Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-205 - Whole effluent toxicity testing and limits
Section 173-205-050 - Effluent testing for toxicity
Universal Citation: WA Admin Code 173-205-050
Current through Register Vol. 24-06, March 15, 2024
(1) The department shall require dischargers meeting the risk definition of WAC 173-205-040(1) to characterize the effluent for toxicity during permit application or during the first year of the permit term.
(a) Each
effluent sample during effluent characterization shall be tested for toxicity
using multiple species which shall at a minimum include a fish, an
invertebrate, and, if deemed appropriate by the department, a plant.
(b) The sampling frequency during effluent
characterization and compliance monitoring shall be at least twice per year and
sampling shall be timed to cover the seasonal extremes of the year such as
wet-dry or cold-hot.
(c) The
duration of an acute toxicity test performed for effluent characterization or
compliance monitoring shall be forty-eight hours for an invertebrate and
ninety-six hours for a fish.
(d)
For effluent characterization and compliance monitoring, the department shall
use toxicity tests published in 40 C.F.R. Part 136, in EPA toxicity test
manuals, or those methods approved by the department considering the following
criteria:
(i) The existence of a detailed
written description of the test method;
(ii) Interlaboratory comparisons of the
method;
(iii) Adequate testing with
complex wastes such as wastewater;
(iv) Measurement of an effect that is clearly
adverse to the production of the species such as reduced survival or growth,
abnormal development, or failed reproduction; and
(v) Use of test organisms that represent
taxonomic families native to the state.
(e) Toxicity testing for effluent
characterization under this section, compliance monitoring as described in WAC
173-205-070, and additional
monitoring as described in WAC
173-205-090 or
173-205-120(2)(d)
shall be performed by laboratories
accredited by the department for the specific toxicity test in accordance with
chapter 173-50 WAC.
(f) Upon
request, the department may approve the performance of toxicity tests for
effluent characterization or compliance monitoring for publicly owned treatment
works discharging less than one-half million gallons per day and small
businesses as defined in RCW 43.31.025(4) as effluent screening tests using one
hundred percent effluent for the acute toxicity tests and the acute critical
effluent concentration for the chronic toxicity tests.
(i) If an acute one hundred percent effluent
screening test demonstrates less than eighty percent survival, the test shall
be repeated as soon as possible on a fresh sample using the full dilution
series test described in the permit or regulatory order.
(ii) The chronic screening tests shall be
expected to have no statistically significant difference in response between
the acute critical effluent concentration and the control using the method in
Appendix H of EPA/600/4-89/001 or an equivalent method approved by the
department, or the test shall be repeated as soon as possible on a fresh sample
using the full dilution series test described in the permit or regulatory
order. The chronic effluent screening tests shall also meet the chronic
statistical power standard.
(2) Effluent characterization shall be used to establish:
(a) Whether a reasonable
potential under 40 C.F.R.
122.44(d)(v) for acute or
chronic toxicity exists which would require a whole effluent toxicity limit.
(i) If at the end of effluent
characterization the median survival in one hundred percent effluent is less
than eighty percent, or if any individual test result shows less than
sixty-five percent survival in one hundred percent effluent, then a reasonable
potential for acute conditions in the receiving water has been demonstrated,
and the whole effluent acute toxicity limit described in WAC
173-205-070 shall be applied to
the discharge.
(ii) If during
effluent characterization any chronic toxicity test using the method in
Appendix H of EPA/600/4-89/001 or an equivalent method approved by the
department demonstrates a statistically significant difference in response
between the control and the acute critical effluent concentration, then a
reasonable potential for chronic conditions in the receiving water has been
demonstrated, and the whole effluent chronic toxicity limit described in WAC
173-205-070 shall be applied to
the discharge.
(iii) If the acute
critical effluent concentration is unknown during effluent characterization,
all chronic toxicity tests shall determine the NOEC for comparison to the acute
critical effluent concentration when it becomes available.
(A) The determination of these NOECs shall
comply with the chronic statistical power standard.
(B) If effluent characterization is completed
and neither the acute critical effluent concentration nor the chronic critical
effluent concentration is known, then the department may require the permittee
to continue the toxicity testing as conducted in effluent characterization
except using single species tests rather than multiple species tests.
(b) The permittee shall
analyze the toxicity test data during effluent characterization to establish a
baseline toxicity level by calculating appropriate point estimates such as the
LC50, the IC50, or the
EC50.
Statutory Authority: Chapter 90.48 RCW and 40 C.F.R. 122.44. 93-20-110 (Order 91-54), § 173-205-050, filed 10/6/93, effective 11/6/93.
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