Thelen Dam Reservoir Report
Last Updated: December 6, 2025
Thelen Dam, located in Polk, Nebraska, is a privately owned structure designed by USDA NRCS and regulated by the Nebraska Department of Natural Resources.
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Summary
Completed in 1969, this earth dam stands at 17 feet high and spans a length of 410 feet along the TR-Big Blue River. With a primary purpose of flood risk reduction, Thelen Dam has a normal storage capacity of 25 acre-feet and a maximum storage of 80 acre-feet, serving as a vital resource for water management in the area.
Despite its low hazard potential, Thelen Dam's condition assessment is rated as poor, indicating a need for maintenance and improvement. The last inspection in May 2019 highlighted this concern, with an inspection frequency of every 5 years. The dam's emergency action plan status, risk assessment, and management measures are currently unknown, raising questions about its preparedness for potential emergencies and the overall safety of the structure.
Water resource and climate enthusiasts interested in Thelen Dam can appreciate its role in flood risk reduction and water management along the TR-Big Blue River in Nebraska. With its historical significance dating back to 1969, this structure faces challenges in maintaining its condition and safety standards, warranting further attention and action to ensure its continued effectiveness in protecting the surrounding area from potential flooding events.
Year Completed |
1969 |
Dam Length |
410 |
Dam Height |
17 |
River Or Stream |
TR-BIG BLUE RIVER |
Primary Dam Type |
Earth |
Surface Area |
3 |
Hydraulic Height |
16 |
Drainage Area |
0.7 |
Nid Storage |
80 |
Structural Height |
18 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
18 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Clear Cr 1.75mi W Of Polk Co Line
|
17cfs |
Platte River Near Duncan
|
243cfs |
Silver Cr
|
6cfs |
Prairie Creek Nr Silver Creek Nebr
|
4cfs |
Loup River Near Genoa
|
3030cfs |
Beaver Creek At Genoa
|
114cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
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. Investigations and studies are necessary.
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.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams 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, environment 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.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Thelen Dam