Mayflower Pond # 5 Reservoir Report

Last Updated: December 4, 2025

Mayflower Pond # 5, located in Frisco, Colorado, is a privately owned Earth dam primarily used for storing tailings.


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Summary

With a height of 237 feet and a storage capacity of 64,300 acre-feet, this dam is regulated by the Colorado Department of Water Resources and is subject to state inspections, permitting, and enforcement. The dam has a high hazard potential, indicating the potential risk to downstream communities in the event of a failure.

Managed by the Mine Safety and Health Administration, Mayflower Pond # 5 has not had its condition assessed recently and lacks an Emergency Action Plan. The dam has not been modified in recent years, and there is limited information available on its current risk assessment and management measures. Despite these gaps in information, the dam remains a significant feature in the water resource infrastructure of Summit County, Colorado.

Water resource and climate enthusiasts interested in the management and safety of dams will find Mayflower Pond # 5 to be a compelling case study. With its high hazard potential and lack of recent condition assessments, there is a need for continued monitoring and risk assessment to ensure the safety of surrounding communities and the integrity of the dam. Further research and action may be necessary to address any potential vulnerabilities and improve the overall resilience of this important water storage structure.

Dam Length

2280

Dam Height

237

Primary Dam Type

Earth

Nid Storage

64300

Hazard Potential

High

Nid Height

237
       
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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.