Dillon Reservoir Report

Last Updated: December 4, 2025

Dillon Dam, located in Summit County, Colorado, is a major earth dam completed in 1963 with a primary purpose of providing water supply.


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Summary

Standing at a height of 231 feet and a length of 4625 feet, this dam has a storage capacity of 305,000 acre-feet and covers a surface area of 3300 acres. Its maximum discharge capacity is 11,750 cubic feet per second, making it a crucial structure for managing water resources in the region.

Managed by the local government and regulated by the Colorado Division of Water Resources, Dillon Dam plays a vital role in supporting multiple purposes including hydroelectric power generation, recreation, and water supply. The dam's high hazard potential and moderate risk assessment highlight the importance of effective risk management measures. With inspections by the Federal Energy Regulatory Commission and emergency action plans in place, Dillon Dam remains a key infrastructure for water management in the area.

Situated on Blue Creek in Silverthorne, Dillon Dam not only serves as a key water supply source but also contributes to recreational activities and hydroelectric power generation. As climate change continues to impact water resources, the significance of structures like Dillon Dam in ensuring water security and resilience in the face of changing conditions becomes increasingly evident.

Year Completed

1963

Dam Length

4625

Dam Height

231

River Or Stream

Blue Creek

Primary Dam Type

Earth

Surface Area

3300

Hydraulic Height

231

Drainage Area

338

Nid Storage

305000

Structural Height

310

Hazard Potential

High

Nid Height

310
       
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.