Floodwater Ret. B-5 Reservoir Report

Last Updated: December 5, 2025

Located in Larimer County, Colorado, Floodwater Retention B-5 is a privately-owned earth dam designed by the USDA NRCS and completed in 1977.


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Summary

With a height of 80 feet and a storage capacity of 2502 acre-feet, this structure plays a crucial role in flood risk reduction along the South Branch Boxelder Creek. The dam covers a surface area of 77 acres and has a drainage area of 18 square miles, providing protection to the surrounding area from potential flooding events.

Managed by the Colorado Department of Water Resources, Floodwater Retention B-5 is classified as having a significant hazard potential but is currently rated as being in satisfactory condition. Regular inspections are conducted to ensure the structure's integrity, with the last assessment carried out in October 2019. Despite its high risk assessment, the dam has no spillway and a maximum discharge capacity of 14,807 cubic feet per second, highlighting its importance in mitigating flood events and protecting downstream communities. With its strategic location and design, Floodwater Retention B-5 stands as a vital asset in the region's water resource management efforts.

In the event of an emergency, the dam's Emergency Action Plan (EAP) is crucial for coordinating response efforts and ensuring public safety. While specific details regarding the EAP's status and adherence to guidelines are not provided in the data, the presence of a risk assessment indicating a high risk level underscores the importance of proactive risk management measures. As climate change continues to impact weather patterns and intensify precipitation events, the role of structures like Floodwater Retention B-5 becomes increasingly vital in safeguarding communities and infrastructure from the dangers of flooding.

Year Completed

1977

Dam Length

1137

Dam Height

80

River Or Stream

SOUTH BRANCH BOXELDER CR

Primary Dam Type

Earth

Surface Area

77

Hydraulic Height

81

Drainage Area

18

Nid Storage

2502

Structural Height

91

Hazard Potential

Significant

Nid Height

91
       
Seasonal Comparison

Weather Forecast

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Nearby Streamflow Levels

Floodwater Ret. B-5N FRK CACHE LA POUDRE R BLW HALLIGAN RES NR V DAL Preview N Frk Cache La Poudre R Blw Halligan Res Nr V Dal
0.25cfs
0cfs
Floodwater Ret. B-5NORTH FORK CACHE LA POUDRE R. AT LIVERMORE Preview North Fork Cache La Poudre R. At Livermore
4.22cfs
4cfs
Floodwater Ret. B-5CACHE LA POUDRE R A MO OF CN Preview Cache La Poudre R A Mo Of Cn
0.00cfs
0cfs
Floodwater Ret. B-5CROW CREEK AT 19TH STREET Preview Crow Creek At 19th Street
3.20cfs
3cfs
Floodwater Ret. B-5CACHE LA POUDRE RIVER AT FORT COLLINS Preview Cache La Poudre River At Fort Collins
28.8cfs
29cfs
Floodwater Ret. B-5CACHE LA POUDRE R AB BOXELDER C Preview Cache La Poudre R Ab Boxelder C
4.61cfs
5cfs

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.
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Nearby Reservoirs

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River Runs