Hypolimnetic oxygenation is a relatively new aeration technology that uses pure oxygen gas to increase dissolved oxygen (DO) concentration and improve water quality in the bottom of lakes. A key design parameter for oxygenation systems is sediment oxygen demand (SOD). Oxygenation tends to increase SOD above natural levels since it elevates turbulence and DO at the sediment-water interface. To assist in the pre-design of an oxygenation system for Lake Perris, CA (0.16 km3 , 930 ha), this study evaluated the effects of mixing and DO levels on SOD. SOD was measured in replicate bench-scale chambers containing minimally disturbed sediment-water interface samples from four stations. Average water velocities overlaying sediments were maintained at 0, 1, 2, 4 and 8 cm/s and DO uptake was continuously monitored using luminescent DO probes. Under quiescent conditions SOD was independent of DO and ranged from 0.15 to 0.35 g/m2 /d. Under mixed conditions SOD followed a simple biochemical model composed of both a biological and chemical component. Values of µb, the maximum biological SOD oxidation rate, ranged from 0.1 to 0.2 g/m2 /d. Values of kc, the chemical SOD first-order rate constant, ranged from 0.03 to 0.06 m/d. Organic sediments from deeper stations tended to have elevated biological SOD, while shallow, sandy sediments rich in benthos tended to have elevated chemical SOD. Based on the SOD model parameters developed in this study, a target DO of 7.5 mg/L, and a hypolimnetic surface area of 7.7 million m2 , a design SOD of 5,500 kg/d was recommended.