Autumn Lake Dam Reservoir Report

Last Updated: December 5, 2025

Autumn Lake Dam, located in Brown County, Indiana, was completed in 1969 and serves as a recreational resource for the surrounding area.


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Summary

The dam, with a height of 32 feet and a hydraulic height of 28 feet, creates a picturesque 6.5-acre lake for boating, fishing, and other outdoor activities. The structure, designed by Emerson Wheeler, is primarily made of earth and stone materials and spans 300 feet in length.

Despite its recreational benefits, Autumn Lake Dam poses a high hazard potential due to its poor condition assessment. The dam lacks outlet gates and features an uncontrolled spillway with a width of 28 feet. The last inspection in September 2018 revealed the need for maintenance and repair to ensure the safety of downstream communities. The dam is state-regulated and inspected regularly by the Indiana Department of Natural Resources, with a moderate risk assessment rating of 3.

Water resource and climate enthusiasts interested in Autumn Lake Dam should be aware of its importance as a recreational destination and potential risks associated with its current condition. The dam, situated on an unnamed tributary of Big Thunder Creek, holds a maximum storage capacity of 81 acre-feet and a normal storage level of 49 acre-feet. While the dam contributes to local water management and conservation efforts, its high hazard potential underscores the need for ongoing monitoring and maintenance to mitigate risks and ensure public safety.

Year Completed

1969

Dam Length

300

Dam Height

32

River Or Stream

UNNAMED TRIBUTARY BIG THUNDER CREEK

Primary Dam Type

Earth

Surface Area

6.5

Hydraulic Height

28

Drainage Area

0.33

Nid Storage

81

Structural Height

32

Outlet Gates

None

Hazard Potential

High

Nid Height

32
       
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.