Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island) dam
Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island)
The Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island) is a key structure located in Humphreys, Tennessee, owned and managed by the Tennessee Valley Authority (TVA). This earth dam, completed in 1968, serves as a containment area for ash disposal from the plant, with a storage capacity of 323 acre-feet. The dam stands at a height of 41 feet and has a spillway width of 15 feet, ensuring controlled water discharge during peak flow events.
With a significant hazard potential and moderate risk assessment score, the Johnsonville Fossil Plant dike is subject to regular inspections and maintenance by TVA. The last inspection in April 2021 confirmed the structure's overall condition as "Not Available", indicating a need for further assessment. While the dam has not been state-regulated, TVA continues to monitor and manage the facility to ensure its safe operation and compliance with federal guidelines.
Water resource and climate enthusiasts will appreciate the critical role of the Johnsonville Fossil Plant dike in managing ash disposal and protecting the surrounding environment. As an essential component of the plant's operations, this earth dam reflects TVA's commitment to responsible resource management and risk mitigation in the face of changing climate conditions.
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 Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island) -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Cypress Creek At Camden | 24 cfs | → |
| Big Sandy River At Bruceton | 154 cfs | → |
| Duck River Above Hurricane Mills | 1,840 cfs | → |
| Buffalo River Below Lobelville | 1,110 cfs | → |
| Crooked Creek Near Huntingdon | 38 cfs | → |
| Piney River At Vernon | 186 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island).
Boat launches
- New Johnsonville Boat Ramp
- Eva Beach Drive 248, Eva
- Birdsong Marina Road Benton County
- Gaynor Slough Boat Ramp
- Humphreys County
Campgrounds
- Nathan Bedford Forrest State Park
- Camp Isengard
- Natchez Trace State Park
- Mousetail Landing State Park
- Beech Bend
- Paris Landing State Park
Track Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island) 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 Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island)
Where does the data for Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island) 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 Johnsonville Fossil Plant - Ash Disposal Area Perimeter Dike (Island).