Ann Road Detention Basin Dam Reservoir Report

Last Updated: December 5, 2025

The Ann Road Detention Basin Dam in Las Vegas, Nevada, is a critical infrastructure designed by The Louis Berger Group Inc to reduce flood risk in the area.


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Summary

Completed in 2007, this earth dam stands at a height of 32 feet and has a hydraulic height of 15 feet, providing a storage capacity of 364 acre-feet to mitigate potential flooding events. Situated along the Las Vegas Wash-TR river or stream, the dam serves a primary purpose of flood risk reduction and is regulated by the Nevada Department of Water Resources.

With a spillway width of 1360 feet and a maximum discharge capacity of 25,200 cubic feet per second, the Ann Road Detention Basin Dam is equipped to manage high hazard potential situations. Despite being classified as having a fair condition assessment as of May 2021, the dam is subject to regular inspections and maintenance to ensure its structural integrity and operational effectiveness. The dam also features an uncontrolled outlet gate and is located in Clark County, under the jurisdiction of the local government with state oversight.

For water resource and climate enthusiasts, the Ann Road Detention Basin Dam represents a vital piece of infrastructure in the region's flood management system. This multi-arch earth dam not only provides flood protection for the surrounding area but also serves as a testament to the collaborative efforts between the local government, design engineers, and regulatory agencies to safeguard the community from potential water-related hazards. As climate change continues to impact weather patterns and increase the frequency of extreme events, the importance of such structures in mitigating risks and ensuring water resource resilience cannot be understated.

Year Completed

2007

Dam Length

1860

Dam Height

20

River Or Stream

LAS VEGAS WASH-TR

Primary Dam Type

Earth

Surface Area

20

Hydraulic Height

15

Drainage Area

3.8

Nid Storage

364

Structural Height

32

Outlet Gates

Uncontrolled - 1

Hazard Potential

High

Foundations

Soil

Nid Height

32
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.