Thornberg Dam; Carol Reservoir Report
Last Updated: December 5, 2025
Thornberg Dam, also known as Carol Wetland 1, is a private dam located in Slope, North Dakota.
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Summary
Built in 1960 by the USFWS, this Earth-type dam stands at 11.5 feet high and serves primarily as a Fish and Wildlife Pond. With a storage capacity of 54.6 acre-feet, the dam covers a surface area of 7.5 acres and has a drainage area of 3.67 square miles.
Managed by the North Dakota State Water Commission, Thornberg Dam is state-regulated and undergoes regular inspections and enforcement measures to ensure its safety and functionality. The dam has a low hazard potential and a moderate risk assessment rating. Its spillway type is uncontrolled, with a width of 30 feet, and it does not have outlet gates or associated locks.
As a crucial component of the ecosystem in the area, Thornberg Dam provides habitat for various fish and wildlife species. Its construction and maintenance are essential for preserving the local environment and supporting biodiversity. Enthusiasts of water resources and climate will find Thornberg Dam to be a fascinating example of human intervention in natural landscapes for conservation purposes.
Year Completed |
1960 |
Dam Height |
11.5 |
River Or Stream |
WEST FORK DEEP CREEK-TR |
Primary Dam Type |
Earth |
Surface Area |
7.5 |
Drainage Area |
3.67 |
Nid Storage |
54.6 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
12 |
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.
Thornberg Dam; Carol