Grassy Creek Watershed Dam G- 87 Reservoir Report

Last Updated: December 6, 2025

Grassy Creek Watershed Dam G-87, located in Ewing, Missouri, was completed in 1993 with a primary purpose of flood risk reduction.


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Summary

Managed by the local government, this earth dam stands at a height of 27 feet and has a length of 480 feet, with a maximum storage capacity of 65 acre-feet and a normal storage capacity of 17 acre-feet. The dam, designed by the USDA NRCS, is situated on Grassy Creek, within the Rock Island District. Despite its low hazard potential, the dam has not been rated for its condition.

With a drainage area of 416 square miles and a maximum discharge of 93.3 cubic feet per second, Grassy Creek Watershed Dam G-87 plays a crucial role in managing water flow and mitigating flood risks in the region. Its spillway, which is uncontrolled and 20 feet wide, helps regulate water levels during high-flow events. Although the dam has not been inspected since September 1999, it is maintained in a condition that ensures its functionality for flood risk reduction. The dam's risk assessment indicates a moderate level of risk, highlighting the importance of ongoing monitoring and maintenance to ensure its effectiveness in protecting the surrounding area from potential flooding events.

Year Completed

1993

Dam Length

480

Dam Height

27

River Or Stream

GRASSY CREEK

Primary Dam Type

Earth

Surface Area

7

Hydraulic Height

27

Drainage Area

416

Nid Storage

65

Structural Height

29

Outlet Gates

None

Hazard Potential

Low

Foundations

Soil

Nid Height

29
       
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.