Markham Reservoir Report
Nearby: Cody Municipal Beck Lake
Last Updated: December 5, 2025
Markham is a local government-owned dam located in Cody, Wyoming, along the South Fork Shoshone Offstream.
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Summary
Built in 1929 by designer Howard F. Bell, this Earth-type dam stands at a height of 11 feet and spans 2500 feet in length. With a primary purpose of water supply for irrigation and other uses, Markham has a storage capacity of 730 acre-feet and a normal storage level of 67 acre-feet.
Despite its fair condition assessment and significant hazard potential, Markham is regulated and inspected by the State Regulatory Agency (SEO) in Wyoming. The dam has an uncontrolled spillway system with a width of 20 feet and is equipped with one other controlled outlet gate for water release. The dam's emergency action plan (EAP) was last revised in 2012, and it meets moderate risk assessments, indicating a need for ongoing risk management measures to ensure public safety and water resource protection in the region.
For water resource and climate enthusiasts, Markham serves as a vital infrastructure for water supply and irrigation in Park County, Wyoming. With its historical significance and ongoing regulatory oversight, this dam represents a key component of the local water management system. As climate change impacts continue to influence water availability and infrastructure resilience, ongoing monitoring and maintenance efforts at Markham are essential to safeguarding this important resource for the community and surrounding areas.
Year Completed |
1929 |
Dam Length |
2500 |
Dam Height |
11 |
River Or Stream |
S FORK SHOSHONE OFFSTREAM |
Primary Dam Type |
Earth |
Surface Area |
12 |
Hydraulic Height |
6 |
Drainage Area |
0.1 |
Nid Storage |
730 |
Structural Height |
11 |
Outlet Gates |
Other Controlled - 1 |
Hazard Potential |
Significant |
Foundations |
Rock, Soil |
Nid Height |
11 |
Seasonal Comparison
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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.
Markham