Hopkinton Milldam is a gravity dam located in Delaware County, Iowa, built in 1925. It carries a Low hazard potential classification.
Dam profile
NID height · 10 ft10 ft tall and 175 ft long. 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 Hopkinton Milldam
The primary purpose of Hopkinton Milldam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Delaware County Conservation Board (local government). It impounds the Maquoketa River near Hopkinton.
The dam stands 10 feet tall and stretches 175 feet across, creates a reservoir covering 90 acres, has a maximum storage capacity of 433 acre-feet, and collects water from a drainage area of 506 square miles. Completed in 1925, the structure is over a century old.
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. The most recent inspection on record was 06/01/1999. That was over 27 years ago.
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Location
| State | Iowa |
| County | Delaware |
| Nearest City | Hopkinton |
| River/Stream | Maquoketa River |
| Coordinates | 42.33770, -91.25770 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 10 ft |
| Dam Height | 10 ft |
| Dam Length | 175 ft |
| Year Completed | 1925 (101 years old) |
Storage & Hydraulics
| NID Storage | 433 acre-ft |
| Max Storage | 433 acre-ft |
| Normal Storage | 433 acre-ft |
| Surface Area | 90 acres |
| Drainage Area | 506 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Delaware County Conservation Board |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 06/01/1999 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | IA01294 |
| Federal ID | IA01294 |
| More Info | State Dam Safety Program |