Hydropower versus Robust Ecosystems
After researching the federal relicensing process for hydropower dams, Thomas argues in his thesis, “Evaluating Dam Relicensing and River Herring Habitat Restoration from a Broad, Multi-Ecosystem Perspective,” for a more transparent regulatory process that better balances ecological concerns with power generation goals.
Dams began cropping up on many of Maine’s rivers in the nineteenth century with little oversight. While they produce enormous amounts of clean electricity, they also block fish like river herring from migrating upstream to spawn.
“By 1828, all major river systems in Maine had at least one dam, and by 1850, 95 percent of inland spawning habitat was obstructed by the presence of major dams,” Thomas, and environmental studies and government major, said.
The collapse of the river herring population—which is currently at 1 percent to 8 percent of historical levels—has had destructive ripple effects, contributing to the collapse of major groundfish species like cod.
But it will be challenging to restore the river herring population, as it would require between 90 percent and 100 percent of the fish reaching their upstream spawning grounds. Currently, fish-run infrastructure designed to help herring surmount dams let less than half of the migrating fish through.
Dams come up for relicensing every thirty to fifty years. As part of his research, Thomas devised a matrix that regulators can use to easily evaluate whether a dam should be relicensed or denied a license and removed. The grid compares the power the dam generates to how much it obstructs fish passage.
For example, he recommends that all four dams on the Kennebec River—which are currently up for renewal—be denied a license. Cumulatively, they provide 0.43 percent of electricity for Maine’s power grid while having “an outsized impact” on fish species.
He also argues that as more solar and wind power comes online, Maine can rely less on the green energy of hydropower dams while still, in time, achieving its climate change goals.
Besides balancing ecological considerations with power generation, Thomas points to other positives to restore the herring population—which would be felt throughout Maine and its sea, the Gulf of Maine.
“The benefits of removing dams come along 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.”