Vesper Reservoir Report

Last Updated: December 15, 2025

Vesper, located in Wood County, Wisconsin, is a privately owned dam on Hemlock Creek, with a primary purpose of recreation.


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Summary

Built in 1944, this concrete gravity dam stands at a height of 13 feet and has a maximum storage capacity of 75 acre-feet. With a surface area of 11 acres and a drainage area of 41.2 square miles, Vesper serves as a significant water resource in the region.

Despite being last inspected in 2009, Vesper is classified as having a significant hazard potential and a moderate risk level. The dam's spillway, with a width of 150 feet, is uncontrolled, and its maximum discharge capacity is reported to be 2070 cubic feet per second. Although the condition of Vesper is currently not rated, it is subject to state regulation, inspection, and enforcement, ensuring its continued safety and compliance with standards.

For water resource and climate enthusiasts, Vesper presents an intriguing case study of a historic dam that continues to provide recreational opportunities while facing potential risks and regulatory oversight. Its location on Hemlock Creek, in the Detroit District, adds to its significance as a water management structure in the region. As efforts to assess and manage the risks associated with dams like Vesper continue, understanding and monitoring its condition and performance are essential for ensuring the safety and sustainability of this important water resource.

Year Completed

1944

Dam Length

125

Dam Height

13

River Or Stream

HEMLOCK CREEK

Surface Area

11

Hydraulic Height

8

Drainage Area

41.2

Nid Storage

75

Structural Height

13

Hazard Potential

Significant

Nid Height

13
       
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.