Upper Big Nemaha L-17 is a local government-owned dam located in Lancaster, Nebraska, designed by the USDA NRCS and regulated by the Nebraska Department of Natural Resources. Completed in 1971, this earth dam stands at 24 feet tall and spans 542 feet in length, serving primarily for flood risk reduction along the TR-MID BR Big Nemaha River. With a storage capacity of 65 acre-feet, it covers a surface area of 3 acres and drains a 0.3 square mile watershed, with a low hazard potential and satisfactory condition assessment as of the last inspection in August 2016.

Managed by the Omaha District of the US Army Corps of Engineers, Upper Big Nemaha L-17 incorporates buttress and stone core types on a soil foundation, with a maximum discharge capacity of 291 cubic feet per second. The dam's primary purpose, aside from flood risk reduction, falls under the category of "Other," with a normal storage capacity of 21 acre-feet. Despite its relatively low hazard potential, the dam is subject to regular state inspection, permitting, and enforcement to ensure its continued safety and functionality in the face of a changing climate and water resource management challenges.

For water resource and climate enthusiasts, Upper Big Nemaha L-17 presents a fascinating case study of local dam infrastructure in Nebraska. With its historical significance dating back to the early 1970s and its critical role in mitigating flood risks along the Big Nemaha River, this dam exemplifies the intersection of engineering, regulatory oversight, and environmental stewardship in safeguarding communities and ecosystems against water-related hazards. As climate change continues to impact precipitation patterns and hydrological dynamics, understanding the design, operation, and maintenance of structures like Upper Big Nemaha L-17 becomes increasingly crucial in ensuring resilience and sustainability in water resource management practices.