A watershed is an area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater. Homes, farms, cottages, forests, small towns, big cities and more can make up watersheds. Some cross municipal, provincial and even international borders. They come in all shapes and sizes and can vary from millions of acres, like the land that drains into the Great Lakes, to a few acres that drain into a pond.
Watersheds are one of the best natural ecosystem units on which to manage resources. Managing resources on a watershed basis means managing wisely upstream so that downstream remains natural and healthy.