Thief Lake Reservoir Report
Nearby: Pool No. 1 Pool No. 25
Last Updated: December 13, 2025
Thief Lake, located in Thief River Falls, Minnesota, is a gravity dam constructed in 1931 with a primary purpose of recreation.
°F
°F
mph
Wind
%
Humidity
Summary
The dam stands at 13 feet tall, with a structural height of 19 feet and a length of 70 feet. It has a storage capacity of 63,900 acre-feet and covers a surface area of 7,430 acres, serving as a popular destination for water resource and climate enthusiasts.
The dam's drainage area spans 280 square miles, with a maximum discharge of 3,190 cubic feet per second. Despite being classified as having a low hazard potential, Thief Lake's condition assessment in 2009 was deemed fair. The dam has undergone structural modifications in 1998 and 2016, ensuring its continued functionality and safety for visitors and surrounding communities.
Thief Lake's risk assessment is very high, indicating the need for active risk management measures to mitigate potential hazards. With its controlled spillway and regulated state oversight, the dam remains a vital resource for water management and recreational activities in the region, offering a unique opportunity for enthusiasts to explore the intersection of water resources and climate dynamics.
Years Modified |
1998 - Structural, 2016 - Structural |
Year Completed |
1931 |
Dam Length |
70 |
Dam Height |
13 |
River Or Stream |
THIEF RIVER |
Primary Dam Type |
Gravity |
Surface Area |
7430 |
Drainage Area |
280 |
Nid Storage |
63900 |
Structural Height |
19 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
19 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Thief Lake