Located in Osage City, Kansas, the 121 (Johnson) dam is a local government-owned structure designed by RHK Enterprises, Inc. with a primary purpose of flood risk reduction. Completed in 2014, this earth dam stands at a height of 26.5 feet and spans 765 feet in length, providing a storage capacity of 188.4 acre-feet. With a low hazard potential and a moderate risk assessment rating, this dam plays a crucial role in mitigating flood risks in the area.

Serving the Swede Creek-TR river/stream, the 121 (Johnson) dam boasts a spillway width of 100 feet and a surface area of 4.7 acres, with a normal storage capacity of 20.6 acre-feet. Despite its relatively low hazard potential, the dam has not been rated for its condition assessment, and there are no emergency action plans prepared or last inspection dates recorded. However, with its strategic location and design, this dam contributes significantly to the flood risk reduction efforts in the region.

Managed by the Tulsa District of the US Army Corps of Engineers, the 121 (Johnson) dam has had no federal agency involvement in its funding, design, construction, regulation, inspection, or operation. With its buttress core type and uncontrolled spillway, this dam exemplifies a local government initiative to address flood risks and protect the surrounding communities from potential water resource-related hazards.