Dam Safety FAQs

What is a dam?

Any man-made barrier or obstruction, together with appurtenant works, if any, across a stream or channel, watercourse, or natural drainage area which impounds or diverts water. All structures necessary to impound a single body of water shall be considered a dam.

Do I need to submit an application and receive written authorization for the construction, enlargement, repair or alteration of my dam?

Yes. Section VII. A. 1 Safety Regulations For Dams states that “Any person proposing to construct, enlarge, repair, or alter a dam or reservoir shall submit an application to the Permit Board on forms prescribed by the Board at least thirty (30) days prior the anticipated commencement of construction”. Written authorization must be obtained from the Board prior to commencement of construction. A copy of the application form and the dam safety regulations is available at this website.

What is the hazard classification of my dam?

All regulated dams are placed into one of three hazard classifications based on the threat to life and property downstream, should dam failure occur. You should also be aware that the hazard classification of a dam may change as residential development or other land use changes occur downstream.
High Hazard – Dam failure may cause loss of life, serious damage to homes, industrial or commercial buildings, important public utilities, main highways or railroads. Dams constructed in existing or proposed residential, commercial or industrial areas will be classified as high hazard dams, unless the applicant presents clear and convincing evidence to the contrary.
Significant Hazard- Dam failure may cause significant damage to main roads, minor railroads, or cause interruption of use or service of relatively important public utilities.
Low Hazard- Dam failure may cause damage to farm buildings (excluding residences), agricultural land, or county or minor roads.

Is my dam regulated under the “Safety Regulations for Dams”?

Not necessarily. For instance, if your dam is less than 8 feet in height, impounds less than 25 acre-feet of water or does not impound a watercourse with a continuous flow of water; it may not be regulated under the safety regulations for dams. However, that determination can only be made by MDEQ on a case-by-case basis after reviewing your plans.

What is an Emergency Action Plan (EAP)?

An emergency action plan is a formal written document that may be required by the Permit Board or Commission for purposes of identifying the area that would be inundated in the event of a dam failure and setting forth the plans and procedures for notifying the individuals, agencies, and public officials that would mobilize resources to respond to the emergency. The EAP, if required, must be submitted to, and approved by, the Permit Board.

Do I need an Emergency Action Plan (EAP) for my dam?

Any dam that has a “High Hazard” classification is required to have an emergency action plan. The requirement for an EAP on dams classified “Significant Hazard” is made on a case-by-case basis. EAP’s are not required for “Low Hazard” dams.

How often should my dam be inspected?

Frequency of inspection for a dam should be commensurate with the danger posed to downstream lives and property if the dam should fail. While some dams need to be inspected almost daily others may only need to be inspected annually. It is always a good idea to inspect a dam after a major rainfall event, especially if the emergency spillway activated or the dam overtopped during the event.

Why is it recommended that trees not be allowed to grow on dams?

While trees on a dam may be aesthetically pleasing they are not good for the dam. As trees grow they tend to shade out grasses that prevent erosion. They also develop large root systems, and one of the leading causes of dam failure is “piping” along the root system of a tree that has died. As the roots rot, conduits are formed allowing the passage of water through the dam. Also, trees uprooted from high winds can cause the loss of a significant section of the dam.

What can I do to help prevent my dam from deteriorating to the point that it becomes unsafe or requires major repair?

The quick answer is maintenance. A regular maintenance program that includes mowing, inspection and repair of minor problems as they occur is the most economical approach to having a dam that’s in good repair. Waiting until a minor problem becomes a major problem only increases the cost of repairs. Erosion of the embankment slopes is a major problem that in almost all cases can be prevented with a good grass cover. Essential to a good grass cover is a fertilization program that is best suited for the type grass being grown and site specific conditions. Animals that burrow into the dam such as beaver and muskrat also must be controlled and damage from their burrows repaired as soon as it is discovered.

Can the State Dam Safety Program assist me in the inspection of my dam?

The State Dam Safety Office does not have resources or manpower available to assist in inspections at the inspection frequency needed for most dams. (See A 7.) However, if you discover problems during your inspection of a high or significant hazard dam, you should notify the staff in the Dam Safety Office immediately and they will perform a follow-up inspection to provide recommendations for dealing with the problem. Otherwise, all high and significant hazard dams are inspected by the State Dam Safety Office staff on a frequency of one three or five years depending on hazard class, overall condition of the dam at the time of the last inspection, and nature of downstream hazards. Low hazard dams are also randomly inspected for a hazard classification review or upon request. The dam owner is encouraged to participate in these official inspections and will be provided a copy of the inspection report. If deficiencies are identified during the official inspection, the report will contain recommended remedial measures and the owner will be required to develop a plan and schedule for correcting deficiencies.