5th Field Watersheds
A watershed is the area of land where all surface and groundwater drains into the same body of water, such as a river, wetland, or the ocean. Watersheds can be many millions of acres like the Columbia River Basin, or less than a dozen acres for a single small stream. Since the term "watershed" can be used for drainage areas of any size, the US Geological Survey (USGS) has divided watersheds into distinct units, or "fields," based on size. Sizes range from multi-million acre first-field watersheds to seventh-fields that can be less than 3,000 acres. Third-field, fourth-field, and fifth-field watershed are the most common units used by agencies and other organizations involved in landscape-level watershed planning and restoration.
Fifth-field watersheds have become the standard size used for research and projects by a variety of agencies and organizations. Therefore, it is convenient for fifth-field watershed to be the unit usually referred to herein by the term "watershed." The Umpqua Basin has 33 fifth-field watersheds. All of the watersheds have their own features, challenges, and potential. The conditions in one watershed may not reflect the conditions in a neighboring watershed.
Mouse-over the map to find a fifth-watershed watershed of interest and click the link to learn more about this area. Or scroll down to read about the history, landscape, climate and forests of the Umpqua Basin.
