G&J Heck No.2 Reservoir Report
Nearby: G&J Heck No.1 D. Woddell
Last Updated: December 13, 2025
G&J Heck No.2 is a privately owned dam located in Dewey, South Dakota, along the TR-GRAND river or stream.
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Summary
Built in 1954, this earth dam stands at a height of 25 feet and has a maximum storage capacity of 90 acre-feet. With a low hazard potential and a condition assessment of "Not Rated," this dam serves as an important water resource structure in the area.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), G&J Heck No.2 is regulated, permitted, inspected, and enforced by the state agency. While it has not been rated for its condition assessment, the dam continues to provide crucial water storage and flood control benefits to the surrounding area. With a normal storage capacity of 50 acre-feet and a maximum discharge rate of 2796 cubic feet per second, this dam plays a key role in water management and climate resilience efforts in South Dakota.
Despite its age, G&J Heck No.2 remains an integral part of the water infrastructure in South Dakota. With no associated structures and a lack of detailed risk management measures, the dam provides a glimpse into the importance of maintaining and monitoring aging water resource structures for the safety and security of communities in the face of changing climate conditions.
Year Completed |
1954 |
Dam Length |
400 |
Dam Height |
25 |
River Or Stream |
TR-GRAND |
Primary Dam Type |
Earth |
Hydraulic Height |
25 |
Nid Storage |
90 |
Hazard Potential |
Low |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Moreau R Near Whitehorse Sd
|
35cfs |
Grand R At Little Eagle Sd
|
47cfs |
Moreau R Near Faith Sd
|
14cfs |
Cedar Creek Nr Raleigh
|
20cfs |
Oak Cr Near Wakpala Sd
|
10cfs |
Cannonball River Nr Raleigh
|
40cfs |
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.
G&J Heck No.2