(1) All samples taken for whole effluent toxicity testing shall be handled as specified in the permit and in any EPA manuals referenced in the permit.

(a) No attempts shall be made before or during the whole effluent toxicity test to modify the sample to remove or otherwise change any toxicant except as provided in subsection (3) of this section.

(b) Except as provided in subsection (3) of this section, no attempts shall be made before or during the whole effluent toxicity test to adjust the hardness, dissolved oxygen, pH, or any other physical or chemical property of the sample, dilution water, or test solutions except as required in the toxicity test method, in the permit, or in appropriate EPA manuals.

(c) For those permittees who received permits prior to the effective date of this chapter, the department may approve in writing the request of a permittee to modify samples, dilution water, or test solutions as long as such modifications meet the intent of this chapter.

(2) Except as provided in subsection (3) of this section, the department shall require that samples for whole effluent toxicity testing be taken just before the chlorinator for dischargers who meet all of the following:

(a) Add chlorine to treated effluent for the purpose of disinfection;

(b) Have received effluent limits based on the water quality criteria for chlorine; and

(c) Are developing or implementing plans to achieve compliance with the chlorine limits.

(3) If any permittee has begun implementing a plan to install dechlorination, then the sample may, as specified by the department, be chemically dechlorinated by a similar method before whole effluent toxicity testing.

(4) The whole effluent toxicity test shall be run on an unmodified sample of final effluent if the effluent can meet effluent limits based on the water quality criteria for chlorine.