Energy supplier Meridian says it has received reports of watercraft approaching the spillway at the dam.
"The lakes throughout the Mackenzie Country and Waitaki basin offer incredible recreational opportunities, but people need to take care while water is being released from the hydro dams, especially through the spillways.
"The last thing we want to see is someone get hurt or worse," Meridian generation general manager Tania Palmer told the Oamaru Mail.
"We know releases like this don’t happen often, so we’re asking people to enjoy the experience, but they need to stay well away [at least 200m] from the spillways while they do so.
"The volume and force of water represent a significant hazard."
All the lake levels are dropping, with flows at Pūkaki gate 19 at 418 cumecs, Benmore 300 cumecs, Aviemore 211 cumecs and Waitaki 129 cumecs.
However, flows are subject to change.
Meridian has been releasing water from Lake Pukaki since December 3, and last week also started releasing water from the Benmore, Aviemore and Waitaki hydro dams.
Environment Canterbury coast and harbours manager Guy Harris is "very concerned" about the behaviour reported near the Benmore Dam spillway.
"Getting that close to a spillway is extremely dangerous, the currents are powerful, unpredictable, and can change quickly without warning," he said.
"If individuals were identified engaging in unsafe behaviour, enforcement action could be considered, but ultimately this comes down to people exercising good judgement and respecting the hazards around dam structures.
"Dam intakes can create strong currents and whirlpools, and when spillways open, large volumes of water move downstream at speed.
"These powerful currents significantly increase the risk of vessels capsizing or taking on water, so keeping your distance is essential.
"It’s important people check the safety signage at boat ramps and always respect buoys and navigation markers — they’re there for your protection. We also ask people to stay at least 200m away from power station structures at all times.
"We encourage anyone using lakes and rivers across the Mackenzie and Upper Waitaki to stay vigilant and follow all guidance."
