Daniels Dam Reservoir Report

Last Updated: December 5, 2025

Located in Ellicott City, Maryland, Daniels Dam is a historic structure built in 1833 on the Patapsco River.


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Summary

With a dam height of 27 feet and a length of 450 feet, it serves primarily for recreational purposes, offering a tranquil setting for visitors to enjoy the surrounding natural beauty. The dam has a low hazard potential and is in satisfactory condition, with regular inspections conducted by the Maryland Dam Safety agency to ensure its safety and integrity.

The original design of Daniels Dam was carried out by Ambursen Engineering, with Stone&Webster later adding a fish ladder to assist with fish migration. Over the years, the dam has undergone modifications in 1993 to reinforce its foundation and structure. With a storage capacity of 1500 acre-feet and a drainage area of 265.8 square miles, the dam plays a crucial role in managing water resources in the region and supporting the ecosystem of the Patapsco River.

Despite its historical significance and recreational value, Daniels Dam poses a moderate risk level (3) according to risk assessments. The dam's spillway, with a width of 278 feet, is uncontrolled, allowing for the release of excess water during periods of high flow. With Elijah E. Cummings representing the area in Congress, efforts are made to ensure the proper management and maintenance of the dam for the safety and enjoyment of all who visit this picturesque location.

Years Modified

1993 - Foundation, 1993 - Other, 1993 - Structural

Year Completed

1833

Dam Length

450

Dam Height

27

River Or Stream

Patapsco River

Primary Dam Type

Buttress

Surface Area

20

Drainage Area

265.8

Nid Storage

1500

Outlet Gates

Needle - 0

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

27
       
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.