Dam failures occur not only during flood events, which may cause overtopping of a dam, but also may occur as a result of poor operation, lack of maintenance and repair, and vandalism. Such failures can be catastrophic because they can occur unexpectedly, with no time for evacuation. A common form of dam failure occurs when tree roots disrupt the integrity of an earthen dam. Water can pass through the dam where the soil has been broken apart by the roots.
In Michigan, all dams over 6 feet high, and create an impoundment with a surface area of more than five acres, are regulated by Part 315, Dam Safety, of the Natural Resources and Environmental Protection Act, (451 P.A. 1994), as amended. This regulation requires that the Michigan Department of Environmental Quality (DEQ) rates each dam as either a low, significant, or high hazard potential. This rating system is based solely on the potential downstream impact if the dam were to fail and not according to the physical condition of the dam. The potential downstream impact is figured by assessing the population concentration and economic activities located downstream from the dam. More information about the MDEQ Dam Safety Program can be found on the DEQ Water Management Divisions website.
Berrien County Dams
In Berrien County, there are a total of 34 dams on record with Michigan Department of Environmental Quality. Five are privately owned dams primarily used to generate hydroelectric power. In addition, there are numerous earthen dams throughout the County used to regulate drainage of rainwater and agricultural watering purposes. Two dams have a high hazard rating and one has a significant hazard rating. The remaining 31 dams are assigned a low hazard potential rating because their failure would result in no probable loss of human life and low economic and environmental impacts. Losses are generally limited to the owner’s property. Dams assigned the significant hazard potential rating are those dams where failure results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, and other impact concerns. Dams assigned the high hazard potential rating are those where failure will most likely cause loss of human life as well as significant economic and environmental damages.
Most dams are owned and operated privately. Dam owners are required to maintain an Emergency Action Plan (EAP) for significant and high hazard potential dams. It is important to note that these ratings of "significant or high" refer to the consequences if a failure were to occur; not a reflection of the maintenance condition of the dam. Owners are also required to coordinate with local emergency management officials to assure consistency with local emergency operation plans. The dam operators of those significant and high hazard dams have made it a common practice to contact homeowners and businesses in the immediate area of danger each time they update their plans. It is important for these homeowners to communicate with the operators if their contact information changes. Their contact information is usually incorporated in the EAP so they can be warned as soon as practical if there is a problem of concern.
Since the hazard level of dams is based upon the potential downstream impacts if the dam were to fail, it is possible for the hazard status of a dam to change over time. As Berrien County becomes more developed and more people and businesses locate downstream from dams, the potential human and economic impact from a catastrophic dam failure is increased.