Siem Lake Dam
Siem Lake Dam is an earth dam located in St. Charles County, Missouri, built in 1973. It carries a Significant hazard potential classification.
About Siem Lake Dam
The primary purpose of Siem Lake Dam 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 Marvin Siem (private). It impounds the Tr-missouri River near Augusta.
The dam stands 23 feet tall and stretches 600 feet across, creates a reservoir covering 1 acres, has a maximum storage capacity of 135 acre-feet, and collects water from a drainage area of 106 square miles. Completed in 1973, the structure is well into its service life at over 50 years old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life.
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Location
| State | Missouri |
| County | St. Charles |
| Nearest City | Augusta |
| River/Stream | Tr-missouri River |
| Coordinates | 38.58082, -90.94365 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 23 ft |
| Dam Height | 23 ft |
| Dam Length | 600 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 135 acre-ft |
| Max Storage | 135 acre-ft |
| Normal Storage | 80 acre-ft |
| Surface Area | 1 acres |
| Drainage Area | 106 sq mi |
| Max Discharge | 1,200 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | MARVIN SIEM |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not Rated |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MO31427 |
| Federal ID | MO31427 |
| More Info | State Dam Safety Program |