Decorah Upper Milldam dam
Decorah Upper Milldam
The Decorah Upper Milldam, located on the Upper Iowa River in Iowa, was completed in 1911 and serves as a recreational destination for water resource and climate enthusiasts. This gravity dam stands at a height of 8 feet and has a length of 300 feet, creating a surface area of 70 acres and providing a storage capacity of 358 acre-feet. The dam is state-regulated by the Iowa Department of Natural Resources and undergoes regular inspections to ensure its safety and functionality.
Despite being rated as having a low hazard potential, the Decorah Upper Milldam is considered to have a moderate risk level due to its age and condition assessment as "Not Rated." The spillway of the dam is uncontrolled with a width of 142 feet, allowing for controlled releases of excess water during periods of high flow. While the dam does not have outlet gates or associated structures, it continues to provide valuable recreational opportunities for the surrounding community and visitors alike.
As the Decorah Upper Milldam remains a prominent feature along the Upper Iowa River, it is important for water resource and climate enthusiasts to appreciate its historical significance and ongoing role in providing recreational benefits. With its scenic location and regulated state oversight, the dam serves as a reminder of the balance between human development and natural ecosystems in the management of water resources.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Decorah Upper Milldam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Upper Iowa River At Decorah | 494 cfs | → |
| Upper Iowa River Near Dorchester | 778 cfs | → |
| Upper Iowa River At Bluffton | 335 cfs | → |
| Turkey River At Spillville | 183 cfs | → |
| Turkey River Near Eldorado | 628 cfs | → |
| Yellow River At Ion | 565 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Decorah Upper Milldam.
Boat launches
- Winneshiek County
- Lycurgus Road Allamakee County
- James Drive Allamakee County
- Great River Rd Allamakee County
- River Street Clermont
- Valley Avenue Howard County
Campgrounds
- Sampson Springs Campground
- Pulpit Rock Campground
- Highland General Store & Campground
- Waukon City Park Campground
- Canoe Landing
- Lake Meyer County Park Campground
Fishing spots
Paddle runs
- The "Lower" Dam, Near The Confluence Of Coon Creek To Lane's Bridge
- The Town Of Bluffton To The "Lower" Dam, Near The Confluence Of Coon Creek
- The Minnesota-Iowa State Border To Ends Near The Town Of Bluffton, Iowa
- Western Boundary Of Effigy Mounds National Monument To Boundary Of Effigy Mounds National Monument
- The Big Green River To The River's Mouth At The Mississippi River
Track Decorah Upper Milldam in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Decorah Upper Milldam
Where does the data for Decorah Upper Milldam come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Decorah Upper Milldam.