A wastewater is discharged to a stream with a reoxygenation constant of 0.5 day-1 and a velocity of 1 m/sec. The oxygen saturation concentration in the stream is 11 mg/L. Immediately downstream of the discharge the oxygen concentration is 9 mg/L and the deoxygenation constant is 0.3 day-1. Upstream of the discharge the ultimate oxygen demand is 8 mg/L and the stream flows at 20 million gallons per day. The plant discharges a waste which has an ultimate oxygen demand of 30 mg/L and has a flow rate of 8 million gallons per day. What will the lowest dissolved oxygen concentration be downstream of the discharge and how far down the stream will it occur?