Clark Mills (pa-490)
Clark Mills (pa-490) is an earth dam located in Mercer County, Pennsylvania, built in 1971. It carries a High hazard potential classification and has a fair condition assessment.
About Clark Mills (pa-490)
The primary purpose of Clark Mills (pa-490) 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 Mercer County Commissioners (local government). It impounds the Calvin Clark Run.
The dam stands 45 feet tall and stretches 430 feet across, creates a reservoir covering 4 acres, has a maximum storage capacity of 790 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1971, 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. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 09/10/2020.
At 45 feet, this dam is taller than 91% 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 Pennsylvania 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 | Pennsylvania |
| County | Mercer |
| River/Stream | Calvin Clark Run |
| Coordinates | 41.40278, -80.18667 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 45 ft |
| Dam Height | 45 ft |
| Dam Length | 430 ft |
| Year Completed | 1971 (55 years old) |
Storage & Hydraulics
| NID Storage | 790 acre-ft |
| Max Storage | 790 acre-ft |
| Normal Storage | 19 acre-ft |
| Surface Area | 4 acres |
| Drainage Area | 3 sq mi |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | MERCER COUNTY COMMISSIONERS |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 09/10/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | PA00246 |
| Federal ID | PA00246 |
| More Info | State Dam Safety Program |