Most dams in Michigan were built decades ago and many have deteriorated due to age, erosion, poor maintenance, flood damage, and poor designs. Those dams that no longer make sense, that stand in disrepair, or are not removed are at significant risk of failure, particularly during high flow events. Hydropower dams that are no longer economical to operate for power generation are often sold to local government or community organizations. These organizations are usually interested in protecting the recreational uses associated with the impoundment behind a particular dam, or even in retrofitting the facility for additional generation purposes. However, dam maintenance and licensure can be costly, particularly since there is an ongoing need to monitor and repair problems that are certain to occur. Local governments and community organizations are often not financially prepared to take on dam ownership and the associated long-term costs. As a result, many of these projects are eventually abandoned. The State is required to take over the obligations of safety repairs and other maintenance of abandoned dams, thus placing large economic burdens on taxpayers across Michigan.
Dams that no longer serve a purpose should be removed for safety, economic, and environmental reasons. Owners of dams need to recognize that ownership carries with it significant legal responsibilities and owners should be responsible for potential liabilities. A hazard potential classification assigned to each dam (high, significant, and low) is used to reference the potential for loss of life, property damage, and environmental damage in the area downstream of a dam in the event of a failure of the dam. A hazard rating is not based upon the structural condition of the dam. In today's society, human development has continued to increase downstream of dams, thereby increasing their hazard rating and increasing the potential risk to public safety. Since dams were not designed to last forever, structural deterioration is inevitable. Furthermore, liability may be imposed on an owner if there is failure to maintain, repair, or operate the dam in a safe and proper manner (PDEP 1995). The repercussions and ultimate failure of unsafe dams may result in: (1) the loss of life; (2) the destruction of property; (3) harm to the downstream environment; (4) the release of toxic sediments; (5) risk to the river users; (6) the loss of critical services to the community such as water supply or flood control (American Rivers 2003). With the number of aging dams that require more frequent repair increasing every year, dam removal is often an economically viable solution.
Good proportions of aging dams are no longer economically practical or cost-effective to operate. Similarly, dam operation and maintenance costs tend to increase as a dam ages. These increased costs, combined with the potentially lower revenue, allow for removal to become the most cost-effective alternative for the dam owner. Potential financial liability is another important factor driving the decision of dam removal. A number of studies (River Alliance of Wisconsin 2003, American Rivers 2003) have found removal costs to be up to three to five times less than the cost of repair, especially when the benefits of the dam are minor. Long-term expenses often include ongoing maintenance, liability insurance, and repeated dredging of silted-in impoundments. Dam removal eliminates the expenses of future maintenance and repairs, and provides several ecological benefits.
Dam removal restores the natural flowing character of a stream and restores essential ecological processes in the river. Large segments of previously inaccessible water may be open to use by a variety of fish species. In addition, dam removal and sediment management can restore buried fish spawning habitat and other critical stream habitat. Overall, dam removal benefits riverine fish by: (1) removing obstructions to upstream and downstream migration; (2) restoring natural riverine habitat; (3) restoring natural seasonal flow variations; (4) eliminating siltation of spawning and feeding habitat above the dam; (5) allowing debris, small rocks and nutrients to pass below the dam, creating healthy habitat; (6) eliminating unnatural temperature variations below the dam; and (7) removing turbines that kill fish (American Rivers 2003).
Selective dam removal is an integral component of successful watershed management. The Michigan Department of Natural Resources promotes river restoration through the selective removal of dams that no longer serve a useful purpose.
PDEP (Pennsylvania Department of Environmental Protection). 1995. Liability and responsibility of dam owners. [Online] PDEP.