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EPA Reverses Cooling Plan For N.H.'s Largest Coal Power Plant

Annie Ropeik
NHPR File Photo

A new federal permit for New Hampshire's largest coal-fired power plant will not require the installation of cooling towers, which advocates say are vital to protect the Merrimack River.

The Environmental Protection Agency hasn’t updated Merrimack Station’s five-year water quality permit since the 1990s. The permit regulates water intake and discharge between the plant and the adjacent Merrimack River.

The facility, built in the 1960s, uses what environmental groups say is an outdated style of cooling system called “once-through,” which discharges heated water straight into the river.

Advocates say this rises to the level of pollution under federal law. They have called for the plant to do more to cool the water before it leaves the plant – including in a 2019 lawsuit.

Those environmental groups supported the EPA’s own recommendation, in a 2011 draft update to the plant’s water permit, that the plant install costly new cooling towers to lower the water temperature before discharge.

“It’s technology that would dramatically improve protection for the Merrimack River and avoid the significant impacts that this coal-fired power plant is having right now,” said attorney Tom Irwin, the New Hampshire director of the Conservation Law Foundation. “The EPA was clearly going down a path of requiring this outdated facility to finally modernize.”

But the cooling tower requirement was cut from the final permit, just issued by the EPA.


An agency spokesperson said, instead, the permit will require the plant to “limit in-stream temperatures,” restrict its discharge times to protect nearby wildlife, and “install technology—wedge wire screens—that will minimize adverse effects to aquatic organisms due to the withdrawal of cooling water rather than build cooling towers.”

The EPA gives a few reasons for the change. For one, the agency’s requirements for cooling technology have changed since 2011, when the towers were recommended.

The spokesman also said the power plant now operates less often than ever, “which has altered the duration and severity of the thermal impacts that informed the limits in the draft permit.”

In 2011, when that draft was issued, coal-fired power plants – including Merrimack and larger facilities – generated more than 5 percent of New England’s electricity. Today, Merrimack Station is the largest coal plant in the six states, which together only get about 1 percent of their electricity from coal.

Credit Army Corps of Engineers, New England District
The Merrimack River.

The plant now mainly operates at times of peak demand, such as during very hot or cold weather. But climate activists, who have been arrested protesting at the plant in the past year, say any burning of coal contributes to global warming and increases air pollution.

Scientists are studying the links between air pollution and increased vulnerability to health problems like COVID-19.


The facility also changed hands recently – it used to be owned by Eversource, an energy provider, which could pass some of the cost of technology upgrades onto ratepayers. In 2018, under a state mandate, Eversource sold Merrimack Station to Granite Shore Power, a private firm based in Connecticut.

GSP says in a statement that they feel their new permit “continues to be protective of the environment while also reflecting the reality of Merrimack Station’s reduced level of operation.”

Environmental groups disagree. The New Hampshire Sierra Club calls the new permit “woefully inadequate,” and CLF’s Tom Irwin says the omission of the cooling towers requirement is a huge disappointment.

“It just sends a signal about this current administration and the interests that it feels beholden to,” Irwin said. “EPA was poised to make a decision that would better protect the Merrimack River, a critical natural resource for New Hampshire and the region, and rather than having this plant eliminate those impacts, it gave it a bit of a free pass.”

Groups like CLF may appeal the permit, which is set to take effect in September.

Annie has covered the environment, energy, climate change and the Seacoast region for NHPR since 2017. She leads the newsroom's climate reporting project, By Degrees.

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