Heron Dam
Heron Dam is an earth dam located in Oakland County, Michigan, built in 1969. It carries a High hazard potential classification and has a fair condition assessment.
About Heron Dam
The primary purpose of Heron Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Mdnr Parks & Recreation (state). It impounds the Thread Creek near Grand Blanc.
The dam stands 26 feet tall and stretches 1,025 feet across, creates a reservoir covering 123 acres, has a maximum storage capacity of 1,600 acre-feet, and collects water from a drainage area of 3 square miles. Completed in 1969, 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 10/17/2018. That was 7 years ago, which is on the longer end for a high-hazard structure.
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 Michigan 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 | Michigan |
| County | Oakland |
| Nearest City | Grand Blanc |
| River/Stream | Thread Creek |
| Coordinates | 42.81103, -83.53075 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 26 ft |
| Dam Height | 26 ft |
| Dam Length | 1,025 ft |
| Year Completed | 1969 (57 years old) |
Storage & Hydraulics
| NID Storage | 1,600 acre-ft |
| Max Storage | 1,600 acre-ft |
| Normal Storage | 1,100 acre-ft |
| Surface Area | 123 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 74 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | MDNR Parks & Recreation |
| Owner Type | State |
| Hazard Classification | High |
| Condition Assessment | Fair |
| Last Inspection | 10/17/2018 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MI00692 |
| Federal ID | MI00692 |
| More Info | State Dam Safety Program |