Lone Tree Reservoir Report

Last Updated: December 5, 2025

Lone Tree, located in Larimer County, Colorado, is a privately owned water reservoir known also as Home Supply Reservoir.


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Summary

With a history dating back to 1882, this Earth dam structure stands at a height of 29 feet, holding a storage capacity of 10,973 acre-feet to support irrigation in the region. The reservoir serves multiple purposes including fish and wildlife habitat, recreation, and irrigation, making it a vital resource for the local community.

Managed by the Colorado Division of Water Resources, Lone Tree is regulated and inspected regularly to ensure its structural integrity and compliance with state standards. With a spillway width of 900 feet and a significant hazard potential, the reservoir has a moderate risk rating and a satisfactory condition assessment as of the last inspection in July 2019. Despite its age, Lone Tree continues to play a crucial role in water resource management, providing essential support for agriculture and conservation efforts in the area.

Located along the Big Thompson River, Lone Tree not only serves as a water source but also contributes to the natural ecosystem and recreational opportunities in the region. With its historical significance and ongoing maintenance efforts, this reservoir remains a key asset for water supply and climate resilience in Larimer County, showcasing the importance of sustainable water management practices for the future.

Year Completed

1882

Dam Length

5265

Dam Height

29

River Or Stream

BIG THOMPSON RIVER-OS

Primary Dam Type

Earth

Surface Area

503

Hydraulic Height

25

Drainage Area

5

Nid Storage

10973

Structural Height

29

Hazard Potential

Significant

Nid Height

29
       
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.