Operational Model of the Belle Fourche Irrigation District

The Belle Fourche River, located in west-central South Dakota and east-central Wyoming, is currently listed in the South Dakota 2004 Integrated Report for Surface Water Quality Assessment as impaired because of elevated total suspended solids (TSS) concentrations. The goal of the Belle Fourche River Watershed Management and Project Implementation Plan (Segment II) is to reduce the TSS concentration by 55 percent within 10 years through the implementation of several best management practices (BMPs). The total maximum daily load (TMDL) report completed for the Belle Fourche River Watershed lists the Belle Fourche Irrigation District (BFID) as a major contributor to the TSS load. The elevated TSS load is a function of the delivery and application efficiency in the BFID where 64 percent of the water released from the reservoir is delivered to the field, 32 percent is used by the crops, and the rest is lost to evaporation and nonused water discharged into adjacent waterways. This paper focuses on the use of an operational model linked with a hydraulic model to improve the operational efficiency of the Belle Fourche Irrigation District and to reduce the TSS load 37 percent. The operational model is comprised of three main objectives. The first objective is to ensure the correct amount of water is delivered to the Vale Flume. The model will also eliminate the need for large surges of water to be released from the dam. Surges tend to increase the head at lateral gates and if the additional head is not accounted for, an unknown increase in water is discharged into the lateral. Finally, the operational model will provide operating procedures and rating curves for control check structures. This paper will discuss the three main objectives in detail.