Grassy Creek Watershed Dam G- 57 Reservoir Report

Last Updated: December 5, 2025

Grassy Creek Watershed Dam G-57, located in Lewis County, Missouri, was completed in 2005 by the USDA NRCS with the primary purpose of flood risk reduction.


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Summary

This earth dam stands at a height of 27 feet and has a structural height of 34 feet, spanning 445 feet in length. With a maximum storage capacity of 160.9 acre-feet and a normal storage of 37.3 acre-feet, the dam serves multiple purposes including fire protection, stock or small fish pond, fish and wildlife pond, in addition to flood risk reduction.

The dam is situated on Grassy Creek and is under the jurisdiction of the Rock Island District of the USACE. With a low hazard potential and a moderate risk assessment rating, the dam has not been rated for its condition. Despite not being state regulated or inspected, the dam serves as a vital infrastructure for the local government of Lewis County, Missouri. With an uncontrolled spillway type and outlet gates, the dam is designed to manage a maximum discharge of 219.6 cubic feet per second. Although the dam has not been assessed for its emergency action plan or inundation maps, it continues to play a crucial role in mitigating flood risks in the region.

Year Completed

2005

Dam Length

445

Dam Height

27

River Or Stream

GRASSY CREEK

Primary Dam Type

Earth

Surface Area

4

Hydraulic Height

27

Drainage Area

147.2

Nid Storage

160.9

Structural Height

34

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Soil

Nid Height

34
       
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.