General Motors Primary Lagoon is an earth dam located in Defiance County, Ohio, built in 1940. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 30 ft30 ft tall and 2,300 ft long, taller than 68% 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 General Motors Primary Lagoon
The primary purpose of General Motors Primary Lagoon is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by Gm Defiance Casting Operations. It impounds the Maumee River - Offstream near Independence.
The dam stands 30 feet tall and stretches 2,300 feet across, creates a reservoir covering 22 acres, has a maximum storage capacity of 230 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1940, the structure is well-established, with more than 75 years of service.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. 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 04/26/2022.
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Location
| State | Ohio |
| County | Defiance |
| Nearest City | Independence |
| River/Stream | Maumee River - Offstream |
| Coordinates | 41.29111, -84.31528 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 30 ft |
| Dam Height | 30 ft |
| Dam Length | 2,300 ft |
| Year Completed | 1940 (86 years old) |
Storage & Hydraulics
| NID Storage | 230 acre-ft |
| Max Storage | 230 acre-ft |
| Normal Storage | 198 acre-ft |
| Surface Area | 22 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 100 cfs |
Ownership & Safety
| Purpose | Water Supply |
| Owner | Gm Defiance Casting Operations |
| Owner Type | Not Listed |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 04/26/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | OH01503 |
| Federal ID | OH01503 |
| More Info | State Dam Safety Program |