A decision support system(DSS)is under development to assist in the control and management of episodes of dissolved oxygen sag in a Deep Water Ship Channel (DWSC), located in Stockton, California. The DWSC was formed by excavating the bed of the San Joaquin River in the 1950's to allow navigation by ocean-going cargo ships to the Port of Stockton. The deepened channel has the effect of increasing hydraulic residence time by a factor of ten. allowing accumulation of decaying algae and other oxygen demanding substances - which creates a barrier to the migration of anadromous fish. This problem, which manifests itself in late summer and early autumn, is an impediment to a multimillion dollar habitat restoration effort for the salmon fishery in the San Joaquin River basin (SJRB). A hydrodynamic and water quality model of the Delta and San Joaquin River forms the basis of the DSS which will provide forecasts of dissolved oxygen sag in the DWSC and provide modeling support for management actions such as forced aeration to improve dissolved oxygen concentrations in the Ship Channel. A graphical user interlace, currently used for displaying flow and salinity forecasts on the San Joaquin River, is being adapted to allow the display of dissolved oxygen forecasts and to encourage the formation of a stakeholder-led entity or institution to adaptively manage the problem.