See also:

  1. Whole Effluent Toxicity Testing
  2. Toxicity Identification Evaluation/Toxicity Reduction Evaluation
  3. Dredged Material Testing
  4. Sediment and Soil Toxicity Testing
  5. Product Testing
  6. Additional Toxicity Testing

For further information, please contact:


Wayne McCulloch, Director, wmcculloch@eaest.com.


Wayne McCulloch



EA's WER studies provide data that can result in cost-saving NPDES permit modifications.

Location: Natural Resources > Ecotoxicology Laboratory > Water Effect Ratio Studies

Water Effect Ratio Studies

EA assists clients with the development of site-specific water quality criteria for individual metals through the performance of water effect ratio (WER) testing. This type of study enables clients to modify National Pollutant Discharge Elimination System (NPDES) discharge permit single metal permit limits. This testing is based on the U.S. Environmental Protection Agency (EPA’s) recognition that the metals can be substantially less toxic in an effluent/receiving water matrix than in clean laboratory water, on which single metal permit limits are based.

EA assists clients with the following permit modification procedures:

  • EPA Water Effect Ratio
  • EPA Recalculation Procedure
  • EPA Resident Species Procedure.