Dane Ridge Watershed Site B-4 is a dam located in Crawford County, Iowa, specifically in the city of Dunlap. Constructed in 1971 by the USDA NRCS, this earth dam serves multiple purposes including fire protection, stock, small fish pond, flood risk reduction, and recreation. With a height of 43 feet and a length of 363 feet, the dam has a storage capacity of 83 acre-feet and covers a surface area of 5 acres.

Managed by the local government, the dam is regulated by the Iowa Department of Natural Resources and undergoes regular inspections, enforcement, and permitting to ensure its safety and functionality. The hazard potential is rated as low, with a moderate risk assessment of 3. While the dam is not currently rated for condition, it meets state jurisdiction and permitting requirements, making it an integral part of the water resource infrastructure in the area.

The location of Dane Ridge Watershed Site B-4 along the TR-Boyer River in Iowa highlights its importance in managing water resources and mitigating flood risks in the region. With its diverse purposes and regulated status, this dam plays a crucial role in both water conservation efforts and recreational activities, making it a key site for water resource and climate enthusiasts to explore and understand its impact on the local environment.