Iterative Approach for Identifying the Causes of Reduced Benthic Macroinvertebrate Diversity in the Willimantic River, Connecticut

摘要

Calculations using data from the toxicity monitoring reports from a permitted publically owned treatment works (POTW) indicated a high probability of exceeding Connecticuts water quality criteria for copper, lead, and zinc in the Willimantic River downstream in Stafford Springs, Connecticut. In 1998, a 2.4-km segment of the Willimantic River in northeastern Connecticut was listed as impaired by the Connecticut Department of Environmental Protection (CT DEP) based on the review of Aquatic Toxicity Monitoring Reports from the POTW. Subsequent monitoring by the CT DEP in the autumn of 1999 confirmed the biological impairment. However, biological impairment was also found upstream from the discharge. This case study outlines the logical arguments used to determine the cause of the biological impairments upstream of the Stafford POTW discharge and is an application of the U.S. Environmental Protection Agencys Stressor Identification (SI) Guidance.