by Colby Kyes
Travel through a small town in Massachusetts with a river and you’re likely to see a mill. Many of these fixtures of picturesque New England are now obsolete and sit abandoned. When the mills were operating, they relied on power from dams. With mills shuttered, many of the dams are no longer needed. Now, communities are looking to remove certain dams to avoid hazardous risks to their homes, simultaneously restoring rivers and streams that have been held back by the dams.
It’s important to differentiate here. The dams we’re talking about are not dams like the Hoover Dam or the Oroville Dam that are used to generate hydroelectric power. We’re talking about dams that are well beyond their life spans. The average lifespan of a dam is around 50 years. According to a 1999 study, by 2020 85% of the nation’s dams will be over 50 years old! Additionally, dams are only registered if they are over 6 feet in height with 50 acre-feet in storage or if they exceed 25 feet in height with 15 acre-feet in storage. That means there are many unregistered dams preventing sediment from reaching river deltas, which is necessary to ensure a healthy river ecosystem.
Right: Washington state’s Elwha river delta pictured in 2011 at the beginning of a large scale dam removal project. Left: The Elwha delta in 2015 roughly 4 years after the dam removal project began. Image: psmfc.org.
There are around 3,000 dams in Massachusetts , and roughly a third of them pose a threat to communities should they break. Groups like the state agency Division of Ecological Restoration are working to remove some of these dams that are deemed dangerous and obsolete.
The red dots on this map from the National Inventory of Dams (NID) represent high-hazard dams, while yellow dots represent low-hazard dams. Image: NID
The dangers of a dam past its prime can be catastrophic as residents of Taunton, MA found out in 2005 when a storm nearly caused the town’s 100 year old Whittenton dam to burst, and 2,000 residents had to be evacuated. Removing these dams can help alleviate flooding damage by allowing a river’s natural floodplain to mitigate the effects of large storms.
Dam removal can extend beyond just benefiting humans. Dams cut off miles of rivers for fish returning from the ocean to spawn and fish are an integral part of any riparian ecosystem. Not only are they a source of food for animals further up the food chain, they bring in crucial nutrients, and feed on smaller life forms that can have negative effects on the environment.
Not every dam is likely to come down (and, not all of them should). There are still some that are functional, and there are some that have become fixtures of recreation providing reservoirs for kayaking and fishing. The process for dams already slated for removal is long and complicated. In Washington state, two dams on the Elwha River took nearly 20 years from the start of planning to removal. Within 5 years of the last pieces of the dams being dismantled, it is hard to tell there was ever a dam in the first place; the river has reshaped and rebuilt its environment spectacularly.
Here in Massachusetts, just like on the west coast, the benefits of removing dangerous dams are unquestionable. We get healthy ecosystems that are more resilient to changing weather patterns. We get stronger natural fisheries, a second boon to ecosystems but also a boon to the fishing economy. We also get the aesthetically pleasing scenery that comes from a rushing river or a babbling brook. As we begin to carefully and thoughtfully undam Massachusetts we will see positive results. That same dam in Taunton that nearly burst in 2005 has since been removed-- the Mill River that the dam once blocked is once again open. Last spring, River Herring and American Eels had 30 miles of river to call their own again. It is our hope that success stories like this allow future projects that have been properly vetted to proceed with less red tape.
Is there an old dam near you? Is it safe? Could it benefit from some improvements (like a fish ladder) or should it be removed? If you are in Massachusetts, reach out to the Division of Ecological Restoration to find out more!