Stressor Identification Analysis

Aquatic life can be affected by many natural and man-made stressors, including flow, sediment, heavy metals, and temperature. It can be difficult to sort out which stressor is the primary limiting factor. This is important if expensive upgrades are proposed for water quality treatment plants, but the aquatic populations are actually limited by habitat constraints. In such a case, spending money on additional treatment may result in no measurable improvements in the biology. The money may have been better spent on habitat improvements. The EPA has developed a formal stressor identification method that provides a framework for partitioning the various factors that affect aquatic life, using both graphical and statistical methods.