Patterson Lake Dam
Patterson Lake Dam is an earth dam located in Osage County, Missouri, built in 1972. It carries a High hazard potential classification.
About Patterson Lake Dam
The primary purpose of Patterson Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by James A Patterson (private). It impounds the Tr-third Creek near Cooper Hill.
The dam stands 31 feet tall, creates a reservoir covering 10 acres, has a maximum storage capacity of 166 acre-feet, and collects water from a drainage area of 230 square miles. Completed in 1972, 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 09/11/1990. That was 35 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 | Osage |
| Nearest City | Cooper Hill |
| River/Stream | Tr-third Creek |
| Coordinates | 38.42094, -91.64786 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 31 ft |
| Dam Height | 31 ft |
| Year Completed | 1972 (54 years old) |
Storage & Hydraulics
| NID Storage | 166 acre-ft |
| Max Storage | 166 acre-ft |
| Normal Storage | 100 acre-ft |
| Surface Area | 10 acres |
| Drainage Area | 230 sq mi |
Ownership & Safety
| Purpose | Recreation |
| Owner | JAMES A PATTERSON |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Not Rated |
| Last Inspection | 09/11/1990 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | MO11294 |
| Federal ID | MO11294 |
| More Info | State Dam Safety Program |