A what?Merriam-webster : a barrier preventing the flow of water or of loose solid materials(as soil or snow); especially : a barrier built across a watercourse for impounding waterTextbook: basic, fundamental management tool used to control, regulate, and deliverwater for a variety of purposes.Classifications: Gravity concrete Concrete arch Earthen embankment
Who cares? “Since 1950, the number of large dams has climbed from 5,000 to more than 45,000—an average construction rate of two large dams per day for half a century.” Globally, 364 large water-transfer schemes move 14 trillion cubic feet (400 billion cubic meters) of water annually from one river basin to another—the equivalent of transferring 22 Colorado Rivers.Purposes: Flood Control Irrigation Recreation Navigation Hydroelectric generation
Benefits of Dams Recreation Flood Control Water Storage Irrigation Mine Tailings Electrical Generation Debris Control Navigation River Regulation
Negative Impacts Altered natural and human environments Reduced stream flows Degraded water quality Impacts on migrating fish Transformation from river system to reservoir Reduced transport of sediment
Dam Removal? Reestablishment of a natural flow regime (flow) Transformation from In some cases it is reservoir to river system beneficial to remove dams Change in river for the following reasons temperatures and oxygen levels (water quality) Sediment release and transport Migration of fish and other organisms (connectivity)
Michigan Purposes: transport goods (ie: logs) milling operations electricity flood control navigation recreation
Michigan 2500 dams across the states 114 hydropower production
Stronach DamManistee County, Michigan Built in 1912, ~ 3 miles upstream of the Manistee River & Pine River confluence No longer serving it’s intended purpose: hydroelectric power Removal began in 1996, gradually restored until 2003. Since 1998 Dr. Hayes has been involved in studying the environmental effects
Big Rapids DamMuskegon River, Mecosta County Built in 1914, 17 foot tall hydropower dam. In 1966 a portion of the dam was removed negligently. There remained a 5 foot section of the dam which lead to several drowning deaths. Many groups rallied to remove the Big Rapids Dam in 2000/2001.
Dam Controversy Should dams be built? Should dams be left alone? Should dams be removed?
What’s at Stake?• Environmental Factors: • Loss of aquatic populations • Damage of habitat Social Factors: • Mortality • Water source • Recreation • Electricity Resources: • Time • Money • Workers
Recommendations Cost/Benefit Analysis every step of the way Dam removal should have priority over dam construction Stress and be very detailed with loss of NR evaluation Quicken the permit approval process for dam repairs and dam removal Increase inspection frequency of high hazard dams to every year Educate dam owners, consultants, emergency management personnel, and the public about dam safety