1.2 Why the watershed?

Figure 1.1. Depiction of typical watershed (USEPA 2010)

Watersheds are regions which ultimately drain to a particular water course or body of water (Figure 1.1). Humans have depended on a vast array of resources provided by rivers, tributaries, and surrounding lands for centuries, and historically the prosperity of many societies has been intricately tied to the watershed resources they controlled (O’Conner and Costa, 2004). Yet many human activities can greatly modify natural watershed processes, resulting in altered patterns and function of riverine and adjacent terrestrial ecosystems (Fight et al. 2000). Effective management and conservation of resources and ecosystems relies on knowledge both of watershed processes and how human activities modify them.

Typically a watershed is a geographic area defined by the movement of water (precipitation) draining to a common point or waterbody. A more all-encompassing definition of a watershed is one which pertains to both natural attributes (e.g. soil, water, vegetation, animal species) and human uses and conditions (e.g. land use, social structure and organization) within the area. The subtle difference is that the latter definition explicitly includes a relationship to people and how they utilize, manage, and are affected by their environment.

We used this more all-encompassing definition of a watershed, one that includes human social and economic elements, in developing the Report Card. Although still geographically based in the traditional sense of a “watershed,” the broader definition facilitated assessment of the degree to which natural process and condition goals are being achieved, knowing that these “watershed” goals are affected by (and perhaps directly correlated with) human social and economic systems and conditions. In using a broader application of the term “watershed,” we gained the ability to assess indicators that measure how physical watershed condition(s) interact with economic and social goals (e.g., fishability of streams, fire frequency, primary productivity), and conversely, how economic and social systems and patterns interact with watershed attributes (e.g., species biodiversity, habitat connectivity, water quality).