Get News Feed
The Basics
Ridgetops of hills or mountains form the boundaries between watersheds. A drop of water falling on the top of a ridge will flow by gravity into your watershed or into an adjacent watershed, depending on the topography or lay of the land. Watershed boundaries often cross county, state, and even international borders.
The upstream areas of a watershed are called the headwaters. As you move downhill and downstream, tiny rivulets and streams combine to form larger rivers which eventually empty into a larger body of water such as a lake or bay.
The area of land in a watershed could be small or it could be immmense, millions of square miles or just a few acres. Within each large watershed, there are many smaller watersheds, called sub-watersheds or sub-drainages. For example, a small creek that flows into the Napa River has its own watershed, but is also part of the much larger Napa River Watershed, which is part of the even larger San Pablo Bay Watershed.
Watersheds are more than just drainage areas. They are the places where we live, work, and recreate.
Source: Napa County Resource Conservation District
