Nelson Dam No. 2 dam
Nelson Dam No. 2
Nelson Dam No. 2, located in South Dakota along the WEST FORK HAY CANYON, is a Federal-owned structure designed by DUCKS UNLIMITED. Built in 1999, this Earth type dam stands at a height of 23 feet and spans 950 feet in length, with a storage capacity of 123 acre-feet. With a low hazard potential and a moderate risk assessment rating, this dam plays a crucial role in water resource management in the area.
Despite not being regulated or inspected by the state, Nelson Dam No. 2 serves as a vital infrastructure for flood control and water storage, with a maximum discharge capacity of 620 cubic feet per second. The dam's uncontrolled spillway, with a width of 60 feet, helps manage excess water flow during heavy rainfall events. While its condition is currently not rated, the dam's risk management measures are in place to ensure its continued functionality.
Situated within the Fall River county of South Dakota, Nelson Dam No. 2 presents an interesting case study for water resource and climate enthusiasts. Its strategic location, design features, and operational history contribute to the broader conversation on dam infrastructure and its role in maintaining water security in 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 Nelson Dam No. 2 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Horsehead Cr At Oelrichs Sd | · | → |
| Beaver Cr Near Buffalo Gap Sd | 2 cfs | → |
| Cheyenne R Near Buffalo Gap Sd | 56 cfs | → |
| Cheyenne R Below Angostura Dam Sd | 1 cfs | → |
| Fall R At Hot Springs Sd | 34 cfs | → |
| White R Near Oglala Sd | 101 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Nelson Dam No. 2.
Boat launches
- Fall River County
- Sheps Canyon Road Fall River County
- South Boat Ramp Road Fall River County
- County Highway 6d Fall River County
Campgrounds
- Angostura State Rec Area
- Cottonwood Springs
- Elk Mountain Campground
- Elk Mountain - Wind Cave National Park
- French Creek
- French Creek Campground
Track Nelson Dam No. 2 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 Nelson Dam No. 2
Where does the data for Nelson Dam No. 2 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 Nelson Dam No. 2.