You are working for an environmental engineering firm monitoring river quality on the Gasconade River on behalf of a major fish hatchery. A spill at a chemical manufacturing plant 200 km (~124 miles) upstream has the potential to drastically increase

You are working for an environmental engineering firm monitoring river quality on the Gasconade River on behalf of a major fish hatchery. A spill at a chemical manufacturing plant 200 km (~124 miles) upstream has the potential to drastically increase the biological oxygen demand (BOD) above normal levels. This was an unhealthy river to begin with because of agricultural runoff, which provided a base oxygen deficit (Do) of 1.2 mg/L. An additional BOD load (Lo) of 30 mg/L was added by the chemical spill. The deoxygenation rate (kd) of the water associated with the total load was found to be 1.9 day-1. The height and velocity of the river were measured near Hazelgreen at roughly h = 0.61 m and v = 52.7 km/day, respectively, which results in a reaeration rate (ka) of 2.89 day-1. These values will go into an equation known as the Streeter-Phelps model, which states that the oxygen deficit at a certain point will be: