Watershed I/IV, for Solo Percussion and Real-time Computer Spatialization was composed in 1995 by Pulitzer prize-winning composer Roger Reynolds. This work is a 25-minute choreographed music drama for one multiple-percussionist, in which Reynolds incorporates the musical transformation of percussion instrument families, the physical gestures of the performer, and the spatialization of processed sounds around the audience. This dissertation addresses several aspects of Watershed, which include: the expressive intent and extra-musical concepts; the formal organization, and several non-musical tools that Reynolds utilized in designing the piece (e.g. logarithmically derived sequences); the primary musical motives; the instrument setup and how the resulting physical gestures contribute to the musical intent; and the real-time computer spatialization. Throughout the document, specific musical passages are demonstrated with notated musical examples and embedded video/audio clips. In addition, transcripts of my interviews with composer Roger Reynolds, percussionist Steven Schick (premiere performer of Watershed) and engineer/technician Greg Dixon (engineer for my performances of Watershed IV) are also included.