Lake Rotorua level highest in five years: Stormwater issues and erosion likely

Lake Rotorua has risen 600mm since April. Photo / NZME

Lake Rotorua is experiencing its highest sustained levels since 2017, following heavy rainfall in June and July, according to Bay of Plenty Regional Council data.

Rotorua has had 308.9mm of rainfall so far in July, exceeding the whole-month average of 133.9mm.

The wettest July on record was 345mm of rain in 1998.

The latest data from the regional council shows the lake level has risen 600mm since April, and engineering manager Mark Townsend says don't expect the level to drop quickly.

"There's only so much water that can go out the Ōhau Channel so there's no quick fix", he said.

The water from Lake Rotorua flows out through the Ōhau Channel and stop-logs were removed in early June to allow more water to flow out of the lake.

"Continued rain will result in the high Lake Rotorua levels being sustained for longer and could even rise further."

The high lake level will affect stormwater drainage in the lower reaches of the streams that flow into Lake Rotorua, and there is likely to be increased erosion along lake frontages.

The regional council has been communicating with Rotorua Lakes Council staff regarding stormwater issues in low-lying areas as they are working to keep stormwater outlets clear to prevent flooding.

The level of Lake Rotoiti is controlled via the Okere Gates so this does not affect the levels in Lake Rotorua.

Rainfall levels for July:
Rotorua 308.9mm
Tauranga 269.1mm
Whitianga 397.8mm
Te Puke 403mm
Whakatane 231.4mm