Whole Effluent Toxicity (WET) is the total effect of wastewater, ambient water, or stormwater on aquatic organisms such as fish and macroinvertebrates typically performed in the laboratory. WET tests are extensively used to measure the effects of wastewaters from industrial and municipal facilities on specific test organisms' ability to survive, grow and reproduce. WET testing is used to assess and regulate the combined effects of all constituents of a complex effluent rather than the traditional approach of controlling the toxicity of single chemicals or constituents. WET testing implements national, basin states, and DRBC narrative water quality policies of no toxics in toxic amounts.  The DRBC and Pennsylvania have also adopted numeric water quality criteria to protect against acute or short-term effects on aquatic life (0.3 Toxic Units acute) and chronic or longer-term effects on aquatic life (1.0 Toxic Units chronic).  

Monitoring toxicity is an essential component of programs designed to protect the valued resources of the waters of the Delaware River Basin. As part of ongoing programs to control toxic substances in the Delaware Estuary, the DRBC conducts periodic monitoring of ambient water toxicity in the Estuary and has requested monitoring of acute and chronic effluent toxicity by dischargers. 

Toxicity Testing in Ambient Water Quality Assessment (pdf 3.26 MB; DRBC presentation given at the January 2013 Partnership for the Delaware Estuary Science Summit)

MacGillivray, AR, DE Russell, SS Brown, TJ Fikslin, R Greene, RA Hoke , C Nally and L O'Donnell. 2011. Monitoring the Tidal Delaware River for Ambient Toxicity. Integr. Environ. Assess. Manag.: 7 (3) 466-477. 

Update on Monitoring Ambient Aquatic Toxicity (pdf 2.2 MB; presentation given at Apr. 2010 Meeting of the DRBC Toxics Advisory Committee's Ambient Toxicity Workgroup) 

Society of Environmental Toxicology and Chemistry Technical Issue Paper (SETACTIP): Whole Effluent Toxicity Testing (pdf 126 KB)

U.S. Environmental Protection Agency: Whole Effluent Toxicity