By Michael Kuser

FERC on Thursday denied FirstLight Hydro Generating’s request to change reservoir levels this winter at a Massachusetts hydroelectric plant, citing inadequate time to assess the impact on the endangered shortnose sturgeon (P-2485-076).

FirstLight requested the temporary amendment to increase operational flexibility at its 1,167-MW Northfield Mountain Project in anticipation of potential reliability challenges in New England this winter. ISO-NE supported the request but did not say the extra capacity would be critical to reliability.

FERC sympathized with FirstLight’s intentions, but ultimately sided with the shortnose.

“While we are very sensitive to the need to take all feasible steps to ensure the reliability of the electric grid, and accordingly have approved previous amendment requests by FirstLight, the presence of an endangered species in the project reservoir that may be affected by the amendment is a significant new circumstance,” the commission said. “We could not lawfully approve the current amendment before completing consultation with the [National Marine Fisheries Service], a process that would require the gathering of information, followed by NMFS review and action.”

In comments filed with FERC last October, NMFS indicated the sturgeon had been found in Northfield Mountain’s lower reservoir, which was historically above the recognized upstream extent of the species’ range.

The commission ordered that “any future proposal of a similar nature should be filed a sufficient time before the winter season such that any necessary efforts with respect to [Endangered Species Act] consultation can be completed in a timely manner.”

Under federal regulations, NMFS has 135 days to complete a consultation. The commission said that “it did not appear possible” that the consultation process could be completed before March 31, the end of the period for which FirstLight requested the temporary amendment.

Technical Limits

FirstLight proposed reducing Northfield Mountain’s minimum reservoir elevation from 938 mean sea level (msl) feet to 920, and bumping up the maximum from 1,000.5 msl feet to 1,004.5, increasing the potential operating range from 62.5 feet to 84.5 and available storage from 12,318 acre-feet to 15,327. The company also sought unrestricted use of the extra capacity.

According to FirstLight, the additional 3,009 acre-feet of storage would increase the facility’s maximum daily generation by 2,050 MWh, or an additional 1.8 hours of generation at full load. Within current limits, it is capable of generating 8,729 MWh/day during peak load conditions.

But FERC signaled that it would seek limits on the flexibility offered by the adjustments. In its decision, the commission ordered that “any future proposal should be restricted to use during ISO-NE discretionary actions taken during emergency operations … unless FirstLight can provide sufficient evidence why a broader amendment is appropriate.”

The commission has previously granted six temporary amendments for the facility. The first three allowed FirstLight to modify operations only when ISO- NE declared an energy emergency, triggered by a forecast showing electric demand could exceed capacity reserves. The fourth and fifth did not restrict FirstLight’s use of the additional storage, but the sixth, most recent amendment also restricted the use of the additional storage to declared emergencies.

Northfield Mountain includes an upper reservoir, an underground powerhouse containing four reversible pump-turbine generators and an intake/outlet structure in the Turners Falls reservoir. The 22-mile-long reservoir on the Connecticut River serves both Northfield Mountain and the Turners Falls Hydroelectric Project, for which FirstLight also holds the license.

Northfield Mountain, Turners Falls and three other hydroelectric facilities directly upstream are all currently undergoing relicensing. As part of that process, the licensees are required to conduct studies for the five facilities to analyze interrelationships in project operations and environmental effects.