The Canterbury Regional Council is warning campers and holidaymakers to take care around rivers, as Meridian Energy is being forced to release dam water.
The lakes above hydro dams on the Tekapo, Pukaki and Ohau rivers are full and the power company is spilling water from them down the rivers.
One of the council's flood controllers, Malcom Miller, says the amount of rainfall over the last week has not been unusual but the fact of two rainfall events has overwhelmed the lakes' capacity.
The council says rivers are dropping after the heavy rain over the past two days but are still high. Mr Miller says they should be back to normal in about a week.