Grinnell Reservoir Report
Last Updated: December 15, 2025
Grinnell, a private irrigation dam located on Grinnell Creek in Carbon County, Wyoming, stands as a testament to water resource management and climate adaptation efforts.
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Summary
Built in 1919, this earth dam with stone core serves the primary purpose of supporting irrigation activities in the region. With a dam height of 8 feet and a hydraulic height of 5 feet, Grinnell offers a storage capacity of 310 acre-feet, providing vital water resources for agricultural needs in the area.
Despite its age, Grinnell maintains a fair condition assessment and a low hazard potential, making it a reliable asset for the community. The dam features an uncontrolled spillway with a width of 40 feet, ensuring proper water discharge during high-flow events. Regular inspections and maintenance activities, conducted approximately every five years, contribute to the overall safety and functionality of the structure. With its moderate risk assessment rating and strategic location in the Sacramento District, Grinnell plays a crucial role in water management and environmental conservation efforts in the region.
As climate change continues to impact water resources and infrastructure resilience, Grinnell serves as a critical asset in ensuring sustainable water supply and irrigation practices in Wyoming. Managed by private owners and regulated by state authorities, this historic dam exemplifies the importance of proactive maintenance, risk assessment, and emergency preparedness in safeguarding water sources for future generations. With its strategic location and operational efficiency, Grinnell stands as a beacon of hope for water resource and climate enthusiasts seeking innovative solutions to address evolving environmental challenges.
Year Completed |
1919 |
Dam Length |
930 |
Dam Height |
8 |
River Or Stream |
GRINNELL CREEK |
Primary Dam Type |
Earth |
Surface Area |
41 |
Hydraulic Height |
5 |
Nid Storage |
310 |
Structural Height |
8 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
8 |
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.
Area Campgrounds
| Location | Reservations | Toilets |
|---|---|---|
Prior Flat Campsite 8
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Prior Flat Campsite 10
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Prior Flat Campsite 11
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Prior Flat Campsite 13
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Prior Flat Campsite 9
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Prior Flat Campsite 12
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Grinnell