An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

CADDIS Volume 1

Example Annotated Conceptual Model Diagram

This conceptual model diagram, based on the Willimantic River case study, has been annotated with the evidence that was used to evaluate whether toxic substances were causing biological effects.

Illustration of an Annotated Conceptual Model