Cornwell Reservoir Report
Nearby: Maraschino Wagner
Last Updated: December 19, 2025
Located in Valley County, Montana, the Cornwell dam is a vital irrigation structure designed by the USDA NRCS in 1952.
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Summary
With a height of 23 feet and a length of 400 feet, the dam provides storage capacity of 423 acre-feet for the Wire Grass Coulee, serving as a crucial water resource for agricultural activities in the region. The dam is regulated by the Montana Department of Natural Resources and Conservation (DNRC), ensuring proper inspection, enforcement, and permitting to maintain its structural integrity and functionality.
The Cornwell dam, situated in Glasgow, Montana, plays a key role in harnessing water from the Wire Grass Coulee for irrigation purposes. Managed by private owners, the dam is state-regulated and falls under the jurisdiction of the DNRC for permitting and inspection. With a significant hazard potential and a spillway width of 100 feet, the dam serves as a critical infrastructure for water management in the area, contributing to the agricultural productivity of the region.
As a primary irrigation structure, the Cornwell dam in Montana's Valley County is an essential component of the region's water resource management. With a storage capacity of 423 acre-feet and a drainage area of 2.27 square miles, the dam provides crucial water supply for agricultural operations in the area. State-regulated and designed by the USDA NRCS, the dam ensures the efficient utilization of water resources for irrigation purposes, highlighting the significance of sustainable water management practices in the face of changing climate conditions.
Year Completed |
1952 |
Dam Length |
400 |
Dam Height |
23 |
River Or Stream |
WIRE GRASS COULEE |
Primary Dam Type |
Earth |
Hydraulic Height |
23 |
Drainage Area |
2.27 |
Nid Storage |
423 |
Hazard Potential |
Significant |
Nid Height |
23 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Cornwell