High fish numbers prevent restart of Nova Scotia Power hydro turbine
A Nova Scotia Power hydroelectricity turbine, shut down after a fish kill several weeks ago, now can't be restarted because of an unusually large number of fish in the Gaspereau River.
The White Rock plant turbine was shut down last month after dozens of dead gaspereau fish were found downstream from the generating station. Nova Scotia Power said they believed the gaspereau were drawn into the turbine when the utility increased the water flow to accommodate the annual Apple Blossom charity rubber duck race.
The kill is still under investigation by Fisheries and Oceans Canada.
Cameras record more than 1.1 million gaspereau
It's normal for turbine operations to be briefly suspended at this time of year to allow gaspereau fishermen downstream to remove fishing gear, but the restart has been delayed by the abundance of gaspereau in the river.
Cameras mounted on a fish ladder have recorded more than 1.1 million gaspereau during the spring run, according to Fisheries and Oceans Canada.
The department said the number is unusually high, while Nova Scotia Power said it is two to 2.5 times higher than normal.
This month large numbers of gaspereau have been showing up in the head pond, which serves as the intake for the White Rock turbine.
Safety concerns
"We simply didn't feel it would be safe to turn the turbine back on. We wanted to reduce the amount of fish mortality as much as possible," said Tiffany Chase, a spokesperson for Nova Scotia Power.
Nova Scotia Power said the numbers in the White Rock intake pond have been declining in recent days.
Fish diversion tactics
The utility briefly restarted the turbine on Tuesday with federal fisheries officers present. Nova Scotia Power felt confident enough to return to full operations on Wednesday, but had to quickly shut down the turbine after a large school of gaspereau — estimated at 5,000 — was seen in the head pond.
"Therefore, we'll continue to monitor and assess conditions day to day with respect to turbine operations," said Chase.
Nova Scotia Power is required to report any fish kills to the department.
The utility has fish ladders, by-passes, spill ways, grates, a canal and a bubble machine along the system to divert gaspereau, which return to the river every spring to spawn in lakes at the headwaters.
Grid supplied despite idling
The White Rock station is part of a multi-dam hydroelectricity system, known as the Black River system, built on the Gaspereau River in the 1920s by Nova Scotia industrialist R.A. Jodrey. A forerunner of Nova Scotia Power purchased the dams and hydrogenerators in the 1940s.
Despite the idling of the White Rock hydro station, Nova Scotia Power said it has still been able to supply the grid with the amount of renewable electricity required by the provincial Environment Department.
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