Johnston Dam, located in Redfield, Iowa, along the Middle Raccoon River, was completed in 1971 by the USDA NRCS. This privately-owned earth dam stands at 43 feet high and spans 245 feet in length, serving primarily for fire protection, stock, and small fish pond purposes. With a storage capacity of 35 acre-feet and a surface area of 2 acres, the dam plays a crucial role in managing water resources in the area.

Managed by the Iowa DNR, Johnston Dam has a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment. Despite its moderate risk level, the dam has not been inspected since June 1978. Its spillway type is uncontrolled, with a spillway width of 0, and it has no outlet gates or associated structures. With a drainage area of only 0.1 square miles, the dam's impact on the surrounding environment is minimal.

Water resource and climate enthusiasts will appreciate Johnston Dam for its contribution to water management in the area. While its risk level is moderate, the dam continues to serve its primary purposes effectively. As a part of the larger water infrastructure in the region, Johnston Dam plays a vital role in supporting the local ecosystem and ensuring water availability for various uses.