Rocky Ridge Reservoir Report

Last Updated: December 5, 2025

Rocky Ridge, also known as Water Supply #1, is a privately owned irrigation dam located in Larimer County, Colorado, near Fort Collins.


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Summary

Built in 1940 by designer James C. Scott, this earth dam stands at a height of 16 feet with a hydraulic height of 35 feet, serving the primary purpose of irrigation along the Cache la Poudre River. With a capacity of 5,173 acre-feet and a surface area of 236 acres, Rocky Ridge plays a vital role in water resource management in the region.

The dam has a spillway width of 290 feet and a maximum discharge of 5,880 cubic feet per second, ensuring effective flood control measures. Despite being classified as having a high hazard potential, Rocky Ridge is in satisfactory condition based on the last inspection conducted in June 2020. The risk assessment for the dam is moderate, with no specific risk management measures identified in the data.

Overall, Rocky Ridge is a significant water infrastructure feature in Colorado, contributing to irrigation practices while also serving as a crucial element in flood control along the Cache la Poudre River. With its historical significance dating back to the 1940s and its continued operational relevance, this dam remains an essential component of the region's water resource and climate resilience efforts.

Year Completed

1940

Dam Length

241

Dam Height

16

River Or Stream

CACHE LA POUDRE RIVER

Primary Dam Type

Earth

Surface Area

236

Hydraulic Height

35

Drainage Area

1

Nid Storage

5173

Structural Height

35

Hazard Potential

High

Nid Height

35
       
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.