what does watershed mean

A watershed is an area of land where all the water from rain, snowmelt, or springs drains into a common water body like a river, lake, or ocean. It includes all the streams, lakes, reservoirs, and groundwater that collect and channel water to a single outlet. The boundaries of a watershed are defined by natural features such as hills and mountains that direct the flow of water. Watersheds can vary greatly in size from small local areas to large river basins covering multiple states or regions. The term "watershed" can also refer to a dividing ridge between two drainage areas or, metaphorically, a crucial turning point or dividing line in events or history.