Gilliand Dam Reservoir Report

Last Updated: December 13, 2025

Gilliand Dam, located in Washington County, Iowa, stands as a testament to effective water resource management and climate adaptation efforts.


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Summary

Built in 1972 by the USDA NRCS, this earth dam serves multiple purposes including fire protection and creating a small fish pond. With a height of 32 feet and a length of 352 feet, the dam has a storage capacity of 41 acre-feet, providing crucial water resources for the surrounding area.

Managed by a private owner and regulated by the Iowa DNR, Gilliand Dam has been deemed to have a low hazard potential and a moderate risk assessment rating. Despite not being currently rated for condition assessment, the dam continues to play a vital role in water conservation and ecosystem preservation along the TR-GOOSE CREEK river system. While the dam does not have outlet gates or a controlled spillway, its uncontrolled spillway type ensures that excess water is safely managed during heavy rainfall events.

As climate change continues to pose challenges to water resources and infrastructure, Gilliand Dam stands as a reliable structure in safeguarding against potential risks. With its strategic location and design, the dam remains a valuable asset in maintaining water security and supporting the local ecosystem. Adhering to state regulations and undergoing regular inspections, Gilliand Dam exemplifies the importance of sustainable water management practices in the face of a changing climate.

Year Completed

1972

Dam Length

352

Dam Height

32

River Or Stream

TR-GOOSE CREEK

Primary Dam Type

Earth

Surface Area

2.9

Drainage Area

0.06

Nid Storage

41

Hazard Potential

Low

Foundations

Soil

Nid Height

32
       
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.