Grand Mesa #9 Reservoir Report

Last Updated: December 5, 2025

Grand Mesa #9, also known as Ternahan, is a privately owned irrigation dam located in Grand Junction, Colorado.


°F

°F

mph

Wind

%

Humidity

Summary

Completed in 1904, this earth dam stands at a height of 15 feet and has a length of 600 feet, providing essential water storage for irrigation purposes. The dam has a storage capacity of 268 acre-feet and is situated on the Kahnah Creek, within a drainage area of 4 square miles.

Despite its age, Grand Mesa #9 is rated as having a low hazard potential and fair condition assessment. The dam is not equipped with a spillway, but instead has slide and uncontrolled gates for water release. Regular inspections are performed, with the last assessment conducted in August 2019. The risk assessment for the dam indicates a high risk level of 2, prompting the need for continued monitoring and management measures to ensure its safety and functionality for the surrounding area.

Grand Mesa #9 serves as a vital component of the local water resource infrastructure, contributing to the irrigation needs of the region. With its historical significance and ongoing importance for agricultural activities, this dam exemplifies the intersection of water management and climate resilience in the dynamic landscape of Colorado. As water resource and climate enthusiasts, the data behind Grand Mesa #9 offers a compelling glimpse into the intricate balance of human intervention and natural processes in sustaining vital water supplies for the community.

Year Completed

1904

Dam Length

600

Dam Height

15

River Or Stream

KAHNAH CREEK

Primary Dam Type

Earth

Surface Area

23

Hydraulic Height

15

Drainage Area

4

Nid Storage

268

Structural Height

15

Outlet Gates

Slide (sluice gate), Uncontrolled

Hazard Potential

Low

Foundations

Rock, Soil

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.