S.L. Gathers misinterprets three scientific studies in their recent guest column about the Megunticook River. The column argues that dams provide essential flood control and that fish passages are ineffective in restoring migration upriver. Gathers gives only vague information about these studies, but I found several likely candidates: Gang Zhao et al., “The Impact of Dams on Design Foods in the Coterminous US” (2020); Julien Boulange et al., “Role of dams in reducing global flood exposure under climate change” (2021); J. Jed Brown, John Waldman and other colleagues, “Fish and hydropower on the U.S. Atlantic coast: failed fisheries policies from half-way technologies” (2013). Waldman also summarizes the hydropower findings in Yale Environment 360.

Citing the Zhao and Boulange studies, Gathers claims that “dams like ours were found to reduce flood exposure in 100-year flooding scenarios by 20%.” But these studies say nothing about “dams like ours.” Zhao’s team corrects the mathematical model used by government agencies to predict downstream flooding. Boulange and his coauthors suggests that many existing dams won’t be able to handle the impact of climate change. The number of people exposed to flooding around the world, they find, is much higher than we think and will increase.

Fish passage is another story. “In a Yale study that ran across three decades,” Gathers argues, “fish run sizes were found to be 10% of stated goals some years and as low as 2% other years.” If I correctly located this unidentified Yale study, it focused on hydroelectric dams along three large Eastern rivers: the Susquehanna (which flows 444 miles from southern New York State through Pennsylvania into Chesapeake Bay); the Connecticut (406 miles through Vermont, New Hampshire, Massachusetts, and Connecticut); and the Merrimack (117 miles in New Hampshire). Researchers concludes that fish ladders can’t offset the damage to migratory species done by dams.

The best solution? Remove more dams. Brown and his team pointed to the Penobscot River, “where dams are being removed or provided the opportunity to increase power generation” while improving fish passage (p. 280).

Three other points about the Megunticook River:
Gathers claims that existing dams prevent “future and greater flood waters from spilling over the riverbanks” and “can perform their job of flood protection flawlessly.” Anyone who saw pictures in this newspaper of recent flooding knows this isn’t true. And it will be less true in the future: over the next 30 years, average yearly rainfall is expected to rise by another nine inches.

The 2021 Inter-Fluve study confirms that sediment has built up behind the Knowlton Dam (with lesser amounts at Montgomery, Knox Mill and Powder Mill Dams). Is it toxic? According to Inter-Fluve, it “does not pose a risk to human health and does not represent any unusual circumstances…when excavating behind the dam.” It must be removed to restore the river channel.

Will fish passages fall apart, as Gathers suggests? The first known fish ladder was patented in 1837 a few miles from here in New Brunswick. Since then, fish passages have been extensively used throughout the U.S. and Canada. Gathers claims that their average lifespan is “uncertain,” because data isn’t available. But the most likely reason for a lack of data about their lifespan is that they’re still around, unless someone took them out. Incidentally, Gathers violates a basic scientific principle here: the absence of data doesn’t support any hypothesis.

No one is proposing to remove the East, West and Seabright Dams, which regulate water levels from the lake to the harbor. The Montgomery Dam hasn’t generated electricity in decades and won’t do so in the future. The Megunticook River is only 3.5 miles long, not hundreds of miles. We should be able to strike a balance between preserving the Montgomery Dam in some form and restoring fish passage to the lake. Misrepresenting scientific and technical evidence won’t get us closer to that goal.

Dr. Robert Wasserstrom, a Camden resident, taught ecology and public health at Columbia University in New York.