Frequently Asked Questions on Maryland Dams and Dam Safety


What is a dam?

​The broad definition of a dam is provided in the Code of Maryland Regulations (COMAR) as any obstruction, wall, or embankment, together with its abutments and appurtenant works, if any, in, along, or across any stream, heretofore or hereafter constructed for the purpose of storing or diverting water or for creating a pool upstream of the dam, as determined by the Administration.

There are no natural lakes or ponds in Maryland, therefore nearly all bodies of water in the State are formed by dams. Note that the Maryland Department of the Environment’s (MDE or Department) Dam Safety program does not regulate water bodies formed by beaver dams or coastal erosion/deposition. Abandoned mines/quarries may also create water bodies, and may be regulated by the Dam Safety program if a dam is constructed to control water levels or discharges.

What is a small pond?

Certain smaller dams, commonly called small ponds, are not assigned a Maryland Dam ID Number, are not included in the Maryland Dam Inventory, and are inspected by MDE Dam Safety staff on an as-requested basis. These small ponds are typically found in agriculture or in smaller scale stormwater management practices.

Persons wishing to construct, reconstruct, modify, remove or repair these small ponds may be able to obtain approval from the local Soil Conservation District, or MDE’s designee, providing the following criteria are met:

  1. Drainage area to the pond must be less than 640 acres; and
  2. The height of the pond (measured from the upstream toe to the top of dam) must be less than 20 feet; and
  3. The dam must be a "low hazard" structure, the failure of which is not likely to cause loss of life or property damage. (Refer to MDE Guidance for Completing a Dam Breach Analysis for Small Ponds and Dams in Maryland); and
  4. The pond must have a maximum storage volume less than 50 acre-feet.

Note that these small ponds located in the watersheds of the Jones Falls, Gwynns Falls, or Herring Run streams in or adjacent to Baltimore City require permits for construction, reconstruction or alteration to be issued by the MDE Dam Safety Permits Division.​​​

Does MDE regulate my dam/small pond?

While the specific laws and regulations have evolved over time, the regulation of dams and reservoirs, of which, “small ponds” is a sub-category, has remained at the State level since 1931. This is codified in the Code of Maryland, Environment Article, §5–501 through 5-514. MDE is responsible under Maryland law to adequately preserve public safety, and promote the general public welfare by implementing a comprehensive Dam Safety program. MDE has promulgated regulations to implement comprehensive Waterway Construction and Dam Safety programs based on the powers authorized in the law cited above. These regulations are located in COMAR 26.17.04, which concerns Construction on Non-Tidal Waters and Floodplains. Additional regulations within this subtitle specific to dams are found in

Review and approval for construction of certain small ponds can be performed by the local SCD and/or the MDE  designee as discussed in the ‘What is a Small Pond” question.​

What is the hazard classification of a dam?

Adapted from FEMA 333: Hazard Potential Classification System for Dams. The hazard potential classification system for dams is based on the probable loss of human life and the potential for economic losses, environmental damage, and/or disruption to lifelines caused by failure or mis-operation of a dam or its appurtenances. The hazard potential classification assigned to a dam is based on consideration of the effects of a failure or mis-operation during both normal and flood flow conditions. The classification should be based on the worst-case probable scenario of failure or mis-operation of the dam. A primary purpose of any classification system is to select appropriate design criteria. In other words, design criteria will become more conservative as the potential for loss of life and/or property damage increases.

Three classification levels are adopted as follows: LOW, SIGNIFICANT, and HIGH, listed in order of increasing adverse consequences. This hazard potential classification system should be utilized with the understanding that the failure of any dam or water-retaining structure, no matter how small, could represent a danger to downstream life and property.

LOW HAZARD POTENTIAL Dams assigned the low hazard potential classification are those where loss of human life due to failure or mis-operation is unlikely and results in low economic and/or environmental losses. Losses are principally limited to the dam owner’s property.

SIGNIFICANT HAZARD POTENTIAL Dams assigned the significant hazard potential classification are those dams where there is a small possibility of loss of life due to failure or mis-operation but can cause economic loss, environmental damage, disruption of lifeline facilities, or can impact other concerns.

HIGH HAZARD POTENTIAL Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life, serious damage to structures, important roads, public utilities or railroads.

Hazard classification categories, low, significant and high are synonymous with Natural Resources Conservation Service (NRCS) Pond Code MD-378 hazard classes “a”, “b”, and “c”, respectively.​

Does a high hazard classification mean the dam is unsafe?

A high hazard classification is not an indication of the condition of the dam. The classification relates to the consequences of a dam failure (e.g., flooding, loss of life, loss of property). In addition, the classification is not an indication of the likelihood of failure.​


Do I need a permit to construct, alter or repair my dam or small pond?

Anyone planning to construct, reconstruct, repair or alter a dam or reservoir in the State of Maryland must receive a permit from MDE Dam Safety or, if the structure qualifies as a small pond, approval by the local SCD or MDE designee. Note that this regulatory requirement includes construction and alteration of the “reservoir” as well, thus work that is planned within the impounded area requires review and approval even if the dam embankment is not directly altered.

Normal maintenance activities at dams, reservoirs and their appurtenant works is encouraged and demonstrates responsible ownership of said structures. Accordingly, certain maintenance activities are considered exempt from the requirement to obtain a permit. These activities are defined in Dam Safety Policy Memorandum #11 – Activities Not Requiring a Dam Safety Permit.

Small pond approval does not relieve the applicant from the requirement of obtaining any other necessary local, State or U.S. Army Corps of Engineers permits. This may include, but is not limited to, erosion and sediment control approvals, grading approvals, and MDE Non-Tidal Wetlands and Waterways Division approvals.​

I want to make a small change to my dam, do I need to repair all known problems?

Yes. The Department must ensure that all permits issued are in the best public interest.  Therefore, all permitted projects must provide for the greatest feasible utilization of the waters of the State, adequately preserve the public safety, and promote the general public welfare. Where deficiencies are known, they must be corrected to preserve public safety.

What kind of permit do I need?

The Dam Safety Permits Division will issue a Dam Safety permit or Small Pond Approval upon approval of a permit application. Local SCDs, or the Department’s designee may issue a “Small Pond Approval” for qualifying small ponds.​

How do I apply for a permit?

Complete a "Joint Federal/State Application for the Alteration of any Floodplain, Waterway, Tidal or Nontidal Wetland in Maryland" application, as well as Appendix B for Dams and Small Ponds. Note that all owners of the dam must sign the application, even if the work is proposed on only a single parcel.

The application must be mailed with the original plus six copies of the application, plans, vicinity maps, and any supporting documentation to: Regulatory Services Coordination Office (RSC) MDE, Water and Science Administration, 1800 Washington Boulevard Baltimore, Maryland 21230.

Application materials that are specific to Dam Safety review (e.g., breach analysis, inundation mapping, basis of design reports) can be emailed to, or to the assigned reviewer, if known.

Prior to submitting your application, it is suggested that you or your engineer contact the Dam Safety Permits Division to discuss the documentation necessary for your submittal and any unique project elements and applicable design requirements.​

What is involved in the permitting process?

The permitting process is a collaborative and iterative effort to ensure that the proposed designs meet high standards for the protection of public safety and environmental resources. The permitting process generally has five (5) phases, which can run concurrently, and are described below:

    1. Application received by the Department
    2. Assigned file number
    3. Assigned to staff member
    4. Acknowledgement of application receipt by the Department
    1. Examination of proposed project
    2. Site inspection
    3. Request for additional information as may be required
    4. Receipt of completed Certification of Notification
    5. Develop "Interested Persons List”
    1. Process additional information as necessary
    2. Detailed project evaluation
    3. Application complete (Plans, Specifications, Reports and Analyses reviewed for technical and regulatory sufficiency and ready for approval)
    4. Publish “Notice of Completed Application”, which includes names and addresses of the applicant, description of project and instructions for submitting comments or requesting a public informational hearing, for one day in a newspaper of general circulation in the county or municipality where the site is located
    5. Mail Notice of Completed Application to each individual on the "Interested Persons List"
    1. If no Hearing Requests are received:
      1. Public comments received
      2. Public Informational Hearing (at the discretion of the Department)
    2. If Hearing requests received (within 14 calendar days of publication of notice):
      1. Public Informational Hearing (required within 45 calendar days of the close of the public comment period)
      2. Set hearing date, time and place within 10 calendar days after receipt of request
      3. Mail Notice of Hearing to persons on "Interested Persons List" no later than 14 calendar days prior to the hearing
      4. Hold Hearing
      5. Certification of Hearing Record
    1. Review written comments and hearing testimony
    2. Make decision
    3. Issue, modify or deny permit application
    4. Issue Decision Notice to Interested Persons and applicant


What is required for a permit for dam construction, repair or rehabilitation?

Each dam and project is unique; therefore, a general list of required submittals should be discussed with the Dam Safety Permits Division prior to making the application. Submittals that are required for nearly every project regardless of size, complexity, dam type, and dam hazard classification include:

  • Detailed construction plans
  • Project specifications
  • Basis of Design Report (to include the following items. Discipline specific reports should be included as an appendix, as needed, and must include all supporting calculations)
    • Summary of proposed work and project goals
    • Summary of design standards applicable to project
    • Hazard Classification Statement
    • Dam Inspection Report (for existing dams)
    • Hydrology & Hydraulics Report
    • Dam Breach Analysis and Hazard Classification Report
    • Geotechnical Engineering Report
    • Structural Engineering Report
  • Operation and Maintenance Plan
  • New/Updated Emergency Action Plan (High and Significant Hazard only)
  • Memorandum of Land Restrictions
  • Engineer-in-Charge (EIC) Affidavit and resume

What design standards apply?

The Department requires the design of high, significant or low hazard (non-378) dams, to incorporate the general requirements found in COMAR and the Dam Safety Policy Memos that are available on the Dam Safety program’s webpage. Applicants and engineers should discuss appropriate design criteria with the Dam Safety Permits Division prior to initiating design of a project. References used by the designer must be cited in the application, especially where unusual features are incorporated in the design.

The design of small ponds is governed by the aforementioned COMAR requirements; Dam Safety Policy Memos; and USDA Natural Resources Conservation Service, Maryland Conservation Practice, Standard Pond Code 378 (January, 2000).​

What is an Engineer-in-Charge?

A permit application to construct, reconstruct, repair or alter a dam must be prepared by a registered professional engineer, practicing in accordance with the laws of Maryland and qualified in the field of dam design and construction.

This engineer, deemed the engineer-in-charge (EIC) must oversee the preparation of the designs and specifications and provide supervision during construction of the proposed works. The EIC is responsible for assuring that the designs conform to the high standards of professional competence in the specialty of dam design and construction, and assures that the construction is carried out in strict accordance with the approved plans and specifications and under the provisions of the permit.

The EIC must submit an affidavit attesting to their qualifications, and must submit a resume of all previous dam design and construction experience, listing specific responsibilities. It is important that the EIC have demonstrated experience working with dams of a similar age, construction method, and hazard potential as the proposed project.​

Can you recommend an engineer?

We do not recommend any specific individual or firm, but we can provide names of consultants that have worked, or are working on nearby projects of similar scope. ASDSO has developed a webpage to serve as a resource for dam owners to assist in selecting and hiring an engineer. This website can be found at:

We also recommend that you check out the following organizations and websites:

      Maryland Society of Professional Engineers:

      Maryland Section, ASCE:​

Why do I need a bond for my dam construction?

The Department may require that an applicant post a construction bond, irrevocable letter of credit, or other security acceptable to the Department to assure that funds are available to complete the construction of the proposed project or render the project safe should an owner become insolvent during construction. This requirement typically applies to new dam construction by private entities that do not have the ability to raise funds by taxing or sale of services (i.e., utilities).​

Dam Ownership

How is dam ownership determined?

An owner of a dam is considered to be anyone who owns any portion of the dam, reservoir, or appurtenant works of the dam. This is generally determined using property boundaries and owner information shown on tax maps from the Maryland Department of Assessments and Taxation. If these records indicate that your property includes any part of the dam, you are judged to be either an owner or partial owner of the dam.​

I just purchased a property with a dam. Do I need to initiate any action?

Yes, you should start by notifying the Dam Safety Inspection and Compliance Division to learn more about the dam, update contact information for the dam, and to obtain general information regarding dam owner responsibilities. The Dam Safety staff member may request an on-site meeting and inspection to evaluate the condition of the dam.​

As a dam owner, what are my responsibilities?

The owner of a dam has certain responsibilities and liabilities according to Maryland law and regulations. The owner must obtain any necessary permits as directed by Maryland law and regulations, and comply with the provisions of those permits. Additionally, the owner must inspect and maintain the dam on a regular basis. Routine inspection and maintenance allows early detection of many problems that may occur with a dam. The dam owner is required to contact the Maryland Dam Safety program when a deficiency or potential failure is noticed.

In addition, responsible dam ownership includes an awareness of the consequences of the failure of your dam, and an ability to respond appropriately. High and Significant hazard dam owners are required to prepare an Emergency Action Plan (EAP) for each dam, review the EAP on a regular basis and update at least annually, and participate in EAP exercises.

Lastly, dam ownership requires responsible financial planning to ensure that adequate funds are available, or can be readily obtained to maintain the dam properly and to repair or replace components that are at the end of their serviceable life or no longer functioning.​

What does a dam inspection consist of?

Dam Safety inspections are intended to identify conditions that may adversely affect the safety and functionality of a dam and its appurtenant structures; to note the extent of deterioration as a basis for long term planning, periodic maintenance or immediate repair; to evaluate conformity with current design and construction practices; and to determine the appropriateness of the existing hazard classification. For additional information regarding dam inspections and a standard inspection checklist, please see the Maryland Dam Operation, Maintenance, and Inspection Manual Template.​

Will MDE inspect my dam for me?

In addition to the inspections by the owner, Maryland Dam Safety staff make periodic inspections of all dams, reservoirs, and other waterway obstructions within its jurisdiction to provide for the public safety and welfare, to detect early signs of deterioration, and to enforce corrective measures. These inspectors must be given free access to every part of the dam or reservoir under consideration, and the operators of these works must assist in the inspection to the best of their abilities.

What types of trees and vegetation are not allowed to grow on my dam?

A healthy cover of grass is desirable as erosion protection. The growth of woody vegetation, such as shrubs and trees is not acceptable. Excessively tall herbaceous vegetation and woody vegetation impedes the inspection process and can hide serious deficiencies that may be occurring at a dam. Additionally, the root structure of trees affects the structural integrity of the dam, can cause seepage pathways for water through the dam, and can cause significant embankment loss if uprooted. Any one of these factors alone can contribute to the failure of a dam.​

How do I know if something is wrong with my dam?

Major indicators of possible dam failure include heavy seepage, overflowing water (overtopping), sinkholes, sand boils, muddy water flow from drains, and unusual water level. Other symptoms of failure include, but are not limited to erosion, surface cracks, settlement, movement, and wetness on the slope of the embankment. These signs of distress can appear rapidly or slowly over time.​ The FEMA Pocket Guide for Dam and Impoundments​ is a valuable tool with visual aids to help identify and understand problems with dams.

My dam has been here for decades. Why make repairs now?

Just because a dam has been in service for a long time does not mean it cannot develop a problem. As dams age, individual components can deteriorate or wear out from use. Additionally, as a changing climate leads to intensifying natural hazards, the loading conditions at the dam may increase beyond previously observed levels and reveal latent defects that were previously unknown. A number of recent dam incidents and failures have occurred at dams that had generally been performing satisfactorily over many decades, including at Oroville Dam in California (2017), Spencer Dam in Nebraska (2019) and Edenville and Sanford Dams in Michigan (2020). In Maryland this list includes incidents at Cascade Lake (2018), Riawalkin Pond (2018), and Greenbrier Dam (2018).​


Who is responsible if my dam fails?

The owner of the dam is responsible if the dam fails. The dam owner is solely responsible for the safe operation and adequate maintenance of the dam, including detecting dam incidents and initiating the appropriate emergency response.​

What are some signs that a dam is in distress or failing?

Conditions that may lead to a dam incident or failure, including the uncontrolled release of water from a pond, lake, or reservoir can be determined based on observations of the following conditions:

  • Unsafe high water level or rapid loss of water in the pond or lake
  • Water overtopping (flowing over) the dam embankment
  • Formation of a vortex (whirlpool) in the pond or lake
  • Cracks in the dam or sliding of dam embankment material
  • Sinkholes
  • Discharge of muddy water from the dam embankment
  • Obstructions in the spillway
  • Damage or failure of gates, valves or other dam components
  • Destructive vandalism

Who should be contacted in case of an emergency?

If any of the conditions listed above are observed, the following steps should be taken immediately:

  • Make sure you are in a safe location before observing the situation and report an appropriate response to the incident.
  • Call 9-1-1 and report your location, the observations that indicate a potential dam failure, and a method to contact you if the call is ended.
  • Report the incident to the Maryland Dam Safety program at 410-537-3538 (9am to 5pm) or call the 24-hour notification hotline at 1-866-MDEGOTO (1-866-633-4686).
  • If you are the owner of a High or Significant Hazard Potential Dam, immediately activate your Emergency Action Plan (EAP) and take appropriate measures to notify emergency responders and, if possible, take actions to reduce the chance of dam failure.

What do I do if there is something wrong with a dam that I do not own?

If you notice a non-emergency issue with a dam that you do not own, you should notify the owner of the dam. If the problems with the dam are impacting your property and you are unable to resolve the matter with the owner, this may become a civil matter and you should seek legal advice. If the situation with the dam is an emergency, call 9-1-1.​

What does Dam Safety do if a problem is identified with my dam?

It is our goal to work closely with dam owners to identify and correct potential problems before they become serious. If we find a deficiency during an inspection, we work with the dam owner to address and remedy the condition in a timely manner. If a dam owner is slow to remediate the problem, or is recalcitrant, a graduated enforcement protocol is in place that can eventually lead to an administrative court hearing and contempt of court charges. When necessary, we may direct the dam owner to implement their emergency action plan (EAP) and hire an engineer to prepare plans to remove or repair the dam. In cases of imminent failure and a failure of the dam owner to take necessary actions, Maryland law allows the Department to take charge of the dam and immediately employ any remedial means necessary to protect life and property. Costs incurred by the Department in such cases must be repaid by the owner in a timely manner. Failure to repay the Department can lead to a lien being placed on the property.​

What is the role of Dam Safety in an Emergency?

Aside from the actions described above, the role of the Dam Safety program during an incident or emergency is to ensure fast and efficient response and coordination in a manner that lessens the risk to the safety and health of the public, as well as unnecessary property loss and environmental damage. Effective emergency preparedness, response, coordination, and training are essential elements to meet this objective.

During an emergency or disaster requiring Dam Safety program assistance, all Dam Safety Personnel located at the scene of the emergency are first under the authority of the Incident Commander (Fire Chief, Police, Emergency Medical Services, etc.) and then under the authority of the Chief of their respective Dam Safety Division. All other Dam Safety staff not located at the scene of the emergency or disaster, but assisting with the response or recovery, are under the authority and direction of the Chief of their respective Dam Safety Division. These authorities will manage the incident consistent with the National Incident Management System/Incident Command System (NIMS/ICS).

During emergencies and disasters, it is the policy of the Dam Safety program to:

  • Provide the most effective and timely response to any dam related emergency or disaster to ensure the safety of the general public.
  • Coordinate with Federal, State, and local authorities as well as the dam owner and/or their engineer to provide technical advice to the Incident Commander and the dam owner. This technical advice shall not be in lieu of, or alleviate the need for the dam owner to obtain the services of a licensed professional engineer to design any necessary temporary or permanent repairs. Advice that may be offered may include, but is not limited to; explanation of the likelihood of dam failure; explanation of the likely downstream consequences dam failure; actions that may lessen the likelihood of failure; actions that may stop a dam from failing; and actions that are necessary to stabilize an already damaged dam to prevent further risks to public safety. This response will be consistent with the federally-initiated National Incident Management System (NIMS) and Incident Command System (ICS) adopted by Federal, State, and local agencies.
  • Coordinate with the appropriate local, State and Federal agencies regarding potential actions during and after the emergency that can lessen the potential impacts to natural resources resulting from the release of debris, water, or sediment. When a risk to public safety exists, these risks will be considered primary.
  • Assist local, State and Federal agencies performing incident damage assessments to determine the resources necessary for recovery and the services that can be restored.
  • Assist in any subsequent incident investigation process conducted by Federal, State, or local authorities or other appropriate agencies.
  • Document and maintain records of all disasters or emergencies.

Why do I need to have an EAP?

Maryland law requires that owners of High and Significant hazard dams develop and maintain EAPs. An effective EAP may be able to save lives and protect property. A well prepared EAP will provide details regarding emergency triggers; monitoring of the dam during flood events; incident mitigation methods; communication protocols; incident command duties; and perhaps most importantly, the information necessary to determine where the at-risk population downstream of the dam is located, and how to safely evacuate those persons.​

How often do I need to revise my EAP?

Maryland law requires that owners of High and Significant hazard dams review and update their EAP annually. The updated EAP must be submitted to the Dam Safety program no later than May 1 of each year. Aside from the annual review and update, dam owners should update their EAP and distribute revised copied to all record holders when:

  • There is a change in personnel or contact information for any person/entity listed in the EAP;
  • Ownership of the dam changes;
  • New inundation maps or revisions to existing maps and linked notification plans; and,
  • Changes in downstream development adds (or removes) potential impacted structures.

Do I ever have to update the hazard classification and inundation map?

Yes. The Department recommends that a simple visual assessment of changes in downstream development occur at least annually – and if changes are observed, a new breach analysis may be required. Even where no changes are observed, the Department recommends that analyses and maps be updated a minimum of every 10 years for high hazard dams and 15 years for significant hazard dams. This ensures that the latest data, models and methodologies are used and can be relied on in an emergency.​

What happens if I do not complete or submit the EAP?

The Department would like to assist you to ensure this does not happen. If you are having difficulty understanding or completing the EAP, please contact the Department. Insufficient or absent EAPs may lead to compliance and enforcement actions, which may result in fines.


Human Trafficking GET HELP

National Human Trafficking Hotline - 24/7 Confidential

1-888-373-7888 233733 More Information on human trafficking in Maryland

Customer Service Promise

The State of Maryland pledges to provide constituents, businesses, customers, and stakeholders with friendly and courteous, timely and responsive, accurate and consistent, accessible and convenient, and truthful and transparent services.

Take Our Survey

Help Stop Fraud in State Government

The Maryland General Assembly’s Office of Legislative Audits operates a toll-free fraud hotline to receive allegations of fraud and/or abuse of State government resources. Information reported to the hotline in the past has helped to eliminate certain fraudulent activities and protect State resources.

More Information