Mississippi River Lock And Dam 5a Reservoir Report

Last Updated: December 5, 2025

Mississippi River Lock and Dam 5a, located in Winona, Minnesota, is a vital structure managed by the US Army Corps of Engineers for the primary purpose of navigation, with additional benefits for recreation.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1936, this concrete dam stands at 46 feet high and spans 21,520 feet in length, with a capacity to store up to 260,000 acre-feet of water. The dam plays a crucial role in managing water levels along the Mississippi River, with a controlled spillway width of 575 feet and a maximum discharge capacity of 268,000 cubic feet per second.

With a significant hazard potential, the dam is subject to regular inspections and risk assessments to ensure its structural integrity and effectiveness in flood risk management. The US Army Corps of Engineers actively monitors and addresses all types of flood risks associated with the dam, working closely with local emergency managers and the public to raise awareness and develop emergency action plans. Continuous maintenance and repairs are carried out to uphold the dam's functionality and readiness for potential emergencies. As a critical component of the regional water resource infrastructure, Mississippi River Lock and Dam 5a serves as a key player in maintaining the safety and stability of the surrounding areas amidst varying hydrological conditions.

Year Completed

1936

Dam Length

21520

Dam Height

17

River Or Stream

MISSISSIPPI

Primary Dam Type

Concrete

Surface Area

7000

Length Of Locks

600

Hydraulic Height

30

Drainage Area

59105

Nid Storage

260000

Structural Height

46

Outlet Gates

Roller - 5, Tainter (radial) - 5, Uncontrolled - 0

Hazard Potential

Significant

Foundations

Soil

Nid Height

46
       
Seasonal Comparison

Weather Forecast

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.