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 This website is no longer updated and links to external websites and some internal pages may not work.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

Long Creek Conceptual Model Diagram

This diagram was developed for Long Creek, a coastal plain stream in Maine. Hexagons represent sources; rectangles represent proximate stressors; ovals represent biological effects; and round-edged rectangles represent additional steps in the causal pathway.

Figure 2-2. Simple Conceptual Model Diagram for Long Creek MaineFigure 2-2. A simple conceptual model diagram illustrating an increased water temperature as a candidate cause of biological impairment.

*Note that invertebrate effects also are proximate stressors for brook trout, due to reductions in fish prey.