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Conservancy critical of pumping more water from Conn. River.

  • Northfield Mountain Pumped Storage Project upper reservoir. Recorder file photo



Staff Writer
Monday, December 03, 2018

NORTHFIELD — Greenfield-based Connecticut River Conservancy has weighed in on an analysis of operations changes at the Northfield Mountain Pumped Storage hydro-generator, telling federal regulators the permanent change would result in increased river bank erosion.

With echoes of past concerns raised by environmental watchdog groups, the comments mark the latest wrinkle in the five-plus-year relicensing process for the hydroelectric project, which generates power by pumping river water to a mountaintop reservoir and releasing it through underground generators back to the Connecticut.

As part of the relicensing by the Federal Energy Regulatory Commission, plant operator FirstLight Hydro Generating Company has proposed a permanent “expanded-use scenario” to increase the usable capacity of the mountaintop reservoir in a way that’s been employed by temporary FERC amendments over the years.

Boosting the water-storage capacity, which has been approved short-term by FERC half a dozen times, allows an additional 22 feet of pumping capacity at Northfield Mountain’s 5-billion-gallon reservoir “to increase its operational flexibility and provide (the regional power pool) with additional energy reserves,” the company has said in prior applications.

A FirstLight study said from various computer modeling and analyses that, “increasing the useable storage volume in the Upper Reservoir resulted in no impact in streambank erosion” in the 20-mile stretch of river between the Vernon, Vt., and Turners Falls dams. But Conservancy River Steward Andrea Donlon wrote, “To us, it still seems logical that this degree of elevation change on various time scales would impact bank erosion. We submit that (the original 2016 Erosion Causation Study) and this evaluation of using the expanded upper reservoir has led to erroneous conclusions. We recommend no further revisions of the expanded use study report because the implementation of the model itself is problematic.”

She added, “The underlying study was skewed to minimize the role of project operations on bank erosion, and so running an alternative scenario will also be skewed. ... Our concerns about the analysis remain, and these would also be the case for a modified operation model.”

Pointing to the 2002 river hydrology data used as the baseline for the analysis, it added, “the difference in the single year run was negligible. We would not expect to see much of a change in erosion in a single year. Erosion happens on a larger time scale than that.”

​​​Donlon told The Recorder, “This is something FirstLight has said they’re interested in doing: using the expanded reservoir year round. They’ve gotten permission to do this over several winters, for a couple summers, but they’ve never had year round full use. Their original study was kind of flawed, so then you build a flawed study on a flawed study, and it’s still flawed.”

The operating license for the plant expired in April, and Donlon said it will be months before the federal regulation agency issues its Notice of Environmental Analysis that sets deadlines for an formal Environmental Impact Report to be written.

During that “holding pattern,” Donlon said, an informal settlement negotiations process continues involving all of the parties in the relicensing, which will set the requirements for operation of the hydroelectric plant for four or more decades ahead.

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