A watershed is defined as the area of land in which water will drain to a single point at a lower elevation from a higher elevation. The general route of the water will be from the tallest hills to the valleys to the sea connecting streams to rivers that will eventually drain into the ocean. Watersheds range in all sizes and shapes depending on the landscape.

Coastal Action works in several different watersheds in southern Nova Scotia. The LaHave River, at 1700 km2, is the largest watershed in which Coastal Action currently works. These watersheds are home to many freshwater fish as well as other aquatic life. They also support terrestrial life. There are many areas along the reaches of the watershed where humans interact with the watershed for better or worse. Some of the work that Coastal Action is involved with includes recovering fish habitat that has been altered by these human interactions.