A drifting buoy sampler system for a stormwater discharge plume formed from stormwater discharged into coastal waters. The system compresan electronics sampling pod for collecting integrated water samples within the stormwater plume as the buoy system drifts with the stormwater plume near the water surface as the plume travels out to sea. The pod includes a watertight section including a GPS/radio module for providing GPS (geo-position) location information and a processor for monitoring and controlling the sampling rate, a pump module and a battery module; a passive sampler bag for collecting the integrated water samples; a free flooding section including a composite sample bag module such that the pump module pumps collected samples from the passive sampler bag to the composite sample bag module at a predetermined sampling rate and a ballast module for providing ballast to the system when drifting within the plume.