E-21b Reservoir Report

Last Updated: December 6, 2025

E-21b, also known as Ksnoname 2755, is a locally owned Earth type dam located in Jefferson County, Kansas on Little Slough Creek.


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Summary

Completed in 1958, this dam stands at a height of 39.9 feet and serves the primary purpose of flood risk reduction. With a storage capacity of 293 acre-feet and a drainage area of 0.8 square miles, E-21b plays a crucial role in managing water resources in the region.

Managed by the Kansas Department of Agriculture, E-21b has a low hazard potential and a moderate risk assessment rating of 3. Although the dam has not been rated for its current condition, it undergoes regular inspections by the state regulatory agency to ensure its safety and effectiveness in flood control. Despite having no outlet gates, E-21b features an uncontrolled spillway with a width of 60 feet, allowing for the controlled release of excess water during heavy rainfall events.

With its strategic location and design features, E-21b serves as a key component in the flood risk reduction infrastructure of Jefferson County, Kansas. Maintaining and monitoring this dam is essential for protecting surrounding communities and managing water resources effectively in the face of climate change and extreme weather events.

Year Completed

1958

Dam Length

500

Dam Height

39.9

River Or Stream

LITTLE SLOUGH CREEK

Primary Dam Type

Earth

Surface Area

11

Hydraulic Height

36.9

Drainage Area

0.8

Nid Storage

293

Structural Height

42.2

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

42
       
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.