During recent hearings on a unit of the Duck River Project, Columbia Dam and Reservoir, the question “How far downstream can water quality problems related to iron and manganese be expected to occur, and why?” arose. The two most prominantly unknown variables were time-of-travel below the dam and oxidation-precipitation rates. No rates were found for field studies and laboratory rates were either very high or very low. Most laboratory studies involved considerable pH shifts. Since the literature produced little information useful for predicting the oxidation rates of iron and manganese in tailrace streams, a study of iron, manganese, and sulfide kinetics was designed and performed at Normandy Dam, a TVA multipurpose project on the Duck River upstream of the Columbia Dam near Tullahoma, Tenn. The study found that manganese in the Normandy tailrace exists largely in the Mn++form which passes a 0.1μ filter. Only a small percentage of the total manganese is particulate. Mn++is oxidized as a linear function of time-of-travel at a rate of 0.041 mg/l per hour at a pH of 7.1 and a temperature of 17°C. The oxidized Mn precipitate is quickly settled and/or sorbed upon rocks and debris resulting in a a linear loss of total Mn with time-of-travel. The total Mn loss rate is 0.035 mg/l per hour at the previously stated conditions. Precipitation rates in the Duck River below Normandy Dam are as much as 50 times greater than rates determined in laboratory studies. Iron in the Normandy tailrace exists in three forms: particulate, colloidal, and dissolved. Exchange between the colloidal fraction and the dissolved Fe++fraction occurs in the river. The total iron decreases only slightly with time-of-travel in the Duck River. The colloidal fraction will not settle and evidently the particulate fraction is too buoyant to settle. Only 27 percent of the total iron was revoved during 29.5 hours of travel time. The presence of Fe++apparently keeps the S=concentration very low at less than 0.025 mg S=/l both in the lake and the tailrace stream due to formation of FeS which is insoluble. This research was conducted during the time period of June through December 1982.