Montello Granite
Montello Granite is a concrete dam located in Marquette County, Wisconsin, built in 1914. It carries a High hazard potential classification and has a fair condition assessment.
About Montello Granite
The primary purpose of Montello Granite is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by City Of Montello (local government). It impounds the Montello River near Montello.
The dam stands 24 feet tall and stretches 55 feet across, creates a reservoir covering 286 acres, has a maximum storage capacity of 3,300 acre-feet, and collects water from a drainage area of 160 square miles. Completed in 1914, the structure is over a century 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 10/13/2020.
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 | Marquette |
| Nearest City | Montello |
| River/Stream | Montello River |
| Coordinates | 43.79338, -89.32888 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 24 ft |
| Dam Height | 24 ft |
| Dam Length | 55 ft |
| Year Completed | 1914 (112 years old) |
Storage & Hydraulics
| NID Storage | 3,300 acre-ft |
| Max Storage | 3,300 acre-ft |
| Normal Storage | 1,430 acre-ft |
| Surface Area | 286 acres |
| Drainage Area | 160 sq mi |
| Max Discharge | 5,353 cfs |
| Spillway Type | Controlled |
Ownership & Safety
| Purpose | Recreation |
| Owner | City Of Montello |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 10/13/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | WI00075 |
| Federal ID | WI00075 |
| More Info | State Dam Safety Program |