Three Outstanding Environmental Studies Students Identify Ways to Help the Planet

Hydroelectricity versus robust ecosystems

After studying the federal permit renewal process for hydroelectric dams, Thomas argues in his thesis, “Assessing the new dams license and river herring habitat restoration from a broad, multi-ecosystem perspective”, for a more transparent regulatory process that better balances environmental concerns with electricity generation goals.

Dams began to appear on many Maine rivers in the 19th century with little oversight. Although they produce huge amounts of clean electricity, they also prevent fish like river herring from migrating upstream to spawn.

“In 1828, every major river system in Maine had at least one dam, and by 1850, 95 percent of inland spawning habitat was obstructed by the presence of large dams,” said Thomas, and environmental studies and government.

The collapse of the river herring population – which is currently between 1 and 8 percent of historic levels – has had destructive ripple effects, contributing to the collapse of major groundfish species like cod.

But it will be difficult to restore the population of river herring, because between 90 and 100% of the fish would have to reach their spawning grounds upstream. Currently, fish management infrastructure designed to help herring overcome dams allows less than half of migrating fish to pass.

The dams are renewed every thirty to fifty years. As part of his research, Thomas designed a matrix that regulators can use to easily assess whether a dam should be renewed or be denied a license and retired. The network compares the power generated by the dam to its degree of obstruction to fish passage.

For example, he recommends that the four dams on the Kennebec River, which currently need to be renewed, be denied a permit. Cumulatively, they provide 0.43% of the electricity for Maine’s power grid while having “an outsized impact” on fish species.

He also argues that as more solar and wind power come online, Maine can rely less on green power from hydroelectric dams while ultimately meeting its climate change goals. .

In addition to balancing ecological considerations with power generation, Thomas points to other positive aspects of restoring the herring population, which would be felt throughout Maine and its sea, the Gulf of Maine.

“The benefits of dam removal come with increased ecosystem resilience,” he said. “Resilient ecosystems will be better equipped to mitigate and adapt to the impacts of climate change in the future.”

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