Dams

Across the United States, 2.5 million dams of all sizes block and harness rivers.  Most of them are quite small. Of those 2.5 million dams, only 80,000 are more than six feet high.

Dams serve a wide range of purposes, such as providing hydroelectric power, water supply, and irrigation, supporting recreation and shipping, and managing flood control.  Many dams have become integral to the identity of their communities.

Beneficial functions notwithstanding, dams produce severe negative impacts on the rivers they harness.  Dams alter a river’s chemical, physical, and biological processes.  Over the past two decades these negative impacts have become more obvious, but the environmental costs of dams have only recently captured scientific attention.

• Dams cause the build-up of sediment.  They block free-flowing water and impede the river’s flushing function, as well as the transport of nutrients and sediment downstream.
• Dams fragment rivers and block the natural movement of fish and other aquatic species.
• Dams contribute to, and sometimes are the sole cause of, many species becoming threatened, endangered, or extinct.  Prime dam sites often are prime fish spawning sites.
• Dams alter water temperatures, dissolve oxygen levels, and produce turbidity and salinity, both upstream and downstream of the structure.

Elevation changes, by river mile, from the headwaters to the mouth of the Huron River. Major mainstem dams and the impoundments they create are shown. Credit: MDNR Fisheries, 1995.

Dams on the Huron

The Huron River system is typical of rivers and tributaries in the Great Lakes Basin.  What was once a free-flowing river system is now interrupted by dams on both the main stem and the tributaries.  State and national inventories record 97 dams on the Huron River system.

As the dams in the watershed age and require investment for repairs, an increasing number of communities, dam owners, and government agencies will face decisions on what to do about dams. The decision to remove or rehabilitate a dam involves many considerations, as do the decisions about what methods to use to restore a free-flowing stream.  Such considerations include dam safety, environmental impact (i.e. possible toxins in the accumulated sediment behind the dam), and economic issues.

Concerned community leaders and citizens have worked together to remove dams and restore reaches of streams in the watershed (Dexter’s former Mill Pond dam on Mill Creek) and throughout Michigan and the country. In the Huron River watershed, we have the opportunity to

• restore more than 100 miles of a freshwater ecosystem;
• expand viable habitat for sensitive species including North America’s most endangered animal, freshwater mussels; and
• support local economies in riverfront communities through improved water quality and enhanced recreation opportunities.

Whatever plan is chosen, success in restoring the Huron River and improving the watershed communities is more likely to be achieved through strong, comprehensive state and national programs.

HRWC Dams and Impoundments Program

The impetus for HRWC’s work on dam management was the 1995 Michigan Department of Natural Resources Fisheries report that recommended removing select dams to improve fisheries. On the Huron River, the MDNR identified three dams for removal: Argo in Ann Arbor; Mill Pond in Dexter; and Peninsular Paper in Ypsilanti. Since then, HRWC has supported the communities in which these dams are located with technical assistance about stream flows, the impacts of dams and other flow alterations, and options for dam management.

Argo Dam, Huron River, City of Ann Arbor: Campaign for removal; article “HRWC advocates Argo Dam removal“; article “The Future of Argo Dam“

Dexter Dam, Mill Creek, Village of Dexter: article “Making History on Mill Creek“

In 2010, during three HRWC-facilitated regional meetings, eighteen organizations from across the state shared their experiences on dam projects, their hopes for Michigan’s rivers, and recommendations to their peers and the DNR and DEQ for how to “make the grade” for the state’s dam infrastructure. HRWC summarized the recommendations of the groups in a report Re*Envisioning Dam Management in Michigan and blogged about it.

Huron River Dams Seminar blog

Hydroelectric Power on the Huron River

Renewing hydroelectric power at dams that previously produced power is being considered by cash-strapped Michigan communities looking to harness renewable sources of energy and encourage local investment. Watershed communities, such as the City of Ann Arbor, have conducted cost-benefit analyses to determine the fiscal viability of hydropower renewal that have produced findings in line with what other Michigan communities have found: renewing hydroelectric power on low-head dams is not a sound investment.

The results of the City’s analysis of renewing hydropower at Argo Dam show that while the potential exists for hydroelectric generation on the Huron River, the cost to license, repair, upgrade, and maintain the existing dam in order to comply with state and federal rules and regulations outweighs the potential revenue from selling electricity generated at the dam. The estimated cost of restoring hydroelectric power generating capacity is $4.35 million, which includes indirect costs such as engineering, licensing/permits, finance, legal and contingencies. The estimated annual revenue from selling electricity is $200,000 (2 million kwh/yr @ $0.10 kwh) for a payback period of 49 years. source: City of Ann Arbor

For more information about Argo dam on the Huron River in Ann Arbor, go here.