Casto Reservoir Report

Last Updated: March 31, 2026

Casto is a privately owned irrigation dam situated in Gateway, Mesa County, Colorado.


Summary

Built in 1940, this Earth-type dam stands at 26 feet high with a storage capacity of 1298 acre-feet to support agricultural activities in the region. The dam, located on Gill Creek, has a spillway width of 50 feet and an uncontrolled spillway type, with a significant hazard potential but assessed to be in fair condition as of June 2020.

Managed by the Colorado Department of Water Resources, Casto Dam plays a crucial role in water resource management and irrigation in the area. With a drainage area of 9 square miles and a maximum discharge capacity of 1470 cubic feet per second, the dam serves as a vital infrastructure for maintaining water supply and controlling downstream flows. Despite its age, the dam continues to be inspected regularly to ensure its structural integrity and safety.

Even though Casto Dam has a moderate risk profile and is categorized as having a significant hazard potential, it remains an essential component of the water resource infrastructure in Mesa County. With its strategic location and function in supporting agricultural activities, the dam contributes to the overall water management efforts in the region. As climate change continues to impact water availability and usage, structures like Casto Dam play a crucial role in ensuring sustainable water resource development and utilization.



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°F

mph

Wind

%

Humidity


15-Day Weather Outlook


Year Completed

1940

Dam Length

910

Dam Height

26

River Or Stream

GILL CREEK

Primary Dam Type

Earth

Surface Area

99

Hydraulic Height

21

Drainage Area

9

Nid Storage

1298

Structural Height

26

Outlet Gates

Slide (sluice gate), Uncontrolled

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

26
       
Seasonal Comparison

5-Day Hourly Forecast Detail

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.