"Due to ongoing rainfall, Lake Pūkaki remains extremely full and we’ve increased the amount of water we’re releasing from the Pūkaki spillway into the Pūkaki River," a Meridian statement said.
"Please do not enter the river under any circumstances and remember to obey all warning signs as currents and river flows will be unpredictable.
"The release from Pūkaki is expected to be around 500cumecs for this current week. Spill has also commenced at Lake Ōhau weir at around 23cumecs."
Meridian began releasing water from Benmore, Aviemore and Waitaki stations on Tuesday morning.
Generation general manager Tania Palmer said it had been releasing water from Lake Pūkaki since December 3, "as required by our consents when the lake reaches its maximum consented level".
The situation was being monitored.
"It’s important people are aware of the risks and take proper caution," she said.
