Sylvan Lake Dam dam
Sylvan Lake Dam
Sylvan Lake Dam, located in Hill City, South Dakota, is a state-regulated structure on Spring Creek with a height of 37 feet and a length of 57 feet. Completed in 1906, this arch dam has a storage capacity of 240 acre-feet and a maximum discharge rate of 2,880 cubic feet per second. The dam is classified as having a high hazard potential and is currently assessed to be in fair condition as of the last inspection in November 2020.
Managed by the South Dakota Department of Agriculture and Natural Resources (DANR), Sylvan Lake Dam plays a crucial role in water resource management in the region. The dam's primary purpose and associated structures are not specified, but it serves as a key infrastructure for flood control, water supply, and recreational activities in the area. With regular inspections, permitting, and enforcement measures in place, the dam ensures the safety and stability of its surrounding community and environment.
As a significant landmark in Custer County, South Dakota, Sylvan Lake Dam stands as a testament to early 20th-century engineering and continues to serve its intended functions to this day. With its picturesque location and vital role in water resource management, the dam remains a focal point for water resource and climate enthusiasts interested in the history and impact of dam infrastructure 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 Sylvan Lake Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Battle Cr Near Keystone Sd | 1 cfs | → |
| Grace Coolidge Cr Nr Game Lodge Nr Custer Sd | 1 cfs | → |
| French Cr Above Fairburn Sd | 2 cfs | → |
| Spring Cr Near Keystone Sd | 1 cfs | → |
| Rapid Cr Below Pactola Dam Sd | 79 cfs | → |
| Rapid Cr Above Pactola Res At Silver City | 23 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Sylvan Lake Dam.
Boat launches
- Bismark Lake Road Custer County
- Calvert Road Pennington County
- Sheridan Lake Road 16451, Rapid City
- Pennington County
- Fsr 450 Pennington County
- Jenney Gulch Picnic Area Fishing Access
Campgrounds
- Sylvan Lake - Custer State Park
- Sylvan Lake Campground
- Oreville
- Oreville Campground
- Rafter J Bar Ranch
- Fort Welikit
Track Sylvan Lake 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 Sylvan Lake Dam
Where does the data for Sylvan Lake 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 High 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 Sylvan Lake Dam.