Utah State University Extension
A watershed is an area of land from which all the water drains to the same location, such as a stream, pond, lake, river, wetland or estuary. A watershed can be quite large, such as the Colorado River drainage basin, or very small, such as a small horse pasture that drains to a farm pond.
Extension, USU, "Watershed Detectives" (2011). All Current Publications. Paper 1258.