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 173-205-020 - Definitions

Current through Register Vol. 24-14, July 15, 2024
"Acute critical effluent concentration" means the maximum
				concentration of effluent during critical conditions at the boundary of the
				zone of acute criteria exceedance assigned in accordance with WAC 173-201A-100.
				The boundary may be based on distance or a percentage of flow. Where no zone of
				acute criteria exceedance is allowed, the acute critical effluent concentration
				shall be one hundred percent effluent.
"Acute statistical power standard" means that the maximum
				acceptable difference in survival that is not statistically significant between
				the control and the acute critical effluent concentration is twenty-nine
				percent. In order to determine if a whole effluent toxicity test with results
				that are not statistically significant meets the acute statistical power
				standard:
1.Subtract the mean survival
			 across the replicates in the acute critical effluent concentration from the
			 mean survival across the replicates in the control.
2.Divide this difference between the mean
			 survivals by the mean survival across the control replicates.
3.Multiply the result by one hundred and
			 express the product as a percent difference in survival.
4.If the percent difference in survival is
			 equal to or less than twenty-nine percent, then the whole effluent toxicity
			 test has met the power standard.
"Acute toxicity test" means a toxicity test with the death of
				test organisms as the measured response.
"Chronic critical effluent concentration" means the maximum
				concentration of effluent during critical conditions at the boundary of the
				mixing zone assigned in accordance with WAC 173-201A-100. The boundary may be
				based on distance or a percentage of flow. Where no mixing zone is allowed, the
				chronic critical effluent concentration shall be one hundred percent
				effluent.
"Chronic statistical power standard" means that the maximum
				acceptable difference in response that is not statistically significant between
				the control and the acute or chronic critical effluent concentration is
				thirty-nine percent. The chronic statistical power standard does not apply to
				Fisher's Exact Test. In order to determine if a whole effluent toxicity test
				with results that are not statistically significant meets the chronic
				statistical power standard:
1.Subtract
			 the mean of the responses across the replicates in the acute or chronic
			 critical effluent concentration from the mean of the responses across the
			 replicates in the control.
2.Divide
			 this difference between the mean responses by the mean response across the
			 control replicates.
3.Multiply the
			 result by one hundred and express the product as a percent difference in
			 response.
4.If the percent
			 difference in response is equal to or less than thirty-nine percent, then the
			 whole effluent toxicity test has met the power standard.
"Chronic toxicity test" means a toxicity test which measures a
				sublethal effect such as failed fertilization, development, growth, or
				reproduction. Organism survival is also a measured endpoint in some chronic
				toxicity tests.
"Critical conditions" means those circumstances when the
				physical, chemical, and biological characteristics of the receiving water
				environment interact with the effluent to produce the greatest potential
				adverse impact on aquatic biota and existing and characteristic water
				uses.
"Department" means the department of ecology of the state of
				Washington.
"EC50" (effective concentration, fifty
				percent) means the effluent concentration estimated to cause an adverse effect
				in fifty percent of the test organisms in a toxicity test involving a series of
				dilutions of effluent.
"Effluent characterization" means, for whole effluent toxicity,
				establishing the baseline toxicity level by toxicity testing using multiple
				species on effluent samples taken over the seasons of one year. The effluent
				characterization toxicity test results shall also be used to determine the need
				for water quality-based whole effluent toxicity limits.
"Effluent screening tests" are full duration whole effluent
				toxicity tests that are conducted as a screen for toxicity in one hundred
				percent effluent or some other high concentration of effluent. No other
				effluent concentrations (except the control) are tested until toxicity has been
				detected in the effluent screening test.
"Hypothesis testing" means the mathematical technique for
				comparing the average response of the replicates of an effluent concentration
				to the average response of the control replicates at the end of a toxicity test
				in order to determine if there is a statistically significant difference in
				response within a level of certainty such as ninety-five percent or ninety-nine
				percent. For purposes of this chapter, Fisher's Exact Test is used as a
				hypothesis test for analyzing survival in the cladoceran survival and
				reproduction test.
"IC50" (inhibition concentration, fifty
				percent) means the effluent concentration estimated to cause a fifty percent
				reduction in a biological function in a toxicity test involving a series of
				dilutions of effluent.
"LC50" (lethal concentration, fifty
				percent) means the effluent concentration estimated to cause death in fifty
				percent of the test organisms in a toxicity test involving a series of
				dilutions.
"Multiple species" toxicity testing means conducting separate
				toxicity tests using different species on the same effluent sample in order to
				assess its effect on a broad range of organisms such as fish, invertebrates, or
				plants.
"NOEC" means the "no observed effect concentration" which is
				the highest concentration of effluent in a toxicity test shown to have no
				statistically significant adverse effects when compared to an appropriate
				control.
"Point estimates" are estimates of the concentration of
				effluent resulting in a specified level of effect and are determined either
				graphically or statistically from the concentration-response relationship
				determined from a toxicity test having a series of dilutions.
"Rapid screening test" means a screening toxicity test on one
				hundred percent effluent or some other high concentration of effluent in order
				to detect unanticipated increases in toxicity. Examples of rapid screening
				tests include twenty-four hour EPA acute tests, acute toxicity tests using
				rotifers produced from cysts, bacterial bioluminescence tests, and two-day life
				cycle tests with rotifers.
"Reasonable potential" under this chapter means that the
				department has determined, in accordance with
				40 C.F.R.
				122.44(d)(v) and based on a
				whole effluent toxicity performance standard, that the effluent could cause
				in-stream toxicity in violation of WAC 173-201A-040(1).
"Species rotation" means the switching to a different toxicity
				test from the list in a discharge permit for each effluent monitoring sample
				according to a rotation schedule set by the department.
"Statistically significant" under this chapter means
				establishing that a difference in response between a control and an effluent
				concentration is likely due to toxicity and not variability. The statistical
				technique for making this determination shall be Fisher's Exact Test or a
				one-tailed hypothesis test specified or approved by the department. These
				hypothesis tests shall be conducted at the ninety-five percent confidence level
				although the department may approve tests at the ninety-nine percent confidence
				level if the statistical power of the test will not be adversely
				affected.
"Technology-based controls" means methods for the treatment,
				prevention, or control of pollutants such as best management practices,
				biological treatment, physical-chemical treatment, use of nontoxic process
				chemicals, secondary containment for spills, control of site run-on/runoff,
				equipment maintenance, equipment operation, implementing site-specific
				pollution prevention plans, and any other technique with the same goals.
"Toxicity identification/reduction evaluation" means the
				process for determining the effective control of effluent toxicity by
				identifying the toxicant and/or its source, and developing a method to reduce
				toxicity by source control or treatment.
"Toxicity test" means a direct measurement of the adverse
				effect of a substance in a controlled test using living organisms. In the
				context of this rule, "toxicity test" and "whole effluent toxicity test" are
				synonymous.
"Whole effluent toxicity" means the total toxic effect of an
				effluent measured directly with a toxicity test so that the interactions of all
				toxicants present in the effluent are assessed.
"Whole effluent toxicity performance standard" means a level of
				effluent toxicity that is consistently so much lower than is necessary to meet
				state water quality standards (chapter 173-201A WAC) that no reasonable
				potential exists to violate the water quality standards. For acute toxicity,
				the performance standard is the median survival in one hundred percent effluent
				being equal to or greater than eighty percent and no individual test result
				showing less than sixty-five percent survival in one hundred percent effluent.
				For chronic toxicity, the performance standard is no chronic toxicity test
				demonstrating a statistically significant difference in response between the
				control and a test concentration equal to the acute critical effluent
				concentration. For permittees that are ineligible for an approved mixing zone,
				the performance standard will equal or be close to equal (in the case of acute
				toxicity) the water quality-based effluent toxicity limit.
"Whole effluent toxicity test" means a toxicity test on an
				effluent.