Mason Nelms Dam Reservoir Report
Nearby: Winters Dam Mestl South Lagoon Dam
Last Updated: December 5, 2025
Mason Nelms Dam, located in Indianola, Nebraska, is a privately owned structure designed for flood risk reduction along the TR-Republican River.
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Summary
Completed in 1980, this earth dam stands at a height of 19.3 feet and has a storage capacity of 119.2 acre-feet, with a normal storage level of 36.7 acre-feet. The dam covers a surface area of 7.9 acres and serves a drainage area of 0.47 square miles.
Owned privately and regulated by the Nebraska Department of Natural Resources, Mason Nelms Dam is structurally sound with a low hazard potential. The dam has not been rated for condition assessment as of the last inspection in September 2018, with a scheduled inspection frequency of every five years. While there are no associated spillways or outlet gates, the dam plays a crucial role in mitigating flood risks in the region, contributing to the overall water resource management efforts in the area.
With its strategic location and purposeful design, Mason Nelms Dam serves as a vital infrastructure for flood control and water management in Red Willow County, Nebraska. Encompassing both state jurisdiction and regulatory oversight, the dam exemplifies the collaborative efforts between private owners and state agencies to ensure the safety and sustainability of water resources in the region. As a key component of the local water infrastructure, Mason Nelms Dam continues to play a crucial role in protecting communities and ecosystems along the TR-Republican River.
Year Completed |
1980 |
Dam Length |
220 |
Dam Height |
19.3 |
River Or Stream |
TR-REPUBLICAN RIVER |
Primary Dam Type |
Earth |
Surface Area |
7.9 |
Hydraulic Height |
19.3 |
Drainage Area |
0.47 |
Nid Storage |
119.2 |
Structural Height |
19.3 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
19 |
Seasonal Comparison
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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.
Mason Nelms Dam