Thomas Reservoir Report

Last Updated: December 5, 2025

Thomas is a privately owned dam located in Pagosa Springs, Colorado, along the San Juan River.


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Summary

Built in 1966 for irrigation purposes, this structure stands at a height of 17 feet and spans 1700 feet in length. With a storage capacity of 93 acre-feet, Thomas serves as a crucial water resource for the surrounding area, storing and distributing water for agricultural use.

Despite its low hazard potential and not being rated for condition assessment, Thomas poses a high risk due to its age and lack of recent inspections. The dam lacks a spillway, which could potentially lead to flooding in the event of overflow. While the last inspection took place in 1988, the structure has not been assessed for condition since then, raising concerns about its long-term stability and safety.

Climate and water resource enthusiasts should monitor the situation at Thomas closely, advocating for regular inspections and maintenance to ensure the dam's safety and resilience in the face of changing climate conditions. As a critical piece of infrastructure for irrigation in the area, Thomas plays a vital role in water management and conservation efforts, highlighting the importance of responsible stewardship and proactive risk management strategies in the face of climate uncertainties.

Year Completed

1966

Dam Length

1700

Dam Height

17

River Or Stream

SAN JUAN RIVER-OS

Primary Dam Type

Other

Surface Area

10

Hydraulic Height

17

Nid Storage

93

Structural Height

17

Hazard Potential

Low

Nid Height

17
       
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.