Little Yellow 20 Reservoir Report
Last Updated: December 13, 2025
Little Yellow 20, located in Necedah, Wisconsin, is a state-regulated dam with a primary purpose of irrigation.
°F
°F
mph
Wind
%
Humidity
Summary
Completed in 1936, this gravity dam stands at a height of 8 feet and has a storage capacity of 70 acre-feet. The dam serves multiple purposes including irrigation, recreation, and water supply, with a drainage area of 3.9 square miles and a maximum discharge of 486 cubic feet per second.
Despite its low hazard potential, Little Yellow 20 is classified as having a very high risk level, emphasizing the importance of effective risk management measures. The dam has not been rated for its condition assessment, with the last inspection taking place in June 2007. With a controlled spillway type and a surface area of 10 acres, this dam plays a crucial role in the water resource management of the area. Water and climate enthusiasts will find Little Yellow 20 to be an intriguing structure with a rich history and significant impact on the local ecosystem.
Year Completed |
1936 |
Dam Length |
42 |
Dam Height |
8 |
River Or Stream |
NEAL LATERAL |
Primary Dam Type |
Gravity |
Surface Area |
10 |
Hydraulic Height |
7 |
Drainage Area |
3.9 |
Nid Storage |
70 |
Structural Height |
8 |
Hazard Potential |
Low |
Nid Height |
8 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Yellow River At Babcock
|
44cfs |
Yellow River At Necedah
|
52cfs |
Lemonweir River At New Lisbon
|
261cfs |
Tenmile Creek Near Nekoosa
|
27cfs |
Wisconsin River At Wisconsin Rapids
|
1960cfs |
Black River Ds St Hwy 54 @ Black River Falls
|
514cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Little Yellow 20