Mill Picayune Watershed Site B-3
Mill Picayune Watershed Site B-3 is an earth dam located in Harrison County, Iowa, built in 1962. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Mill Picayune Watershed Site B-3
The primary purpose of Mill Picayune Watershed Site B-3 is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Harrison County Swcd (local government). It impounds the Tr-picayune Creek near Dunlap.
The dam stands 38 feet tall and stretches 493 feet across, creates a reservoir covering 8 acres, has a maximum storage capacity of 247 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1962, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. Notably, no emergency action plan is currently on file for this high-hazard dam. The most recent inspection on record was 06/20/2023.
At 38 feet, this dam is taller than 85% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Iowa dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Iowa |
| County | Harrison |
| Nearest City | Dunlap |
| River/Stream | Tr-picayune Creek |
| Coordinates | 41.85240, -95.59030 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 38 ft |
| Dam Height | 38 ft |
| Dam Length | 493 ft |
| Year Completed | 1962 (64 years old) |
Storage & Hydraulics
| NID Storage | 247 acre-ft |
| Max Storage | 247 acre-ft |
| Normal Storage | 70 acre-ft |
| Surface Area | 8 acres |
| Drainage Area | 0 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Harrison County SWCD |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/20/2023 |
| Emergency Action Plan | No |
Identifiers
| NID ID | IA00467 |
| Federal ID | IA00467 |
| More Info | State Dam Safety Program |