A watershed is the area of land where water from rain or snowmelt runs off and drains to a waterbody such as a river, lake or pond. Watershed boundaries are defined by hills, mountains or other higher ground. Because all water eventually flows to a particular waterbody, all land is located in a distinct watershed.
A good analogy of a watershed is a bathtub. The “sides” of the tub define the boundary of the watershed while the “bottom” is the land area” that slopes slightly towards the “drain” or waterbody.
Specific information about CRWD can be found here.