Granby Dike 4 Reservoir Report

Last Updated: December 5, 2025

Granby Dike 4 is a crucial federal water infrastructure located in Grand County, Colorado, protecting the surrounding area from potential flooding along the Colorado River.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1950, this earth dam stands at a height of 15 feet and spans 370 feet in length, with a maximum storage capacity of 539,760 acre-feet. Its primary purpose is hydroelectric generation and irrigation, serving as a vital resource for water management in the region. Managed by the Bureau of Reclamation, Granby Dike 4 is subject to regular state inspections, permitting, and enforcement to ensure its structural integrity and compliance with regulatory standards.

With a high hazard potential and a very high risk assessment rating, Granby Dike 4 is closely monitored for any signs of deterioration or potential threats to its stability. The dam features a controlled spillway and is equipped to handle a maximum discharge of 12,000 cubic feet per second, mitigating the risk of overtopping during periods of high water flow. As part of the broader network of associated structures within the NID system, Granby Dike 4 plays a critical role in water storage and distribution for agricultural and hydroelectric purposes, highlighting its significance in sustaining the local ecosystem and economy. Climate and water resource enthusiasts can appreciate the intricate design and operational complexities of this essential infrastructure that safeguards against natural disasters and supports sustainable water management practices in the Colorado River basin.

Year Completed

1950

Dam Length

370

Dam Height

15

River Or Stream

COLORADO RIVER

Primary Dam Type

Earth

Surface Area

7260

Hydraulic Height

15

Nid Storage

539760

Structural Height

15

Hazard Potential

High

Foundations

Rock

Nid Height

15
       
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.