(1) If a toxicity test result fails the compliance test described in WAC 173-205-070, then the permittee shall take a new sample as soon as possible for retesting and begin additional monitoring unless the permittee chooses the option in subsection (4) of this section.

(a) If the noncompliance was with an acute toxicity limit, the additional monitoring shall be conducted weekly for four weeks using the same toxicity test as in the failed compliance test or shall be conducted on the next four discharge events in the case of an intermittent discharge.

(b) If the noncompliance was with a chronic toxicity limit, the additional monitoring shall be conducted monthly for three months using the same toxicity test as in the failed compliance test or shall be conducted on the next three discharge events in the case of an intermittent discharge.

(c) This additional monitoring shall be conducted the same as in effluent characterization and shall determine the LC50, IC50, or EC50, as appropriate, and measure compliance with the permit limit.

(d) If the permittee believes that the compliance test failure will be identified by the department as an anomalous test result in accordance with WAC 173-205-070 (5)(c), the permittee may send the department notification with the compliance test result that the compliance test result might be anomalous and that the permittee intends to take only one additional sample for toxicity testing and wait for notification from the department before completing the additional monitoring required in this subsection.

(i) The notification must identify the reason for considering the compliance test result to be anomalous.

(ii) The permittee shall take the additional sample and retest as soon as possible after receiving the compliance test result.

(iii) The additional test result shall replace the compliance test result upon determination by the department that the compliance test result was anomalous.

(iv) The permittee shall complete all of the additional monitoring required by this subsection as soon as possible after notification by the department that the compliance test result was not anomalous.

(v) If the additional sample fails the compliance test, then the permittee shall proceed without delay to complete all of the additional monitoring required by this subsection.

(e) The department may determine any compliance test result to be anomalous regardless of whether it was accompanied by permittee notification that it may be anomalous.

(f) The department may notify a permittee to take another sample for toxicity testing because a compliance test result was anomalous and could not be used to determine compliance in accordance with this section.

(2) Any permittee failing the compliance test for a whole effluent toxicity limit shall take all reasonable actions to achieve compliance including conducting a toxicity identification/reduction evaluation as defined in WAC 173-205-100.

(3) The discharger shall return to the original monitoring frequency after conducting the additional monitoring described in subsection (1) of this section.

(4) The permittee may proceed directly to a toxicity identification/reduction evaluation and not perform the additional testing.