Glen Ullin Rr Dam 1 Reservoir Report
Last Updated: December 8, 2025
Glen Ullin Rr Dam 1, also known as South Reservoir, is a state-owned structure located in Morton County, North Dakota.
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Summary
Built in 1909 by NDSWC & NPRR, this buttress type dam stands at a height of 15.8 feet and has a storage capacity of 143.6 acre-feet. Situated on Big Muddy Creek, the dam serves primarily for recreational purposes and has a normal storage level of 77.3 acre-feet, covering a surface area of 19.7 acres.
With a significant hazard potential and a moderate risk assessment rating, Glen Ullin Rr Dam 1 is regulated by the North Dakota State Water Commission (NDSWC) and undergoes regular inspections, permitting, and enforcement processes. The dam features an uncontrolled spillway with a width of 170 feet and is equipped with a single slide (sluice gate) outlet. While the dam's condition assessment is currently not rated, it remains an important structure for water resource management and climate enthusiasts in the region.
For those interested in water resource management and climate resilience, Glen Ullin Rr Dam 1 offers insights into dam engineering, regulatory oversight, and risk assessment. As a historic structure with a long-standing presence in the community, the dam continues to provide recreational opportunities while also serving as a critical infrastructure for water storage and flood control. With its location in the St. Paul District and alignment with state jurisdiction and permitting requirements, the dam showcases the collaborative efforts between state agencies and the local community to ensure the safety and sustainability of water resources in North Dakota.
Year Completed |
1909 |
Dam Length |
182 |
Dam Height |
15.8 |
River Or Stream |
BIG MUDDY CREEK |
Primary Dam Type |
Buttress |
Surface Area |
19.7 |
Drainage Area |
80 |
Nid Storage |
143.6 |
Structural Height |
15.8 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
16 |
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.
Glen Ullin Rr Dam 1