Decorah Upper Milldam is a gravity dam located in Winneshiek County, Iowa, built in 1911. It carries a Low hazard potential classification.
Dam profile
NID height · 8 ft8 ft tall and 300 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 Decorah Upper Milldam
The primary purpose of Decorah Upper Milldam 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 Upper Iowa River near Lansing.
The dam stands 8 feet tall and stretches 300 feet across, creates a reservoir covering 70 acres, has a maximum storage capacity of 358 acre-feet, and collects water from a drainage area of 568 square miles. Completed in 1911, 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 10/01/2003. That was over 23 years ago.
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Location
| State | Iowa |
| County | Winneshiek |
| Nearest City | Lansing |
| River/Stream | Upper Iowa River |
| Coordinates | 43.32210, -91.68650 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 8 ft |
| Dam Height | 8 ft |
| Dam Length | 300 ft |
| Year Completed | 1911 (115 years old) |
Storage & Hydraulics
| NID Storage | 358 acre-ft |
| Max Storage | 358 acre-ft |
| Normal Storage | 283 acre-ft |
| Surface Area | 70 acres |
| Drainage Area | 568 sq mi |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Iowa Department of Natural Resources |
| Owner Type | State |
| Hazard Classification | Low |
| Condition Assessment | Not assessed |
| Last Inspection | 10/01/2003 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | IA01289 |
| Federal ID | IA01289 |
| More Info | State Dam Safety Program |