The WAC Bennett dam was spilled briefly Sunday evening and overnight into Monday.
BC Hydro spokesman Dave Conway says the spill was done on relatively short notice, and the result of the recent high rainfall and higher than average snowmelt. At full pool, the reservoir is 672.08 metres, and was recorded at 670.08 metres Monday afternoon.
A generator was also taken offline for repairs and there was one less turbine available to handle water volume. Ten units operate at the power station.
"We did a small spill to make up the difference of that turbine not being available," said Conway, "And that ensures that the reservoir levels on the Williston Reservoir and on the Peace River are where they need to be to meet diversion for Site C this fall."
There was no public notice of the spill, which lasted just over 12 hours, starting at 7:25 p.m. and ending at 8 a.m. Roughly 570 cubic metres a second of water was released, and the spill was limited to WAC Bennett Dam.
The Peace Canyon dam and Dinosaur Lake reservoir downstream can handle the increased water volume without spilling. Four turbines operate at the sister site.
Conway says further spills may be needed, but it's unclear when.
"We'll be advising local governments, First Nations, residents, and recreational users about that, and that they can expect higher than normal water levels for this time of year," said Conway.
Email reporter Tom Summer at firstname.lastname@example.org