The Oklahoma Department of Environmental Quality (ODEQ) has proposed certian modifications to State rules concerning biomonitoring (whole effluent toxicity, or WET) requirements for wastewater dischargers. Permittees with biomonitoring requirements must collect samples of their effluent periodically and conduct standardized laboratory toxicity tests to determine if the effluent exhibits any adverse responses to test organisms.
Under the proposed rules, a sublethal test failure (failure to demonstrate growth or reproduction) will be handled the same as a lethal test failure (death to the test organisms). This change is required based on changes in US EPA requirements and has already been promulgated into Oklahoma’s Water Quality Standards.
The proposed rule modifications also refine under what circumstances a facility may request a change biomonitoring organism from Daphnia pulex or Ceriodaphnia dubia to Daphnia magna.
One additional change is being proposed by ODEQ which is unrelated to biomonitoring. ODEQ has proposed rule modifications would require monthly monitoring for phosphorus and/or nitrogen if a facility is discharging to a nutrient limited watershed as designated by Oklahoma’s Water Quality Standards.
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