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 West Fork Trinity River begins in Archer County and flow in a southeasterly direction for approximately 715 miles to empty into Trinity Bay which empties into Galveston Bay and then into the Gulf of Mexico. The Trinity River and its principal tributaries West Fork, Clear Fork, Denton Creek, Elm Fork, and East Fork flow through the urban populations of the Fort Worth/Dallas Metropolitan area. The Trinity River then flows from Dallas to the Texas coast through primarily agricultural land. The total drainage area of the Trinity River basin is approximately 17,969 square miles. The precipitation varies from northwest to southeast portion of the basin. The northern portion of the basin receives 35-40 inches of precipitation, on average, each year. As one travel southeast, the average annual precipitation exceeds 50 inches. The basin, particularly in the southeast, can experience extremely intense precipitation events capable of producing staggering rainfall totals. These systems range from intense thunderstorms to hurricanes. The range in average annual precipitation is shown on the figure below.
Many reservoirs were constructed in the Trinity Basin, and they are managed for flood control, water supply, recreation, and other uses. Several entities assist with water management operations including: U.S. Army Corp of Engineers (USACE), Tarrant Regional Water District (TRWD), Dallas Water Utilities, Trinity River Authority (TRA), and North Texas Municipal Water District (NTMWD). Reservoirs in the basin with USACE regulatory authority include; Benbrook Dam, Joe Pool Dam, Ray Roberts Dam, Lewisville Dam, Grapevine Dam, Lavon Dam, Navarro Mills Dam, and Bardwell Dam.
The Upper Trinity encompasses the Fort Worth/Dallas Metropolitan area and five of the USACE reservoirs provide flood reduction management for the urban area. During non-flood control operation, the USACE reservoirs are operated for water supply requests from local water authorities: TRWD, Dallas Water Utilities, and, NTWMD. During flood control operations, the USACE reservoirs are operated to multiple downstream USGS gages within the urban area to provide a balanced system approach of the USACE flood storage and the local water supply reservoir releases. Priority is first given to the local water supply reservoir releases at the downstream USGS gage locations. The USGS gages within the Fort Worth/Dallas Metropolitan area that are key downstream constraints for system balancing are: West Fork Trinity River at Fort Worth, West Fork Trinity River at Grand Prairie, Elm Fork Trinity River near Carrollton, and Trinity River at Dallas.