Located in Lancaster, Nebraska, Upper Big Nemaha 15-B is a local government-owned earth dam designed by USDA NRCS and completed in 1970 for the primary purpose of flood risk reduction. The dam stands at a height of 22 feet with a structural height of 26 feet, spanning 713 feet in length. It has a storage capacity of 235 acre-feet and a normal storage of 29 acre-feet, serving a drainage area of 0.5 square miles along the TR-MID BR Big Nemaha River.

With a low hazard potential and a satisfactory condition assessment as of October 2016, Upper Big Nemaha 15-B is regulated by the Nebraska Department of Natural Resources, with state permitting, inspection, and enforcement in place. The dam's location in Firth, Nebraska, underscores its importance in mitigating flood risks and protecting the surrounding area. Water resource and climate enthusiasts will appreciate the role of this dam in managing water levels and ensuring the safety of the community.