Great Lakes Water Quality Initiative Tier II Values for the Protection of Aquatic Life, 1994 Environmental Conference Proceedings

William R. Alsop, Jay Unwin

The Great Lakes Water Quality Initiative (GLWQI) contains protocols and methodologies for developing criteria for the protection of aquatic life. These protocols consist of two parts. Tier I criteria contain minor modifications of the current EPA Ambient Water Quality Criteria (AWQCs) and are developed when sufficient acute toxicity test data are available for representative species from at least eight taxonomic groups. Tier II values are developed for the protection of aquatic life for those compounds without the requisite amount of data to calculate a Tier I criteria. The Tier II values include conservative Secondary Acute Factors (SAFs) that insure that the calculated Tier II value will be below the corresponding means that Tier II values calculated from data bases with little information will be extremely conservative, in some cases below analytical detection limits. This paper will discuss the development of SAFs and will demonstrate how the combination of a number of conservative assumptions results in potential Tier II values that will be difficult to measure and employ as criteria.