Rock Manor Golf Course Dam Reservoir Report

Last Updated: December 5, 2025

Rock Manor Golf Course Dam, located in Wilmington, Delaware, is a gravity dam built in 2007 primarily for flood risk reduction along Matson Run.


°F

°F

mph

Wind

%

Humidity

Summary

Standing at a height of 23.94 feet and stretching 475 feet in length, the dam has a storage capacity of 100 acre-feet and a maximum discharge capacity of 4522 cubic feet per second. Although the dam is classified as having a high hazard potential, its condition was assessed as fair in 2008, with a moderate risk level assigned.

Operated by the local government and regulated by the Delaware Department of Natural Resources and Environmental Control (DNREC), the Rock Manor Golf Course Dam plays a crucial role in mitigating flooding risks in the area. Despite its fair condition assessment, the dam continues to undergo regular inspections and enforcement measures to ensure its structural integrity and effectiveness in flood control. With its presence on Matson Run, the dam serves as a vital infrastructure piece contributing to water resource management and climate resilience efforts in New Castle County, Delaware.

Year Completed

2007

Dam Length

475

Dam Height

23.94

River Or Stream

MATSON RUN

Primary Dam Type

Gravity

Surface Area

5

Drainage Area

0.72

Nid Storage

100

Outlet Gates

None

Hazard Potential

High

Foundations

Unlisted/Unknown

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.