What is Whole Effluent Toxicity (WET) testing?
Whole Effluent Toxicity (WET) testing is an important component of the U.S. Environmental Protection Agency’s (USEPA’s) integrated approach for detecting and addressing toxicity in surface waters. The National Pollutant Discharge Elimination System (NPDES) permit program, authorized by the Clean Water Act, controls water pollution by regulating point source discharges into waters of the United States. Point sources are discrete structures such as pipes or manmade ditches. The wastewater discharges from point sources are commonly called “effluents.” Facilities must obtain permits for direct discharges to surface waters and, in many cases, for storm sewer systems. A permit specifies the conditions that must be met to discharge. Permits often include WET tests as a monitoring requirement and sometimes for compliance determination. “WET” is a term used to describe the adverse effects or toxicity to a population of aquatic organisms caused by exposure to an effluent. This toxicity can be ex
