wä-ter-shed (n.): the geological & geographical area of land that contributes or drains water through its springs, seeps, ditches, pools, culverts, marshes, swamps, & streams to the same body of water.
The area’s highest ridges form the boundary between two watersheds. At these boundaries, rain falling on one side flows toward the low point of one watershed, while rain falling on the other side of the boundary flows toward the low point of a different watershed. No matter where you are, you are in a watershed. No matter what you do, it likely involves and impacts that entire watershed.
John Wesley Powell, a prominent 19th century geologist & ethnologist, put it best when he defined a watershed as “that area of land…within which all living things are inextricably linked by their common water course & where, as humans settled, simple logic demanded that they become part of a community.”