Lake Needwood Reservoir Report

Last Updated: December 5, 2025

Lake Needwood, also known as Upper Rock Creek Watershed Site 5, is a captivating water resource nestled in Montgomery, Maryland.


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Summary

Managed by the local government, this reservoir serves as a popular recreational spot for residents and visitors alike. Originally designed in 1965 by USDA NRCS and USDA SCS, the dam stands at a height of 65 feet and boasts a storage capacity of 7,023 acre-feet, with a surface area of 74 acres.

With a drainage area of 12.8 square miles and a maximum discharge of 25,652 cubic feet per second, Lake Needwood plays a crucial role in managing water flow and providing flood control for the Rock Creek watershed. Although the dam is classified as having a high hazard potential, its fair condition assessment suggests that it is currently stable. Regular inspections and maintenance ensure the safety and functionality of this earth dam, which has undergone repairs in 2007 to reinforce its foundation.

As one of the key structures in the region's water management system, Lake Needwood offers a serene setting for outdoor activities and wildlife observation. With its uncontrolled spillway and slide gates for outlet control, the reservoir is equipped to handle the demands of both recreation and flood protection. Climate and water resource enthusiasts can appreciate the balance of ecological conservation and human enjoyment that Lake Needwood embodies, making it a valuable asset in Maryland's landscape.

Years Modified

2007 - Foundation

Year Completed

1965

Dam Length

426

Dam Height

65

River Or Stream

Rock Creek

Primary Dam Type

Earth

Surface Area

74

Drainage Area

12.8

Nid Storage

7023

Outlet Gates

Slide (sluice gate) - 0

Hazard Potential

High

Foundations

Soil

Nid Height

65
       
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.