Highland Mary Reservoir Report
Nearby: Middle Lake Little Lake
Last Updated: February 22, 2026
Highland Mary, located in San Juan, Colorado, is a privately owned masonry dam built in 1903 for water supply purposes along Cunningham Creek.
Summary
With a height of 27 feet, the dam boasts a storage capacity of 722 acre-feet and a normal storage of 168 acre-feet, serving the surrounding area with its 48-acre surface area. Despite its low hazard potential, the dam's condition assessment in 2018 was deemed unsatisfactory, highlighting the need for maintenance and potential risk management measures.
Owned and regulated by private entities, Highland Mary falls under the jurisdiction of the Colorado Department of Water Resources for permitting, inspection, and enforcement. The dam has no spillway and a low hazard potential, but its risk assessment is rated as high (2), signaling the importance of implementing effective emergency action plans and risk management strategies. The last inspection in 2018 identified unsatisfactory conditions, indicating the need for closer monitoring and maintenance efforts to ensure the safety and reliability of the structure for the community's water supply.
Highland Mary, with its historic significance and crucial role in water supply, stands as a reminder of the intricate balance between human infrastructure and natural resources. As climate change impacts water resources, the maintenance and management of dams like Highland Mary become increasingly vital in ensuring water security for communities. With its unique features and challenges, the dam serves as a focal point for water resource and climate enthusiasts seeking to understand the intersection of infrastructure, regulation, and environmental stewardship in the face of a changing climate.
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°F
mph
Wind
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Humidity
15-Day Weather Outlook
Year Completed |
1903 |
Dam Length |
117 |
Dam Height |
27 |
River Or Stream |
CUNNINGHAM CREEK |
Primary Dam Type |
Masonry |
Surface Area |
48 |
Hydraulic Height |
25 |
Drainage Area |
1 |
Nid Storage |
722 |
Structural Height |
28 |
Hazard Potential |
Low |
Nid Height |
28 |
Seasonal Comparison
5-Day Hourly Forecast Detail
Nearby Streamflow Levels
Little Cottonwood River Near Courtland
|
33cfs |
Cottonwood River Near New Ulm
|
215cfs |
Minnesota River At New Ulm
|
1130cfs |
Minnesota River At Mankato
|
3720cfs |
Blue Earth River Near Rapidan
|
328cfs |
Le Sueur River Near Rapidan
|
179cfs |
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 |
|---|---|---|
Minneopa State Park
|
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Flandrau State Park
|
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Flandrau State Park- Non-Electric Campground
|
||
Flandrau State Park- Rustic Campground
|
Swan Lake
Minnesota River Boat Landing