A stream is in equilibrium with atmospheric oxygen upstream of a waste outfall. The waste outfall creates a BODo of 20 mg/L in the stream. The k(BOD) is 0.4 /day and the k(o2) is 1.4 / day. The stream temperature is 15 degrees Celsius. How far downstream, in terms of travel time, is the maximum DO sag. What is the minimum DO in the river?