Spence Reservoir Report
Last Updated: December 5, 2025
Spence is a privately owned earth dam located in Archuleta, Colorado, serving primarily for irrigation purposes.
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Summary
Built in 1965, this structure stands at a height of 44 feet, with a hydraulic height of 48 feet and a structural height of 58 feet. It has a storage capacity of 617 acre-feet, with a normal storage level of 425 acre-feet and a maximum discharge of 4243 cubic feet per second.
The dam is situated on Spence Creek, with a drainage area of 2 square miles and a surface area of 32 acres. It features an uncontrolled spillway with a width of 110 feet and is inspected every two years, with the last assessment in December 2020 rating its condition as satisfactory. With a significant hazard potential and a moderate risk assessment, Spence is a vital infrastructure for water resource management in the region, contributing to fire protection, stock watering, and wildlife conservation efforts.
Managed by the Colorado Division of Water Resources, Spence plays a crucial role in supporting the agricultural activities in the area, while also ensuring the safety and well-being of the surrounding communities. With its strategic location and reliable design, this dam continues to be a key asset for water supply and climate resilience in Colorado, highlighting the importance of sustainable water resource management in the face of changing environmental conditions.
Years Modified |
2003 - Hydraulic |
Year Completed |
1965 |
Dam Length |
915 |
Dam Height |
44 |
River Or Stream |
SPENCE CREEK |
Primary Dam Type |
Earth |
Surface Area |
32 |
Hydraulic Height |
48 |
Drainage Area |
2 |
Nid Storage |
617 |
Structural Height |
58 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Significant |
Foundations |
Rock, Soil |
Nid Height |
58 |
Seasonal Comparison
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Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Spence