A drifting particle simulator buoy system for a stormwater discharge plume which includes a GPS unit for tracking the buoy GPS location at the surface of the plume and a drogue/winch unit including a drogue chute and winch package which is lowered to the seafloor at a controlled descent rate which is comparable to the descent rate of certain size sediment particles of interest within the stormwater discharge plume. The drogue chute controls lateral drift with the underwater current at approximately the same velocity of the sediment particles of interest. A control unit controls the drogue/winch unit, including controlling the speed of the chute/winch unit to mimic the settling rate of the sediment particles of interest. A bottom detection sensor determines the GPS location where the chute/winch package reaches the seafloor and determining the depositional footprint of contamination at the determined GPS location.