Response Assessment and Application
to Environmental Mixtures (EPA/600/9-96-001F). For a discussion of the
body weight, water consumption, and fish and shellfish consumption
factors, see the Human Health Guidelines. For a discussion of the BCF,
see the 304(a) criteria guidance document for PCBs (included in the
administrative record for today's rule).
e. Excluded Section 304(a) Human Health Criteria
As is the case in the NTR, as amended, today's rule does not
promulgate criteria for certain priority pollutants for which CWA
section 304(a) criteria guidance exists because those criteria were not
based on toxicity to humans or aquatic organisms. The basis for those
particular criteria is organoleptic effects (e.g., taste and odor)
which would make water and edible aquatic life unpalatable but not
toxic. Because the basis for this rule is to protect the public health
and aquatic life from toxicity consistent with the language and intent
in CWA section 303(c)(2)(B), EPA is promulgating criteria only for
those priority toxic pollutants whose criteria recommendations are
based on toxicity. The CWA section 304(a) human health criteria based
on organoleptic effects for zinc and 3-methyl-4-chlorophenol are
excluded for this reason. See the 1992 NTR discussion at 57 FR 60864.
[[Page 31699]]
f. Cancer Risk Level
EPA's CWA section 304(a) criteria guidance documents for priority
toxic pollutants that are based on carcinogenicity present
concentrations for upper bound risk levels of 1 excess cancer case per
100,000 people (10<SUP>-5</SUP>), per 1,000,000 people
(10<SUP>-6</SUP>), and per 10,000,000 people (10<SUP>-7</SUP>).
However, the criteria documents do not recommend a particular risk
level as EPA policy.
As part of the proposed rule, EPA requested and received comment on
the adoption of a 10 <SUP>-5</SUP> risk level for carcinogenic
pollutants. The effect of a 10<SUP>-5</SUP> risk level would have been
to increase (i.e., make less stringent) carcinogenic pollutant criteria
values (noted in the matrix by footnote c) that are not already
promulgated in the NTR, by one order of magnitude. For example, the
organism-only criterion for gamma BHC (pollutant number 105 in the
matrix) is 0.013 <greek-m>g/l; the criterion based on a 10<SUP>-5</SUP>
risk level would have been 0.13 <greek-m>g/l. EPA received several
comments that indicated a preference for a higher (10<SUP>-4</SUP> and
10<SUP>-5</SUP>) risk level for effluent dependent waters or other
types of special circumstances.
In today's rule, EPA is promulgating criteria that protect the
general population at an incremental cancer risk level of one in a
million (10<SUP>-6</SUP>) for all priority toxic pollutants regulated
as carcinogens, consistent with the criteria promulgated in the NTR for
the State of California. Standards adopted by the State contained in
the Enclosed Bays and Estuaries Plan (EBEP), and the Inland Surface
Waters Plan (ISWP), partially approved by EPA on November 6, 1991, and
the Ocean Plan approved by EPA on June 28, 1990, contained a risk level
of 10<SUP>-6</SUP> for most carcinogens. The State has historically
protected at a 10<SUP>-6</SUP> risk level for carcinogenic pollutants.
EPA, in its recent human health methodology revisions, proposed
acceptable lifetime cancer risk for the general population in the range
of 10<SUP>-5</SUP> to 10<SUP>-6</SUP>. EPA also proposed that States
and Tribes ensure the most highly exposed populations do not exceed a
10<SUP>-4</SUP> risk level. However, EPA's draft methodology revisions
also stated that it will derive 304(a) criteria at a 10<SUP>-6</SUP>
risk level, which the Agency believes reflects the appropriate risk for
the general population and which applies a risk management policy which
ensures protection for all exposed population groups. (Draft Water
Quality Criteria Methodology: Human Health, EPA 822-Z-98-001, August
1998, Appendix II, page 72).
Subpopulations within a State may exist, such as recreational and
subsistence anglers, who as a result of greater exposure to a
contaminant are at greater risk than the standard 70 kilogram person
eating 6.5 grams per day of fish and shellfish and drinking 2.0 liters
per day of drinking water with pollutant levels meeting the water
quality criteria. EPA acknowledges that at any given risk level for the
general population, those segments of the population that are more
highly exposed face a higher relative risk. For example, if fish are
contaminated at a level permitted by criteria derived on the basis of a
risk level of 10<SUP>-6</SUP>, individuals consuming up to 10 times the
assumed fish consumption rate would still be protected at a
10<SUP>-5</SUP> risk level. Similarly, individuals consuming 100 times
the general population rate would be protected at a 10<SUP>-4</SUP>
risk level. EPA, therefore, believes that derivation of criteria at the
10<SUP>-6</SUP> risk level is a reasonable risk management decision
protective of designated uses under the CWA. While outside the scope of
this rule, EPA notes that States and Tribes, however, have the
discretion to adopt water quality criteria that result in a higher risk
level (e.g., 10<SUP>-5</SUP>). EPA expects to approve such criteria if
the State or Tribe has identified the most highly exposed subpopulation
within the State or Tribe, demonstrates the chosen risk level is
adequately protective of the most highly exposed subpopulation, and has
completed all necessary public participation.
This demonstration has not happened in California. Further, the
information that is available on highly exposed subpopulations in
California supports the need to protect the general population at the
10<SUP>-6</SUP> level. California has cited the Santa Monica Bay
Seafood Consumption Study as providing the best available data set for
estimating consumption of sport fish and shellfish in California for
both marine or freshwater sources (Chemicals in Fish Report No. 1:
Consumption of Fish and Shellfish in California and the United States,
Final Draft Report, July 1997). Consumption rates of sport fish and
shellfish of 21g/day, 50 g/day, 107 g/day, and 161 g/day for the
median, mean, 90th, and 95th percentile rates, respectively, were
determined from this study. Additional consumption of commercial
species in the range of approximately 8 to 42 g/day would further
increase these values. Clearly the consumption rates for the most
highly exposed subpopulation within the State exceeds 10 times the 6.5
g/day rates used in the CTR. Therefore, use of a risk level of
10<SUP>-5</SUP> for the general population would not be sufficient to
protect the most highly exposed population in California at a
10<SUP>-4</SUP> risk level. On the other hand, even the most highly
exposed subpopulations cited in the California study do not have
consumption rates approaching 100 times the 6.5 g/day rates used in the
CTR. The use of the 10<SUP>-6</SUP> risk level to protect average level
consumers does not subject these subpopulations to risk levels as high
as 10<SUP>-4</SUP>.
EPA believes its decision to establish a 10<SUP>-6</SUP> risk level
for the CTR is also consistent with EPA's policy in the NTR to select
the risk level that reflect the policies or preferences of CWA programs
in the affected States. California adopted standards for priority toxic
pollutants for its ocean waters in 1990 using a 10<SUP>-6</SUP> risk
level to protect human health (California Ocean Plan, 1990). In April
1991, and again in November 1992, California adopted standards for its
inland surface waters and enclosed bays and estuaries in its Inland
Surface Waters Plan (ISWP) and its Enclosed Bays and Estuaries Plan
(EBEP) using a 10<SUP>-6</SUP> risk level. To be consistent with the
State's water quality standards, EPA used a 10<SUP>-6</SUP> risk level
for California in the NTR at 57 FR 60867. The State has continued using
a 10<SUP>-6</SUP> risk level to protect human health for its standards
that were not withdrawn with the ISWP and EBEP. The most recent
expression of risk level preference is contained in the Draft
Functional Equivalent Document, Amendment of the Water Quality Control
Plan for Ocean Waters of California, October 1998, where the State
recommended maintaining a consistent risk level of 10<SUP>-6</SUP> for
the human health standards that it was proposing to revise.
EPA received several comments requesting a 10<SUP>-5</SUP> risk
level based on the risk level chosen for the Great Lakes Water Quality
Guidance (the Guidance). There are several differences between the
guidelines for the derivation of human health criteria contained in the
Guidance and the California Toxics Rule (CTR) that make a
10<SUP>-5</SUP> risk factor appropriate for the Guidance, but not for
the CTR. These differences result in criteria developed using the
10<SUP>-5</SUP> risk factor in the Guidance being at least as stringent
as criteria derived under the CTR using a 10<SUP>-6</SUP> risk factor.
The relevant aspects of the Guidance include:
<bullet> Use of fish consumption rates that are considerably higher
than fish consumption rates for the CTR.
<bullet> Use of bioaccumulation factors rather than
bioconcentration factors in
[[Page 31700]]
estimating exposure, considerably increasing the dose of carcinogens to
sensitive subgroups.
<bullet> Consideration of additivity of effects of mixtures for
both carcinogenic and noncarcinogenic pollutants.
This combination of factors increase the calculated carcinogenic
risk substantially under the Guidance (the combination would generally
be more than one order of magnitude), making a lower overall risk
factor acceptable. The Guidance risk factor provides, in fact, criteria
with at least the same level of protection against carcinogens as
criteria derived with a higher risk factor using the CTR. A lower risk
factor for the CTR would not be appropriate absent concomitant changes
in the derivation procedures that provide equivalent risk protection.
G. Description of Final Rule
1. Scope
Paragraph (a) in 40 CFR 131.38, entitled ``Scope,'' states that
this rule is a promulgation of criteria for priority toxic pollutants
in the State of California for inland surface waters, enclosed bays,
and estuaries. Paragraph (a) in 40 CFR 131.38 also states that this
rule contains an authorizing compliance schedule provision.
2. EPA Criteria for Priority Toxic Pollutants
EPA's criteria for California are presented in tabular form at 40
CFR 131.38. For ease of presentation, the table that appears combines
water quality criteria promulgated in the NTR, as amended, that are
outside the scope of this rulemaking, with the criteria that are within
the scope of today's rule. This is intended to help readers determine
applicable water quality criteria for the State of California. The
table contains footnotes for clarification.
Paragraph (b) in 40 CFR 131.38 presents a matrix of the applicable
EPA aquatic life and/or human health criteria for priority toxic
pollutants in California. Section 303(c)(2)(B) of the CWA addresses
only pollutants listed as ``toxic'' pursuant to section 307(a) of the
CWA for which EPA has developed section 304(a) criteria guidance. As
discussed earlier in this preamble, the section 307(a) list of toxics
contains 65 compounds and families of compounds, which potentially
include thousands of specific compounds. Of these, the Agency
identified a list of 126 ``priority toxic pollutants'' to implement the
CWA (see 40 CFR 131.36(b)). Reference in this rule to priority toxic
pollutants, toxic pollutants, or toxics refers to the 126 priority
toxic pollutants.
EPA has not developed both aquatic life and human health CWA
section 304(a) criterion guidance for all of the priority toxic
pollutants. The matrix in 40 CFR 131.38(b) contains human health
criteria in Column D for 92 priority toxic pollutants which are divided
into Column 1: criteria for water consumption (i.e., 2.0 liters per
day) and aquatic organism consumption (i.e., 6.5 grams per day of
aquatic organisms); and Column 2: criteria for aquatic organism
consumption only. The term aquatic organism includes fish and shellfish
such as shrimp, clams, oysters and mussels. One reason the total number
of priority toxic pollutants with criteria today differs from the total
number of priority toxic pollutants contained in earlier published CWA
section 304(a) criteria guidance is because EPA has developed and is
promulgating chromium criteria for two valence states with respect to
aquatic life criteria. Thus, although chromium is a single priority
toxic pollutant, there are two criteria for chromium for aquatic life
protection. See pollutant 5 in today's rule at 40 CFR 131.38(b).
Another reason is that EPA is promulgating human health criteria for
nine priority pollutants for which health-based national criteria have
been calculated based on information obtained from EPA's IRIS database
(EPA provided notice of these nine criteria in the NTR for inclusion in
future State triennial reviews. See 57 FR 60848, 60890).
The matrix contains aquatic life criteria for 23 priority
pollutants. These are divided into freshwater criteria (Column B) and
saltwater criteria (Column C). These columns are further divided into
acute and chronic criteria. The aquatic life criteria are considered by
EPA to be protective when applied under the conditions described in the
section 304(a) criteria documents and in the TSD. For example, water
body uses should be protected if the criteria are not exceeded, on
average, once every three year period. It should be noted that the
criteria maximum concentrations (the acute criteria) are short-term
concentrations and that the criteria continuous concentrations (the
chronic criteria) are four-day averages. It should also be noted that
for certain metals, the actual criteria are equations which are
included as footnotes to the matrix. The toxicity of these metals is
water hardness dependent and may be adjusted. The values shown in the
table are illustrative only, based on a hardness expressed as calcium
carbonate of 100 mg/l. Finally, the criterion for pentachlorophenol is
pH dependent. The equation is the actual criterion and is included as a
footnote. The value shown in the matrix is for a pH of 7.8. Several of
the freshwater aquatic life criteria are incorporated into the matrix
in the format used in the 1980 criteria methodology which uses a final
acute value instead of a continuous maximum concentration. This
distinction is noted in footnote g of the table.
The final rule at 40 CFR 131.38(c) establishes the applicability of
the criteria to the State of California. 40 CFR 131.38(d) is described
later in Section F, of this preamble. EPA has included in this rule
provisions necessary to implement numeric criteria in a way that
maintains the level of protection intended. These provisions are
included in 40 CFR 131.38(c) of today's rule. For example, in order to
do steady state waste load allocation analyses, most States have low
flow values for streams and rivers which establish flow rates for
various purposes. These low flow values become design flows for sizing
treatment plants and developing water quality-based effluent limits
and/or TMDLs. Historically, these design flows were selected for the
purposes of waste load allocation analyses which focused on instream
dissolved oxygen concentrations and protection of aquatic life. With
the publication of the 1985 TSD, EPA introduced hydrologically and
biologically based analyses for the protection of aquatic life and
human health. (These concepts have been expanded subsequently in EPA's
Technical Guidance Manual for Performing Wasteload Allocations, Book 6,
Design Conditions, U.S. EPA, 1986. These analyses are included in
Appendix D of the revised TSD. The discussion here is greatly
simplified and is provided to support EPA's decision to promulgate
design flows for instream flows and thereby maintain the adequacy of
the criteria for priority toxic pollutants.) EPA recommended either of
two methods for calculating acceptable low flows, the traditional
hydrologic method developed by the U.S. Geological Survey or a
biological based method developed by EPA. Other methods for evaluating
the instream flow record may be available; use of these methods may
result in TMDLs and/or water quality-based effluent limitations which
adequately protect human health and/or aquatic life. The results of
either of these two methods, or an equally protective alternative
method, may be used.
The State of California may adopt specific design flows for streams
and rivers to protect designated uses against the effects of toxics.
EPA believes it is
[[Page 31701]]
important to specify design flows in today's rule so that, in the
absence of state design flows, the criteria promulgated today would be
implemented appropriately. The TSD also recommends the use of three
dynamic models to perform wasteload allocations. Dynamic wasteload
models do not generally use specific steady state design flows but
accomplish the same effect by factoring in the probability of
occurrence of stream flows based on the historical flow record.
The low flows specified in the rule explicitly contain duration and
frequency of occurrence which represent certain probabilities of
occurrence. Likewise, the criteria for priority toxic pollutants are
defined with duration and frequency components. Dynamic modeling
techniques explicitly predict the effects of variability in receiving
water, effluent flow, and pollution variation. Dynamic modeling
techniques, as described in the TSD, allow for calculating wasteload
allocations that meet the criteria for priority toxic pollutants
without using a single, worst-case concentration based on a critical
condition. Either dynamic modeling or steady state modeling can be used
to implement the criteria promulgated today. For simplicity, only
steady state conditions are discussed here. Clearly, if the criteria
were implemented using design flows that are too high, the resulting
toxic controls would not be adequate, because the resulting ambient
concentrations would exceed EPA's criteria.
In the case of aquatic life, assuming exceedences occur more
frequently than once in three years on the average, exceedences would
result in diminished vitality of stream ecosystems characterized by the
loss of desired species. Numeric water quality criteria should apply at
all flows that are equal to or greater than flows specified below. The
low flow values are:
------------------------------------------------------------------------
Type of criteria Design flow
------------------------------------------------------------------------
Acute Aquatic Life (CMC).................. 1 Q 10 or 1 B 3
Chronic Aquatic Life (CCC)................ 7 Q 10 or 4 B 3
Human Health.............................. harmonic mean flow
------------------------------------------------------------------------
Where:
1 Q 10 is the lowest one day flow with an average recurrence frequency
of once in 10 years determined hydrologically;
1 B 3 is biologically based and indicates an allowable exceedence of
once every 3 years. It is determined by EPA's computerized method
(DFLOW model);
7 Q 10 is the lowest average 7 consecutive day low flow with an average
recurrence frequency of once in 10 years determined hydrologically;
4 B 3 is biologically based and indicates an allowable exceedences for
4 consecutive days once every 3 years. It is determined by EPA's
computerized method (DFLOW model);
EPA is requiring that the harmonic mean flow be applied with human
health criteria. The harmonic mean is a standard calculated statistical
value. EPA's model for human health effects assumes that such effects
occur because of a long-term exposure to low concentration of a toxic
pollutant, for example, two liters of water per day for seventy years.
To estimate the concentrations of the toxic pollutant in those two
liters per day by withdrawal from streams with a high daily variation
in flow, EPA believes the harmonic mean flow is the correct statistic
to use in computing such design flows rather than other averaging
techniques. (For a description of harmonic means see ``Design Stream
Flows Based on Harmonic Means,'' Lewis A. Rossman, Jr. of Hydraulics
Engineering, Vol. 116, No. 7, July, 1990.)
All waters (including lakes, estuaries, and marine waters), whether
or not suitable for such hydrologic calculations, are subject to the
criteria promulgated today. Such criteria will need to be attained at
the end of the discharge pipe, unless the State authorizes a mixing
zone. Where the State plans to authorize a mixing zone, the criteria
would apply at the locations allowed by the mixing zone. For example,
the chronic criteria (CCC) would apply at the defined boundary of the
chronic mixing zone. Discussion of and guidance on these factors are
included in the revised TSD in Chapter 4.
EPA is aware that the criteria promulgated today for some of the
priority toxic pollutants are at concentrations less than EPA's current
analytical detection limits. Analytical detection limits have never
been an acceptable basis for setting water quality criteria since they
are not related to actual environmental impacts. The environmental
impact of a pollutant is based on a scientific determination, not a
measuring technique which is subject to change. Setting the criteria at
levels that reflect adequate protection tends to be a forcing mechanism
to improve analytical detection methods. See 1985 Guidelines, page 21.
As the methods improve, limits based on the actual criteria necessary
to protect aquatic life and human health become measurable. The Agency
does not believe it is appropriate to promulgate criteria that are not
sufficiently protective. EPA discusses this issue further in its
Response to Comment Document for today's final rule.
EPA does believe, however, that the use of analytical detection
limits are appropriate for assessing compliance with National Pollutant
Discharge Elimination System (NPDES) permit limits. This view of the
role of detection limits was first articulated in guidance for
translating dioxin criteria into NPDES permit limits. See ``Strategy
for the Regulation of Discharges of PHDDs and PHDFs from Pulp and Paper
Mills to Waters of the U.S.'' Memorandum from the Assistant
Administrator for Water to the Regional Water Management Division
Directors, May 21, 1990. This guidance presented a model for addressing
toxic pollutants which have criteria less than current detection
limits. EPA, in more recent guidance, recommends the use of the
``minimum level'' or ML for reporting sample results to assess
compliance with WQBELs (TSD page 111). The ML, also called the
``quantification level,'' is the level at which the entire analytical
system gives recognizable mass spectra and acceptable calibration
points, i.e., the point at which the method can reliably quantify the
amount of pollutant in the sample. States can use their own procedures
to average and otherwise account for monitoring data, e.g., quantifying
results below the ML. These results can then be used to assess
compliance with WQBELs. (See 40 CFR part 132, Appendix F, Procedure
8.B.) This approach is applicable to priority toxic pollutants with
criteria less than current detection limits. EPA's guidance explains
that standard analytical methods may be used for purposes of assessing
compliance with permit limits, but not for purposes of establishing
water quality criteria or permit limits. Under the CWA, analytical
methods are appropriately used in connection with NPDES permit limit
compliance assessments. Because of the function of water quality
criteria, EPA has not considered the sensitivity of analytical methods
in deriving the criteria promulgated today.
EPA has promulgated 40 CFR 131.38(c)(3) to determine when
freshwater or saltwater aquatic life criteria apply. This provision
incorporates a time parameter to better define the critical condition.
The structure of the paragraph is to establish
[[Page 31702]]
applicable rules and to allow for site-specific exceptions where the
rules are not consistent with actual field conditions. Because a
distinct separation generally does not exist between freshwater and
saltwater aquatic communities, EPA is establishing the following: (1)
The freshwater criteria apply at salinities of 1 part per thousand and
below at locations where this occurs 95% or more of the time; (2)
saltwater criteria apply at salinities of 10 parts per thousand and
above at locations where this occurs 95% more of the time; and (3) at
salinities between 1 and 10 parts per thousand the more stringent of
the two apply unless EPA approves the application of the freshwater or
saltwater criteria based on an appropriate biological assessment. The
percentiles included here were selected to minimize the chance of
overlap, that is, one site meeting both criteria. Determination of
these percentiles can be done by any reasonable means such as
interpolation between points with measured data or by the application
of calibrated and verified mathematical models (or hydraulic models).
It is not EPA's intent to require actual data collection at particular
locations.
In the brackish water transition zones of estuaries with varying
salinities, there generally will be a mix of freshwater and saltwater
species. Generally, therefore, it is reasonable for the more stringent
of the freshwater or saltwater criteria to apply. In evaluating
appropriate data supporting the alternative set of criteria, EPA will
focus on the species composition as its preferred method. This
assignment of criteria for fresh, brackish and salt waters was
developed in consultation with EPA's research laboratories at Duluth,
Minnesota and Narragansett, Rhode Island. The Agency believes such an
approach is consistent with field experience.
Paragraph (d) in 40 CFR 131.38 lists the designated water and use
classifications for which the criteria apply. The criteria are applied
to the beneficial use designations adopted by the State of California;
EPA has not promulgated any new use classifications in this rule.
Exceedences Frequency: In a water quality criterion for aquatic
life, EPA recommends an allowable frequency for excursions of the
criteria. See 1985 Guidelines, pages 11-13. This allowable frequency
provides an appropriate period of time during which the aquatic
community can recover from the effect of an excursion and then function
normally for a period of time before the next excursion. An excursion
is defined as an occurrence of when the average concentration over the
duration of the averaging period is above the CCC or the CMC. As
ecological communities are naturally subjected to a series of stresses,
the allowable frequency of pollutant stress may be set at a value that
does not significantly increase the frequency or severity of all
stresses combined. See also TSD, Appendix D. In addition, providing an
allowable frequency for exceeding the criterion recognizes that it is
not generally possible to assure that criteria are never exceeded.
(TSD, page 36.)
Based on the available data, today's rule requires that the acute
criterion for a pollutant be exceeded no more than once in three years
on the average. EPA is also requiring that the chronic criterion for a
pollutant be exceeded no more than once in three years on the average.
EPA acknowledges that States may develop allowable frequencies that
differ from these allowable frequencies, so long as they are
scientifically supportable, but believes that these allowable
frequencies are protective of the designated uses where EPA is
promulgating criteria.
The use of aquatic life criteria for developing water quality-based
effluent limits in permits requires the permitting official to use an
appropriate wasteload allocation model. (TSD, Appendix D-6.) As
discussed above, there are generally two methods for determining design
flows, the hydrologically-based method and the biologically-based
method.
The biologically-based method directly uses the averaging periods
and frequencies specified in the aquatic life criteria for determining
design flows. (TSD, Appendix. D-8.) Because the biologically-based
method calculates the design flow directly from the duration and
allowable frequency, it most accurately provides the allowed number of
excursions. The hydrologically based method applies the CMC at a design
flow equal to or equivalent to the 1Q10 design flow (i.e., the lowest
one-day flow with an average recurrence frequency of once in ten
years), and applies the CCC at the 7Q10 design flow (i.e., the lowest
average seven consecutive day flow with a recurrence frequency of once
in ten years).
EPA established a three year allowable frequency in the NTR. In
settlement of the litigation on the NTR, EPA stated that it was in the
midst of conducting, sponsoring, or planning research aimed at
addressing scientific issues related to the basis for and application
of water quality criteria and mentioned the issue of allowable
frequency. See Partial Settlement Agreement in American Forest and
Paper Ass'n, Inc. et al. v. U.S. EPA (Consolidated Case No. 93-0694
(RMU) D.D.C. To that end, EPA is reevaluating issues raised about
allowable frequency as part of its work in revising the 1985
Guidelines.
EPA recognizes that additional data concerning (a) the probable
frequency of lethal events for an assemblage of taxa covering a range
of sensitivities to pollutants, (b) the probable frequency of sublethal
effects for such taxa, (c) the differing effects of lethal and
sublethal events in reducing populations of such taxa, and (d) the time
needed to replace organisms lost as a result of toxicity, may lead to
further refinement of the allowable frequency value. EPA has not yet
completed this work. Until this work is complete, EPA believes that
where EPA promulgates criteria, the three year allowable frequency
represents a value in the reasonable range for this parameter.
3. Implementation
Once the applicable designated uses and water quality criteria for
a water body are determined, under the National Pollutant Discharge
Elimination System (NPDES) program discharges to the water body must be
characterized and the permitting authority must determine the need for
permit limits. If a discharge causes, has the reasonable potential to
cause, or contributes to an excursion of a numeric or narrative water
quality criteria, the permitting authority must develop permit limits
as necessary to meet water quality standards. These permit limits are
water quality-based effluent limitations or WQBELs. The terms
``cause,'' ``reasonable potential to cause,'' and ``contribute to'' are
the terms in the NPDES regulations for conditions under which water
quality-based permit limits are required. See 40 CFR 122.44(d)(1).
Since the publication of the proposed CTR, the State of California
adopted procedures which detail how water quality criteria will be
implemented through NPDES permits, waste discharge requirements, and
other regulatory approaches. These procedures entitled, Policy for
Implementation of Toxics Standards for Inland Surface Waters, Enclosed
Bays, and Estuaries of California were adopted on March 2, 2000. Once
these procedures are submitted for review under CWA section 303(c), EPA
will review them as they relate to water quality standards, and approve
or disapprove them.
Several commenters understood the language in the preamble to the
proposed rule regarding implementation
[[Page 31703]]
to mean that site-specific criteria, variances, and other actions would
be prohibited or severely limited by the CTR. Site-specific criteria,
variances and other actions modifying criteria are neither prohibited
nor limited by the CTR. The State, if it so chooses, still can make
these changes to its water quality standards, subject to EPA approval.
However, with this Federal rule in effect, the State cannot implement
any modifications that are less stringent than the CTR without an
amendment to the CTR to reflect these modifications. EPA will make
every effort to expeditiously accommodate Federal rulemaking of
appropriate modifications to California's water quality standards. In
the preamble to the proposed CTR, and here today, EPA is emphasizing
that these efforts to amend the CTR on a case-by-case basis will
generally increase the time before a modification can be implemented.
4. Wet Weather Flows
EPA has for a longtime maintained that CWA section 301(b)(1)(C)
applies to NPDES permits for discharges from municipal separate storm
sewer systems. Recently, the U.S. Court of Appeals for the Ninth
Circuit upheld NPDES permits issued by EPA for five Arizona municipal
separate storm sewer systems and addressed this issue specifically.
Defenders of Wildlife, et al. v. Browner, No. 98-71080 (9th Cir.,
October 1999). The Court held that the CWA does not require ``strict
compliance'' with State water quality standards for municipal storm
sewer permits under section 301(b)(1)(C), but that at the same time,
the CWA does give EPA discretion to incorporate appropriate water
quality-based effluent limitations under another provision, CWA section
402(p)(3)(B)(iii).
The Court based its decision on the structure of section 402(p)(3),
which contains distinct language for discharges of industrial storm
water and municipal storm water. In section 402(p)(3)(A), Congress
requires that ``dischargers associated with industrial activity shall
meet all applicable provisions of [section 402] and section [301].'' 33
U.S.C. section 1342(p)(3)(A). The Court noted, therefore, that by
incorporation, industrial storm water discharges need to achieve ``any
more stringent limitation, including those necessary to meet water
quality standards * * *'' The Court explained that industrial storm
water discharges ``must comply strictly with State water quality
standards'' but that Congress chose not to include a similar provision
for municipal storm sewer discharges, including instead a requirement
for controls to reduce pollutants to the maximum extent practicable or
MEP standard in section 402(p)(3)(B). Reading the two related sections
together, the Court concluded that section 402(p)(3)(B)(iii) does not
require ``strict compliance'' by municipal storm sewer discharges
according to section 301(b)(1)(C). At the same time, however, the Court
found that the language in CWA section 402(p)(3)(B)(iii) which states
that permits for discharges from municipal storm sewers shall require
``such other provisions as the Administrator of the state determines
appropriate for the control of such pollutants'' provides EPA with
discretion to incorporate provisions lending to ultimate compliance
with water quality standards.
EPA believes that compliance with water quality standards through
the use of Best Management Practices (BMPs) is appropriate. EPA
articulated its position on the use of BMPs in storm water permits in
the policy memorandum entitled, ``Interim Permitting Approach for Water
Quality-Based Effluent Limitations In Storm Water Permits'' which was
signed by the Assistant Administrator for Water, Robert Perciasepe on
August 1, 1996 (61 FR 43761, August 9, 1996). A copy of this memorandum
is contained in the administrative record for today's rule. The policy
affirms the use of BMPs as a means to attain water quality standards in
municipal storm water permits, and embraces BMPs as an interim
permitting approach.
The interim permitting approach uses BMPs in first-round storm
water permits, and expanded or better-tailored BMPs in subsequent
permits, where necessary, to provide for the attainment of water
quality standards. In cases where adequate information exists to
develop more specific conditions or limitations to meet water quality
standards, these conditions or limitations are to be incorporated into
storm water permits, as necessary and appropriate.
This interim permitting approach, however, only applies to EPA. EPA
encourages the State to adopt a similar policy for municipal storm
water permits. This interim permitting approach provides time, where
necessary, to more fully assess the range of issues and possible
options for the control of storm water discharges for the protection of
water quality. More information on this issue is included in the
response to comment document in response to specific storm water issues
raised by commenters.
5. Schedules of Compliance
A compliance schedule refers to an enforceable sequence of interim
requirements in a permit leading to ultimate compliance with water
quality-based effluent limitations or WQBELs in accordance with the
CWA. The authorizing compliance schedule provision authorizes, but does
not require, the permit issuing authority in the State of California to
include such compliance schedules in permits under appropriate
circumstances. The State of California is authorized to administer the
National Pollutant Discharge Elimination System (NPDES) program and may
exercise its discretion when deciding if a compliance schedule is
justified because of the technical or financial (or other)
infeasibility of immediate compliance. An authorizing compliance
schedule provision is included in today's rule because of the potential
for existing dischargers to have new or more stringent effluent
limitations for which immediate compliance would not be possible or
practicable.
New and Existing Dischargers: The provision allows compliance
schedules only for an ``existing discharger'' which is defined as any
discharger which is not a ``new California discharger.'' A ``new
California discharger'' includes ``any building, structure, facility,
or installation from which there is, or may be, a `discharge of
pollutants', the construction of which commences after the effective
date of this regulation.'' These definitions are modeled after the
existing 40 CFR 122.2 definitions for parallel terms, but with a cut-
off date modified to reflect this rule. Only ``new California
dischargers'' are required to comply immediately upon commencement of
discharge with effluent limitations derived from the criteria in this
rule. For ``existing dischargers'' whose permits are reissued or
modified to contain new or more stringent limitations based upon
certain water quality requirements, the permit could allow up to five
years, or up to the length of a permit, to comply with such
limitations. The provision applies to new or more stringent effluent
limitations based on the criteria in this EPA rule.
EPA has included ``increasing dischargers'' within the category of
``existing dischargers'' since ``increasing dischargers'' are existing
facilities with a change--an increase--in their discharge. Such
facilities may include those with seasonal variations. ``Increasing
dischargers'' will already have treatment systems in place for their
current discharge, thus, they have less
[[Page 31704]]
opportunity than a new discharger does to design and build a new
treatment system which will meet new water quality-based requirements
for their changed discharge. Allowing existing facilities with an
increasing discharge a compliance schedule will avoid placing the
discharger at a competitive disadvantage vis-a-vis other existing
dischargers who are eligible for compliance schedules.
Today's rule does not prohibit the use of a short-term ``shake down
period'' for new California dischargers as is provided for new sources
or new dischargers in 40 CFR 122.29(d)(4). These regulations require
that the owner or operator of (1) a new source; (2) a new discharger
(as defined in 40 CFR 122.2) which commenced discharge after August 13,
1979; or (3) a recommencing discharger shall install and implement all
pollution control equipment to meet the conditions of the permit before
discharging. The facility must also meet all permit conditions in the
shortest feasible time (not to exceed 90 days). This shake-down period
is not a compliance schedule. This approach may be used to address
violations which may occur during a new facility's start-up, especially
where permit limits are water quality-based and biological treatment is
involved.
The burden of proof to show the necessity of a compliance schedule
is on the discharger, and the discharger must request approval from the
permit issuing authority for a schedule of compliance. The discharger
should submit a description of the minimum required actions or
evaluations that must be undertaken in order to comply with the new or
more restrictive discharge limits. Dates of completion for the required
actions or evaluations should be included, and the proposed schedule
should reflect the shortest practicable time to complete all minimum
required actions.
Duration of Compliance Schedules: Today's rule provides that
compliance schedules may provide for up to five years to meet new or
more stringent effluent limitations in those limited circumstances
where the permittee can demonstrate to the permit authority that an
extended schedule is warranted. EPA's regulations at 122.47 require
compliance with standards as soon as possible. This means that permit
authorities should not allow compliance schedules where the permittee
fails to demonstrate their necessity. This provision should not be
considered a default compliance schedule duration for existing
facilities.
In instances where dischargers wish to conduct toxicological
studies, analyze results, and adopt and implement new or revised water
quality-based effluent limitations, EPA believes that five years is
sufficient time within which to complete this process. See the preamble
to the proposed rule.
Under this rule, where a schedule of compliance exceeds one year,
interim requirements are to be specified and interim progress reports
are to be submitted at least annually to the permit issuing authority,
in at least one-year time intervals.
The rule allows all compliance schedules to extend up to a maximum
duration of five years, which is the maximum term of any NPDES permit.
See 40 CFR 122.46. The discharger's opportunity to obtain a compliance
schedule occurs when the existing permit for that discharge is issued,
reissued or modified to contain more stringent limits based on the
water quality criteria in today's rule. Such compliance schedules,
however, cannot be extended to any indefinite point of time in the
future because the compliance schedule provision in this rule will
sunset on May 18, 2005. The sunset applies to the authorizing provision
in today's rule (40 CFR 131.38(e)), not to individual schedules of
compliance included in specific NPDES permits. Delays in reissuing
expired permits (including those which continue in effect under
applicable NPDES regulations) cannot indefinitely extend the period of
time during which a compliance schedule is in effect. This would occur
where the permit authority includes the single maximum five-year
compliance schedule in a permit that is reissued just before the
compliance schedule provision sunsets (having been previously issued
without WQBELS using the rule's criteria on the eve of the effective
date of this rule). Instead, the effect of the sunset provision is to
limit the longest time period for compliance to ten years after the
effective date of this rule.
EPA recognizes that where a permit is modified during the permit
term, and the permittee needs the full five years to comply, the five-
year schedule may extend beyond the term of the modified permit. In
such cases, the rule allows for the modified permit to contain a
compliance schedule with an interim limit by the end of the permit
term. When the permit is reissued, the permit authority may extend the
compliance schedule in the next permit, provided that, taking into
account the amount of time allowed under the previous permit, the
entire compliance schedule contained in the permit shall not exceed
five years. Final permit limits and compliance dates will be included
in the record for the permit. Final compliance dates must occur within
five years from the date of permit issuance, reissuance, or
modification, unless additional or less time is provided for by law.
EPA would prefer that the State adopt an authorizing compliance
schedule provision but recognizes that the State may not be able to
complete this action for some time after promulgation of the CTR. Thus,
EPA has chosen to promulgate the rule with a sunset provision which
states that the authorizing compliance schedule provision will cease or
sunset on May 18, 2005. However, if the State Board adopts, and EPA
approves, a statewide authorizing compliance schedule provision
significantly prior to May 18, 2005, EPA will act to stay the
authorizing compliance schedule provision in today's rule.
Additionally, if a Regional Board adopts, and the State Board adopts
and EPA approves, a Regional Board authorizing compliance schedule
provision, EPA will act to stay today's provision for the appropriate
or corresponding geographic region in California. At that time, the
State Board's or Regional Board's authorizing compliance schedule
provision will govern the ability of the State regulatory entity to
allow a discharger to include a compliance schedule in a discharger's
NPDES permit.
Antibacksliding: EPA wishes to address the potential concern over
antibacksliding where revised permit limits based on new information
are the result of the completion of additional studies. The Agency's
interpretation of the CWA is that the antibacksliding requirements of
section 402(o) of the CWA do not apply to revisions to effluent
limitations made before the scheduled date of compliance for those
limitations.
State Compliance Schedule Provisions: EPA supports the State in
adopting a statewide provision independent of or as part of the effort
to readopt statewide water quality control plans, or in adopting
individual basin-wide compliance schedule provisions through its nine
Regional Water Quality Control Boards (RWQCBs). The State and RWQCBs
have broad discretion to adopt a provision, including discretion on
reasonable lengths of time for final compliance with WQBELs. EPA
recognizes that practical time frames within which to set interim goals
may be necessary to achieve meaningful, long-term improvements in water
quality in California.
At this time, two RWQCBs have adopted an authorizing compliance
schedule provision as an amendment to
[[Page 31705]]
their respective Basin Plans during the Boards' last triennial review
process. The Basin Plans have been adopted by the State and have come
to EPA for approval. Thus, the Basin Plans' provisions are effective
for the respective Basins. If and when EPA approves of either Regional
Basin Plan, EPA will expeditiously act to amend the CTR, staying its
compliance schedule provision, for the appropriate geographic region.
6. Changes From Proposed Rule
A few changes were made in the final rule from the proposal both as
a result of the Agency's consideration of issues raised in public
comments and Endangered Species Act consultation with the U.S. Fish and
Wildlife Service (FWS) and U.S. National Marine Fisheries Service
(NMFS). The important changes include: reserving the mercury aquatic
life criteria; reserving the selenium freshwater acute aquatic life
criterion; reserving the chloroform human health criteria; and adding a
sunset provision to the authorizing compliance schedule provision. EPA
also clarified that the CTR will not replace priority toxic pollutant
criteria which were adopted by the San Francisco Regional Water Quality
Control Board in its 1986 Basin Plan, adopted by the State Board, and
approved by EPA; specifying the harmonic mean for human health criteria
for non-carcinogens and adding a provision which explicitly allows the
State to adopt and implement an alternative averaging period,
frequency, and design flow for a criterion after opportunity for public
comment.
The first two changes, the reservation of mercury criteria and
selenium criterion, are discussed in more detail below in Section L.,
The Endangered Species Act (ESA). The selenium criterion is also
discussed in more detail above in Section E., Derivation of Criteria,
in subsection 2.b., Freshwater Acute Selenium Criterion. EPA has also
decided to reserve a decision on numeric criteria for chloroform and
therefore not promulgate chloroform criteria in the final rule. As part
of a large-scale regulation promulgated in December l998 under the Safe
Drinking Water Act, EPA published a health-based goal for chloroform
(the maximum contaminant level goal or MCLG) of zero, see 63 FR 69390,
Dec. 16, 1998. EPA provided new data and analyses concerning chloroform
for public review and comment, including a different, mode of action
approach for estimating the cancer risk, 63 FR 15674, March 31, 1998,
but did not reach a conclusion on how to use that new information in
establishing the final MCLG, pending further review by the Science
Advisory Board. EPA has now concluded that any further actions on water
quality criteria should take into account the new data and analysis as
reviewed by the SAB. This decision is consistent with a recent federal
court decision vacating the MCLG for chloroform (Chlorine Chemistry
Council v. EPA, No. 98-1627 (DC Cir., Mar. 31,2000)). EPA intends to
reassess the human health 304(a) criteria recommendation for
chloroform. For these reasons, EPA has decided to reserve a decision on
numeric criteria for chloroform in the CTR and not promulgate water
quality criteria as proposed. Permitting authorities in California
should continue to rely on existing narrative criteria to establish
effluent limitations as necessary for chloroform.
The sunset provision for the authorizing compliance schedule
provision has been added to ease the transition from a Federal
provision to the State's provision that was adopted in March 2000 as
part of its' new statewide implementation plan. The sunset provision is
discussed in more detail in Section G.5 of today's preamble. The CTR
matrix at 40 CFR 131.38(b)(1) makes it explicit that the rule does not
supplant priority toxic pollutant criteria which were adopted by the
San Francisco Regional Water Quality Control Board in its 1986 Basin
Plan, adopted by the State Board, and approved by EPA. This change is
discussed more fully in Section D.4. of today's preamble. EPA modified
the design flow for implementing human health criteria for non-
carcinogens from a 30Q5 to a harmonic mean. Human health criteria for
non-carcinogens are based on an RfD, which is an acceptable daily
exposure over a lifetime. EPA matched the criteria for protection over
a human lifetime with the longest stream flow averaging period, i.e.,
the harmonic mean. Lastly, the CTR now contains language which is
intended to make it easier for the State to adopt and implement an
alternative averaging period, frequency and related design flow, for
situations where the default parameters are inappropriate. This
language is found at 40 CFR 131.38(c)(2)(iv).
H. Economic Analysis
This final rule establishes ambient water quality criteria which,
by themselves, do not directly impose economic impacts (see section K).
These criteria combined with the State-adopted designated uses for
inland surface waters, enclosed bays and estuaries, and implementation
policies, will establish water quality standards. Until the State
implements these water quality standards, there will be no effect of
this rule on any entity. The State will implement these criteria by
ensuring that NPDES permits result in discharges that will meet these
criteria. In so doing, the State will have considerable discretion.
EPA has analyzed the indirect potential costs and benefits of this
rule. In order to estimate the indirect costs and benefits of the rule,
an appropriate baseline must be established. The baseline is the
starting point for measuring incremental costs and benefits of a
regulation. The baseline is established by assessing what would occur
in the absence of the regulation. At present, State Basin Plans contain
a narrative water quality criterion stating that all waters shall be
maintained free of toxic substances in concentrations that produce
detrimental physiological responses in human, plant, animal, or aquatic
life. EPA's regulation at 40 CFR 122.44(d)(1)(vi) requires that where a
discharge causes or has the reasonable potential to cause an excursion
above a narrative criterion within a State water quality standard, the
permitting authority must establish effluent limits but may determine
limits using a number of options. These options include establishing
``effluent limits on a case-by-case basis, using EPA's water quality
criteria published under section 304(a) of the CWA, supplemented where
necessary by other relevant information'' (40 CFR 122.44(d)(1)(vi)(B)).
Thus, to the extent that the State is implementing its narrative
criteria by applying the CWA section 304(a) criteria, this rule does
not impose any incremental costs because the criteria in this rule are
identical to the CWA section 304(a) criteria. Alternatively, to the
extent that the State is implementing its narrative criteria on a
``case-by-case basis'' using ``other relevant information'' in its
permits this rule may impose incremental indirect costs because the
criteria in these permits may not be based on CWA 304(a) criteria. Both
of these approaches to establishing effluent limits are in full
compliance with the CWA.
Because a specific basis for effluent limits in all existing
permits in California is not known, it is not possible to determine a
precise estimate of the indirect costs of this rule. The incremental
costs of the rule may be as low as zero, or as high as $61 million. The
high estimate of costs is based on the possibility that most of the
effluent limits now in effect are not based on 304(a) criteria. EPA
evaluated these
[[Page 31706]]
indirect costs using two different approaches. The first approach uses
existing discharge data and makes assumptions about future State NPDES
permit limits. Actual discharge levels are usually lower than the level
set by current NPDES permit limits. This approach, representing the
low-end scenario, also assumes that some of the discretionary
mechanisms that would enhance flexibility (e.g., site specific
criteria, mixing zones) would be granted by the State. The second
approach uses a sample of existing permit limits and assumes that
dischargers are actually discharging at the levels contained in their
permits and makes assumptions about limits statewide that would be
required under the rule. This approach, representing the high-end
scenario, also assumes that none of the discretionary mechanisms that
would enhance flexibility (e.g., site specific criteria, mixing zones)
would be granted by the State. These two approaches recognize that the
State has significant flexibility and discretion in how it chooses to
implement standards within the NPDES permit program, the EA by
necessity includes many assumptions about how the State will implement
the water quality standards. These assumptions are based on a
combination of EPA guidance and current permit conditions for the
facilities examined in this analysis. To account for the uncertainty of
EPA's implementation assumptions, this analysis estimates a wide range
of costs and benefits. By completing the EA, EPA intends to inform the
public about how entities might be potentially affected by State
implementation of water quality standards in the NPDES permit program.
The costs and benefits sections that follow summarize the methodology
and results of the analysis.
1. Costs
EPA assessed the potential compliance costs that facilities may
incur to meet permit limits based on the criteria in today's rule. The
analysis focused on direct compliance costs such as capital costs and
operation and maintenance costs (O&M) for end-of-pipe pollution
control, indirect source controls, pollution prevention, monitoring,
and costs of pursuing alternative methods of compliance.
The population of facilities with NPDES permits that discharge into
California's enclosed bays, estuaries and inland surface waters
includes 184 major dischargers and 1,057 minor dischargers. Of the 184
major facilities, 128 are publicly owned treatment works (POTWs) and 56
are industrial facilities. Approximately 2,144 indirect dischargers
designated as significant industrial users discharge wastewater to
those POTWs. In the EA for the proposed CTR, EPA used a three-phased
process to select a sample of facilities to represent California
dischargers potentially affected by the State's implementation of
permit limits based on the criteria contained in this rule.
The first phase consisted of choosing three case study areas for
which data was thought to exist. The three case studies with a total of
5 facilities included: the South San Francisco Bay (the San Jose/Santa
Clara Water Pollution Control Plant and Sunnyvale Water Pollution
Control Plant); the Sacramento River (the Sacramento Regional
Wastewater Treatment Plant); and the Santa Ana River (the City of
Riverside Water Quality Control Plant and the City of Colton Municipal
Wastewater Treatment Facility). The second phase consisted of selecting
five additional major industrial dischargers to complement the case-
study POTWs.
The third phase involved selecting 10 additional facilities to
improve the basis for extrapolating the costs of the selected sample
facilities to the entire population of potentially affected
dischargers. The additional 10 facilities were selected such that the
group examined: (1) Was divided between major POTWs and major
industrial discharger categories in proportion to the numbers of
facilities in the State; (2) gave greater proportionate representation
to major facilities than minor facilities based on a presumption that
the majority of compliance costs would be incurred by major facilities;
(3) gave a proportionate representation to each of four principal
conventional treatment processes typically used by facilities in
specified industries in California; and (4) was representative of the
proportionate facilities located within the different California
Regional Water Quality Control Boards. Within these constraints,
facilities were selected at random to complete the sample.
In the EA for today's final rule, EPA primarily used the same
sample as the EA for the proposed rule with some modifications. EPA
increased the number of minor POTWs and minor industrial facilities in
the sample. EPA randomly selected four new minor POTW facilities and
five new minor industrial facilities to add to the sample. The number
of sample facilities selected in each area under the jurisdiction of a
Regional Water Quality Control Board was roughly proportional to the
universe of facilities in each area.
For those facilities that were projected to exceed permit limits
based on the criteria, EPA estimated the incremental costs of
compliance. Using a decision matrix or flow chart, costs were developed
for two different scenarios--a ``low-end'' cost scenario and a ``high-
end'' cost scenario--to account for a range of regulatory flexibility
available to the State when implementing permit limits based on the
water quality criteria. The assumptions for baseline loadings also vary
over the two scenarios. The low-end scenario generally assumed that
facilities were discharging at the maximum effluent concentrations
taken from actual monitoring data, while the high-end scenario
generally assumed that facilities were discharging at their current
effluent limits. The decision matrix specified assumptions used for
selection of control options, such as optimization of existing
treatment processes and operations, in-plant pollutant minimization and
prevention, and end-of-pipe treatment.
The annualized potential costs that direct and indirect dischargers
may incur as a result of State implementation of permit limits based on
water quality standards using today's criteria are estimated to be
between $33.5 million and $61 million. EPA believes that the costs
incurred as a result of State implementation of these permit limits
will approach the low-end of the cost range. Costs are unlikely to
reach the high-end of the range because State authorities are likely to
choose implementation options that provide some degree of flexibility
or relief to point source dischargers. Furthermore, cost estimates for
both scenarios, but especially for the high-end scenario, may be
overstated because the analysis tended to use conservative assumptions
in calculating these permit limits and in establishing baseline
loadings. The baseline loadings for the high-end were based on current
effluent limits rather than actual pollutant discharge data. Most
facilities discharge pollutants in concentrations well below current
effluent limits. In addition, both the high-end and low-end cost
estimates in the EA may be slightly overstated since potential costs
incurred to reduce chloroform discharges were included in these
estimates. EPA made a decision to reserve the chloroform human health
criteria after the EA was completed.
Under the low-end cost scenario, major industrial facilities and
POTWs would incur about 27 percent of the potential costs, indirect
dischargers would incur about 70 percent of the potential costs, while
minor dischargers would incur about 3 percent. Of the major direct
dischargers, POTWs would incur the largest share of projected costs (87
percent). However, distributed