Greenfield Dam Reservoir Report

Last Updated: December 6, 2025

Greenfield Dam, located in Jefferson County, Iowa, is a privately-owned structure designed by the NRCS and completed in 1998.


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Summary

With a primary purpose of serving as a fire protection, stock, or small fish pond, this earth dam stands at a height of 35 feet and spans a length of 435 feet. The dam has a storage capacity of 76 acre-feet and covers a surface area of 5.3 acres, with a drainage area of 0.09 square miles.

Situated on TR- South Walnut Creek, Greenfield Dam is regulated by the Iowa Department of Natural Resources and is subject to state jurisdiction, permitting, inspection, and enforcement. The dam has a low hazard potential and its condition assessment is currently not rated. Despite its moderate risk classification, the dam has not been evaluated for emergency action preparedness, and there are no documented risk management measures in place.

Greenfield Dam, a key structure in the water resource management of the region, serves multiple purposes while ensuring the safety and protection of the surrounding community. As a significant feature in the local landscape, its construction and maintenance are overseen by state regulatory agencies to mitigate potential risks and ensure the continued functionality of the dam for fire protection, stock maintenance, and small fish pond management.

Year Completed

1998

Dam Length

435

Dam Height

35

River Or Stream

TR- SOUTH WALNUT CREEK

Primary Dam Type

Earth

Surface Area

5.3

Drainage Area

0.09

Nid Storage

76

Hazard Potential

Low

Foundations

Soil

Nid Height

35
       
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.