(1) A discharge is in compliance with the narrative water quality standard for acute toxicity when the most recent acute toxicity test has shown no statistically significant difference in response between the acute critical effluent concentration and a control.

(a) Acute toxicity testing shall be performed using one hundred percent effluent, the acute critical effluent concentration, and a control.

(b) The acute critical effluent concentrations in a whole effluent toxicity test shall be compared to the control using the method in Appendix H of EPA/600/4-89/001 or an equivalent method approved by the department.

(c) If a statistically significant difference in response is determined between the control and the acute critical effluent concentration in an acute toxicity test, then the effluent has failed the test for compliance with the whole effluent acute toxicity limit and the permittee shall immediately begin the process described in WAC 173-205-090.

(d) The compliance test for acute toxicity shall be considered to be a maximum daily discharge permit limitation.

(2) A discharge is in compliance with the narrative water quality standard for chronic toxicity when the most recent chronic toxicity test has shown no statistically significant difference in response between the chronic critical effluent concentration and a control.

(a) Chronic toxicity testing shall be performed using the acute critical effluent concentration, the chronic critical effluent concentration, and a control.

(b) The chronic critical effluent concentrations in a whole effluent toxicity test shall be compared to the control using the method in Appendix H of EPA/600/4-89/001 or an equivalent method approved by the department.

(c) If a statistically significant difference in response is determined between the control and the chronic critical effluent concentration in a chronic toxicity test, then the effluent has failed the test for compliance with the whole effluent chronic toxicity limit and the permittee shall immediately begin the process described in WAC 173-205-090.

(d) The compliance test for chronic toxicity shall be considered to be a maximum daily discharge permit limitation.

(3) During compliance monitoring, the one hundred percent effluent concentration in an acute test and the acute critical effluent concentration in a chronic test shall be performed in order to assess the attainment of the performance standards in accordance with WAC 173-205-120(1).

(4) Toxicity tests conducted for monitoring for compliance with whole effluent toxicity limits shall meet, as appropriate, the acute or chronic statistical power standards. If a whole effluent toxicity test does not meet appropriate statistical power standard, then the effluent shall immediately be resampled and the toxicity test repeated with the number of replicates increased in order to meet the statistical power standard.

(5) The permittee shall provide the department with all information and records required in the permit in order to evaluate toxicity test results to determine their adequacy for effluent characterization, compliance monitoring, effluent screening tests, or rapid screening tests.

(a) The result of the most recent reference toxicant test conducted by the laboratory for that toxicity test method shall accompany each whole effluent toxicity test result.

(b) Every reference toxicant test shall be conducted on a minimum of five dilutions.

(c) The response in all replicates at every effluent concentration and the control shall be reported for all tests analyzed by hypothesis testing so that the department can check for compliance with statistical power standards and for anomalous test results which should not be used for the compliance determinations in this chapter.