Hermit Hollow Lake Dam is an earth dam located in Franklin County, Missouri, built in 1962. It carries a High hazard potential classification.
Dam profile
NID height · 33 ft33 ft tall, taller than 76% 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 Hermit Hollow Lake Dam
The primary purpose of Hermit Hollow Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Trustees O Hermit Hollow (private). It impounds the Lartto Creek near St Charles.
The dam stands 33 feet tall, creates a reservoir covering 9 acres, has a maximum storage capacity of 159 acre-feet, and collects water from a drainage area of 249 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 05/07/1979. That was 47 years ago — unusually long for a high-hazard dam, which typically requires more frequent inspections.
At 33 feet, this dam is taller than 76% 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 | Franklin |
| Nearest City | St Charles |
| River/Stream | Lartto Creek |
| Coordinates | 38.52767, -90.81185 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 33 ft |
| Dam Height | 33 ft |
| Year Completed | 1962 (64 years old) |
Storage & Hydraulics
| NID Storage | 159 acre-ft |
| Max Storage | 159 acre-ft |
| Normal Storage | 82 acre-ft |
| Surface Area | 9 acres |
| Drainage Area | 249 sq mi |
Ownership & Safety
| Purpose | Recreation |
| Owner | Trustees O Hermit Hollow |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Not assessed |
| Last Inspection | 05/07/1979 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MO31054 |
| Federal ID | MO31054 |
| More Info | State Dam Safety Program |