Hoffman Dam is an earth dam located in Dubuque County, Iowa, built in 2022. It carries a Low hazard potential classification.
Dam profile
NID height · 30 ft30 ft tall and 400 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 Hoffman Dam
The primary purpose of Hoffman Dam 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 Ashley Hoffman (private). It impounds the Little Maquoketa R near Graf.
The dam stands 30 feet tall and stretches 400 feet across, creates a reservoir covering 3 acres, has a maximum storage capacity of 49 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 2022, the structure is relatively new.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life.
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Location
| State | Iowa |
| County | Dubuque |
| Nearest City | Graf |
| River/Stream | Little Maquoketa R |
| Coordinates | 42.46910, -90.91090 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 30 ft |
| Dam Height | 30 ft |
| Dam Length | 400 ft |
| Year Completed | 2022 (4 years old) |
Storage & Hydraulics
| NID Storage | 49 acre-ft |
| Max Storage | 49 acre-ft |
| Normal Storage | 17 acre-ft |
| Surface Area | 3 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 245 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | Ashley Hoffman |
| Owner Type | Private |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | IA04472 |
| Federal ID | IA04472 |
| More Info | State Dam Safety Program |