Decorah Lower Milldam is a gravity dam located in Winneshiek County, Iowa, built in 1973. It carries a Low hazard potential classification.
Dam profile
NID height · 27 ft27 ft tall and 500 ft long, taller than 59% 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 Decorah Lower Milldam
The primary purpose of Decorah Lower 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 27 feet tall and stretches 500 feet across, creates a reservoir covering 80 acres, has a maximum storage capacity of 1,318 acre-feet, and collects water from a drainage area of 645 square miles. Completed in 1973, the structure is well into its service life at over 50 years 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 | 43.33910, -91.64220 |
Physical Characteristics
| Dam Type | Gravity |
| NID Height | 27 ft |
| Dam Height | 27 ft |
| Dam Length | 500 ft |
| Year Completed | 1973 (53 years old) |
Storage & Hydraulics
| NID Storage | 1,318 acre-ft |
| Max Storage | 1,318 acre-ft |
| Normal Storage | 1,091 acre-ft |
| Surface Area | 80 acres |
| Drainage Area | 645 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 | IA01288 |
| Federal ID | IA01288 |
| More Info | State Dam Safety Program |