Causal Assessment of Biological Impairment in the Bogue Homo River, Mississippi Using the U.S. EPA'S Stressor Identification Methodology

摘要

This assessment of biological impairment in the Bogue Homo River, Mississippi is taken from more than 700 court ordered assessments of the causes of impairments requiring development of a total maximum daily load (TMDL). A TMDL is the calculation of the maximum amount of a pollutant that a body of water can receive and still meet water quality standards, and an allocation of that amount to the pollutants sources. The calculation of a TMDL is required for all waters that are listed as impaired, in accordance with 303(d) of the Clean Water Act.This case study describes impairments, identifies candidate causes, evaluates relationships between causes and biological response variables, and identifies the most likely causes of impairment through a combined approach of elimination and strength of evidence. The MDEQ identified altered food resources (which include organic enrichment and nutrient enrichment and could lead to decreased DO) as probable causes of impairment. Subsequent to this assessment, TMDLs were developed for the applicable causes of impairment to Bogue Homo as identified through this causal analysis process.