The U.S. Army Corps of Engineers has developed one-and two-dimensional models as tools for water resources management. CE-QUAL-R1 is a variable-layer, horizontally averaged water quality model. CE-QUAL-W2 is a two-dimensional (laterally averaged) finite-difference hydro-dynamic and transport water quality model. The water quality algorithms in both models are similar and both have been applied to DeGray Lake, Ark., a reservoir that has been extensively studied by the Corps of Engineers. The reservoir is of particular interest because of dissolved oxygen declines in the metalimnion of the main pool during summer and fall months. Both models successfully predict spatial and temporal variations in dissolved oxygen concentrations in their respective dimensions. Evaluations were made of all flux values contributing to simulated oxygen dynamics.