Mississippi River Locks And Dam 27 Reservoir Report
Last Updated: January 12, 2026
Mississippi River Locks and Dam 27, located in Granite City, Missouri, is a vital structure owned and operated by the US Army Corps of Engineers for navigation purposes on the Mississippi River.
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Summary
Completed in 1962, this rockfill dam stands at a height of 25 feet and spans a length of 3240 feet. With two locks facilitating the movement of water traffic, this dam plays a crucial role in managing water levels and ensuring safe navigation along the river.
Despite its significance, Mississippi River Locks and Dam 27 poses a significant hazard potential and is subject to regular inspections and risk assessments to mitigate potential risks. The US Army Corps of Engineers actively manages dam-related flood risks by monitoring the dam's condition, prioritizing maintenance activities, and engaging with local emergency managers and the public to raise awareness and preparedness for potential emergencies. The dam's emergency action plan is regularly updated, and measures are in place to address any issues that may arise during severe weather events or unexpected water flow conditions.
In light of the dam's critical role in water resource management and navigation, ongoing efforts are being made to enhance risk management measures and ensure the structural integrity of Mississippi River Locks and Dam 27. By maintaining a proactive approach to monitoring and addressing potential risks, the US Army Corps of Engineers aims to safeguard the surrounding communities and water resources while supporting the efficient movement of goods and vessels along the Mississippi River.
Year Completed |
1962 |
Dam Length |
3240 |
Dam Height |
25 |
River Or Stream |
MISSISSIPPI RIVER |
Primary Dam Type |
Rockfill |
Hydraulic Height |
25 |
Nid Storage |
50 |
Structural Height |
25 |
Hazard Potential |
Significant |
Nid Height |
25 |
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.
Mississippi River Locks And Dam 27
Lake Drive Pontoon Beach