The purpose of this report is to determine future total and background (i.e., total minus return flow) streamflow conditions in selected reaches of the Trinity River and its tributary streams. The streamflow conditions will then be used by the Trinity River Authority in connection with development of an overall basin water quality management plan, and particularly to do the following: 1. Establish recommendations of stream quality standards in regard to flow criteria; 2. Assess the significance of stream standards being based on minimum flow conditions that occur for either a 1-day, 7-day, 15-day, or 30-day duration period; 3. Assess the extent of the effluent dominated condition occurring in the selected reaches of the Trinity River and its tributary streams; 4. Serve as the basis for estimating the fraction of time for which levels of stream assimilative capacity are potentially available; 5. Serve as the basis for estimating the fraction of time during which the river dissolved oxygen levels may be at various levels.