Scotland — The state Department of Energy and Environmental Protection has warned the operator of the hydroelectric dam on the Shetucket River that it may revoke its permit because the facility is not complying with federal and state requirements.

In a letter sent last week to federal regulators and FirstLight Power Resources, a subsidiary of the French multinational Engie, DEEP said conditions of the federal license and state permit to operate the dam require that it generate power with a “run-of-river” low-flow turbine.

“We made it very clear in our comments that instantaneous run-of-the-river was a top priority for us,” Stephen Gephard, supervising fisheries biologist for DEEP, said Friday. “FirstLight said it would operate as an instantaneous run-of-river in many different ways.”

In November 2013, the Federal Energy Regulatory Commission awarded FirstLight a 40-year license to operate the dam, after a three-year competitive process with Norwich Public Utilities. Both FirstLight and NPU said in their applications that they would operate the dam as a run-of-river facility with a low-flow turbine that generates power from natural flows rather than by impounding and releasing water. FirstLight also operates the hydroelectric dam in Taftville, where there are separate, but unrelated, problems with the ability of fish to use a fish ladder there.

The Scotland dam, first built at the site off Route 97 in 1909, has a power generation capacity of about 3 megawatts, according to FERC. Along with the FERC license, the company also received a water quality permit from DEEP allowing it to operate the dam.

After the license and permit were awarded, Gephard said, FirstLight informed the state that it would not be able to install the low-flow turbine until 2016. DEEP agreed to let FirstLight operate in a modified “pond and release” mode until the new generator could be installed, Gephard said. But since then, the company has told DEEP that it has scrapped plans for the low-flow turbine, which generates less power but is better for the environment, he said.

“They’ve determined that a low-flow generator would cost too much money, and that they weren’t going to do it,” Gephard said.

Len Greene, spokesman for government and regulatory affairs for GDF Suez Energy North America, the U.S. subsidiary of Engie, said in an email message that the company is “not prepared to comment on the CT DEEP letter at this time.”

DEEP raised its objections to the way FirstLight is operating the dam in response to the company’s request for comments about the design of fish ladders that it is required to build within three years of receiving the FERC license and state permit. DEEP said it will not comment on the proposed fish ladder design until the run-of-river issue is resolved, leaving the company at risk of being out of compliance with its license and permit.

Celeste Miller, spokeswoman for FERC, said the agency is reviewing the information from DEEP about the run-of-river issue.

"We are aware of the issue," she said, "but there is no formal response from FERC at this point."

Miller said the FERC license requires FirstLight to submit a plan for the fish ladder by May 21. As part of the design process, the company was obligated to incorporate input from DEEP and other regulatory agencies, she said. 

The U.S. Fish & Wildlife Service and the National Marine Fisheries Service also weighed in with FERC on the fish ladder design and dam operations. In letters sent to FERC and FirstLight last month, both agencies noted that U.S. Geological Survey data on flows in the Shetucket River clearly show that the current pond-and-release operation is not meeting run-of-river requirements. The wide variations in flow shown in the data are contrary to the company’s claims that its current operations are in compliance with run-of-river, the agencies said.

Pond-and-release operations use extreme, rapid water level fluctuations that make large areas of habitat unusable by wildlife, Gephard said. The variations are also harmful to fish.

“The changes in flows disrupt the behavior of migratory fish,” he said. In addition, year-round fish populations, “don’t feed as well when the water levels are going up and down all day long.”

There are also public safety concerns for anglers who wade into the river as the levels are moving rapidly higher and lower, he said.

In its letter, DEEP referred a clause in FirstLight's permit that states that if the applicant provides information that proves to be “false, deceptive, incomplete or inaccurate,” the agency has the authority to revoke the permit. By now claiming that by its interpretation, the current operations are in compliance, FirstLight has provided information in its application to DEEP that was, “at a minimum … inaccurate given the newly identified changes in operations,” DEEP said. DEEP said that because of the company's "operational changes and inconsistencies," the agency would initiate a review of the the application to determine whther the water quality permit should be revoked.

John Bilda, general manager of NPU, said FirstLight’s operations of the Scotland dam are “a huge disappointment,” and that NPU has demonstrated success at running low-flow turbines at its other hydroelectric dams.

“We’re going to do our best to hold them accountable,” he said.

j.benson@theday.com

Twitter: @BensonJudy