Deerfield Reservoir Report

Last Updated: December 5, 2025

Deerfield is a Federal-owned structure located in Rapid City, South Dakota, along Castle Creek.


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Summary

Completed in 1946, this Earth-type dam stands at a height of 171 feet and has a storage capacity of 42,310 acre-feet. Its primary purpose is for Fish and Wildlife Pond, with additional functions including irrigation and water supply. The dam has a high hazard potential and a moderate risk assessment rating.

Managed by the Bureau of Reclamation, Deerfield plays a crucial role in regulating water resources in the region. With a maximum discharge capacity of 103,400 cubic feet per second and a surface area of 423 acres, the dam serves as a key infrastructure for both flood control and water storage. Despite its age, Deerfield has undergone modifications in 1984 to enhance its hydraulic and structural capabilities, ensuring its continued effectiveness in water management.

While Deerfield has not been assessed for its current condition, its last inspection was conducted in August 2020. The dam is operated and inspected by the Bureau of Reclamation, with oversight from the Forest Service. As a vital component of the water supply infrastructure in Pennington, South Dakota, Deerfield remains a critical asset for maintaining the ecological balance of the area and supporting various water-related activities.

Years Modified

1984 - Hydraulic, 1984 - Structural

Year Completed

1946

Dam Length

1125

Dam Height

171

River Or Stream

CASTLE CREEK

Primary Dam Type

Earth

Surface Area

423

Hydraulic Height

145

Drainage Area

90

Nid Storage

42310

Structural Height

171

Hazard Potential

High

Nid Height

171
       
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.