Backbone Dam is a gravity dam located in Delaware County, Iowa, built in 1938. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 33 ft33 ft tall and 908 ft long, 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 concrete gravity section and the water level is illustrative.
About Backbone Dam
The primary purpose of Backbone Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Iowa Department of Natural Resources (state). It impounds the Maquoketa River near Dundee.
The dam stands 33 feet tall and stretches 908 feet across, creates a reservoir covering 125 acres, has a maximum storage capacity of 1,000 acre-feet, and collects water from a drainage area of 120 square miles. Completed in 1938, 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 10/16/2024.
At 33 feet, this dam is taller than 76% of dams nationwide.
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Location
| State | Iowa |
| County | Delaware |
| Nearest City | Dundee |
| River/Stream | Maquoketa River |
| Coordinates | 42.60030, -91.53620 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 33 ft |
| Dam Height | 33 ft |
| Dam Length | 908 ft |
| Year Completed | 1938 (88 years old) |
Storage & Hydraulics
| NID Storage | 1,000 acre-ft |
| Max Storage | 1,000 acre-ft |
| Normal Storage | 600 acre-ft |
| Surface Area | 125 acres |
| Drainage Area | 120 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Iowa Department of Natural Resources |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/16/2024 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | IA01965 |
| Federal ID | IA01965 |
| More Info | State Dam Safety Program |