Lake Montowese Dam
Lake Montowese Dam is an earth dam located in Jefferson County, Missouri, built in 1942. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Lake Montowese Dam
The primary purpose of Lake Montowese Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Lake Montowese Corp (private). It impounds the Tr Big River near Times Beach.
The dam stands 54 feet tall and stretches 1,000 feet across, creates a reservoir covering 48 acres, has a maximum storage capacity of 800 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1942, the structure is well-established, with more than 75 years of service.
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. An emergency action plan is in place for this dam. The most recent inspection on record was 09/01/2022.
At 54 feet, this dam is taller than 94% 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 Missouri 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 | Missouri |
| County | Jefferson |
| Nearest City | Times Beach |
| River/Stream | Tr Big River |
| Coordinates | 38.43779, -90.56516 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 54 ft |
| Dam Height | 54 ft |
| Dam Length | 1,000 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 800 acre-ft |
| Max Storage | 800 acre-ft |
| Normal Storage | 606 acre-ft |
| Surface Area | 48 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 1,740 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | LAKE MONTOWESE CORP |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 09/01/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MO30151 |
| Federal ID | MO30151 |
| More Info | State Dam Safety Program |