East Lake #3 Reservoir Report

Last Updated: December 5, 2025

East Lake #3, located in Thornton, Colorado, is a local government-owned Earth dam completed in 1887 for irrigation purposes.


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Summary

With a height of 11 feet and a length of 2000 feet, this dam has a storage capacity of 790 acre-feet and a surface area of 35 acres. The dam is regulated by the Colorado Department of Water Resources, with state permitting, inspection, and enforcement in place to ensure its safety and compliance with regulations.

Despite its low hazard potential and satisfactory condition assessment, East Lake #3 poses a moderate risk due to its moderate flood risk reduction capabilities and moderate drainage area. The spillway, which is uncontrolled and 179 feet wide, can handle a maximum discharge of 7894 cubic feet per second. The last inspection of the dam was conducted in 2013, with an inspection frequency of 6 years. While the Emergency Action Plan (EAP) was last revised in 1998, East Lake #3 is equipped with emergency contacts and measures to manage risks in case of any potential incidents.

Overall, East Lake #3 serves as a vital water resource infrastructure in the region, showcasing the historical significance of irrigation practices dating back to the late 19th century. As climate change continues to impact water resources, the maintenance and regulation of dams like East Lake #3 play a crucial role in ensuring water security and disaster preparedness for the community. Enthusiasts of water resources and climate resilience will find East Lake #3 to be an intriguing example of sustainable water management in a changing environment.

Year Completed

1887

Dam Length

2000

Dam Height

11

River Or Stream

BRANTNER GULCH-TR

Primary Dam Type

Earth

Surface Area

35

Hydraulic Height

11

Nid Storage

790

Structural Height

11

Hazard Potential

Low

Nid Height

11
       
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.