What is a Watershed?

A watershed is the land area from which all flowing surface water drains into a river system, lake or sea.

A watershed is an area of land, which drains into a river, or other body of water. One way to understand how it functions is to compare it to a bathtub; when water falls onto the floor of the tub, it runs downhill to the drain because of the pull of gravity. The drain is the lowest point, so naturally the water ends up in the drain. Take this concept and apply it to an area of land; when rainwater falls onto the land it will flow to the lowest point, which is always a river, stream, lake or other body of water. So, therefore, a watershed is the land surrounding a river, which funnels rainwater into this waterbody.

Everyone, everywhere lives in a watershed. Homes, farms, ranches, forest, small towns and big cities can all be contained in a watershed. Some watershed boundaries cross municipal, provincial and even international borders. Watersheds come in all shapes and sizes. Some are millions of square miles, others are just a few acres.