Gannon Dam dam
Gannon Dam
Gannon Dam, located in Jasper County, Iowa, was completed in 1969 and serves multiple purposes including fire protection, stock watering, and small fish pond recreation. Owned privately, the dam is regulated by the Iowa Department of Natural Resources and is subject to state permitting, inspection, and enforcement. The dam, designed by the USDA NRCS, is an earth structure with a height of 27 feet and a length of 300 feet, providing a storage capacity of 48 acre-feet and covering a surface area of 3 acres.
Situated on the TR-Skunk River, Gannon Dam has a low hazard potential and a moderate risk assessment rating. Its spillway type is uncontrolled, and it has not been modified in recent years. Although the dam's condition has not been formally assessed, it is deemed to be in a satisfactory state. While the dam does not fall under the jurisdiction of the US Army Corps of Engineers, it is subject to state regulations and oversight, ensuring its safe operation and maintenance for the surrounding community and ecosystem. Water resource and climate enthusiasts can appreciate the role of Gannon Dam in providing essential services while managing potential risks associated with its operation.
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 Gannon Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Indian Creek Near Mingo | 724 cfs | → |
| South Skunk River At Colfax | 1,880 cfs | → |
| Fourmile Creek Near Ankeny | 154 cfs | → |
| Fourmile Creek At Des Moines | 217 cfs | → |
| Des Moines River At 2nd Avenue | 5,350 cfs | → |
| Des Moines River Near Saylorville | 4,250 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Gannon Dam.
Boat launches
- Arney Avenue Marshall County
- Southeast Vandalia Drive Pleasant Hill
- Polk County
- 255th Street Story County
- 250th Street Story County
Track Gannon Dam 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 Gannon Dam
Where does the data for Gannon Dam 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 Gannon Dam.