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EPA Updates Online Application for Determining Causes of Ecological Impairment

October 11, 2007

On Oct. 4, EPA announced the update of an online application that helps scientists and engineers find, access, organize and share information to evaluate causes of biological impairment in aquatic systems.

The "Causal Analysis/Diagnosis Decision Information System -- 2007" (CADDIS) Web site was developed by EPA's National Center for Environmental Assessment (NCEA) in response to strong demand within the agency and from stakeholders seeking a defensible method for determining causes of ecological impairment. CADDIS guides users through EPA's Stressor Identification process, with interactive tools, methods and worksheets.

Thousands of water bodies in the United States have been reported to have an "unknown" cause of impairment. To formulate appropriate management actions for impaired water bodies, it is critical to identify the causes of biological impairment, such as excess fine sediments, nutrients or toxic substances. Effective causal analyses call for knowledge of the mechanisms, symptoms and stressor-response relationships for various stressors.

The first version of CADDIS was released in 2006. The update includes the following changes:

• The addition of eight modules, each describing a common stressor or candidate cause of biological impairment. The stressor modules include metals, sediments, nutrients, dissolved oxygen, temperature alteration and unspecified toxic chemicals.
• An interactive Flash-based conceptual model diagram for phosphorus, a common stressor.