Fish, Floods, and Dam Removal

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Tack Factory Dam in Hanover. Photo courtesy of NSRWA.

 The South Shore has a rich industrial history. In centuries past, there were water-powered mills on nearly every river and stream -- mills for sawing logs, for grinding grain, for making boxes, and plenty more. For every mill there was a dam.

The South Shore also has a history rich in anadromous (migratory) fish. Herring, shad, alewives -- fish that swim upstream to spawn. Before European settlement, the Native American tribes that inhabited our region knew when to expect these fish in our rivers, and planned their food gathering cycle accordingly. The herring were abundant. Accounts from the Pilgrims and their contemporaries relate scenes in which herring populated the rivers so densely that one could practically cross the water on their backs!

But what happened when a migratory fish encountered a dam? Could it still swim upstream?

Yes and no. Some dams were small enough that stronger fish could propel themselves right over them. Some streams were outfitted with fish ladders (but most were not). So while our region experienced an industrial boom in the 1700s, it also saw its numbers of anadromous fish drop.

The mills are all but gone now -- most of the factories too. Unfortunately, most of the fish are as well. Long ago, our region’s industries relocated to cities like Brockton, but the dams remained. And while the original structures – made of wood, and subject to rot – may not have stood the test of time, the replacement dams – made of less-susceptible concrete and rebar – in many cases have. And thus the fish cannot make it upstream to their spawning grounds.

This is not a new problem. Many of the dams in our region are more than 100 years old, so the breeding habits of anadromous fish have been stymied for a century already. Declining numbers of herring have led to declining cod populations, but that’s a story for another day. What’s making dam removal a hot topic these days is a more far-reaching concern: flooding.

There is a common misperception that dams prevent flooding. In one way, they do – they hold back the flow of water, so that only a controlled portion goes downstream. But in the meantime, what’s happening on the other side of the dam? Upstream, the flood water collects and begins to back up and overflow. Streams swell, marshes fill with water, roads become flooded, and the increasing pressure on the dam raises the threat of a breach. In 2005, portions of downtown Taunton were evacuated when heavy rains strained the Mill River’s Whittendon Dam to the breaking point.

These days, there is a lot of talk about dam removal. It seems simple enough: remove the dams so the rivers can flow freely. The flood water won’t back up, and the fish will be able to return – at last! – to their spawning grounds.

Unfortunately, dam removal is expensive. It also requires years and years of work. There are engineering studies and environmental impact studies. There are pages and pages of permits to be obtained. There is the formidable task of getting all of the landowners and abutters to support and sign off on the project. And then there is the work itself: diverting the stream, deconstructing the dam in an environmentally sound manner, and rebuilding the landscape to facilitate the flow of the rehabilitated stream.

But it can be done! One shining example is the Wapping Road Dam on the Jones River in Kingston. Planning for the removal of this dam began in the 1990s. The structure itself was removed in 2011. Post-project monitoring work is ongoing, even as the Jones River Watershed Association (JRWA) embarks on a new project to remove a dam nearby at Forge Pond. For a captivating glimpse at the JRWA’s first successful dam removal project, search online for the “Wapping Road Dam Story” video, or follow this link. http://www.youtube.com/watch?v=3RrS4VoV4ZI&feature=c4-overview&list=UUuuFa7Ehbc63xtGpXflNoCw

Meanwhile on the Third Herring Brook, a tributary to the North River that flows through Hanover and Norwell, the North and South Rivers Watershed Association has embarked upon dam removal projects at both Mill Pond and Tack Factory Pond. On the former, owned by the South Shore YMCA, the dam will be removed in 2014. On the latter, owned by Cardinal Cushing Centers, the dam removal project in the funding and permitting phase.

Wapping Road, Forge Pond, Mill Pond and Tack Factory: these dams – their histories and the stories about their removal processes -- are each worthy of their own article. I hope to discuss each of them in further detail in the future.

by Kezia Bacon

November 2013 
 

Kezia Bacon's articles appear courtesy of the North and South Rivers Watershed Association, a local non-profit organization devoted to the preservation, restoration, maintenance and conservation of the North and South Rivers and their watershed. For membership information and a copy of their latest newsletter, contact NSRWA at (781) 659-8168 or visit www.nsrwa.org. To browse 15 years of Nature (Human and Otherwise) columns, visit http://keziabaconbernstein.blogspot.com