ODEQ Biomonitoring – Whole Effluent Toxicity Testing Changes

The Oklahoma Department of Environmental Quality (ODEQ) is proposing to modify its rules concerning biomonitoring (whole effluent toxicity, or WET) requirements for wastewater dischargers. 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. Additionally, the proposed rule modifications further refine when a facility may request a biomonitoring organism change from Daphnia pulex or Ceriodaphnia dubia to Daphnia magna. Finally, the 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.

Caltha LLP provides expert technical support to clients nationwide to address State water quality standards. Caltha provides specialized expertise in biomonitoring, aquatic toxicology and impacts to aquatic communities.

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