Little Grassy Dam dam
Little Grassy Dam
Little Grassy Dam is a Federal-owned structure located in Carbondale, Illinois, along the picturesque Little Grassy Creek. Built in 1942, this Earth dam stands at a height of 88 feet and serves multiple purposes, including fish and wildlife pond management, flood risk reduction, and recreation. With a normal storage capacity of 24,000 acre-feet and a drainage area of 15.6 square miles, the dam plays a crucial role in managing water resources in the area.
Managed by the US Fish & Wildlife Service, Little Grassy Dam has undergone several modifications over the years to enhance its hydraulic, seismic, and structural capabilities. The dam has a spillway width of 598 feet and a maximum discharge capacity of 35,943 cubic feet per second. Despite its high hazard potential, the dam is currently assessed to be in fair condition, with inspections conducted every three years to ensure its safety and functionality.
Water resource and climate enthusiasts will appreciate the significance of Little Grassy Dam in maintaining ecosystem health and mitigating flood risks in the region. Its strategic location, multiple purposes, and ongoing maintenance efforts by the Fish and Wildlife Service highlight the importance of this structure in sustaining water resources and preserving the natural environment for future generations.
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 Little Grassy Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Big Muddy River At Rte 127 At Murphysboro | 3,540 cfs | → |
| Crab Orchard Creek Near Marion | 209 cfs | → |
| Big Muddy River At Plumfield | 198 cfs | → |
| Cache River At Forman | 3,250 cfs | → |
| South Fork Saline River Nr Carrier Mills | 1,220 cfs | → |
| Lusk Creek Near Eddyville | 5,330 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Little Grassy Dam.
Campgrounds
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Fishing spots
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River runs
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About Little Grassy Dam
Where does the data for Little Grassy 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 below 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.
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.