Nyman Lake Reservoir Report

Last Updated: December 26, 2025

Nyman Lake, located in Allen County, Kansas, is a privately owned dam constructed by the USA WPA with the primary purpose of flood risk reduction.


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Summary

The dam, classified as an Earth dam with a buttress core type, stands at a height of 16 feet and has a hydraulic height of 15 feet. With a storage capacity of 106 acre-feet and a surface area of 5.74 acres, Nyman Lake plays a crucial role in managing water resources in the area.

The dam's low hazard potential and moderate risk assessment make it a reliable structure for flood control and water management. Despite not having a designated inspection frequency or condition rating, Nyman Lake remains an essential asset for the local community in Shaw City. With no associated structures and no outlet gates, the dam's uncontrolled spillway width of 78 feet ensures proper water discharge during periods of heavy rainfall, contributing to the overall resilience of the region's water infrastructure.

Nyman Lake's strategic location on Big Creek Rocky Branch-TR, as part of the Kansas City District, highlights its significance in the broader water resource management system. While not regulated or inspected by state agencies, the dam's design and purpose align with the need for effective flood risk reduction measures in the region. As climate change impacts continue to affect water resources, Nyman Lake stands as a vital asset in safeguarding against potential flooding and ensuring the sustainable management of water in Allen County, Kansas.

Dam Length

550

Dam Height

16

River Or Stream

BIG CREEK ROCKY BRANCH-TR

Primary Dam Type

Earth

Surface Area

5.74

Hydraulic Height

15

Drainage Area

1.75

Nid Storage

106

Structural Height

21

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

21
       
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.