Terrace Reservoir Report

Last Updated: December 5, 2025

Terrace, also known as Alamosa River Reservoir, is a privately-owned irrigation structure located in Conejos County, Colorado.


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Summary

Built in 1912 by the USDA NRCS, this Earth-type dam stands at a height of 166 feet and has a hydraulic height of 182 feet, providing crucial water storage for the region. With a storage capacity of 19,195 acre-feet and a surface area of 300 acres, Terrace plays a vital role in supporting agricultural activities along the Alamosa River.

Managed by the Colorado Division of Water Resources, Terrace is subject to state regulation, inspection, and enforcement to ensure its safety and compliance with standards. The dam's spillway, classified as uncontrolled, has a width of 138 feet to manage potential overflow during high-discharge events. Despite being assessed as in fair condition during the last inspection in October 2020, Terrace has a high hazard potential, highlighting the importance of ongoing monitoring and maintenance to mitigate risks to downstream communities.

Terrace's strategic location and design make it a critical water resource infrastructure in the region, with a moderate risk assessment rating. As water resource and climate enthusiasts, understanding the role of structures like Terrace in sustaining irrigation and water supply systems is essential for promoting resilience and sustainable management practices in the face of changing environmental conditions.

Year Completed

1912

Dam Length

545

Dam Height

166

River Or Stream

ALAMOSA RIVER

Primary Dam Type

Earth

Surface Area

300

Hydraulic Height

182

Drainage Area

110

Nid Storage

19195

Structural Height

183

Outlet Gates

Valve - 1, Valve - 2

Hazard Potential

High

Nid Height

183
       
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.