Lewis Dam dam
Lewis Dam
Lewis Dam, located in Union Mills, Iowa, along the TR-North Skunk River, was completed in 1963 by the USDA NRCS. This private dam serves primarily for fire protection, stock, or small fish pond purposes, with a height of 25 feet and a length of 327 feet. The dam has a storage capacity of 45 acre-feet, with a normal storage level of 25 acre-feet and a surface area of 4 acres. Despite its low hazard potential and moderate risk assessment, the dam's condition is currently not rated, and it is not regularly inspected.
Managed by the Iowa Department of Natural Resources, Lewis Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and compliance with regulations. The dam features an uncontrolled spillway type and is constructed with an earth foundation and soil core. While the dam has not been modified in recent years and lacks certain emergency preparedness measures, it remains a key structure for water resource management in the region. The dam's location, design, and purpose make it a vital component in the local ecosystem and water supply infrastructure.
Water resource and climate enthusiasts will find Lewis Dam intriguing for its historical significance, structural design, and environmental impact. As a privately owned dam with state oversight, Lewis Dam showcases the importance of balancing water management needs with regulatory requirements. With its unique characteristics and role in fire protection and stock pond maintenance, Lewis Dam serves as a focal point for understanding the intersection of human development and natural resource conservation in the context of climate change and water sustainability.
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 Lewis Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| South Skunk River Near Oskaloosa | 1,180 cfs | → |
| Des Moines River Near Pella | 6,290 cfs | → |
| Des Moines River Near Tracy | 6,480 cfs | → |
| Walnut Creek Near Hartwick | 32 cfs | → |
| Cedar Creek Near Bussey | 22 cfs | → |
| English Creek Near Knoxville | 4 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lewis Dam.
Boat launches
- Jade Street Jasper County
- Rock Creek East Street Jasper County
- Mahaska County
- 198th Place Marion County
- Marion County
Campgrounds
- Robertson Access
- Diamond Lake County Park
- Union Mills Access
- Glendale Access
- Kellogg Rv Park
- Rock Creek State Park
More reservoirs
Track Lewis 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 Lewis Dam
Where does the data for Lewis 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 Lewis Dam.