  This paper describes the design of the active muon veto subsystem for the
MiniCLEAN dark matter direct detection experiment at SNOLAB in Sudbury,
Ontario, Canada. The water-filled veto is instrumented with 48 PMTs which are
read out by front end electronics to time multiplex 48 photomultiplier channels
into 6 digitizer channels and provide an instantaneous hit sum across the
subsystem (N-Hit) for the veto trigger. We describe the primary system
components: the PMTs, the support structure, the front-end electronics, and the
data acquisition system.
