SECTION 252:690-3-31. WET test requirements

  WET testing is required for all major dischargers and those minor dischargers identified by DEQ as posing a significant unaddressed toxic risk. Q* is calculated as described in Appendix D.

(1)   The following requirements apply to all WET testing:

(A)   Acute testing only. Acute testing only is required for all discharges to lakes and where Q* < 0.054 in streams.

(B)   Chronic testing only. Chronic testing only is required where Q* > 0.3333.

(C)   Acute and chronic testing, except for Daphnia Magna. Both acute and chronic testing are required where 0.054 #Q* # 0.3333.

(2)   Acute and/or chronic testing using Daphnia magna. Acute and/or chronic testing using Daphnia magna may substitute for acute and/or chronic testing for Daphnia pulex or Ceriodaphnia dubia in the following circumstances:

(A)   acute testing using Daphnia magna for streams where the instream concentration of TDS is less than or equal to 1000 mg/l after mixing using the 7Q2, may be considered by the DEQ on a case-by-case basis where the TDS level in an effluent has been demonstrated to cause WET test failures to Daphnia pulex.

(B)   acute testing using Daphnia magna for streams where the instream concentration of TDS is greater than 1000 mg/l after mixing using the 7Q2, may be considered on a case-by-case basis where the TDS level in an effluent has been demonstrated to cause WET test failures to Daphnia pulex and the background TDS level of the receiving stream causes toxicity to Daphnia pulex in a control dilution (0% effluent).

(C)   chronic testing using Daphnia magna may be considered by the DEQ on a case-by-case basis where the TDS level in the effluent has demonstrated WET test failures to Ceriodaphnia dubia, where the background TDS levels of the receiving stream causes toxicity to Ceriodaphnia dubia, in a control dilution (0% effluent), and where the permittee can demonstrate that the ionic ratios in the effluent are similar to the ionic ratios in the receiving stream.

(3)   Mussels. Acute and/or chronic testing of mussels shall be required if the DEQ determines that the discharge may affect an indigenous population(s) of mussels.

[Source: Added at 19 Ok Reg 1721, eff 6-13-02; Amended at 24 Ok Reg 1542, eff 6-15-07; Amended at 26 Ok Reg 1962, eff 7-1-09]