Current through all regulations passed and filed through September 16, 2024
(A) For discharges of
whole effluent toxicity (WET) to flowing receiving waters, the WQBEL for WET
shall be calculated using the following mass balance equation:
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Where:
WQC = toxicity level as established in paragraph (A) of
rule 3745-1-44
of the Administrative Code.
Qeff = effluent flow as established in
paragraph (A)(4) of rule
3745-2-05 of the Administrative
Code.
Qup = stream design flow as established
in paragraphs (A)(1) and (A)(2) of rule
3745-2-05 of the Administrative
Code.
WQup = background water quality as
established in paragraph (C) of this rule.
An alternative modeling method may be used if the discharger
demonstrates to Ohio EPA's satisfaction that it is appropriate and protective
of water quality criteria.
(B) Background water
quality for WET calculations shall be determined using the following
requirements.
(1) Use 0.0chronic toxic units (TUc
) for background chronic toxicity unless there is
specific information indicating additivity between the discharge and another
source or sources in the background waters. If there is evidence of additivity,
use 0.5 TUc for background chronic toxicity. If
sufficient data exists, use the average value of the data for background
chronic toxicity.
(2) To establish
background levels of acute toxicity, Ohio EPA shall consider the likelihood for
acute toxicity to exist in the background waters of the discharge using
available information on the following factors:
(a) The degree and type of biological effects
in the background waters determined with biological index measurements.
(b) The frequency and magnitude of acute
toxicity occurrences in the background waters used in toxicity tests.
(c) Data on additive, synergistic, or
antagonistic effects of a discharge when it is combined with receiving
water.
(d) The
quality and quantity of each type of data available.
(e) Other relevant factors.
(3) After an analysis of the
likelihood for acute toxicity to exist in the background waters of the
discharge, background toxicity shall be set equal to one of the following
values:
(a) If there is likelihood, use
0.15acute toxic units (TUa
) or if sufficient data are available and
indicate that acute toxicity levels are routinely exceeded, use the average
value of the data.
(b) If
there is no likelihood or there are no data available to make an assessment of
the likelihood, use 0.0 TUa
.
(c) If background toxicity is due to an
identifiable discharge that has not yet achieved toxicity limits required by
paragraph (B) of rule
3745-33-07 of the Administrative
Code, use 0.0 TUa.
(C)
Wasteload allocation (WLA) results for acute toxicity shall not exceed 1.0
TUa unless the provisions in paragraph (B) of rule
3745-33-07 of the Administrative
Code are met.
(D) Multiple discharges. When the director determines
that it is necessary to consider multiple discharges in a WLA, the procedures
defined in paragraph (A)(8) of rule
3745-2-05 of the Administrative
Code shall be followed.
(E) WQBELs for WET for
direct discharges to lakes or non-flowing receiving waters.
(1) WLAs to maintain chronic toxicity levels
for direct discharges to non-flowing receiving waters shall be determined using
the following equation:
11 (WQC) - 10 (BACK)
Where:
WQC = chronic toxicity level as established in paragraph (A) of
rule 3745-1-44
of the Administrative Code.
BACK = background water quality as established in paragraph
(B) of
this rule.
(2) WLAs for
acute levels shall be set equal to 1.0 TUa.
(3) A mixing demonstration may be conducted
in accordance with rule 3745-1-06 of the Administrative Code to justify a
different quantity of receiving water in the WLA determination for chronic
levels. Allocation results for acute toxicity shall not exceed 1.0
TUa unless the provisions in paragraph (B) of rule
3745-33-07 of the Administrative
Code are met.
(4) An alternate
modeling method may be used if the discharger demonstrates to Ohio EPA's
satisfaction that it is appropriate and protective of water quality
levels.
