Diamond Lake Watershed Site C-14 Reservoir Report

Last Updated: December 6, 2025

Diamond Lake Watershed Site C-14 in Iowa is a significant earth dam completed in 1972 by the USDA NRCS with a primary purpose of fire protection, stock, or small fish pond, and flood risk reduction.


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Summary

Located in Poweshiek County, Iowa, near the city of Montezuma, this dam has a height of 29 feet and a length of 638 feet, providing a storage capacity of 115 acre-feet. The dam is state-regulated and inspected by the Iowa DNR, with a significant hazard potential and a moderate risk assessment rating.

The dam's spillway type is uncontrolled, and it is situated on TR-Moon Creek, with a drainage area of 0.81 square miles. With a surface area of 7.9 acres and a normal storage capacity of 42 acre-feet, Diamond Lake Watershed Site C-14 plays a crucial role in managing water resources in the region. Despite not being rated for condition assessment, the dam is actively monitored for potential risks and management measures are in place to ensure its safety and functionality for the local community and environment.

Water resource and climate enthusiasts can appreciate Diamond Lake Watershed Site C-14 for its role in fire protection, stock, and small fish pond management, as well as flood risk reduction in the area. With its historical significance and ongoing regulatory oversight, this earth dam serves as a key infrastructure for water management and environmental protection efforts in Poweshiek County, Iowa.

Year Completed

1972

Dam Length

638

Dam Height

29

River Or Stream

TR-MOON CREEK

Primary Dam Type

Earth

Surface Area

7.9

Drainage Area

0.81

Nid Storage

115

Hazard Potential

Significant

Foundations

Soil

Nid Height

29
       
Seasonal Comparison

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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.