Torrential rains dropped more than 28 centimeters (nearly a foot) of water on the region, flooding more than 5,000 homes.
The water rushed into the area around the hard-hit town of Krimsk with such speed and volume that residents accused local officials of opening a water reservoir in the mountains above.
Federal investigators acknowledged Sunday that water had been released from the reservoir, but they said it did not cause the flooding.
The Interior Ministry said Sunday that 150 bodies had been recovered, 139 of them in Krimsk, a town of 57,000 people.
Many people were asleep when the flooding hit late Friday and early Saturday.