The Texas part of the Red River Basin has been divided into five reaches or subbasins (fig. 1) to facilitate improved planning, monitoring, geographical analysis, and dissemination of information. The U.S. Geological Survey (USGS), in cooperation with the Red River Authority of Texas, is studying the five subbasins, each for a period of about 1 year. Baldys and Phillips (1998) discuss various components and the associated scope of study of each of the five reaches. Data from the first reach studied—reach 2, the Wichita River Basin—were presented in a fact sheet by Baldys and Phillips (2000). This fact sheet presents an assessment of data collected at 11 sites during 1997–98 for reach 1—the lower Red River (main stem) Basin from the confluence of Cache Creek downstream to the Texas-Arkansas State Line (fig. 1).