Granby #5-11 Reservoir Report

Last Updated: December 13, 2025

Granby #5-11, located in Cedaredge, Colorado, is a privately owned earth dam constructed in 1930 for irrigation purposes on the Dirty George Creek.


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Summary

With a height of 30 feet and a length of 3400 feet, this dam has a storage capacity of 1135 acre-feet, making it an essential structure for water resource management in the area. The dam has a spillway width of 18 feet and is equipped with slide and uncontrolled outlet gates.

Despite being classified as having a high hazard potential, Granby #5-11 is currently in fair condition, as per its last inspection in August 2020. The dam has a moderate risk assessment rating of 3, indicating the need for ongoing risk management measures. While the dam meets state regulatory requirements for permitting, inspection, and enforcement, there is a need for continued monitoring and maintenance to ensure its safety and functionality for the surrounding community and agricultural operations. Overall, Granby #5-11 serves as a vital infrastructure for water storage and distribution in the region, highlighting the importance of sustainable water resource management in the face of changing climate conditions.

Year Completed

1930

Dam Length

3400

Dam Height

30

River Or Stream

DIRTY GEORGE CREEK-TR

Primary Dam Type

Earth

Surface Area

72

Hydraulic Height

30

Drainage Area

2

Nid Storage

1135

Structural Height

31

Outlet Gates

Slide (sluice gate), Uncontrolled

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

31
       
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.