Lower Riley Lake Dam Reservoir Report

Last Updated: December 6, 2025

Lower Riley Lake Dam, also known as O'Boyle Lake Dam #4, is a state-owned structure located in Maxwell, Georgia.


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Summary

Built in 1968, this earth dam stands at a height of 40 feet and has a hydraulic height of 29 feet. The primary purpose of the dam is for recreation, providing a storage capacity of 267 acre-feet and a normal storage level of 205 acre-feet.

With a low hazard potential and a moderate risk assessment rating, Lower Riley Lake Dam serves as a vital resource for water recreation enthusiasts in the Jasper County area. Although not state-regulated, the dam undergoes regular inspections, with the last one conducted in November 2018. The dam features an uncontrolled spillway and outlet gates, ensuring the safety of the surrounding environment and communities in the event of flooding or emergencies.

Located in a picturesque setting with a surface area of 17 acres and a drainage area of 145 acres, Lower Riley Lake Dam is a significant landmark in Georgia's water resource management. As a state-owned structure, it provides both recreational opportunities and essential water storage capacity, contributing to the overall environmental balance and resilience of the region.

Year Completed

1968

Dam Length

850

Dam Height

40

River Or Stream

UNKNOWN

Primary Dam Type

Earth

Surface Area

17

Hydraulic Height

29

Drainage Area

145

Nid Storage

267

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

40
       
Seasonal Comparison

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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.