Levels on the Exploits River in central Newfoundland are still high as the controlled release of water continues to flow from Nalcor's dam further upstream.
The water has been flowing from the Crown corporation's Red Indian Lake dam since Sunday, in an effort to drain pressure off its reservoir.
Wilmore Eddy, who manages the Exploits watershed for Nalcor, said water levels shot up by more than a third over the weekend — the highest he's seen in 25 years.
Eddy said they're trying to lower lake levels after recent heavy rains caused the dam to reach a critical point.
"When that warm rain fell on the snow, this time of year the snow would've been saturated, so its ability to absorb any of that rain would've been virtually zero," he said.
"The water from the melting snow, coupled with the significant rainfall, created an awful lot of water," he said.
Nalcor surveyed the watershed by helicopter on Wednesday.
Eddy said the lake levels are under control, but are not yet back to normal.
"There's still some snow on the high country. With that snow melt occurring, we think that's keeping the inflows going into Red Indian Lake at a higher level, so making it more difficult to get the level down," he said.
Crews were concerned that part of the Exploits near the salmon ladder was approaching its breaking point, but they said for now, the situation is under control.
Eddy said crews will need several more days of dry weather to help drain the watershed.