Located in Johnson, Nebraska, Upper Big Nemaha J-12 is a local government-owned earth dam designed by the USDA NRCS with a height of 43 feet and a hydraulic height of 42 feet. Completed in 1980, this dam serves multiple purposes including flood risk reduction and has a normal storage capacity of 55 acre-feet. With a drainage area of 1.2 square miles and a maximum discharge of 722 cubic feet per second, this structure plays a crucial role in managing water resources in the area.

Managed by the Nebraska Department of Natural Resources, Upper Big Nemaha J-12 has a low hazard potential and was last assessed to be in satisfactory condition in 2016. The dam is regulated, permitted, inspected, and enforced by the state agency, ensuring its safety and functionality. With a comprehensive emergency action plan in place, the structure is well-prepared to handle any potential risks or emergencies, meeting guidelines for risk management and ensuring the safety of surrounding communities.

As part of the flood risk reduction system along the TR-N FK Big Nemaha River, Upper Big Nemaha J-12 is a vital infrastructure asset in the region. With its stone core and soil foundation, the dam stands at a structural height of 44 feet and has a length of 715 feet. The dam's location, design, and capacity make it an essential component in protecting the local area from flooding and managing water resources effectively, showcasing the importance of sustainable infrastructure for climate resilience.