Lake Rotorua is the highest it has been in five years because of heavy rain in the past two months, and the water levels could lead to stormwater draininage problems and increased erosion.
The waterfront at Lake Rotorua. Photo: 123rf/ pstedrak
The latest data showed the water had risen by 600mm since April, to reach its highest sustained level since 2017.
Bay of Plenty Regional Council said that could cause stormwater issues in low-lying areas and increase lake-front erosion.
The regional council was working with the Rotorua Lakes council to prevent flooding by ensuring stormwater outlets remain clear.
Council engineering manager Mark Townsend said the water levels were not expected to drop quickly.
Water leaves Lake Rotorua through the Ōhau Channel at its north-east.
The council said stop-logs in the channel were removed in early June to allow more water to flow through..
"There's only so much water that can go out the Ōhau Channel, so there's no quick fix", Townsend said.
"Continued rain will result in the high Lake Rotorua levels being sustained for longer and [it] could even rise further."
The areas most likely to experience stormwater draininage problems were places near the lower parts of streams that flow into Lake Rotorua.