Whole Effluent Toxicity (WET)

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) from toxic pollutants such as pesticides, dioxins/furans, and polycyclic aromatic hydrocarbons (PAHs).  

DRBC's ambient toxicity monitoring program is the only on-going program that tests for water column toxicity in the Delaware Estuary. Monitoring toxicity helps assess compliance with regulatory standards, which state that no adverse effects should be observed in toxicity tests with undiluted ambient water. 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. 

Reports and Informational Links

Monitoring the Tidal Delaware River for Ambient Toxicity: 2012 Narrative Report (pdf 543 KB; April 2013)

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