For many years, data relating to the quality of water and sediment have been collected in the Galveston Bay system by a variety of organizations and individuals. The purpose of the project was to compile these data, and to perform a quantitative assessment of water and sediment quality of Galveston Bay and its evolution over time. The study focused on the following categories of parameters: temperature, salinity and related parameters, suspended sediments and turbidity, pH, dissolved oxygen, nutrients as measured by nitrogen, phosphorous and organic carbon, organics as measured by oil and grease, volatile solids and biochemical oxygen demand, chlorophyll-a, coliforms, metals (total and dissolved), and trace organics, including pesticides, herbicides, PAH's, PCB's, and priority pollutants.