East Lemmon dam
East Lemmon
East Lemmon is a state-owned earth dam located in South Dakota, specifically in Perkins County. Built in 1930 by the Works Progress Administration (WPA), this dam sits on TR-GRAND river and serves multiple purposes, including flood control and water storage. With a height of 30 feet and a length of 1200 feet, East Lemmon has a normal storage capacity of 1360 acre-feet and a maximum storage capacity of 2600 acre-feet, making it a crucial water resource in the region.
Despite being classified as having a low hazard potential and a moderate risk assessment, East Lemmon is regulated, permitted, inspected, and enforced by the South Dakota Department of Agriculture and Natural Resources (DANR). The dam has an uncontrolled spillway with a width of 125 feet and a drainage area of 88 square miles. While the condition assessment is not rated, the last inspection in November 2018 deemed the dam to be in satisfactory condition. With its strategic location and key role in water management, East Lemmon continues to be a vital infrastructure for the community and the environment.
Managed by the St. Paul District of the US Army Corps of Engineers, East Lemmon contributes to the overall water resource management in the region. With its stone core type and soil foundation, this dam represents a blend of engineering excellence and natural resilience. As climate change continues to impact water resources, East Lemmon stands as a testament to the importance of sustainable infrastructure in mitigating the effects of extreme weather events and ensuring water security for future generations.
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 East Lemmon -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| North Fork Grand R Near White Butte Sd | 2 cfs | → |
| South Fork Grand R Near Cash Sd | 25 cfs | → |
| Cedar Creek Nr Haynes | 3 cfs | → |
| Cedar Creek Nr Raleigh | 11 cfs | → |
| Moreau R Near Faith Sd | 78 cfs | → |
| Cannonball River Nr Raleigh | 14 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near East Lemmon.
Track East Lemmon 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 East Lemmon
Where does the data for East Lemmon 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 East Lemmon.