Dam Report

Hiwassee Dam dam

North Carolina, USA Hiwassee River Hazard High
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Dam height
248ft
Hazard rating
High
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Hiwassee Dam -- None dam
Hiwassee Dam None · Hiwassee River
About this dam

Hiwassee Dam

Hiwassee Dam, located on the Hiwassee River in North Carolina, is a concrete gravity dam with a height of 248 feet and a hydraulic height of 254 feet. Completed in 1940 by the Tennessee Valley Authority (TVA), the dam serves multiple purposes including flood risk reduction, hydroelectric power generation, navigation, and recreation. With a normal storage capacity of 398,583 acre-feet and a maximum storage capacity of 471,954 acre-feet, Hiwassee Dam plays a crucial role in managing water resources in the region.

The dam has undergone several modifications over the years to enhance its structural integrity, including seismic and structural upgrades in the early 1990s and ongoing maintenance in the following decades. Despite being classified as having a high hazard potential, the dam is regularly inspected by TVA to ensure its safety and reliability. Hiwassee Dam's controlled spillway, Tainter radial outlet gates, and proximity to the Savannah District of the US Army Corps of Engineers highlight its importance in water resource management and flood control efforts in the area.

With a very high risk assessment rating, Hiwassee Dam remains a critical infrastructure for water resource and climate enthusiasts to monitor and study. The dam's location on the Hiwassee River, its significant storage capacity, and its multi-purpose design make it a key component in the region's water management system. As climate change continues to impact water resources, understanding and maintaining structures like Hiwassee Dam will be essential in ensuring the safety and sustainability of water supplies for the surrounding communities.

StateNone
River / streamHiwassee River
NID IDNC00419
Owner typeFederal
Primary purposeFlood Risk Reduction
Dam typeConcrete
Year built1940
Dam height248 ft
Dam length1,376 ft
Max storage471,954 AF
Normal storage398,583 AF
Surface area5,870.0 ac
Drainage area968.0 sq mi
Hazard potentialHigh
ConditionNot Available
Last inspectionTue, 10 Mar 2020 00:00:00 GMT

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.
Detailed forecast

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.

Hourly detail

Next 5 days, hour by hour

Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.

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Deep dive

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.

TimeConditionTemp (°F)Snow (in)Rain (in)Humidity (%)Wind (mps)Wind dir
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Long-term outlook

15-day temperature & precipitation

Daily temperatures, snow, and rain projected over the next two weeks.

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Regional inflow

Nearby streamflow gauges

USGS streamgauges around Hiwassee Dam -- inflows here typically show up in storage 24-72 hours later.

Track Hiwassee Dam in the Snoflo app

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FAQ

About Hiwassee Dam

Where does the data for Hiwassee 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.

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Manage alerts in the Snoflo app

Custom alerts are configured in the iOS app -- favorite this dam, set a threshold, and you'll get a push the moment conditions cross.

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