Lenape Lake Dam Reservoir Report

Last Updated: December 20, 2025

Lenape Lake Dam in Sullivan, Indiana, also known as Jason (Lenape) Lake Dam, is a state-owned structure designed by the USDA NRCS for recreational purposes.


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Summary

Completed in 1968, this earth dam stands at 29 feet high and spans 667 feet in length, creating a reservoir with a normal storage capacity of 341 acre-feet and a maximum storage of 957 acre-feet. The dam is located on an unnamed tributary of Big Branch and is regulated by the Indiana Department of Natural Resources.

Despite its low hazard potential, Lenape Lake Dam is rated as being in poor condition, with its last assessment conducted in 2013. The dam lacks a spillway and outlet gates, raising concerns about its ability to safely handle maximum discharge. Its risk assessment is classified as high, highlighting the need for further risk management measures to ensure the safety of the surrounding community. With a history of state inspection and enforcement, Lenape Lake Dam remains under state jurisdiction and regulation, underscoring the importance of ongoing maintenance and monitoring to mitigate potential risks associated with its aging infrastructure.

Year Completed

1968

Dam Length

667

Dam Height

29

River Or Stream

UNNAMED TRIBUTARY BIG BRANCH

Primary Dam Type

Earth

Surface Area

47.81

Hydraulic Height

29

Drainage Area

0.4

Nid Storage

957

Structural Height

29

Outlet Gates

None

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

29
       
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.