Lake Brennand Reservoir Report

Last Updated: December 5, 2025

Lake Brennand, also known as Lake Irwin, is a picturesque reservoir nestled in Gunnison, Colorado, just 17 miles from Somerset.


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Summary

This state-regulated water source serves multiple purposes, including water supply, fish and wildlife habitat, and recreational activities. Completed in 1963, the earth dam stands at 22 feet high and spans 350 feet in length, with a storage capacity of 896 acre-feet and a surface area of 65 acres.

The dam on Lake Brennand, managed by the Colorado Department of Water Resources, is classified as having a low hazard potential and fair condition assessment. With a maximum discharge capacity of 1160 cubic feet per second and an uncontrolled spillway width of 30 feet, the reservoir plays a crucial role in managing water resources in the region. Despite its moderate risk assessment level, Lake Brennand remains a vital component of the local water supply infrastructure.

Water resource and climate enthusiasts will appreciate the strategic location of Lake Brennand on Anthracite Creek, which contributes to a drainage area of 3 square miles. This reservoir, with its serene surroundings and diverse ecological functions, exemplifies the balance between human needs and environmental conservation. As a key component of the Sacramento District's water management system, Lake Brennand continues to play a significant role in supporting the surrounding ecosystem and supplying water to the community.

Year Completed

1963

Dam Length

350

Dam Height

22

River Or Stream

ANTHRACITE CREEK-TR

Primary Dam Type

Earth

Surface Area

65

Hydraulic Height

23

Drainage Area

3

Nid Storage

896

Structural Height

24

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

24
       
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.