The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:
- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)
The Neches River begins in Van Zandt County approximately 60 miles southeast of Dallas, Texas, and flows in a southeasterly direction for approximately 416 miles to empty into Sabine Lake, 20 miles southeast of Beaumont, Texas. The Neches River and its principal tributary, the Angelina River, flow through areas of moderately hilly relief until the vicinity of Jasper and Woodville, where the terrain abruptly changes to the flat coastal prairie. The total drainage area of the Neches River basin is approximately 10,000 square miles.
Sam Rayburn Dam sits on the Angelina River within the Neches River basin in East Texas. The drainage area of the Angelina River is 3,556 square miles and has an overall length of 205 miles. The average slope of the streambed varies from 10.3 feet per mile at the headwaters to 1.1 foot per mile above Sam Rayburn Reservoir to 0.5 foot per mile in the pine flats between Sam Rayburn Dam and the Neches River. The Angelina River is located in the West Gulf Coast Plains region of timbered hills and Texas Pine flats. In the area of Sam Rayburn Dam, the Angelina River has cut a valley into the sediment deposits approximately 2,000 feet wide. Alluvial deposits are approximately 30 feet deep in the valley, consisting of layers of sand and silt. There are no large cities in the Angelina watershed. Sam Rayburn Dam is regulated for flood control to maintain flows at the downstream Control Point, Neches River at Evadale, below 20,000 cfs.
Town Bluff Dam, also known as Dam B and Steinhagen Lake, is located on the Neches River at river mile 113.7, about 12.4 miles downstream of its confluence with the Angelina River. The total drainage area above Town Bluff Dam is 7,585 square miles, which includes the entire Angelina River basin and 4,011 square miles of the Neches River basin. In the vicinity of the dam, the Neches River has a slope of approximately 0.7 feet per mile.
The Neches River has been improved for navigation as far upstream as Beaumont, and the basin is transversed by a network of highways and railroads. Numerous oil and gas fields are located within the basin, with a concentration of oil refineries and associated petroleum industries at Beaumont and Port Arthur. Over one half of the watershed area is classified as timber, and commercial timber is produced at lumber mills and manufacturing plants throughout the basin.