Mlsna
Mlsna is an earth dam located in Vernon County, Wisconsin, built in 1956. It carries a High hazard potential classification and has a unsatisfactory condition assessment.
About Mlsna
The primary purpose of Mlsna 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 Vernon County (local government). It impounds the Un Trib. To Knapp Creek.
The dam stands 35 feet tall and stretches 580 feet across, creates a reservoir covering 18 acres, has a maximum storage capacity of 257 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1956, 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 unsatisfactory, indicating serious safety deficiencies exist that require immediate attention or remedial action. An emergency action plan is in place for this dam. The most recent inspection on record was 05/11/2020.
At 35 feet, this dam is taller than 82% 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 Wisconsin 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 | Wisconsin |
| County | Vernon |
| Nearest City | None |
| River/Stream | Un Trib. To Knapp Creek |
| Coordinates | 43.71218, -90.75239 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 35 ft |
| Dam Height | 35 ft |
| Dam Length | 580 ft |
| Year Completed | 1956 (70 years old) |
Storage & Hydraulics
| NID Storage | 257 acre-ft |
| Max Storage | 257 acre-ft |
| Surface Area | 18 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 1,800 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Vernon County |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Unsatisfactory |
| Last Inspection | 05/11/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WI00403 |
| Federal ID | WI00403 |
| More Info | State Dam Safety Program |