Huff Subwatershed Station 94+07 #3 is a local government-owned structure located in Monona, Iowa, specifically in the city of Castana. This earth dam was completed in 1963 with a height of 29 feet and a length of 416 feet, serving purposes such as fire protection, stock, small fish pond, and flood risk reduction. The dam has a drainage area of 0.63 square miles and a storage capacity of 76 acre-feet, with a normal storage level of 41 acre-feet.

Managed by the USDA NRCS, this dam on the TR-Maple River has a low hazard potential with a moderate risk assessment. Despite not having a condition rating, the structure meets state regulatory requirements for inspection, permitting, and enforcement. The spillway is uncontrolled, and there are no associated locks or gates. While the dam has not been modified in recent years, it remains an important feature for water resource management and climate resilience efforts in the region.