Rynearson Dam No. 1 Reservoir Report

Last Updated: December 13, 2025

Located in Necedah, Wisconsin, Rynearson Dam No.


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Summary

1 is a Federal-owned structure designed by the US Fish and Wildlife Service for the primary purpose of serving as a Fish and Wildlife Pond. Completed in 1939, this earth dam stands at a height of 24 feet and stretches 1145 feet in length, with a maximum storage capacity of 10,292 acre-feet and a normal storage capacity of 2,121 acre-feet. Situated on a branch of Little Yellow Creek, the dam plays a crucial role in managing water resources and habitat for aquatic wildlife in the area.

With a low hazard potential and a satisfactory condition assessment, Rynearson Dam No. 1 has undergone multiple modifications over the years, including hydraulic and structural upgrades in 1989 and 2003. The dam features other controlled outlet gates and a spillway width of 216 feet, allowing for a maximum discharge of 5,355 cubic feet per second. Despite not being regulated by the state, the dam is inspected every five years to ensure its continued safe operation. As a key component of the Fish and Wildlife Service's operations, Rynearson Dam No. 1 serves as an important structure in the conservation and management of water resources in the region.

In the picturesque landscape of Juneau County, Wisconsin, Rynearson Dam No. 1 stands as a testament to the intersection of water resource management and environmental conservation. With its strategic location and design tailored for fish and wildlife habitat, the dam serves as a vital component in the broader ecosystem of the area. From its humble beginnings in 1939 to its continued role in safeguarding water resources and supporting biodiversity, Rynearson Dam No. 1 exemplifies the harmonious coexistence of human infrastructure and natural ecosystems in the fight against climate change and the preservation of our planet's precious resources.

Years Modified

1989 - Hydraulic, 1989 - Structural, 2003 - Hydraulic, 2003 - Structural

Year Completed

1939

Dam Length

1145

Dam Height

24

River Or Stream

BRANCH OF LITTLE YELLOW CREEK

Primary Dam Type

Earth

Surface Area

800

Hydraulic Height

23

Drainage Area

14.29

Nid Storage

10292

Structural Height

24

Outlet Gates

Other Controlled

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

24
       
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.