One Horse Gap dam
One Horse Gap
One Horse Gap, located in Pope County, Illinois, is a federal-owned earth dam completed in 1973 for the primary purpose of recreation. Standing at a height of 30 feet with a hydraulic height of 23 feet, the dam boasts a length of 443 feet and a storage capacity of 304 acre-feet. Managed by the USDA Forest Service, the dam is regulated, inspected, and enforced by the agency to ensure its safety and functionality.
With a significant hazard potential and a fair condition assessment as of August 2019, One Horse Gap poses moderate risk according to a risk assessment rating of 3. The spillway type is uncontrolled, with a width of 20 feet, and the dam is situated on the TR-GRAND PIERRE river. Despite its age, the dam remains a key feature for recreation in the area, offering opportunities for water-based activities and scenic views for water resource and climate enthusiasts to enjoy.
Overall, One Horse Gap serves as an important structure within the federal-owned land, providing both recreational opportunities and water management benefits. As a well-maintained and regulated earth dam, it stands as a testament to the ongoing efforts of the USDA Forest Service to ensure the safety and sustainability of water resources in Illinois.
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 One Horse Gap -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Lusk Creek Near Eddyville | 7 cfs | → |
| South Fork Saline River Nr Carrier Mills | 12 cfs | → |
| Ohio River At Old Shawneetown | 259,000 cfs | → |
| Crab Orchard Creek Near Marion | 1 cfs | → |
| Cache River At Forman | 2 cfs | → |
| Ohio River At Metropolis | 444,000 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near One Horse Gap.
Boat launches
- 1st Street Rosiclare
- Front Street Elizabethtown
- Cr-1385 Crittenden County
- Golconda Ferry Road Livingston County
- Main Street Golconda
- Tower Rock Road Hardin County
Campgrounds
- Pharaoh Campground
- Bear Branch Horse Resort
- High Knob Campground
- Teal Pond Campground
- Red Bud Campground
- Camp Cadiz Campground
Fishing spots
- One Horse Gap Lake
- Lake Tecumseh
- Whoopie Cat Lake
- Little Cache Lake #1 (Bowman Lake)
- Lake Of Egypt
- Dutchman Lake
Paddle runs
- Bridge At Eddyville Blacktop To Confluence With Ohio River At Golconda,Il
- Wallace Cemetery Approx 2.5 Miles Nw Of Herod, Il To Confluence With Ohio River At Golconda Jobs Corp Center
- Source, About 2 Miles East Of Delwood, Il (Sec 10, T11s, R6e) To Bridge At Eddyville Blacktop (Se1/4,Sec.16,T12s, R6e)
- 1 Minle Southwest Of Delwood, Il (Sec. 18, T11s, R13e) To Reesville, 1/4 Mile South Of The Confluence With Sugar Creek
- Russell Cemetery, Approx 1/4 Mile North Of Karbers Ridge Road To Proclamation Boundary, 1 Mile Nw Of Elizabethtown,Il
- 1 Mile West Of Alto Pass, Il To 1/2 Mile South Of Confluence With Clear Creek, West Of Trail Of Tears State Forest
Track One Horse Gap 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 One Horse Gap
Where does the data for One Horse Gap 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 Significant 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 One Horse Gap.