Upper Turtle R.Fld.Ret.#9 Reservoir Report
Last Updated: December 13, 2025
Upper Turtle R.Fld.Ret.#9, also known as Larimore Dam, is a local government-owned structure located in Arvilla, North Dakota.
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Summary
Constructed in 1979 by the USDA NRCS, this earth dam stands at a height of 67.6 feet and serves the primary purpose of flood risk reduction along the South Branch Turtle River. With a storage capacity of 10,410 acre-feet and a surface area of 72 acres, this dam plays a crucial role in managing water resources in the region.
Managed by the NDSWC, Upper Turtle R.Fld.Ret.#9 has a spillway width of 300 feet and is classified as having a high hazard potential. Despite its fair condition assessment, the dam has a moderate risk level, highlighting the importance of regular inspections and maintenance. With one slide gate as its outlet structure, this dam is equipped to release excess water during high flow events, safeguarding the surrounding communities from potential flooding.
The dam's association with the Omaha District of the USACE and its designation as a key flood risk reduction asset underscore its significance in water resource management. Ensuring the continued functionality and safety of Upper Turtle R.Fld.Ret.#9 is essential for protecting downstream areas and maintaining the resilience of the local ecosystem in the face of changing climate conditions.
Year Completed |
1979 |
Dam Length |
1040 |
Dam Height |
67.6 |
River Or Stream |
SOUTH BRANCH TURTLE RIVER |
Primary Dam Type |
Earth |
Surface Area |
72 |
Drainage Area |
64.9 |
Nid Storage |
10410 |
Structural Height |
71 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
71 |
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.
Upper Turtle R.Fld.Ret.#9