The combined BODy in a stream mixed with sewage effluent is 25 mg/L. The stream rearation rate is found to be 0.4/d, and the deoxygenation constant is assumed to be 0.1/d. The initial combined DO in the stream is 8.0 mg/L, and the DO saturation level is 11 mg/L. Compute the minimum DO level in the stream due to the sewage discharge