Lake Mcmaster Dam Reservoir Report

Last Updated: December 14, 2025

Lake McMaster Dam, also known as Snakeden Hollow Dam, is a state-owned structure located in Dahinda, Illinois, within Knox County.


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Summary

Completed in 1981, this earth dam stands at a height of 81 feet and spans 850 feet across. Its primary purpose is for recreation, offering a beautiful setting for outdoor enthusiasts to enjoy activities such as fishing, boating, and picnicking within its 178-acre surface area.

The dam is regulated by the Illinois Department of Natural Resources (IDNR) and has a high hazard potential due to its location on Snakeden Creek. With a maximum storage capacity of 5350 acre-feet, it serves as a vital resource for water supply and flood control in the region. The spillway, with a width of 313 feet, is uncontrolled, allowing excess water to flow out during heavy rainfall events.

Despite its high hazard potential, the condition assessment of Lake McMaster Dam is currently listed as not available. Regular inspections are conducted, with the last inspection taking place in July 2020. While the risk assessment is considered moderate, the dam's emergency action plan (EAP) status and risk management measures are unspecified. Overall, Lake McMaster Dam serves as a key recreational and water resource for the community, warranting ongoing monitoring and maintenance to ensure its safety and functionality.

Year Completed

1981

Dam Length

850

Dam Height

81

River Or Stream

SNAKEDEN CREEK

Primary Dam Type

Earth

Surface Area

178

Drainage Area

2.13

Nid Storage

5350

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

Nid Height

81
       
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.