Big Monitor #1 Reservoir Report

Last Updated: December 5, 2025

Big Monitor #1 is a privately owned dam located in Montrose, Colorado, specifically in the city of DELTA.


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Summary

Built in 1946 for irrigation purposes, this earth dam stands at a height of 19 feet with a hydraulic height of 20 feet. With a maximum storage capacity of 107 acre-feet and a normal storage of 80 acre-feet, this structure plays a crucial role in managing water resources in the area. Despite being classified as low hazard potential with a fair condition assessment, the dam poses a high risk due to its location and age.

Situated on the ROUBIDEAU CREEK-TR, Big Monitor #1 is regulated by the state of Colorado with permitting, inspection, and enforcement conducted by the Department of Water Resources (DWR). The dam has a spillway width of 10 feet and is equipped with flap and uncontrolled outlet gates. Even though it does not have an inundation map prepared or an emergency action plan (EAP) in place, the dam undergoes inspections every 6 years to ensure its safety and functionality. With a high risk assessment rating of 2, it is essential for stakeholders and authorities to closely monitor and manage the risks associated with this structure.

As a vital component of the local irrigation system, Big Monitor #1 serves as a key water resource for agricultural activities in the region. Its stone core and rock-soil foundations support a dam length of 280 feet, providing a surface area of 9 acres. With a maximum discharge capacity of 161 cubic feet per second, this dam plays a crucial role in water management and distribution. As climate change continues to impact water resources, it is imperative to safeguard and maintain structures like Big Monitor #1 to ensure sustainable water usage and security for the future.

Year Completed

1946

Dam Length

280

Dam Height

19

River Or Stream

ROUBIDEAU CREEK-TR

Primary Dam Type

Earth

Surface Area

9

Hydraulic Height

20

Nid Storage

107

Structural Height

21

Outlet Gates

Flap, Uncontrolled

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

21
       
Seasonal Comparison

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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.