Decorah Lower Milldam dam
Decorah Lower Milldam
Decorah Lower Milldam, located in Iowa's Winneshiek County along the Upper Iowa River, was completed in 1973 and serves as a popular recreational spot for water resource and climate enthusiasts. This gravity dam stands at a height of 27 feet and spans 500 feet, with a storage capacity of 1,318 acre-feet and a normal storage level of 1,091 acre-feet. The dam's surface area covers 80 acres, providing a picturesque setting for outdoor activities like fishing, boating, and birdwatching.
Managed by the Iowa Department of Natural Resources, Decorah Lower Milldam is regulated and inspected by the state to ensure its safety and functionality. With a low hazard potential and a moderate risk assessment rating, the dam poses minimal risk to the surrounding community. Although its condition is currently not rated, the dam's recreational value and contribution to the local ecosystem make it a key feature in the region's water resource management efforts.
Decorah Lower Milldam's presence along the Upper Iowa River not only enhances the area's natural beauty but also provides valuable recreational opportunities for residents and visitors alike. As a gravity dam with a focus on recreation, this structure showcases the importance of sustainable water resource development and management in a changing climate. With its low hazard potential and moderate risk assessment, the dam continues to serve as a safe and enjoyable destination for outdoor enthusiasts seeking to connect with nature and explore the diverse ecosystem of the region.
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 Lower Milldam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Upper Iowa River At Decorah | 398 cfs | → |
| Upper Iowa River Near Dorchester | 637 cfs | → |
| Upper Iowa River At Bluffton | 264 cfs | → |
| Turkey River At Spillville | 114 cfs | → |
| Turkey River Near Eldorado | 400 cfs | → |
| Yellow River At Ion | 210 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Decorah Lower Milldam.
Boat launches
- Lycurgus Road Allamakee County
- Winneshiek County
- James Drive Allamakee County
- Great River Rd Allamakee County
- Mississippi River -- Big Slough Landing
- Voyageur Highway Houston County
Campgrounds
- Sampson Springs Campground
- Highland General Store & Campground
- Pulpit Rock Campground
- Waukon City Park Campground
- Trollskogen City Park
- Canoe Landing
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 Lower 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 Lower Milldam
Where does the data for Decorah Lower 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 Lower Milldam.