Heart Butte Reservoir Report

Last Updated: December 8, 2025

Heart Butte is a federal-owned earth dam located in Mandan, North Dakota, along the Heart River.


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Summary

Built in 1948 by the Bureau of Reclamation, it serves the primary purpose of flood risk reduction and irrigation. Standing at a height of 142 feet with a hydraulic height of 118 feet, the dam has a storage capacity of 451,200 acre-feet and covers a surface area of 10,953 acres. It is regulated and inspected by the Bureau of Reclamation, ensuring its structural integrity and operational efficiency.

The dam features an uncontrolled spillway and two slide gates for outlet control, with a hazard potential rated as high due to its location and potential impact in case of failure. Despite being modified in 1987 for hydraulic and structural improvements, the condition assessment remains unavailable as of the last inspection in July 2020. The dam's risk assessment is moderate, highlighting the need for ongoing risk management measures to mitigate potential hazards and ensure the safety of surrounding communities.

Overall, Heart Butte plays a crucial role in managing water resources and protecting against flooding in the area. Its historical significance and continued operation under federal oversight underscore the importance of maintaining and monitoring dams to safeguard against potential risks and ensure sustainable water management practices for the future.

Years Modified

1987 - Hydraulic, 1987 - Structural

Year Completed

1948

Dam Length

1850

Dam Height

142

River Or Stream

HEART RIVER

Primary Dam Type

Earth

Surface Area

10953

Hydraulic Height

118

Drainage Area

1810

Nid Storage

451200

Structural Height

142

Outlet Gates

Slide (sluice gate) - 2

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

142
       
Seasonal Comparison

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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. 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

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, 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.