Process waters from two commercial-scale steamflood tar sand extraction operations have been characterized for chemical, physical, and toxicological properties. The characterization effort included wet chemical analyses, elemental analyses, particle-size analysis, and MICROTOX assays. The results of these tests indicate that both waters require treatment before reuse or discharge into the environment. Depending on the intended use, reductions of hardness, silica, oil and grease, suspended solids, iron, chloride, and dissolved solids may be required. 13 refs., 2 figs., 11 tabs.