Autumn Lake Dam is an earth dam located in Jefferson County, Missouri, built in 1962. It carries a High hazard potential classification.
Dam profile
NID height · 32 ft32 ft tall, taller than 74% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Autumn Lake Dam
The primary purpose of Autumn Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Autumn Lake Devl. Co. (private). It impounds the Tributary to Rock Creek near Imperial.
The dam stands 32 feet tall, creates a reservoir covering 7 acres, has a maximum storage capacity of 120 acre-feet, and collects water from a drainage area of 346 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. The most recent inspection on record was 09/08/1978. That was 48 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.
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 | Imperial |
| River/Stream | Tributary to Rock Creek |
| Coordinates | 38.39620, -90.45650 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 32 ft |
| Dam Height | 32 ft |
| Year Completed | 1962 (64 years old) |
Storage & Hydraulics
| NID Storage | 120 acre-ft |
| Max Storage | 120 acre-ft |
| Normal Storage | 81 acre-ft |
| Surface Area | 7 acres |
| Drainage Area | 346 sq mi |
Ownership & Safety
| Purpose | Recreation |
| Owner | Autumn Lake Devl. Co. |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 09/08/1978 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MO30446 |
| Federal ID | MO30446 |
| More Info | State Dam Safety Program |