County Line Impoundment dam
County Line Impoundment
County Line Impoundment is a federal-owned earth dam located in Lyman, South Dakota, on Antelope Creek. Completed in 1992, this dam stands at a height of 17 feet and has a storage capacity of 96 acre-feet. While its primary purpose is not specified, it serves as a crucial water resource for the region, with a normal storage capacity of 42 acre-feet and a drainage area of 4 square miles.
Despite being categorized as having a low hazard potential and a "Not Rated" condition assessment, County Line Impoundment has not undergone recent inspections or maintenance updates. It lacks an Emergency Action Plan (EAP) and other risk management measures, raising concerns about its readiness in the face of potential emergencies or natural disasters. With no designated outlet gates or associated structures, the dam's operations and safety protocols remain ambiguous, highlighting the need for enhanced regulatory oversight and proactive maintenance efforts to ensure the longevity and resilience of this vital water infrastructure.
As climate change continues to impact water resources and weather patterns, the importance of maintaining and monitoring dams like County Line Impoundment becomes increasingly urgent. With its strategic location on Antelope Creek, this dam plays a pivotal role in water storage and flood control for the surrounding area. Moving forward, prioritizing comprehensive inspections, risk assessments, and emergency preparedness measures will be essential to safeguarding not only the dam itself but also the communities and ecosystems that rely on its stability and functionality.
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 County Line Impoundment -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Bad R Near Fort Pierre Sd | 4 cfs | → |
| White River Near White River | 47 cfs | → |
| Little White R Below White River Sd | 117 cfs | → |
| White R Near Oacoma Sd | 131 cfs | → |
| Black Pipe Creek Nr Belvidere | 8 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near County Line Impoundment.
Track County Line Impoundment 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 County Line Impoundment
Where does the data for County Line Impoundment 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 County Line Impoundment.